U.S. patent application number 15/087062 was filed with the patent office on 2017-10-05 for reducing power dissipation in driver circuits.
The applicant listed for this patent is Infineon Technologies AG. Invention is credited to Fabrizio Cortigiani, Maurizio Galvano, Andrea Logiudice, Marco Pamato.
Application Number | 20170290112 15/087062 |
Document ID | / |
Family ID | 59885742 |
Filed Date | 2017-10-05 |
United States Patent
Application |
20170290112 |
Kind Code |
A1 |
Cortigiani; Fabrizio ; et
al. |
October 5, 2017 |
REDUCING POWER DISSIPATION IN DRIVER CIRCUITS
Abstract
In one example, a method includes generating, by a current
source of a device, a first portion of a power signal that drives
one or more load elements. In this example, a second portion of the
power signal is generated by one or more components that are
external to the device and are in parallel to the current source
such that the second portion of the power signal does not flow
through the current source.
Inventors: |
Cortigiani; Fabrizio;
(Padova, IT) ; Logiudice; Andrea; (Padova, IT)
; Galvano; Maurizio; (Padova, IT) ; Pamato;
Marco; (Schio, IT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Infineon Technologies AG |
Neubiberg |
|
DE |
|
|
Family ID: |
59885742 |
Appl. No.: |
15/087062 |
Filed: |
March 31, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
Y02B 20/30 20130101;
Y02B 20/345 20130101; H05B 45/37 20200101; H02M 1/08 20130101; H05B
45/395 20200101; G05F 1/56 20130101; H02M 3/156 20130101; Y02B
20/343 20130101 |
International
Class: |
H05B 33/08 20060101
H05B033/08; H02M 1/08 20060101 H02M001/08; H02M 3/156 20060101
H02M003/156 |
Claims
1. A method comprising: generating, by a current source of a
device, a first portion of a power signal that drives one or more
load elements, wherein a second portion of the power signal is
generated by one or more components that are external to the device
and are in parallel to the current source such that the second
portion of the power signal does not flow through the current
source that generated the first portion of the power signal and the
first portion of the power signal does not flow through the one or
more components that generated the second portion of the power
signal.
2. The method of claim 1, further comprising: adjusting, by the
device and based on a current level of the second portion of the
power signal, a current level of the first portion of the power
signal to maintain a total current level of the power signal.
3. The method of claim 1, further comprising: preventing, based on
a control signal received from an external device, the current
source from generating the first portion of the power signal and
the one or more components from generating the second portion of
the power signal.
4. The method of claim 3, wherein preventing the one or more
components from generating the second portion of the power signal
comprises: opening a switch positioned in series with the one or
more components.
5. The method of claim 3, wherein the one or more components are
not active current sources.
6. The method of claim 1, wherein the one or more components
comprise one or more resistors.
7. The method of claim 1, wherein the one or more load elements
comprise one or more light emitting diodes (LEDs).
8. A driver device comprising: a current source configured to
generate a first portion of a power signal that drives one or more
load elements, wherein a second portion of the power signal is
generated by one or more components that are external to the device
and are in parallel to the current source such that the second
portion of the power signal does not flow through the current
source that generated the first portion of the power signal and the
first portion of the power signal does not flow through the one or
more components that generated the second portion of the power
signal.
9. The driver device of claim 8, further comprising: a loop
controller configured to adjust, based on a current level of the
second portion of the power signal, a current level of the first
portion of the power signal to maintain a total current level of
the power signal.
10. The driver device of claim 8, wherein, based on a control
signal received from an external device, the loop controller is
configured to prevent the current source from generating the first
portion of the power signal and prevent the one or more components
from generating the second portion of the power signal.
11. The driver device of claim 10, wherein, to prevent the one or
more components from generating the second portion of the power
signal, the loop controller is configured to: open a switch
positioned in series with the one or more components.
12. The driver device of claim 10, wherein the one or more
components are not active current sources.
13. The driver device of claim 8, wherein the one or more
components comprise one or more resistors.
14. The driver device of claim 8, wherein the one or more load
elements comprise one or more light emitting diodes (LEDs).
15. A driver device comprising: means for generating a first
portion of a power signal that drives one or more load elements,
wherein a second portion of the power signal is generated by one or
more components that are external to the device and are in parallel
to the means for generating the first portion of the power signal
such that the second portion of the power signal does not flow
through the means for generating the first portion of the power
signal and the first portion of the power signal does not flow
through the one or more components that generated the second
portion of the power signal; and means for outputting the first
portion of the power signal.
16. The driver device of claim 15, further comprising: means for
adjusting, based on a current level of the second portion of the
power signal, a current level of the first portion of the power
signal to maintain a total current level of the power signal.
17. The driver device of claim 16, further comprising: means for
combining the first portion and the second portion to generate the
power signal, wherein the means for outputting comprise means for
outputting the power signal.
18. The driver device of claim 15, further comprising: means for
preventing, based on a control signal received from an external
device, the means for generating from generating the first portion
of the power signal and the one or more components from generating
the second portion of the power signal.
19. The method of claim 1, further comprising: receiving, by the
device and from the one or more components, the second portion of
the power signal; combining, by the device, the second portion of
the power signal with the first portion of the power signal,
wherein a total current level of the power signal is a combination
of a current level of the first portion of the power signal and a
current level of the second portion of the power signal.
