U.S. patent application number 13/439538 was filed with the patent office on 2013-10-10 for overcurrent based power control and circuit reset.
This patent application is currently assigned to HONEYWELL INTERNATIONAL INC.. The applicant listed for this patent is Thomas J. Bingel, John Justin Kelly. Invention is credited to Thomas J. Bingel, John Justin Kelly.
Application Number | 20130265088 13/439538 |
Document ID | / |
Family ID | 48095533 |
Filed Date | 2013-10-10 |
United States Patent
Application |
20130265088 |
Kind Code |
A1 |
Kelly; John Justin ; et
al. |
October 10, 2013 |
OVERCURRENT BASED POWER CONTROL AND CIRCUIT RESET
Abstract
In one embodiment, a circuit is provided. The circuit includes a
load configured to receive power through a power path. The circuit
also includes a current monitor configured to sense a current draw
on the power path. A switch on the power path is coupled in series
between the load and a power rail, and a control circuit is coupled
to the current monitor. The control circuit is configured to set
the switch to a non-conducting state and to send a reset signal to
the load if the current monitor senses an overcurrent on the power
path.
Inventors: |
Kelly; John Justin; (New
Port Richey, FL) ; Bingel; Thomas J.; (Indian Rocks
Beach, FL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kelly; John Justin
Bingel; Thomas J. |
New Port Richey
Indian Rocks Beach |
FL
FL |
US
US |
|
|
Assignee: |
HONEYWELL INTERNATIONAL
INC.
Morristown
NJ
|
Family ID: |
48095533 |
Appl. No.: |
13/439538 |
Filed: |
April 4, 2012 |
Current U.S.
Class: |
327/142 |
Current CPC
Class: |
H02H 3/066 20130101;
H02H 5/005 20130101; H02H 3/087 20130101 |
Class at
Publication: |
327/142 |
International
Class: |
H03L 7/00 20060101
H03L007/00 |
Claims
1. A circuit comprising: a load configured to receive power through
a power path; a current monitor configured to sense a current draw
on the power path; a switch on the power path coupled in series
between the load and a power rail; and a control circuit coupled to
the current monitor, wherein the control circuit is configured to
set the switch to a non-conducting state and to send a reset signal
to the load if the current monitor senses an overcurrent on the
power path.
2. The circuit of claim 1, wherein the load comprises a circuit
configured to be reset via an input signal.
3. The circuit of claim 1, wherein upon receiving the reset signal
the load is configured to one or more of: return to a known
hardware and software state, power down, clear its memory, and
drain power therein.
4. The circuit of claim 1, wherein the control circuit is
configured to set the switch back to a conducting state after the
reset signal is sent to the load.
5. The circuit of claim 4, wherein the control circuit is
configured to hold the load in reset mode for a set length of time
after setting the switch back to a conducting state.
6. The circuit of claim 1, wherein the load comprises a sub-circuit
within a larger circuit, and wherein the switch is configured to
control power to the sub-circuit and not other sub-circuits of the
larger circuit and wherein the reset signal is configured to reset
the load and not the other sub-circuits of the larger circuit.
7. The circuit of claim 6, wherein the current monitor is
configured to monitor the power path to the load and not power to
the other sub-circuits.
8. The circuit of claim 1, wherein the reset signal is configured
to change a state of the load caused by a single event effect
causing the load to draw excessive current.
9. The circuit of claim 1, wherein the current monitor, switch, and
control circuit are radiation hardened circuits and wherein the
load is a non-radiation hardened circuit.
10. A system having radiation and temperature event mitigation, the
system comprising: a first functional sub-circuit configured to
receive power from a power supply; a second functional sub-circuit
configured to receive power from the power supply; a power switch
coupled in series between the power supply and the second
functional sub-circuit and not in series between the power supply
and the first functional sub-circuit; a current monitor configured
to monitor a current flowing between the power supply and the
second functional sub-circuit, and to provide an overcurrent signal
if the current flowing between the power supply and the second
functional sub-circuit exceeds a threshold; a control circuit
coupled to the current monitor and configured to set the power
switch to cut-off power to the second functional sub-circuit and to
send a reset signal to the second functional sub-circuit if an
overcurrent signal is received from the current monitor.
