U.S. patent application number 17/132092 was filed with the patent office on 2022-01-27 for instability management in a signal driver circuit.
This patent application is currently assigned to SEMICONDUCTOR COMPONENTS INDUSTRIES, LLC. The applicant listed for this patent is SEMICONDUCTOR COMPONENTS INDUSTRIES, LLC. Invention is credited to Pavel BAROS, Michal OLSAK.
Application Number | 20220029616 17/132092 |
Document ID | / |
Family ID | |
Filed Date | 2022-01-27 |
United States Patent
Application |
20220029616 |
Kind Code |
A1 |
OLSAK; Michal ; et
al. |
January 27, 2022 |
INSTABILITY MANAGEMENT IN A SIGNAL DRIVER CIRCUIT
Abstract
A method of operating a driver circuit includes receiving a data
signal at a first input of an amplification circuit; amplifying,
using the amplification circuit, the data signal to produce an
output signal through an output pin; attenuating, using a feedback
network, the output signal to produce a feedback signal; coupling
the feedback signal to a second input of the amplification circuit;
detecting, using a control circuit, a fault condition; and
decoupling, responsive to detecting the fault condition, the
feedback signal from the second input of the amplification circuit.
In some embodiments, the driver circuit transmits a fault condition
signal to an electronic control unit of an automobile.
Inventors: |
OLSAK; Michal; (Sokolnice,
CZ) ; BAROS; Pavel; (Zastavka U Brna, CZ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SEMICONDUCTOR COMPONENTS INDUSTRIES, LLC |
Phoenix |
AZ |
US |
|
|
Assignee: |
SEMICONDUCTOR COMPONENTS
INDUSTRIES, LLC
Phoenix
AZ
|
Appl. No.: |
17/132092 |
Filed: |
December 23, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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63057032 |
Jul 27, 2020 |
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International
Class: |
H03K 17/12 20060101
H03K017/12; H03K 17/042 20060101 H03K017/042 |
Claims
1.-17. (canceled)
18. A signal transmittal system, comprising: an amplification
circuit having a first input operable to receive a feedback signal
corresponding to an output signal, a second input operable to
receive a data signal, a first output operable to provide the
output signal, and a second output operable to provide a current
signal; a detector circuit having a detector input coupled to the
second output of the amplification circuit and a detector output
operable to provide a detection signal, wherein the detection
signal indicates that a present magnitude of the current signal
exceeds a threshold; a control circuit having a first input coupled
to the detector output, and a first output coupled to the second
input of the amplification circuit operable to provide the data
signal to the amplification circuit; and a feedback circuit having
a first input coupled to the output signal of the amplification
circuit, a second input operable to receive a control signal, and
an output coupled to the first input of the amplification circuit,
wherein the feedback circuit is configured to decouple the output
signal from the first input of the amplification circuit in
response to receiving the control signal, wherein the control
circuit is operable to provide the control signal to the feedback
circuit, responsive to detecting a fault condition in the
amplification circuit.
19. The signal transmittal system of claim 18, wherein the fault
condition corresponds to receipt of the detection signal from the
detector circuit during one or more falling edge intervals of the
output signal.
20. The signal transmittal system of claim 19, wherein receipt of
the detection signal from the detector circuit during one or more
falling edge intervals of the output signal corresponds to
oscillations in the amplification circuit.
21. The signal transmittal system of claim 18, wherein the
amplification circuit includes a third output operable to provide a
second current signal, wherein the signal transmittal system
further includes a second detector circuit having a second detector
input coupled to the third output of the amplification circuit and
a second detector output operable to provide a second detection
signal to the control circuit, and wherein the second detection
signal indicates whether a present magnitude of the second current
signal exceeds a second threshold.
22. The signal transmittal system of claim 21, wherein the
detection signal further indicates whether the current signal is
within a first operating range, and wherein the second detection
signal further indicates whether the second current signal is
within a second operating range.
23. The signal transmittal system of claim 18, wherein the detector
circuit comprises: a capacitor having a first terminal and a second
terminal, wherein the capacitor is charged by the current signal;
and a comparator having a comparator input coupled to the first
terminal of the capacitor and a comparator output coupled to the
detector output operable to provide the detection signal.
24. The signal transmittal system of claim 23, wherein the detector
circuit further comprises: a switch having a first terminal coupled
to the first terminal of the capacitor, a second terminal coupled
to the second terminal of the capacitor, and a control input
operable to receive a detector activation signal, and wherein the
control circuit has a second output coupled to the control input
operable to provide the detector activation signal to the detector
circuit.
25. The signal transmittal system of claim 21, further comprising a
PMOS transistor configured to produce the current signal and an
NMOS transistor configured to produce the second current
signal.
26. The signal transmittal system of claim 21, further comprising:
a feedback network having a first input coupled to the output
signal of the amplification circuit, a second input operable to
receive the control signal, and an output coupled to the first
input of the amplification circuit, wherein the feedback network is
configured to decouple the output signal from the first input of
the amplification circuit in response to receiving the control
signal; and wherein the control circuit has a control output
coupled to the second input of the feedback network operable to
provide the control signal to the feedback network, responsive to
detecting a fault condition.
27. The signal transmittal system of claim 26, wherein the fault
condition corresponds to oscillations in the amplification
circuit.