Description
TECHNICAL FIELD
[0001] This disclosure relates to reducing the amount of power
dissipated in driver circuits, and in particular, to using one or
more low-cost components to reduce the amount of power dissipated
in driver circuits.
BACKGROUND
[0002] Driver circuits may be used to control the amount of power
provided to loads from power sources. In operation, a driver
circuit may dissipate an amount of power that is proportional to
the voltage across the driver circuit and the current flowing
through the driver circuit. In some examples, such power
dissipation may cause a driver circuit to overheat, which may
negatively impact the functionality of the driver circuit. As such,
in some examples, it may be desirable to reduce the amount of power
dissipated by driver circuits.
SUMMARY
[0003] In general, this disclosure is directed to reducing the
amount of power dissipated in driver circuits. For example, a
system may include one or more external components in parallel with
a current source of a driver device to reduce amount of power
dissipated in the driver device.
[0004] As one example, a method includes generating, by a current
source of a device, a first portion of a power signal that drives
one or more load elements, wherein a second portion of the power
signal is generated by one or more components that are external to
the device and are in parallel to the current source such that the
second portion of the power signal does not flow through the
current source.
[0005] As another example, a driver device includes a current
source configured to generate a first portion of a power signal
that drives one or more load elements, wherein a second portion of
the power signal is generated by one or more components that are
external to the device and are in parallel to the current source
such that the second portion of the power signal does not flow
through the current source.
[0006] As another example, a driver device includes means for
generating a first portion of a power signal that drives one or
more load elements, wherein a second portion of the power signal is
generated by one or more components that are external to the device
and are in parallel to the current source such that the second
portion of the power signal does not flow through the current
source; and means for outputting the first portion of the power
signal.
[0007] The details of one or more examples of the disclosure are
set forth in the accompanying drawings and the description below.
Other features, objects, and advantages will be apparent from the
description and drawings, and from the claims.
BRIEF DESCRIPTION OF DRAWINGS
[0008] FIGS. 1A-1D are a conceptual diagrams illustrating example
systems that each include a driver device configured to drive a
load with a power signal, in accordance with one or more exemplary
techniques of this disclosure.
[0009] FIG. 2 is a conceptual diagram illustrating an example
system that includes a plurality of driver devices configured to
collectively drive a load with a power signal, in accordance with
one or more exemplary techniques of this disclosure.
[0010] FIG. 3 is a conceptual diagram illustrating an example
system that includes a driver device and one or more passive
elements configured to collectively drive a load with a power
signal, in accordance with one or more exemplary techniques of this
disclosure.
[0011] FIG. 4 is a conceptual diagram illustrating an example
system that includes a driver device and one or more passive
elements configured to collectively drive a load with a power
signal, in accordance with one or more exemplary techniques of this
disclosure.
[0012] FIG. 5 is a conceptual diagram illustrating an example
system that includes a driver device and one or more passive
elements configured to collectively drive a load with a power
signal, in accordance with one or more exemplary techniques of this
disclosure.
[0013] FIG. 6 is a conceptual diagram illustrating an example
system that includes a driver device and one or more passive
elements configured to collectively drive a load with a power
signal, in accordance with one or more exemplary techniques of this
disclosure.
[0014] FIG. 7 is a graph illustrating example current levels in a
system that includes a driver device and one or more passive
elements configured to collectively drive a load with a power
signal, in accordance with one or more exemplary techniques of this
disclosure.
[0015] FIG. 8 is a conceptual diagram illustrating an example
system that includes a multi-channel driver device and a plurality
of passive elements configured to collectively drive a plurality of
loads with a plurality of power signals, in accordance with one or
more exemplary techniques of this disclosure.
[0016] FIG. 9 is a schematic diagram illustrating an example load 6
that may be driven using a power signal generated by a driver
device and one or more passive elements in parallel with the driver
device, in accordance with one or more techniques of this
disclosure.
[0017] FIG. 10 is a flow diagram illustrating an example technique
reducing the power dissipation of a driver device, in accordance
with one or more techniques of this disclosure.
DETAILED ABSTRACT OF THE INVENTION
[0018] In general, this disclosure is directed to reducing the
amount of power dissipated in driver circuits. As discussed above,
driver circuits may control the amount of power provided to loads
from power sources. In some examples, the power source may be a
variable power source, such as a battery with an operating voltage
range of 8 volts (V) to 18V As the power dissipated by a driver
circuit increases in proportion to the voltage across the driver
circuit and excess power dissipation may negatively impact the
functionality of the driver circuit, it may be desirable for the
driver circuit to be able to dissipate the "worst case" amount of
power without negatively impacting the functionality of the driver
circuit. In some examples, the functionality of the driver circuit
may be negatively impacted if the power dissipated by the driver
circuit causes a temperature of the driver circuit (e.g., a
junction temperature) to exceed a threshold (e.g., 50.degree. C.,
100.degree. C., 150.degree. C., 200.degree. C.).
[0019] In some examples, the amount of power dissipated in a driver
circuit may be reduced through the use of a ballast regulator in
which power is distributed in a series element and regulated via a
loop. In some examples, the stability of the regulation loop in
such a circuit may have the same characteristics and drawbacks as a
low-drop out voltage regulator. In some examples, external
transistors may also be used in the regulation loop.
[0020] In other examples, the amount of power dissipated in a
driver circuit may be reduced through the use of a DC/DC regulator.