11. The system of claim 10, wherein the second functional
sub-circuit is configured to be reset via an input signal.
12. The system of claim 10, wherein upon receiving a reset signal,
the second functional sub-circuit is configured to one or more of:
return to a known hardware and software state, power down, clear
its memory, and drain power therein.
13. The system of claim 10, wherein the control circuit is
configured to set the switch to re-apply power to the second
functional sub-circuit after the reset signal is sent.
14. The system of claim 13, wherein the control circuit is
configured to hold the second functional sub-circuit in reset mode
for a period of time after re-applying power to the second
functional sub-circuit.
15. The system of claim 10, wherein the switch is configured to
control power to the second functional sub-circuit and not the
first functional sub-circuit and wherein the first functional
sub-circuit is configured to maintain normal operation while the
second functional sub-circuit is resetting.
16. A method for mitigating radiation and temperature events, the
method comprising: sensing a current draw of a circuit; cutting off
power to the circuit if the current draw of the circuit exceeds a
threshold; and sending a reset signal to the circuit if the current
draw of the circuit exceeds the threshold.
17. The method of claim 16, comprising: at the circuit, performing
one or more of: returning to a known hardware and software state,
powering down, clearing memory, and draining power in response to
receiving the reset signal.
18. The method of claim 16, comprising: maintaining normal
operation of other circuits within an electronic device that share
power with the circuit while cutting off power and resetting the
circuit.
19. The method of claim 16, comprising: re-applying power to the
circuit after sending the reset signal.
20. The method of claim 19, comprising: holding the circuit in
reset for a period of time after re-applying power to the circuit.
Description
BACKGROUND
[0001] In high-reliability systems such as spacecraft electronics
systems, semiconductor devices are often susceptible to single
event effects such as a single event transient (SET) due to high
temperature or radiation. This problem is common when using
commercial non-radiation hardened components in spacecraft
electronics design. In an elevated temperature or radiation event,
these non-radiation hardened components can begin to draw excessive
current that can result in bringing down an entire power rail
potentially causing system failure.
SUMMARY
[0002] In one embodiment, a circuit is provided. The circuit
includes a load configured to receive power through a power path.
The circuit also includes a current monitor configured to sense a
current draw on the power path. A switch on the power path is
coupled in series between the load and a power rail, and a control
circuit is coupled to the current monitor. The control circuit is
configured to set the switch to a non-conducting state and to send
a reset signal to the load if the current monitor senses an
overcurrent on the power path.
DRAWINGS
[0003] Understanding that the drawings depict only exemplary
embodiments and are not therefore to be considered limiting in
scope, the exemplary embodiments will be described with additional
specificity and detail through the use of the accompanying
drawings, in which:
[0004] FIG. 1 is a block diagram of an example system having an
overcurrent based power control and circuit reset.
[0005] FIG. 2 is a block diagram of an example circuit for
overcurrent based control and circuit reset.
[0006] FIG. 3 is a circuit diagram of an example current monitor
circuit.
[0007] In accordance with common practice, the various described
features are not drawn to scale but are drawn to emphasize specific
features relevant to the exemplary embodiments.
DETAILED DESCRIPTION
[0008] In the following detailed description, reference is made to
the accompanying drawings that form a part hereof, and in which is
shown by way of illustration specific illustrative embodiments.
However, it is to be understood that other embodiments may be
utilized and that logical, mechanical, and electrical changes may
be made. Furthermore, the method presented in the drawing figures
and the specification is not to be construed as limiting the order
in which the individual steps may be performed. The following
detailed description is, therefore, not to be taken in a limiting
sense.
[0009] FIG. 1 is a block diagram of an example system 100 having an
overcurrent based power and control reset. The system 100 includes
an electronic device 102 that receives power from a power supply
104. The power supply 104 can be any suitable power supply such as
a battery, line power, or other entity that can provide power, and
can be integral with or separate from the electronic device 102.