28. The signal transmittal system of claim 26, wherein the fault
condition corresponds to detection, by the detector circuit during
one or more falling edge intervals of the output signal, that the
present magnitude of the current signal exceeds the first
threshold.
29. The signal transmittal system of claim 26, wherein the fault
condition corresponds to detection, by the second detector circuit
during one or more rising edge intervals of the output signal, that
the present magnitude of the second current signal exceeds the
second threshold.
30. The signal transmittal system of claim 26, wherein the output
signal of the amplification circuit is connected to a stabilization
circuit, wherein the stabilization circuit is charged by current of
the output signal during one or more rising edge intervals of the
output signal when the output signal is coupled to the first input
of the amplification circuit by the feedback network.
31. The signal transmittal system of claim 30, wherein the fault
condition corresponds to an increased resistance of the
stabilization circuit.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is related to U.S. Provisional App.
63/057,032, filed Jul. 27, 2020, entitled "Apparatus and Method for
Instability Detection in Amplifiers," which is entirely
incorporated by reference herein.
BACKGROUND
[0002] The output of data signal drivers can be stabilized using
one or more stabilization circuits. These stabilization circuits
are frequently effective in stabilizing the output of data signal
drivers. However, sometimes they fail to perform as desired due to
environmental conditions or other causes. While methods for coping
with such failure conditions exist, there nevertheless remains room
for improvement in the art.
SUMMARY
[0003] Accordingly, there are disclosed herein systems and methods
for detecting stabilization circuit failure and adjusting data
signal driver operations to minimize the effects of stabilization
circuit failure on the data signal driver.
[0004] One embodiment of this disclosure is a signal driver,
comprising: an amplification circuit having a first input operable
to receive a feedback signal corresponding to an output signal, a
second input operable to receive a data signal, a first output
operable to provide the output signal, a second output operable to
provide a first current signal, and a third output operable to
provide a second current signal; a first detector circuit having a
first detector input coupled to the second output of the
amplification circuit and a first detector output operable to
provide a first detection signal, wherein the first detection
signal indicates whether a current (present) magnitude of the first
current signal exceeds a first threshold; a second detector circuit
having a second detector input coupled to the third output of the
amplification circuit and a second detector output operable to
provide a second detection signal, wherein the second detection
signal indicates whether a current magnitude of the second current
signal exceeds a second threshold; and a control circuit having a
first input coupled to the first detector output, a second input
coupled to the second detector output, and a first output coupled
to the second input of the amplification circuit operable to
provide the data signal to the amplification circuit, wherein the
control circuit is operable to generate a control signal to control
one or more operations of the amplification circuit, responsive to
at least one of the first detection signal or the second detection
signal.
[0005] Another embodiment of this disclosure is a method of
operating a driver circuit, comprising: receiving a data signal at
a data input of an amplification circuit; amplifying, using the
amplification circuit, the data signal to produce an output signal
through an output pin; attenuating, using a feedback network, the
output signal to produce a feedback signal; coupling the feedback
signal to a feedback input of the amplification circuit; detecting,
using a control circuit, a fault condition of the amplification
circuit; and decoupling, responsive to detecting the fault
condition, the feedback signal from the feedback input of the
amplification circuit, wherein detecting the fault condition
comprises detecting at least one of a high side current between a
high side transistor and the output pin during a falling edge
interval of the output signal or a low side current between a low
side transistor and the output pin during a rising edge interval of
the output signal.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a block diagram of an electronic network, in
accordance with an example of this disclosure.
[0007] FIG. 2 illustrates aspects of the electronic network of FIG.
1, in accordance with an example of this disclosure.
[0008] FIG. 3. illustrates the relationships of various signals of
the electronic network to an amplified data output signal produced
using the electronic network.
[0009] FIG. 4 illustrates plots of various signals of this
disclosure and their relationship to the output signal.
[0010] FIG. 5A illustrates details of a high side current detector
circuit of this disclosure.
[0011] FIG. 5B illustrates details of a low side current detector
circuit of this disclosure.
[0012] FIG. 6 illustrates a characteristic curve of an
amplification circuit.
[0013] FIG. 7 illustrates a method of operating a driver circuit,
in accordance with an example of this disclosure.
DETAILED DESCRIPTION
[0014] Please note that the drawings and corresponding detailed
description are provided for explanatory purposes, not to limit the
disclosure. To the contrary, they provide the foundation for
understanding all modifications, equivalents, and alternatives
falling within the scope of the appended claims.
[0015] FIG. 1 is a block diagram of an electronic network 100, in
accordance with an example of this disclosure. The electronic
network 100 includes a sensor circuit 102, a control circuit 104,
and a driver circuit 106. The driver circuit 106 includes an
amplification circuit 108 and a feedback (FB) network 110. In some
embodiments, the amplification circuit 108 comprises a class A-B
amplifier. The electronic network 100 also includes a detection
block 112, a stabilization circuit 114, and an electronic control
unit (ECU) 116. In at least one embodiment of this disclosure, the
ECU 116 is a microcontroller unit (MCU). In some embodiments, the
MCU is an automotive MCU. Both the ECU 116 and the stabilization
circuit 114 are connected to signal ground 115.
[0016] The sensor circuit 102 includes one or more sensors 118.
Output(s) from the one or more sensors 118 is (are) received by the
control circuit 104 at one or more sensor inputs 120.