For instance, an external DC/DC regulator, which may be
electrically positioned between the variable power source and the
driver circuit, may generate a continuous supply voltage from the
variable power source and the driver circuit may use the generated
continuous supply voltage to provide power to a load. In operation,
the DC/DC regulator may reduce the amount of power dissipated in a
driver circuit by preventing the supply voltage from reaching the
"worst case" level.
[0021] In other examples, the amount of power dissipated in a
driver circuit may be reduced through the use of one or more
passive components in series with the load. For instance, one or
more resistors and/or one or more diodes may be placed in series
with the load. In operation, the one or more passive components may
reduce the amount of power dissipated. in a driver circuit by
reducing the voltage drop across the driver circuit.
[0022] In other examples, the amount of power dissipated in a
driver circuit may be reduced through the use of one or more
additional driver circuits in parallel with the driver circuit. In
operation, the use of one or more additional driver circuits in
parallel with the driver circuit may reduce the amount of power
dissipated in a driver circuit by reducing the current level
flowing through the driver circuit in proportion to the number of
additional driver circuits used. For example, if one additional
driver circuit is used, the amount of power dissipated in the
driver circuit may be reduced by half.
[0023] In some examples, the above techniques for reducing power
dissipation may present one or more disadvantages. As one example,
the above techniques may be not be cost effective in that
additional active components may be needed to handle "worst case"
power distribution which may result in a cost adder that may be
proportional to the extra power needed. As another example, the
above techniques may require extra design effort in that more
design work may be needed, especially for the ballast solutions, to
consider topics such as stability and performance at low battery
level which may depend from load characteristics (e.g. total output
current, harness on the output network, etc.
[0024] In accordance with one or more techniques of this
disclosure, one or more external components may be placed in
parallel with a driver device to reduce amount of power dissipated
in the driver device. As one example, one or more resistors and one
or more switches may be placed in parallel with a current source of
a driver device. In operation, a current source of the driver
device may generate a first portion of a power signal with a first
current level and the one or more external components may generate
a second portion of the power signal with a second current level.
The first portion of the power signal and the second portion of the
power signal may be combined to form the power signal (which may
have a current level equal to the first current level and the
second current level) that is used to drive one or more load
elements. By placing the one or more external components in
parallel with the current source of the driver device, the amount
of current flowing through the driver device may be reduced without
reducing the amount of current provided to the one or more load
elements. As discussed above, the amount of power dissipated by a
driver device is proportional to the amount of current flowing
through the driver device. Therefore, by placing the one or more
external components in parallel with the current source of the
driver device, the amount of power dissipated by the driver may be
reduced without reducing the amount of current provided to the one
or more load elements.
[0025] As discussed above, in some examples, the power source that
supplies the driver circuit may be a variable power source, such as
a battery with an operating voltage range of 8V to 18V. In some
examples, the current level of the second portion of the power
signal generated by the one or more external components may be
proportional to the voltage of the power source. For instance, the
current level of the second portion of the power signal generated
by the one or more external components may increase as the voltage
of the power source increases. However, in some examples, it may be
desirable for the current level of the overall power signal (the
combined first portion and second portion) to be independent of the
voltage of the power source.
[0026] In accordance with one or more techniques of this
disclosure, a driver device placed in parallel with one or more
external components configured to reduce amount of power dissipated
in the driver device may be configured to adjust the current level
of the first portion of the power signal such that the current
level of the overall power signal is independent of the voltage of
the power source. For instance, the driver device may adjust the
amount of current provided by a current source included in the
driver device based on the current level of the second portion of
the power signal that is generated by the one or more external
components
[0027] In some examples, it may be desirable to selectively
activate/deactivate the load driven by the power signal. For
instance, where the load includes one or more light emitting diodes
(LEDs), it may be desirable to turn the LEDs on and off. As one
example, the load driven by the power signal may be
activated/deactivated by activating/deactivating the power source
that supplies the driver device. As another example, the load
driven by the power signal may be activated/deactivated by
decoupling the power source that supplies the driver device from
the driver device. However, in some examples, it may be desirable
to selectively activate/deactivate the load driven by the power
signal without deactivating the driver device.
[0028] In accordance with one or more techniques of this
disclosure, a driver device may be configured to selectively
activate/deactivate the load driven by the power signal while still
receiving power from a power source. For instance, a driver device
may selectively cause a current source of the driver device to
cease generating the first portion of the power signal and cause
the one or more components to cease generating the second portion
of the power signal. In some examples, a driver device may be
configured to selectively activate/deactivate the load driven by
the power signal based on a control signal received from an
external device, such as a microcontroller.
[0029] FIGS. 1A-1D are a conceptual diagrams illustrating example
systems that each include a driver device configured to drive a
load with a power signal, in accordance with one or more exemplary
techniques of this disclosure. As illustrated in FIGS. 1A-1D, each
of systems 1A-1D includes a driver device 3 configured to drive a
load 6 with a power signal.
[0030] In some examples, systems 1A-1D may include a load 6, which
may be configured to receive power from driver device 3. In sonic
examples, load 6 may include one or more light emitting devices
(e.g., one or more light bulbs, one or more light emitting diodes
(LEDs), one or more laser diodes, and the like), one or more
batteries, one or more computing devices, one or more resistive
devices, one or more capacitive devices, one or more inductive
devices, any other device that uses electrical power, or any
combination of the same. In one specific example, load 6 may
include one or more LEDs located on an automobile (e.g.,
headlights, fowlights, tail-lights, reverse lights, brake lights,
turn signals, and the like). As illustrated in FIGS. 1A-1D, load 6
may be connected such that driver device 3 may be a high-side
driver with respect to load 6.