The electronic device 102 can be composed of two or more functional
sub-circuits (e.g., loads), shown as a susceptible sub-circuit 106
and other sub-circuits 108. The sub-circuits 106, 108 share a power
rail 110 to which power is provided from the power supply 104.
Individual power paths 112, 114 branch off and couple each
sub-circuit respectively to the power rail 110. Power path 112
couples the susceptible sub-circuit 106 to the power rail 110 and
power path 114 couples the other sub-circuits 108 to the power rail
110. In other examples, more than two power paths can be included
to provide power to more than two distinct sub-circuits.
[0010] Susceptible sub-circuit 106 comprises a circuit that is
prone to draw excessive current from the power rail 110. In an
example, susceptible sub-circuit 106 comprises a non-radiation
hardened circuit and electronic device 102 is to be used in a space
environment. As a non-radiation hardened circuit used in a space
environment the susceptible sub-circuit 106 is susceptible to
single event effects caused by high temperature and/or radiation.
This single event effects can include a single event transient
(SET) which can cause the susceptible sub-circuit 106 to enter a
state in which the susceptible sub-circuit 106 draws excessive
current from the power rail 110.
[0011] Susceptible sub-circuit 106 is configured to be reset with
an input signal. That is, susceptible sub-circuit 106 is configured
such that the proper signal received at a reset input (also
referred to herein as a "reset signal") causes the sub-circuit 106
to operate in reset mode. In reset mode, the susceptible
sub-circuit 106 performs one or more of the following, powers down,
returns to a known hardware and software state, clears its memory
and drains power of components therein. Reset mode can be used to
change a state of the susceptible sub-circuit 106 when the
susceptible sub-circuit 106 is in a state that causes the
susceptible sub-circuit 106 to draw excessive current. In
particular, reset mode can be used to put the susceptible
sub-circuit 106 back into a state that draws normal current levels
from the power rail 110. In an example, the reset signal used to
reset the susceptible circuit 106 can be a defined logic level
(e.g., one of a high or a low level) at the reset input. For
example, while a logic low is provided to the reset input the
susceptible sub-circuit 106 operates in reset mode. If a signal
other than a logic low (e.g., a logic high) is received at the
reset input, the susceptible sub-circuit 106 operates in normal
mode.
[0012] To mitigate the susceptibility of susceptible sub-circuit
106 to drawing excessive power from the power rail 110, a switch
116, a current monitor 118, and a control circuit 120 are included
to control power and to send a reset signal to the susceptible
sub-circuit 106 when an overcurrent event occurs. In an example,
the switch 116, current monitor 118, and control circuit 120 are
radiation hardened circuits composed of appropriate radiation
hardened components.
[0013] The switch 116 is coupled on the power path 112 in series
between the power supply 104 and the susceptible sub-circuit 106.
When the switch 116 is in a conducting state, power from the power
rail 110 is applied to the susceptible sub-circuit 106, when the
switch 116 is in a non-conducting state power from the power rail
110 is cut-off from the susceptible sub-circuit 106. The switch 116
can include any suitable switching device including a
transistor.
[0014] The current monitor 118 is coupled to the power path 112 and
is configured to sense (e.g., monitor) a current draw on the power
path 112 for the susceptible sub-circuit 106 (e.g., the current
flowing between the power supply 104 and the susceptible
sub-circuit 106). If an overcurrent event (e.g., the current
exceeds a threshold) is sensed on the power path 112, the current
monitor 118 is configured to output an overcurrent signal
indicating the overcurrent event. The current monitor 118 can be
implemented by any suitable circuit such as, for example, the
circuit shown in FIG. 3.
[0015] The control circuit 120 is coupled to the current monitor
118 and is configured to receive the overcurrent signal from the
current monitor 118. The control circuit 120 is also coupled to the
switch 116 and is configured to control the switch 116 by setting
the switch in either a conducting or a non-conducting state. The
control circuit 106 is also coupled to the reset input of the
susceptible sub-circuit 106 and is configured to send a reset
signal to the reset input. The control circuit 120 can be
implemented by any suitable components such as, for example,
Boolean logic or a microprocessor.