[0017] The control circuit 104 outputs a data signal 122 from a
data output 124 to the amplification circuit 108. In some examples,
the data signal 122 is a pulse width modulated analog signal
representing information gathered by the sensor circuit 102. The
control circuit 104 outputs an enable signal 126 to the detection
block 112 from an enable signal output 128. The control circuit 104
has a high side input 130 and a low side input 132 connected to the
detection block 112. The control circuit 104 has a FB control
output 134 connected to a FB control input 136 of the FB network
110. As will be explained in greater detail, the control circuit
104 controls whether the FB network 110 provides FB to the
amplification circuit 108.
[0018] The amplification circuit 108 includes a data signal input
140 connected to the data output 124 of the control circuit 104
through which the amplification circuit 108 receives the data
signal 122. The amplification circuit 108 includes a FB input 140
connected to a FB output 142 of the FB network 110. The
amplification circuit 108 includes a high side (HS) transistor 144,
a HS current sensor 146, a low side (LS) transistor 148, and a LS
current sensor 150. The amplification circuit 108 is configured to
amplify the data signal 122 and generate an output signal 152
corresponding to the amplified data signal 122. The output signal
152 is coupled to an output pin 154 of the amplification circuit
108.
[0019] The HS transistor 144 can be a p-channel metal-oxide
semiconductor (PMOS) transistor comprising a source, a gate, and a
drain. The drain of the HS transistor is connected to the output
pin 154 through a HS current line 156. The HS current sensor 146 is
connected to the detection block 112. The HS current sensor 146
senses current in the HS current 156 line and presents a copy of
the HS current to the detection block 112 when active.
[0020] The LS transistor can be an n-channel metal-oxide
semiconductor (NMOS) transistor comprising a source, a gate, and a
drain. The drain of the LS transistor is connected to the output
pin 154 through a LS current line. The LS current sensor is
connected to the detection block 112. The LS current sensor 150
senses current in the LS current line 158 and presents a copy of
the LS current to the detection block 112 when active.
[0021] As noted, the amplification circuit 108 outputs the output
signal 152 based on the data signal 122 through the output pin 154.
The output pin 154 is connected to the FB network 110, the ECU 116,
and--under normal conditions--the stabilization circuit 114. The
amplification circuit 108 amplifies the data signal 122 to produce
the output signal 152. Under normal conditions, the amplification
circuit 108 and output signal 152 which it produces are stabilized
by the stabilization circuit 114. Under normal conditions, the
output signal 152 is received by the ECU 116 at an ECU input 160.
The output pin 154 is connected to a FB input 162 of the FB network
110.
[0022] As noted, the FB network 110 includes the FB input 162
connected to the output pin 154 of the amplification circuit 108.
In some embodiments of this disclosure, the FB network 110 includes
a resistive network. In at least one embodiment, the FB network 110
is an attenuator circuit. Under normal conditions, the FB network
110 receives the output signal 152, scales the output signal 152,
and outputs a scaled signal 164 to the amplification circuit 108
through the FB output 142. The FB output 142 is connected to the FB
input 140 of the amplification circuit 108. The scaled signal 164
is scaled to the scale of the data signal 122. That is, the FB
network 110 reduces the amplitude of the output signal 152 to the
same extent that the amplification circuit 108 amplifies the data
signal 122 so that the amplitude of the scaled signal 164 and the
amplitude of the data signal 122 are matched (or very nearly
matched). When the scaled signal 164 is provided to the
amplification circuit 108, the amplification circuit 108 can be
said to be operating in a closed-loop mode. There can be times,
however, when it is advantageous for the FB network 110 to not
provide the scaled signal 164 to the amplification circuit 108.
When the FB network 110 does not provide the scaled signal 164 to
the amplification circuit 108, the amplification circuit 108 can be
said to be operating in an open-loop mode. The control input 136 of
the FB network 110 is connected to the control output 134 of the
control circuit 104. The control circuit controls 104 whether the
FB network 110 provides the scaled signal 164 to the amplification
circuit 108 through a control signal 166. In at least embodiment,
when the control signal 166 is set to logic zero, the FB network
110 provides the scaled signal 164 to the amplification circuit
108. In some embodiments, when the control signal 166 is set to
logic one, the FB network does not provide the scaled signal 164 to
the amplification circuit 108. Thus, the control circuit 104
controls whether the amplification circuit 108 operates in the
closed-loop mode or the open-loop mode.
[0023] The detection block 112 includes a HS detector circuit 168
and a LS detector circuit 170. The HS detector circuit 168 includes
a HS enable input 172 connected to the enable output 128 of the
control circuit 104 and a HS sensor input 174 connected to the HS
current sensor 146 of the amplification circuit 108. The HS
detector circuit 168 receives a copy of the HS current sensed by
the HS current sensor 146 through the HS sensor input 174 when the
HS detector circuit 168 is activated in accordance with the enable
signal 126 received from the control circuit 104. When the HS
detector circuit 168 is active and the HS detector circuit 168
detects a HS current (above a predetermined threshold), the HS
detector circuit 168 outputs a HS detection signal 176 to the HS
input 130 of the control circuit 104.
[0024] The LS detector circuit 170 includes a LS enable input 178
connected to the enable output 128 of the control circuit 104 and a
LS sensor input 180 connected to the LS current sensor 150 of the
amplification circuit 108. The LS detector circuit 170 receives a
copy of the LS current sensed by the LS current sensor 150 through
the LS sensor input 180 when the LS detector circuit 170 is
activated in accordance with the enable signal 126 received from
the control circuit 104. When the LS detector circuit 170 is active
and the LS detector circuit 170 detects a LS current (above a
predetermined threshold), the LS detector circuit 170 outputs a LS
detection signal 182 to the LS input 132 of the control circuit
104.