[0031] In some examples, systems 1A-1D may include a driver device
3, which may be configured to control the amount of power provided
to loads from power sources. For instance, driver device 3 may
control the amount of power provided to load 6 from a power source
that supplies power signal V. In some examples, the power source
may be a variable power source, such as a battery that supplies
power signal V.sub.s in a voltage range of 8V to 18V As the power
dissipated by driver device 3 increases in proportion to the
voltage across driver device 3 and excess power dissipation may
negatively impact the functionality of driver device 3, it may be
desirable for driver device 3 to be able to dissipate the "worst
case" amount of power without negatively impacting the
functionality of driver device 3. In the example of FIG. 1A, the
power dissipated by driver 3 may be determined in accordance with
Equation (1), below
P=(V.sub.s-V.sub.Load)*I (1)
[0032] As discussed above, it may be desirable to reduce the amount
of power dissipated in driver circuits, such as driver device 3
(e.g., to reduce the amount of power dissipated by the driver
circuit in the "worst case"). In accordance with one or more
techniques of this disclosure and as shown in FIGS. 1B-1D, the
amount of power dissipated in driver device 3 may be reduced
through the use of one or more passive components in series with
load 6. In the example of FIG. 1B, the amount of power dissipated
in driver device 3 may be reduced through the use of resistor 8 in
series with load 6. The power dissipated by driver 3 in the example
of FIG. 1B may be determined in accordance with Equation (2),
below.
P=(V.sub.s-R*I-V.sub.Load)*I (2)
[0033] In the example of FIG. 1C, the amount of power dissipated in
driver device 3 may be reduced through the use of diodes 10A and
10B in series with load 6. The power dissipated by driver 3 in the
example of FIG. 1C may be determined in accordance with Equation
(3), below.
P=(V.sub.s-2*V.sub.DiodeV.sub.load)*I (3)
[0034] In the example of FIG. 1D, the amount of power dissipated in
driver device 3 may be reduced through the use of zener diode 12 in
series with load 6. The power dissipated by driver 3 in the example
of FIG. 1D may be determined in accordance with Equation (4),
below.
P=(V.sub.s-V.sub.Zener-V.sub.Load)*I (4)
[0035] As can be seen from Equations (1)(4), the amount of power
dissipated in driver device 3 may be reduced through the use of one
or more passive components in series with load 6. However, in some
examples, it may not be desirable to use one or more passive
components in series with load 6 to reduce the amount of power
dissipated in driver device 3.
[0036] FIG. 2 is a conceptual diagram illustrating an example
system that includes a plurality of driver devices configured to
collectively drive a load with a power signal, in accordance with
one or more exemplary techniques of this disclosure. As illustrated
in FIG. 2, system 1E includes a driver device 3 and additional
driver devices 5A-5N (collectively, "additional driver devices 5")
that are configured to collectively drive a load 6 with a power
signal.
[0037] In some examples, system 1E may include additional driver
devices 5, which may be configured to perform operations similar to
driver device 3. For instance, additional driver devices 5 may be
configured to control the amount of power provided to load 6 from a
power source that supplies power signal V.sub.s.
[0038] As discussed above, it may be desirable to reduce the amount
of power dissipated in driver circuits, such as driver device 3
(e.g., to reduce the amount of power dissipated by the driver
circuit in the "worst case"). In accordance with one or more
techniques of this disclosure, the amount of power dissipated in
driver device 3 may be reduced through the use of one or more
additional driver devices 5 in parallel with driver device 3. For
instance, in the example of FIG. 2, the amount of power dissipated
in driver device 3 may reduced in proportion to the number of
driver devices included in additional driver devices 5. As one
example, if additional driver devices 5 includes three driver
devices, the amount of power dissipated in the driver circuit may
be reduced by one-quarter (25%).
[0039] However, in sonic examples, it may not be desirable to use
additional driver devices 5 in parallel with driver device 3 to
reduce the amount of power dissipated in driver device 3. As one
example, the use of additional driver devices 5 may increase a cost
of system 1E. As another example, the use of additional driver
devices 5 may require extra design effort.
[0040] FIG. 3 is a conceptual diagram illustrating an example
system that includes a driver device and one or more passive
elements configured to collectively drive a load with a power
signal, in accordance with one or more exemplary techniques of this
disclosure. As illustrated in FIG. 3, system 2A may include driver
device 4A, load 6, and one or more passive elements 16.
[0041] In some examples, system 2A may include driver device 4A,
which may be configured to control and amount of power provided to
a load. For instance, driver device 4A may be configured to
generate a portion of a power signal that drives load 6. As shown
in FIG. 3, driver 4A may include current source 18, loop controller
20, shunt 22, and connectors 24A-24C (collectively, "connectors
24"). In some examples, such as the example of FIG. 3, driver
device 4A may be a high-side driver with respect to load 6. In some
examples, such as the example of FIG. 4, driver device 4A may be a
low-side driver with respect to load 6.
[0042] In some examples, driver device 4A may include current
source 18, which may be configured to generate a power signal. For
instance, current source 18 may generate a power signal with
current level I.sub.CS, which may be a portion of the power signal
that drives load 6. In some examples, the current level of the
power signal generated by current source 18 may be set by one or
more other components, such as loop controller 20. In some
examples, current source 18 may be a linear current source.