[0016] In operation, the system 100 can mitigate overcurrent events
as follows. If the current monitor 118 senses an overcurrent on the
power path 112 to the susceptible sub-circuit 106, the current
monitor 118 sends an overcurrent signal to the control circuit 120
indicating an overcurrent event. In response to receiving the
overcurrent signal indicating the overcurrent event, the control
circuit 120 cuts-off power to the susceptible sub-circuit 106 by
setting the switch 116 in a non-conducting state. In an example,
the control circuit 120 can immediately cut-off power to the
susceptible sub-circuit 106 after receiving the overcurrent signal.
In addition to cutting-off power to the susceptible sub-circuit
106, the control circuit 120 can send a reset signal to the
susceptible sub-circuit 106 to set the susceptible sub-circuit in
reset mode.
[0017] After the reset signal has been sent to the susceptible
sub-circuit 106, the control circuit 106 can re-apply power to the
susceptible sub-circuit 106 by setting the switch 116 back to a
conducting state. In an example, the reset signal can re-apply
power in response to a signal from the current monitor 118
indicating that the current level on the power path 112 has dropped
to an acceptable level. Since the switch 116 has been set to a
non-conducting state, the current should drop to an acceptable
level quickly, resulting in the control circuit 120 quickly
re-apply power to the susceptible sub-circuit 106. In another
example, the control circuit 106 can hold the switch 116 in a
non-conducting state for a set length of time after which the
control circuit 106 sets the switch 116 back to a conducting
state.
[0018] As mentioned above, the control circuit 120 can send a reset
signal to the susceptible sub-circuit 106 after powering down and
before powering up. Thus, when the susceptible sub-circuit 106
powers up, the susceptible sub-circuit 106 operates in reset mode
in response to receiving the reset signal from the control circuit
120.
[0019] In an example, the control circuit 120 can hold the
susceptible sub-circuit 106 in reset mode for a set length of time
after power is re-applied to the susceptible sub-circuit 106. The
control circuit 120 can hold the susceptible sub-circuit 106 in
reset mode by maintaining application of the reset signal to the
susceptible sub-circuit 106. In examples where the reset signal is
a defined logic level, the control circuit 120 can maintain
application of the defined logic level on the reset input of the
susceptible sub-circuit 106. The set length of time for holding the
susceptible sub-circuit in reset mode can be based on a length of
time needed for the susceptible sub-circuit 106 to reset. For
example, the set length of time can be based on a length of time
needed to allow power within the susceptible sub-circuit 106 to
drain or to enable memory within the susceptible sub-circuit 106 to
be cleared and initialized.
[0020] Notably, since the other sub-circuits 108 have power paths
114 to the power rail 110 that are distinct from the power path
112, the switch 116 does not control power to the other
sub-circuits 108 and the current monitor 118 does not monitor
current flowing to the other sub-circuits 108. Thus, the switch 116
can be controlled based solely on the current draw of the
susceptible sub-circuit 106 and cut-off power to the susceptible
sub-circuit 106 without cutting-off power to the other sub-circuits
108, enabling the susceptible sub-circuit 106 to have its power
cut-off and be reset while the other sub-circuits 108 maintain
normal operation.
[0021] FIG. 2 is a block diagram of an example circuit 200 for
overcurrent based control and circuit reset. As shown, the current
monitor 118 is coupled to the power path 112 for the susceptible
sub-circuit 106. The current monitor 118 uses a sense resistor
coupled in series between the susceptible sub-circuit 106 and the
power rail 110 to sense a current on the power path 112. The
current monitor 118 provides an overcurrent signal on current
monitor path 202 indicating whether an overcurrent event has
occurred. In an example, the overcurrent signal comprises a logic
signal wherein a first logic level indicates current that exceeds a
threshold and a second logic level indicates current below the
threshold.