[0025] As noted, the data signal 122 is a pulse width modulated
(PWM) analog signal, and the output signal 152 from the
amplification circuit 108 is an amplified version of that PWM
analog signal. Under normal conditions, (e.g., when the
stabilization circuit 114 is well connected), when the voltage of
the output signal 152 is rising, the HS detector circuit 168 will
detect HS current in the HS current line 156 and will output a HS
detection signal 176 accordingly. The HS detector circuit will
not--under normal conditions--detect HS current in the HS current
line 156 when the voltage of the output signal 152 is falling (or
stable).
[0026] Similarly, when the stabilization circuit 114 is well
connected and the voltage of the output signal 152 is falling, the
LS detector circuit 170 will detect LS current in the LS current
line 158 and will output a LS detection signal 182 to the control
circuit 104. The LS detector circuit will not--under normal
conditions--detect LS current in the LS current line 158 when the
voltage of the output signal 152 is rising (or stable). When
operating properly, the stabilization circuit 114 minimizes or
eliminates unwanted oscillations in the amplification circuit 108.
When operating properly, the stabilization circuit 114 helps to
ensure that output signal 152 is driven only by the HS transistor
144 during the rising edge periods of the output signal 152 and
driven only by the LS transistor 148 during the falling edge
periods of the output signal 152. During rising edge periods of the
output signal 152, current flows out of the amplification circuit
108. In embodiments of this disclosure, current which flows out of
the output pin 154 of the amplification circuit 108 is considered
negative current. Conversely, current which flows into the
amplification circuit 108 through the output pin 154 is considered
positive current.
[0027] There can be times, however, when the stabilization circuit
114 does not function properly. For example, a capacitor of the
stabilization circuit 114 could become partially or fully
disconnected. The resistance (reactance) of the stabilization
circuit 114 could rise due to environmental conditions. For
example, if a capacitor of the stabilization circuit 114 is
soldered or glued in place, heat and/or normal wear and tear may
cause the stabilization circuit 114 to perform poorly or not at
all. As will be explained in greater detail, a partial or complete
failure of the stabilization circuit 114 can cause the
amplification circuit 108 to oscillate. Such oscillations can be
manifested in the detection block's detection of HS current and/or
LS current when HS current and/or LS current should not be
detected. In at least one embodiment of this disclosure, the
control circuit 104 is configured to switch the amplification
circuit 108 from operating in a closed-loop mode to operate in an
open-loop mode when HS detection signal 176 and/or LS detection
signal 182 are received from the detection block 112 at
inappropriate times.
[0028] FIG. 2 illustrates aspects of the electronic network 100 of
FIG. 1, in accordance with an example of this disclosure. FIG. 3
illustrates plots of signals of the electronic network 100. The
control circuit 104 provides a V(IN) data signal 122 to the
positive input 140 of the amplification circuit 108. The FB network
110 provides the V(FB) scaled signal 164 to the negative
(inverting) input 140 of the amplification circuit 108. The V(IN)
data signal 122 is amplified by the amplification circuit 108 to
produce V(OUT) 152. The difference 184 between the voltage at the
negative input 138 and the voltage at the positive input 140 is
[V(IN)-V(FB)] 184. The relationship of V(IN) and V(FB) to V(OUT) is
shown in the upper plot 300 of FIG. 3. The relationship of
[V(IN)-V(FB)] 184 to V(OUT) is shown in the lower plot 302 of FIG.
3. The voltage difference 184 between the positive input 140 and
the negative input 138 produces HS current 186 in HS current line
156 and/or LS current 188 in LS current line 158. When current
I(OUT) 190 of output signal 152 flows out of amplification circuit
108, current I(OUT) 190 is negative. When current I(OUT) 190 of
output signal 152 flows into amplification circuit 108, current
I(OUT) 190 is positive.
[0029] The signal V(OUT) 152 trails (slightly) the data signal 122
because of physical characteristics of the amplification circuit
108, such as slew-rate and/or bandwidth, as shown in upper plot
300. As discussed, the V(OUT) signal 152 is monitored by the FB
network 110 (e.g., resistive divider) and fed back to negative
input 138 of the amplification circuit 108. The V(FB) signal 164 is
a scaled version of V(OUT) signal 152. V(FB) signal 164 thus trails
V(OUT) signal 152, as shown in the upper plot 300 of FIG. 3. As
shown in the lower plot 302 of FIG. 3, the difference between the
voltage of the data signal 122 and the voltage of the FB signal 164
[V(IN)-V(FB)] can be positive, negative, or zero.
[0030] The rising signal edge of V(IN) signal 122 causes the
voltage of V(OUT) signal 152 to rise during in interval 304. But,
as noted above, the V(OUT) signal 152 trails the V(IN) signal 122.
In these periods 304, V(IN) exceeds V(FB), and thus the difference
between the voltage of the data signal 122 and the voltage of the
V(FB) signal 164 is positive (see interval 304 in lower plot 302).
During those periods 304 in which V(OUT) rises, the absolute value
of I(HS) current 186 is greater than that of the I(LS) current 188.