[0043] As discussed above, while it may be generally desirable to
reduce the power dissipated by driver devices, it may not be
desirable to achieve the reduction in power dissipation through the
use of additional driver devices in parallel or the use of passive
components in series with the driver devices. In accordance with
one or more techniques of this disclosure, system 2A may include,
one or more passive elements 16 that are positioned in parallel to
driver device 4A and may be configured to generate a portion of a
power signal that drives load 6. For instance, current source 18
may generate a first portion of a power signal that drives load 6
with a first current level (i.e., I.sub.CS) and one or more passive
elements 16 may generate a second portion of the power signal that
drives load 6 with a second current level (i.e., I.sub.Pass). The
first portion of the power signal and the second portion of the
power signal may be combined to create a total power signal that
drives load 6 and has a current level (i.e., I.sub.Total) that is a
sum of the first current level and the second current level. As all
of the current of the power signal is not flowing through current
source 18 (e.g., because a portion of the current of the power
signal is flowing through passive elements 16 in parallel to
current source 18), the amount of power dissipated by current
source 18 may be reduced.
[0044] In some examples, passive elements 16 may include one or
more resistors and the current level of the portion of the power
signal generated by passive elements 16 may be determined in
accordance with Equation (5), where I.sub.Pass is the current level
of the portion of the power signal generated by passive elements
16, V.sub.Pass is the voltage across passive elements 16, and
R.sub.Pass is the resistance of passive elements 16.
I Pass = V Pass R Pass ( 5 ) ##EQU00001##
[0045] As discussed above, in some examples, the power source that
supplies driver device 4A may be a variable power source, such as a
battery with an operating voltage range of 8V to 18V In some
examples, the current level of the second portion of the power
signal generated by passive elements 16 may be proportional to the
voltage of the power source (i.e., V.sub.s). For instance, the
current level of the second portion of the power signal generated
by passive elements 16 may increase as the voltage of the power
source increases. However, in some examples, it may be desirable
for the current level of the overall power signal (i.e.,
I.sub.Pass) to be independent of the voltage of the power
source.
[0046] In accordance with one or more techniques of this
disclosure, in some examples, driver device 4A may include loop
controller 20, which may be configured to adjust a current level of
the power signal generated by current source 18. In some examples,
loop controller 20 may adjust the current level of the power signal
generated by current source 18 based on a current level of the
power signal generated by passive elements 16. For instance, loop
controller 20 may adjust the current level of the power signal
generated by current source 18 (i.e., I.sub.CS) based on a current
level of the power signal generated by passive elements 16 (i.e.,
I.sub.Pass) such that a total current level of the power signal
that drives load 6 (i.e., I.sub.Total) is maintained at a
particular current level. In this way, loop controller 20 may
enable the current level of the overall power signal (i.e.,
I.sub.Total) to be independent of the voltage of the power
source.
[0047] As discussed above, it may be desirable to selectively
activate/deactivate a load, such as load 6, being driven by a
driver device, such as driver 4A or 4B without deactivating the
driver device (e.g., without disconnecting or decoupling the driver
device from a power source). In some examples, loop controller 20
may selectively activate/deactivate current source 18 in order to
activate/deactivate load 6. However, in some examples, simply
activating/deactivating current source 18 may be insufficient to
activate/deactivate load 6. For instance, in the example of FIG. 3
where a portion of the power signal that drives load 6 is generated
by passive elements 16, simply activating/deactivating current
source 18 may be insufficient to activate/deactivate load 6 because
load 6 may still receive power from passive elements 16 even where
current source 18 is deactivated.
[0048] In accordance with one or more techniques of this
disclosure, driver device 4B may be configured to selectively
activate/deactivate load 6 by both selectively preventing current
source 18 from generating the first portion of the power signal and
selectively preventing passive elements 16 from generating the
second portion of the power signal. In some examples, driver device
4B may selectively prevent passive elements 16 from generating the
second portion of the power signal by opening/closing a switch
positioned in series with passive elements 16. As such, in some
examples, driver device 4B may include a control terminal via which
driver device 4B may output a signal to selectively prevent passive
elements 16 from generating the second portion of the power signal.
Further details of some example driver devices that may selectively
prevent passive elements from generating the second portion of the
power signal are discussed below with reference to FIGS. 5 and
6.
[0049] FIG. 5 is a conceptual diagram illustrating an example
system 4C that includes a driver device and one or more passive
elements configured to collectively drive a load with a power
signal, in accordance with one or more exemplary techniques of this
disclosure. As illustrated in FIG. 5, system 2C may include driver
device 4C, load 6, switch 28, and one or more passive elements
16.
[0050] In some examples, system 2C may include driver device 4C,
which may be configured to perform operations similar to driver
device 4A of FIG. 3. For instance, driver device 4C may be
configured to generate a portion of a power signal that drives load
6.
[0051] In accordance with one or more techniques of this
disclosure, driver device 4C may be configured to selectively
activate/deactivate load 6 by both selectively preventing current
source 18 from generating the first portion of the power signal and
selectively preventing passive elements 16 from generating the
second portion of the power signal. In some examples, driver device
4C may selectively prevent passive elements 16 from generating the
second portion of the power signal by opening/closing a switch
positioned in series with passive elements 16, such as switch 28.
As illustrated in FIG. 5, switch 28 may include a PMOS switch.