[0022] In response to an overcurrent signal indicating current that
exceeds the threshold, the control circuit 120 provides a signal
over a switch path 204 to the switch 116 to set the switch in a
non-conducting state. As shown, the switch 116 can include a
transistor that is coupled in series between the susceptible
sub-circuit 106 and the power supply 104. Thus, the switch 116 can
cut-off power to the susceptible sub-circuit 106. The signal from
the control logic 120 can be a logic signal coupled to a gate of
the transistor, wherein a first logic level sets the switch 116 in
a conducting state and a second logic level set the switch 116 in
non-conducting state.
[0023] The control circuit 120 also provides a reset signal over a
reset path 206 to the susceptible sub-circuit 106 in response to
the overcurrent signal indicating current that exceeds the
threshold. As mentioned above, this reset signal can also be a
logic signal. The control circuit 120 can then set the switch 116
back to a conducting state and hold the susceptible sub-circuit 106
in reset mode for a set length of time to reset the susceptible
sub-circuit 106 after power is re-applied.
[0024] FIG. 3 is a circuit diagram of an example current monitor
circuit 120. The current monitor 120 includes a sense resistor 302
coupled on the power path 112 in series between the susceptible
sub-circuit 106 and the power rail 110. In an example, the power
rail 110 is at 3.3V and the threshold current level on the power
path 112 is between 2.5-2.7 Amps. In an example, the sense resistor
302 has a resistance of around 0.1 Ohms. The current monitor 118
includes an operational amplifier 304 to sense changes in current
through the sense resistor 302 and to provide an overcurrent signal
indicating whether the current is above or below a threshold. The
current monitor 118 also includes a first resistor 306 and a second
resistor 308 coupled to provide a voltage divider for the positive
input of the operational amplifier 304. In an example, the first
resistor 306 and second resistor 308 are high precision, low
tolerance resistors that have a resistance of between 9-11 kOhms. A
third and fourth resistors 310, 312 are coupled to provide a
voltage divider for the negative input of the operational amplifier
304. Similar to the first and second resistors 306, 308, the third
and fourth resistors 310, 312 can be high precision, low tolerance
resistors that have a resistance of between 9-11 kOhms. The current
threshold is based on the ratio between the positive input and the
negative input of the operational amplifier 304 and can be set
based on the values of the first, second, third, and fourth
resistors 306, 308, 310, 312. In an example, the current monitor
118 can include a first capacitor coupled between the positive
input of the operational amplifier and ground and a second
capacitor coupled between the negative input of the operational
amplifier and ground. The first and second capacitor can slow
variation in the inputs to the positive and negative inputs in
order to reduce ripple in the output of the operational amplifier
120. The current monitor 118 can also include a hysteresis resistor
314 to provide a hysteresis thereto and another resistor 316
coupled between the power rail 110 and the output 318.
Example Embodiments
[0025] Example 1 includes a circuit comprising a load configured to
receive power through a power path; a current monitor configured to
sense a current draw on the power path; a switch on the power path
coupled in series between the load and a power rail; and a control
circuit coupled to the current monitor, wherein the control circuit
is configured to set the switch to a non-conducting state and to
send a reset signal to the load if the current monitor senses an
overcurrent on the power path.
[0026] Example 2 includes the circuit of Example 1, wherein the
load comprises a circuit configured to be reset via an input
signal.
[0027] Example 3 includes the circuit of any of Examples 1 or 2,
wherein upon receiving the reset signal the load is configured to
one or more of: return to a known hardware and software state,
power down, clear its memory, and drain power therein.
[0028] Example 4 includes the circuit of any of Examples 1-3,
wherein the control circuit is configured to set the switch back to
a conducting state after the reset signal is sent to the load.
[0029] Example 5 includes the circuit of Example 4, wherein the
control circuit is configured to hold the load in reset mode for a
set length of time after setting the switch back to a conducting
state.
[0030] Example 6 includes the circuit of any of Examples 1-5,
wherein the load comprises a sub-circuit within a larger circuit,
and wherein the switch is configured to control power to the
sub-circuit and not other sub-circuits of the larger circuit and
wherein the reset signal is configured to reset the load and not
the other sub-circuits of the larger circuit.