During the rising edge interval 304, I(OUT) current 190 flows from
the amplification circuit 108. That is, I(OUT) current 190 is
positive during the rising edge interval 304. The I(OUT) current
190 from the amplification circuit 108 flows into the stabilization
circuit 114. Noting that I(OUT) 190=I(HS) 186-I(LS) 188, the
negative I(OUT) current charges one or more capacitors of the
stabilization circuit 114, causing V(OUT) and V(FB) to rise until
V(FB) and V(IN) are equal, [V(FB)=V(IN)] and the amplification
circuit 108 achieves a steady state in which V(OUT) is constant, as
shown in interval 306. During the rising signal edge periods 304,
the HS detector circuit 168 will detect HS current 186 which
exceeds a HS threshold. When the HS detector circuit 168 detects
the HS current 186 above the threshold, the HS detector circuit
emits HS detection signal 176, which is received by the control
circuit 104. During the rising signal edge periods 304, the LS
detector circuit 170 will not detect LS current 188 whose magnitude
does not exceed a LS threshold, so the LS detector circuit 170 will
not emit a LS detection signal 182.
[0031] When the amplification circuit 108 is in a (high) steady
[V(FB)=V(IN)], as shown in interval 306, FB signal 164 from the
output pin 154 of the amplification circuit 108 is received at the
amplification circuit's input 138 through the FB network 110 (e.g.,
resistive divider). As indicated, the FB network 110 continues to
regulate V(FB) such that it is equal to (VIN); I(HS)=I(LS) and
therefore I(OUT) is zero. It will be understood by persons of skill
that although current flows into the FB network 110, this current
is not included in the equation to simplify the explanation.
[0032] During those periods 308 in which the voltage of the data
signal 122 falls, the voltage of output signal 152 and FB signal
164 also fall but are delayed. During the falling edge periods 308,
V(FB) exceeds V(IN), making V(IN)-V(FB) negative (see interval 308
of plot 302. During the falling edge periods 308, the absolute
value of I(HS) current 186 is lower than I(LS) current 188, and
therefore I(OUT) current is positive (flowing into the
amplification circuit 108 and out of the stabilization circuit 114
until the amplification circuit 108 reaches a (low) steady state
310. Note that I(OUT)=I(HS)-I(LS). The positive I(OUT) current
discharges one or more capacitors of stabilization circuit 114,
causing V(OUT) and V(FB) to fall until the amplification circuit
108 achieves the (low) steady state 310, in which V(FB)=V(IN) and
VIN-VFB=0. During the falling signal edge periods 308, the LS
detector circuit 170 will detect LS current 188 when the magnitude
of the LS current 188 exceeds a LS threshold (606). When the LS
detector 170 detects the LS current 188 above the threshold, the LS
detector circuit 170 emits an LS detection signal 182, which is
received by the control circuit 104. During the falling signal edge
periods 308, the HS detector circuit 168 will not detect HS current
186 above the HS threshold, so the HS detector circuit 168 will not
emit a HS detection signal 176.
[0033] It will be understood by those of skill that although
V(IN)-V(FB) can be positive, negative, or zero, V(OUT)--under
normal conditions--does not have a negative value.
[0034] Under normal conditions, the control circuit 104 receives HS
detection signals during the rising edge periods and receives LS
detection signals during the falling edge periods.
[0035] If the stabilization circuit 114 partially or wholly fails,
such failure may cause the amplification circuit 108 to oscillate.
Consequently, HS current 186 above the threshold may be detected by
the HS detector circuit 168 during the falling edge periods 308.
The HS detector circuit 168 will emit a HS detection signal 176 as
a result. Alternately or additionally, if the stabilization circuit
114 partially or wholly fails, LS current 188 (whose magnitude
exceeds the LS threshold) may be detected by the LS detector
circuit 170 during the rising edge periods 304. The LS detector
circuit 170 will emit a LS detection signal 182 as a result.
[0036] The control circuit 104 is configured such that when the
control circuit 104 receives one or more HS detection signals 176
during a falling edge period 308 and/or one or more LS detection
signals 182 during a rising edge period 304, the control circuit
104 determines that the stabilization circuit 114 has failed. When
the control circuit 104 determines that the stabilization circuit
114 has failed, the control circuit 104 sends a logic one control
signal 166 to the FB network 110, which causes the FB network 110
to stop (at least temporarily) providing the FB signal 164 to the
negative input 138 of the amplification circuit 108, causing the
amplification circuit 108 to operate in an open-loop mode. In some
examples, the control circuit 104 will send a signal to the ECU 116
indicating that the stabilization circuit 114 has failed. In some
examples, although the stabilization circuit 114 has failed (and is
no longer stabilizing amplification circuit 108) the amplification
circuit 108 will continue to send information (signals 152) to the
ECU 116. In some examples, control circuit 104 will not determine
that the stabilization circuit 114 has failed unless a minimum
number of inappropriate HS detection signals 176 and/or LS
detection signals 182 are received in a predetermined interval.
[0037] FIG. 4 illustrates plots of various signals of this
disclosure and their relationship to output signal 152. Plot 400
shows a plot of output signal 152. Plot 402 shows a plot of enable
signal 126.
[0038] As discussed, the control circuit 104 emits a logic one
enable signal 401 during the rising edge intervals 304 of the
output signal 152 and the falling edge intervals 308 of the output
signal 152.