[0052] In one example operation, switch 28 may be closed, driver 4C
may generate a first portion of a power signal used to drive load 6
and passive elements 16 may generate a second portion of the power
signal. Driver 4C may receive a control signal from an external
device, such as a microcontroller, that causes driver 4C to
deactivate load 6. In response to the control signal, loop
controller 20 may prevent current source 18 from generating the
first portion of the power signal and switch 30 may open. The
opening of switch 30 may cause switch 28 to cease allowing current
to flow through passive elements 16. In this way, driver device 4C
may be configured to selectively activate/deactivate load 6 without
being disconnected or decoupled from V.sub.s.
[0053] FIG. 6 is a conceptual diagram illustrating an example
system 4D that includes a driver device and one or more passive
elements configured to collectively drive a load with a power
signal, in accordance with one or more exemplary techniques of this
disclosure. As illustrated in FIG. 6, system 2D may include driver
device 4D, load 6, switch 28, and one or more passive elements 16.
However, as opposed to the example of FIG. 5 where switch 28 is
illustrated as a PMOS switch, FIG. 6 illustrates an example where
switch 28 includes an NMOS switch. In some examples, the use of an
NMOS switch may be desirable over a PMOS switch. For instance, NMOS
switches may be cheaper than PMOS switches.
[0054] In some examples, system 2D may include driver device 4D,
which may be configured to perform operations similar to driver
device 4C of FIG. 4. For instance, driver device 4D may be
configured to selectively activate/deactivate load 6 by both
selectively preventing current source 18 from generating the first
portion of the power signal and selectively preventing passive
elements 16 from generating the second portion of the power signal.
However, as opposed to driver device 4C which is configured to
operate switch 28 as a PMOS switch, driver device 4D is configured
to operate switch 28 as an NMOS switch.
[0055] Referring to both FIGS. 5 and 6, the resistances the
resistors included in passive elements 16 may be selected to
minimize the power dissipated by switch 28. Specifically, if the
resistances the resistors included in passive elements 16 are
properly dimensioned, the power dissipated by switch 28 may be
negligible in nearly all conditions (i.e., operative), especially
if the conductance of switch 28 (gm) is high at low gate-source
voltage (V.sub.gs) levels. As such, in some examples, switch 28 may
comprise a relatively high-ohmic MOS in a small non-exposed
package. For instance, in examples where load 6 includes LEDs used
on the rear of an automobile, switch 28 may comprise a relatively
high-ohmic MOS in a small non-exposed package while still complying
with a typical power budget for the rear light LED arena.
[0056] FIG. 7 is a graph 700 illustrating example current levels in
a system that includes a driver device and one or more passive
elements configured to collectively drive a load with a power
signal, in accordance with one or more exemplary techniques of this
disclosure. As illustrated in FIG. 7, graph 700 includes a
horizontal x-axis indicating a voltage level, a vertical y-axis
indicating a current level, first plot 702 representing a first
voltage/current relationship, second plot 704 representing a second
voltage/current relationship, and third plot 706 representing a
third voltage/current relationship. In some examples, first plot
702 may represent the voltage/current relationship for the first
portion of the power signal generated by current source 18 of
driver device 4 of system 2 of FIGS. 3-6 (i.e., I.sub.CS), second
plot 704 may represent the voltage/current relationship for the
second portion of the power signal generated by passive elements 16
of system 2 of FIGS. 3-6 (i.e., I.sub.Pass), and third plot 706 may
represent the voltage/current relationship for the total power
signal used to drive load 6 of system 2 of FIGS. 3-6 (i.e.,
I.sub.Total).
[0057] As discussed above, it may be desirable for the current
level of the overall power signal (i.e., I.sub.Total) to be
independent of the voltage of the power source. In accordance with
one or more techniques of this disclosure, loop controller 20 of
driver device 4 may adjust a current level of the power signal
generated by current source 18 (i.e., I.sub.CS) based on a current
level of the power signal generated by passive elements 16 (i.e.,
I.sub.CS) such that a total current level of the power signal that
drives load 6 (i.e., I.sub.Total) is maintained at a particular
current level. As shown by graph 700, as the current level of the
power signal generated by passive elements 16 (i.e., I.sub.Pass)
changes, loop controller 20 may adjust the current level of the
power signal generated by current source 18 (i.e., I.sub.CS) such
that the total current level of the power signal that drives load 6
(i.e., I.sub.Total) is maintained at a particular current
level.
[0058] In some examples, loop controller 20 may perform the
adjustment such that the total current level of the power signal
that drives load 6 (i.e., I.sub.Total) is maintained at a
particular current level within a particular voltage range. For
instance, where load 6 comprises one or more LEDs that have a
forward activation voltage level (i.e., V.sub.fLED) 708 and a
voltage level of the power source of driver device 4 (i.e.,
V.sub.s) is voltage level 710, loop controller 20 may perform the
adjustment such that the total current level of the power signal
that drives load 6 (i.e., I.sub.Total) is maintained between
voltage level 708 and voltage level 710. In this way, loop
controller 20 may enable the current level of the overall power
signal (i.e., I.sub.Total) to be independent of the voltage of the
power source across the entire operational range of load 6.