[0031] Example 7 includes the circuit of Example 6, wherein the
current monitor is configured to monitor the power path to the load
and not power to the other sub-circuits.
[0032] Example 8 includes the circuit of any of Examples 1-7,
wherein the reset signal is configured to change a state of the
load caused by a single event effect causing the load to draw
excessive current.
[0033] Example 9 includes the circuit of any of Examples 1-8,
wherein the current monitor, switch, and control circuit are
radiation hardened circuits and wherein the load is a non-radiation
hardened circuit.
[0034] Example 10 includes a system having radiation and
temperature event mitigation, the system comprising a first
functional sub-circuit configured to receive power from a power
supply; a second functional sub-circuit configured to receive power
from the power supply; a power switch coupled in series between the
power supply and the second functional sub-circuit and not in
series between the power supply and the first functional
sub-circuit; a current monitor configured to monitor a current
flowing between the power supply and the second functional
sub-circuit, and to provide an overcurrent signal if the current
flowing between the power supply and the second functional
sub-circuit exceeds a threshold; a control circuit coupled to the
current monitor and configured to set the power switch to cut-off
power to the second functional sub-circuit and to send a reset
signal to the second functional sub-circuit if an overcurrent
signal is received from the current monitor.
[0035] Example 11 includes the system of Example 10, wherein the
second functional sub-circuit is configured to be reset via an
input signal.
[0036] Example 12 includes the system of any of Examples 10 or 11,
wherein upon receiving a reset signal, the second functional
sub-circuit is configured to one or more of: return to a known
hardware and software state, power down, clear its memory, and
drain power therein.
[0037] Example 13 includes the system of any of Examples 10-12,
wherein the control circuit is configured to set the switch to
re-apply power to the second functional sub-circuit after the reset
signal is sent.
[0038] Example 14 includes the system of Example 13, wherein the
control circuit is configured to hold the second functional
sub-circuit in reset mode for a period of time after re-applying
power to the second functional sub-circuit.
[0039] Example 15 includes the system of any of Examples 10-14,
wherein the switch is configured to control power to the second
functional sub-circuit and not the first functional sub-circuit and
wherein the first functional sub-circuit is configured to maintain
normal operation while the second functional sub-circuit is
resetting.
[0040] Example 16 includes the system of any of Examples 10-15,
wherein the reset signal is configured to change a state of the
second functional sub-circuit caused by a single event effect
causing the second functional sub-circuit to draw excessive
current.
[0041] Example 17 includes the system of any of Examples 10-16,
wherein the current monitor, power switch, and control circuit are
radiation hardened circuits and wherein the second functional
sub-circuit is a non-radiation hardened circuit.
[0042] Example 18 includes a method for mitigating radiation and
temperature events, the method comprising sensing a current draw of
a circuit; cutting off power to the circuit if the current draw of
the circuit exceeds a threshold; and sending a reset signal to the
circuit if the current draw of the circuit exceeds the
threshold.
[0043] Example 19 includes the method of Example 18, comprising at
the circuit, performing one or more of: returning to a known
hardware and software state, powering down, clearing memory, and
draining power in response to receiving the reset signal.
[0044] Example 20 includes the method of any of Examples 18 or 19,
comprising maintaining normal operation of other circuits within an
electronic device that share power with the circuit while cutting
off power and resetting the circuit.
[0045] Example 21 includes the method of any of Examples 18-20,
comprising re-applying power to the circuit after sending the reset
signal.
[0046] Example 22 includes the method of Example 21, comprising
holding the circuit in reset for a period of time after re-applying
power to the circuit.
[0047] Although specific embodiments have been illustrated and
described herein, it will be appreciated by those of ordinary skill
in the art that any arrangement, which is calculated to achieve the
same purpose, may be substituted for the specific embodiments
shown. Therefore, it is manifestly intended that this invention be
limited only by the claims and the equivalents thereof.
* * * * *