[0039] Plot 404 shows a plot of output current 190 at the
stabilization circuit 114. During normal operations, when the
amplification circuit 108 is operating in a closed-loop mode,
output current 190 flows into the stabilization circuit 114 from
the HS transistor 144 during the rising edge intervals 304, and
output current 190 flows out of the stabilization circuit 114 into
the LS transistor 148 during falling edge intervals 308.
[0040] Plot 406 shows a plot of a HS detection signal 176 in the HS
detector circuit 168 and plot 408 shows a plot of a LS detection
signal 182 in the LS detector circuit 170. Plot 406 and plot 408
collectively illustrate the situation in which the stabilization
circuit 114 is operating within normal parameters. Because the
stabilization circuit 114 is stabilizing the amplification circuit
108, the HS detector circuit 168 detects HS current 186 only during
rising edge intervals 304, and so emits a logic one (HS detection)
signal 403 only during the rising edge intervals 304. Likewise,
because the stabilization circuit 114 is stabilizing the
amplification circuit 108 (along with output signal 152), the LS
detector circuit 170 detects LS current 188 only during falling
edge intervals 308, and so emits a logic one (LS detection) signal
405 only during the falling edge intervals 308.
[0041] Plot 410 shows a plot of a HS detection signal 176 in the HS
detector circuit 168 and plot 412 shows a plot of a LS detection
signal 182 in the LS detector circuit 170. In plot 410, the HS
detector circuit 168 detects HS current 186 during falling edge
intervals 308, and so emits a logic one (HS detection) signal 407
during the falling edge intervals 308. In plot 412, the LS detector
circuit 170 detects LS current 188 during rising edge intervals
304, and so emits a logic one (LS detection) signal 409 during the
falling edge intervals 308. Plot 410 and plot 412 thus correspond
to a situation in which the stabilization circuit 114 is partially
or wholly failing (and the amplification circuit 108 is oscillating
due to the failure).
[0042] Plot 414 shows a plot of a HS detection signal 176 in the HS
detector circuit 168 and plot 416 shows a plot of a LS detection
signal 182 in the LS detector circuit 170. Plot 414 and plot 416
illustrates detection patterns of the HS detector circuit 168 and
LS detector circuit 170 which correspond to a failure condition in
the stabilization circuit 114 which is different from the failure
condition shown in plot 410 and plot 412. In this alternate failure
condition, the HS detector circuit 168 does not detect HS current
186 during one or more rising edges 304 of the output signal 152
and/or the LS detector circuit 170 does not detect LS current 188
during one or more falling edge intervals 308 of the output signal
152. As in the failure condition illustrated in plot 410 and 412,
the control circuit 104 can determine that the stabilization
circuit 114 has failed. As a result, the control circuit 104 will
send a control signal 166 to the FB network 110, which causes the
FB network 110 to stop (at least temporarily) providing the FB
signal 164 to the negative input 138 of the amplification circuit
108, causing the amplification circuit 108 to operate in the
open-loop mode. In some examples, the control circuit 104 will send
a signal to the ECU 116 indicating that the stabilization circuit
114 has failed. In some examples, although the stabilization
circuit 114 has failed (and is no longer stabilizing amplification
circuit 108) the amplification circuit 108 will continue to send
output signals 152 to the ECU 116. In some examples, control
circuit 104 will not determine that the failure condition
corresponding to plot 414 and plot 416 unless the control circuit
104 fails to receive a HS detection signal 176 during one or more
rising edge intervals 304 and/or fails to receive a LS detection
signal 182 during one or more falling edge intervals 308 during
predetermined length of time.
[0043] In at least one example, the control circuit 104 will return
the amplification circuit 108 to the closed-loop mode after causing
the amplification circuit 108 to operate in the open-loop mode for
a predetermined length of time. If, after returning the
amplification circuit 108 to closed-loop mode, another failure of
the stabilization circuit 114 occurs, the control circuit 104 may
return the amplification circuit 108 to the open-loop operating
mode.
[0044] FIG. 5A illustrates details of a HS detector circuit 168.
The HS detector circuit 168 includes HS detection input 174 and
enable input 172. The enable input 172 includes an inverter. The HS
detector circuit 168 also includes a switch 500, a capacitor 502, a
resistor 504 and a comparator 506. The comparator 506 is connected
to the control circuit 104 through detection pin 508. In at least
one example, the switch 500, the capacitor 502, and the resistor
504 are connected to signal ground 115. When the enable signal is
zero (e.g., the controller 104 is not sending an enable signal 126
to the HS detector circuit 168), the enable input 172 closes the
switch 500. That is, the HS detector circuit 168 is shorted by the
switch 500 when the enable signal 126 is logic zero. When the HS
detector circuit 168 is shorted by the switch 500, any charge
stored by the capacitor 502 will be discharged (the capacitor 502
will be in a discharged state when the electronic network 100 is
powered on). When the HS detector circuit 168 is shorted by the
switch 500, the detector circuit 168 is disabled and any current
received through the input 174 will be sent to signal ground 115.
However, under normal conditions, the controller 104 sends an
enable signal 126 (e.g., logic one) only during the rising edge
intervals 304 and the falling edge intervals 308 of the output
signal 152. Unless amplification circuit 108 oscillates, the
detector circuit 168 will detect HS current 156 only during the
rising edge periods 304 when activated by enable signal 126.