[0059] FIG. 8 is a conceptual diagram illustrating an example
system 2E that includes a multi-channel driver device and a
plurality of passive elements configured to collectively drive a
plurality of loads with a plurality of power signals, in accordance
with one or more exemplary techniques of this disclosure. As
illustrated in FIG-. 8, system 2E may include driver device 4E, one
or more loads 6A-6N (collectively, "loads 6"), and one or more sets
of passive elements 16A-16N (collectively, "passive element sets
16").
[0060] In some examples, system 2E may include driver device 4E,
which may be configured to perform operations similar to driver
device 4A of FIG. 3, driver device 4B of FIG. 4, driver device 4C
of FIG. 5, and/or driver device 4D of FIG. 6. For instance, driver
device 4E may be configured to generate a portion of a power signal
that drives a load. However, as shown in FIG. 8, driver device 4E
may be a multi-channel driver device which may simultaneously
generate respective portions of respective power signals that each
drive a respective load of loads 6. For instance, each of current
sources 18A-18N (collectively "current sources 18") may generate a
respective first portion of a respective power signal that drives a
respective load of loads 6. Similarly, each of passive element sets
16 may generate a respective second portion of a respective power
signal that drives a respective load of loads 6. As one example,
current source 18A may generate a first portion of a power signal
with current level I.sub.CS.sub._.sub.A, passive elements 16A may
generate a second portion of the power signal with current level
I.sub.PASS.sub._.sub.A, and the first and second portions of the
power signal may be combined to generate a total power signal with
current level I.sub.Total.sub._.sub.A that drives load 6A. As
another example, current source 18B may generate a first portion of
a power signal with current level I.sub.CS.sub._.sub.B, passive
elements 16B may generate a second portion of the power signal with
current level I.sub.PASS.sub._.sub.B, and the first and second
portions of the power signal may be combined to generate a total
power signal with current level I.sub.Total.sub._.sub.B that drives
load 6B.
[0061] In accordance with one or more techniques of this
disclosure, driver device 4E may be configured to selectively
activate/deactivate loads 6 by both selectively preventing current
sources 18 from generating respective first portions of the power
signals and selectively preventing respective passive elements of
passive elements 16A-6N from generating respective second portions
of the power signals.
[0062] FIG. 9 is a schematic diagram illustrating an example load 6
that may be driven using a power signal generated by a driver
device and one or more passive elements in parallel with the driver
device, in accordance with one or more techniques of this
disclosure. As discussed above, load 6 may include one or more LEDs
located on an automobile (e.g., headlights, fowlights, tail-lights,
reverse lights, brake lights, turn signals, and the like). In some
examples, it may be desirable to drive a more than one LED with a
single driver device. For instance, as shown in the example of FIG.
8, load 6 may include an array of LEDs. In examples where load 6
includes a plurality of LEDs (in an array, in series, in parallel),
the current requirements of load 6 may increase as compared to
examples where load 6 includes a single LED. As the current
requirements of load 6 increase, the power dissipated by the driver
device, such as driver device 4, may correspondingly increase. As
discussed above and in accordance with one or more techniques of
this disclosure, the power dissipation of a current source of a
driver device may be reduced through the use of one or more passive
elements in parallel with the current source that generate a
portion of the power signal used to drive the load.
[0063] FIG. 10 is a flow diagram illustrating an example technique
reducing the power dissipation of a driver device, in accordance
with one or more techniques of this disclosure. For purposes of
illustration only, the example operations are described below
within the context of driver device 4, as shown in FIGS. 3-6,
though driver devices other than driver device 4 may perform the
techniques of FIG. 10.
[0064] In accordance with one or more techniques of this
disclosure, driver device 4 may generate a first portion of a power
signal (1002). For instance, current source 18 of driver device 4
may generate a portion of a power signal that drives load 6. In
some examples, the current level of the portion of the power signal
that is generated by current source 18 may be denoted as
I.sub.CS.
[0065] Driver device 4 may determine a current level of a second
portion of the power signal that is generated by one or more
passive components (1004). For instance, loop controller 2.0 of
driver device 4 may determine a current level of a portion of the
power signal that is generated by passive elements 16 of FIGS. 3-6.
In some examples, loop controller 2.0 may determine the current
level of the portion of the power signal that is generated by
passive elements 16 based on a voltage across a sense resistor,
such as shunt 22. In some examples, the sense resistor may be
included within driver device 4. In some example, the sense
resistor may be external to driver device 4. In some examples, the
current level of the portion of the power signal that is generated
by passive components 16 may be denoted as I.sub.Pass.
[0066] Driver device 4 may adjust a current level of the first
portion of the power signal based on the current level of the
second portion of the power signal (1006). For instance loop
controller 20 may adjust a current level of the power signal
generated by current source 18 (i.e., I.sub.CS) based on the
current level of the power signal generated by passive elements 16
(i.e., I.sub.Pass) such that a total current level of the power
signal that drives load 6 (i.e., I.sub.Total) is maintained at a
particular current level. In this way, the power dissipation of
driver device 4 may be reduced without changing the characteristics
(i.e., current level) of the the power signal that drives load
6.
[0067] The following numbered examples may illustrate one or more
aspects of the disclosure:
[0068] Example 1. A method comprising: generating, by a current
source of a device, a. first portion of a power signal that drives
one or more load elements, wherein a second portion of the power
signal is generated by one or more components that are external to
the device and are in parallel to the current source such that the
second portion of the power signal does not flow through the
current source.
[0069] Example 2. The method of example 1, further comprising:
adjusting, by the device and based on a current level of the second
portion of the power signal, a current level of the first portion
of the power signal to maintain a total current level of the power
signal.