[0045] FIG. 5B illustrates details of a LS detector circuit 170.
The LS detector circuit 170 includes LS detection input 180 and
enable input 178. The enable input 178 includes an inverter. The LS
detector circuit 170 also includes a switch 510, a capacitor 512, a
resistor 514 and a comparator 516. The comparator 516 is connected
to the control circuit 104 through detection pin 518. In at least
one example, the switch 510, the capacitor 512, and the resistor
514 are connected to a supply voltage 520. When the enable signal
126 is logic zero, the enable input 178 closes the switch 510. That
is, the LS detector circuit 170 is shorted by the switch 510 when
the enable signal 126 is logic zero. When the LS detector circuit
170 is shorted by the switch 510, any charge stored by the
capacitor 512 will be discharged (the capacitor 512 will be in a
discharged state when the electronic network 100 is initially
powered on). When the LS detector circuit 170 is shorted by the
switch 510, the LS detector circuit 170 is disabled and any current
received through the input 180 will be sent to supply voltage
520.
[0046] However, under normal conditions, the controller 104 sends
an enable signal 126 (logic one) only during the rising edge
intervals 304 and the falling edge intervals 308 of the output
signal 152. Unless amplification circuit 108 oscillates, the LS
detector circuit 170 will detect LS current 188 only during the
falling edge periods 308 when activated by enable signal 126.
[0047] FIG. 6 illustrates a characteristic curve (I-V curve) 600 of
the amplification circuit 108, in which the horizontal axis 602
corresponds to the difference between the voltage of the data
signal 122 and the voltage of the FB signal 164 and the vertical
axis 604 corresponds to current at output pin 154. FIG. 6
illustrates the relationship between HS current 186, LS current
188, and output current 190 (corresponding to output signal 152) on
the one hand, and the difference 184 between the voltage (V(IN) of
data signal 122 and the voltage (V(FB)) of FB signal 164. (FIG. 3
and FIG. 4 illustrate how the voltage (V(OUT) of output signal 152
changes during operation of network 100). Under normal conditions,
during falling edge periods 308 of output signal 152, the LS
detector circuit 170 detects LS current 188 having a magnitude
greater than LS current threshold 606. Similarly, under normal
conditions, during rising edge periods 304, the HS detector circuit
168 will detect HS current 186 having a magnitude greater than HS
current threshold 608. However, if the HS detector circuit 168
detects HS current 186 with a magnitude greater than HS threshold
608 during a falling edge interval 308 (indicating that the
amplification circuit 108 is oscillating), the HS detector circuit
168 will output a HS detection signal 176 to the control circuit
104. If the LS detector circuit 170 detects LS current 188 with a
magnitude that is greater than the LS current threshold 606 during
a rising edge interval 304 (indicating that the amplification
circuit 108 is oscillating), the LS detector circuit 170 will send
a LS detection signal 182 to the control circuit 104. In one or
more embodiments, if the control circuit 104 receives a HS
detection signal 176 during a falling edge interval 308 and/or
receives a LS detection signal 182 during a rising edge interval
304, the control circuit 104 will send a control signal 166 to the
FB network 110 to cause the amplification circuit 108 to switch to
an open-loop operating mode in which the amplification circuit 108
will not receive the FB signal 164 at negative input 138.
[0048] FIG. 7 illustrates a method 700 of operating a driver
circuit, in accordance with an example of this disclosure. The
method comprises receiving 702 a data signal (122) at a data input
(140) of an amplification circuit (108); amplifying 704, using the
amplification circuit (108), the data signal (122) to produce an
output signal (152) through an output pin (154); attenuating 706,
using a feedback network (110), the output signal (152) to produce
a feedback signal (164); coupling 708 the feedback signal (164) to
a feedback input (138) of the amplification circuit (108);
detecting 710, using a control circuit (104), a fault condition of
the amplification circuit (108); and decoupling 712, responsive to
detecting the fault condition, the feedback signal (164) from the
feedback input (138) of the amplification circuit (108).
[0049] In at least one example of the method 700, detecting the
fault condition comprises detecting at least one of a high side
current between a high side transistor and the output pin during a
falling edge interval (308) of the output signal (152) or a low
side current between a low side transistor and the output pin
during a rising edge interval (304) of the output signal (152).
[0050] Embodiments of this disclosure include the following
examples:
[0051] 1. A signal driver, comprising: an amplification circuit
(108) having a first input (138) operable to receive a FB signal
(164) corresponding to an output signal (152), a second input (140)
operable to receive a data signal (122), a first output (154)
operable to provide the output signal (152), a second output (157)
operable to provide a first current signal (186), and a third
output (159) operable to provide a second current signal (188); a
first detector circuit (168) having a first detector input (174)
coupled to the second output (157) of the amplification circuit
(108) and a first detector output (508) operable to provide a first
detection signal (176), wherein the first detection signal (176)
indicates whether a current magnitude of the first current signal
(186) exceeds a first threshold (608); a second detector circuit
(170) having a second detector input (180) coupled to the third
output (159) of the amplification circuit (108) and a second
detector output (518) operable to provide a second detection signal
(182), wherein the second detection signal (182) indicates whether
a current magnitude of the second current signal (188) exceeds a
second threshold (606); and a control circuit (104) having a first
input (130) coupled to the first detector output (508), a second
input (132) coupled to the second detector output (518), and a
first output (124) coupled to the second input (140) of the
amplification circuit (108) operable to provide the data signal
(122) to the amplification circuit (108), wherein the control
circuit (104) is operable to generate a control signal to control
one or more operations of the amplification circuit (104),
responsive to at least one of the first detection signal (176) or
the second detection signal (182)
[0052] 2. The signal driver of embodiment 1, wherein the first
detection signal (176) further indicates whether the first current
signal (186) is within a first operating range (610), and wherein
the second detection signal (182) further indicates whether the
second current signal (188) is within a second operating range
(612).