[0070] Example 3. The method of any combination of examples 1-2,
further comprising: preventing, based on a control signal received
from an external device, the current source from generating the
first portion of the power signal and the one or more components
from generating the second portion of the power signal.
[0071] Example 4. The method of any combination of examples 1-3,
wherein preventing the one or more components from generating the
second portion of the power signal comprises: opening a switch
positioned in series with the one or more components.
[0072] Example 5. The method of any combination of examples 1-4,
wherein the one or more components are not active current
sources.
[0073] Example 6. The method of any combination of examples 1-5,
wherein the one or more components comprise one or more
resistors.
[0074] Example 7. The method of any combination of examples 1-6,
wherein the one or more load elements comprise one or more light
emitting diodes (LEDs).
[0075] Example 8. A driver device comprising: a current source
configured to generate a first portion of a power signal that
drives one or more load elements, wherein a second portion of the
power signal is generated by one or more components that are
external to the device and are in parallel to the current source
such that the second portion of the power signal does not flow
through the current source.
[0076] Example 9. The driver device of example 8, further
comprising: a loop controller configured to adjust, based on a
current level of the second portion of the power signal, a current
level of the first portion of the power signal to maintain a total
current level of the power signal.
[0077] Example 10. The driver device of any combination of examples
8-9, wherein, based on a control signal received from an external
device, the loop controller is configured to prevent the current
source from generating the first portion of the power signal and
prevent the one or more components from generating the second
portion of the power signal.
[0078] Example 11. The driver device of any combination of examples
8-10, wherein, to prevent the one or more components from
generating the second portion of the power signal, the loop
controller is configured to: open a switch positioned in series
with the one or more components.
[0079] Example 12. The driver device of any combination of examples
8-11, wherein the one or more components are not active current
sources.
[0080] Example 13. The driver device of any combination of examples
8-12, wherein the one or more components comprise one or more
resistors.
[0081] Example 14. The driver device of any combination of examples
8-13, wherein the one or more load elements comprise one or more
light emitting diodes (LEDs).
[0082] Example 15. A driver device comprising: means for generating
a first portion of a power signal that drives one or more load
elements, wherein a second portion of the power signal is generated
by one or more components that are external to the device and are
in parallel to the current source such that the second portion of
the power signal does not flow through the current source; and
means for outputting the first portion of the power signal.
[0083] Example 16. The driver device of example 15, further
comprising: means for adjusting, based on a current level of the
second portion of the power signal, a current level of the first
portion of the power signal to maintain a total current level of
the power signal.
[0084] Example 17. The driver device of any combination of examples
15-16, further comprising: means for combining the first portion
and the second portion to generate the power signal, wherein the
means for outputting comprise means for outputting the power
signal.
[0085] Example 18. The driver device of any combination of examples
15-17, further comprising: means for preventing, based on a control
signal received from an external device, the means for generating
from generating the first portion of the power signal and the one
or more components from generating the second portion of the power
signal.
[0086] The techniques described in this disclosure may be
implemented, at least in part, in hardware, software, firmware, or
any combination thereof. For example, various aspects of the
described techniques may be implemented within one or more
processors, including one or more microprocessors, digital signal
processors (DSPs), application specific integrated circuits (ARCO,
field programmable gate arrays (FPGAs), or any other equivalent
integrated or discrete logic circuitry, as well as any combinations
of such components. The term "processor" or "processing circuitry"
may generally refer to any of the foregoing logic circuitry, alone
or in combination with other logic circuitry, or any other
equivalent circuitry. A control unit including hardware may also
perform one or more of the techniques of this disclosure.
[0087] Such hardware, software, and firmware may be implemented
within the same device or within separate devices to support the
various techniques described in this disclosure. In addition, any
of the described units, modules, or components may be implemented
together or separately as discrete but interoperable logic devices.
Depiction of different features as modules or units is intended to
highlight different functional aspects and does not necessarily
imply that such modules or units must be realized by separate
hardware, firmware, or software components. Rather, functionality
associated with one or more modules or units may be performed by
separate hardware, firmware, or software components, or integrated
within common or separate hardware, firmware, or software
components.
[0088] The techniques described in this disclosure may also be
embodied or encoded in an article of manufacture including a
computer-readable storage medium encoded with instructions.
Instructions embedded or encoded in an article of manufacture
including a computer-readable storage medium encoded, may cause one
or more programmable processors, or other processors, to implement
one or more of the techniques described herein, such as when
instructions included or encoded in the computer-readable storage
medium are executed by the one or more processors. Computer
readable storage media may include random access memory (RAM), read
only memory (ROM), programmable read only memory (PROM), erasable
programmable read only memory (EPROM), electronically erasable
programmable read only memory (EEPROM), flash memory, a hard disk,
a compact disc ROM (CD-ROM), a floppy disk, a cassette, magnetic
media, optical media, or other computer readable media. In some
examples, an article of manufacture may include one or more
computer-readable storage media.
[0089] In some examples, a computer-readable storage medium may
include a non-transitory medium. The term "non-transitory" may
indicate that the storage medium is not embodied in a carrier wave
or a propagated signal. In certain examples, a non-transitory
storage medium may store data that can, over time, change (e.g., in
RAM or cache).
[0090] Various aspects have been described in this disclosure.
These and other aspects are within the scope of the following
claims.
* * * * *