[0053] 3. The signal driver of embodiment 1, wherein the first
detector circuit (168) comprises: a capacitor (502) having a first
terminal (522) and a second terminal (524), wherein the capacitor
(502) is charged by the first current signal (186); and a
comparator (506) having a comparator input (526) coupled to the
first terminal (522) of the capacitor (502) and a comparator output
(528) coupled to the first detector output (508) operable to
provide the first detection signal (176).
[0054] 4. The signal driver of embodiment 3, wherein the first
detector circuit (168) further comprises: a switch (500) having a
first terminal (538) coupled to the first terminal (522) of the
capacitor (502), a second terminal (540) coupled to the second
terminal (524) of the capacitor (502), and a control input (172)
operable to receive a detector activation signal (126); and wherein
the control circuit (104) has a second output (128) coupled to the
control input (172) operable to provide the detector activation
signal (126) to the first detector circuit (168).
[0055] 5. The signal driver of embodiment 3, wherein the comparator
is a Schmitt trigger.
[0056] 6. The signal driver of embodiment 1, wherein the second
detector circuit (170) comprises: a capacitor (512) having a first
terminal (530) and a second terminal (532), wherein the capacitor
(512) is charged by the second current signal (188); and a
comparator (516) having a comparator input (534) coupled to the
first terminal (530) of the capacitor (512) and an output (536)
coupled to the second detector output (518) operable to provide the
second detection signal (182)
[0057] 7. The signal driver of embodiment 6, wherein the second
detector circuit (170) further comprises: a switch (510) having a
first terminal (542) coupled to the first terminal (530) of the
capacitor (512), a second terminal (544) coupled to the second
terminal (532) of the capacitor (512), and a control input (178)
operable to receive a detector activation signal (126); and wherein
the control circuit (104) has a second output (128) coupled to the
control input (178) operable to provide the detector activation
signal (126) to the first detector circuit (168).
[0058] 8. The signal driver of embodiment 6, wherein the comparator
(516) comprises an analog-to-digital converter.
[0059] 9. The signal driver of embodiment 1, further comprising a
PMOS transistor (144) configured to produce the first current
signal (186).
[0060] 10. The signal driver of embodiment 1, further comprising a
NMOS transistor (148) configured to produce the second current
signal (188).
[0061] 11. The signal driver of embodiment 1, wherein the
amplification circuit (108) comprises a class AB amplifier.
[0062] 12. The signal driver of embodiment 1, further comprising: a
feedback network (110) having a first input (162) coupled to the
output signal (152) of the amplification circuit (108), a second
input operable to receive the control signal (166), and an output
(142) coupled to the first input (138) of the amplification circuit
(108), wherein the feedback network (110) is configured to decouple
the output signal (152) from the first input (138) of the
amplification circuit (108) in response to receiving the control
signal (166); and wherein the control circuit (104) has a control
output (134) coupled to the second input (136) of the feedback
network (110) operable to provide the control signal (166) to the
feedback network (110), responsive to detecting a fault
condition.
[0063] 13. The signal driver of embodiment 12, wherein the fault
condition corresponds to oscillations in the amplification circuit
(108).
[0064] 14. The signal driver of embodiment 12, wherein the fault
condition corresponds to detection of current by the first detector
circuit during one or more falling edge intervals of the output
signal (152).
[0065] 15. The signal driver of embodiment 12, wherein the fault
condition corresponds to detection of current by the second
detector circuit during one or more rising edge intervals of the
output signal (152).
[0066] 16. The signal driver of embodiment 12, wherein the control
circuit (104) is further configured to transmit a fault condition
signal to an electronic control unit in response to receiving at
least one of the first detection signal (176) or the second
detection signal indicating the fault condition.
[0067] 17. The signal driver of embodiment 12, wherein the output
signal (152) of the amplification circuit (108) is connected to a
stabilization circuit, wherein the stabilization circuit is charged
by current of the output signal (152) during one or more rising
edge intervals of the output signal (152) when the output signal
(152) is coupled to the first input (138) of the amplification
circuit (108) by the feedback network (110).
[0068] 18. The signal driver of embodiment 17, wherein the
stabilization circuit is operable to discharge current to the
amplification circuit (108) during one or more falling edge
intervals of the output signal (152) when the output signal (152)
is coupled to the first input (138) of the amplification circuit
(108) by the feedback network (110).
[0069] 19. The signal driver of embodiment 17, wherein the fault
condition corresponds to an increased resistance of the
stabilization circuit.
[0070] 20. The signal driver of embodiment 17, wherein the
stabilization circuit includes a capacitive network comprising one
or more capacitors.
[0071] 21. The signal driver of embodiment 20, wherein the fault
condition corresponds to an increased resistance in at least one of
the one or more capacitors.
[0072] 22. A method of operating a driver circuit, comprising:
receiving a data signal (122) at a data input (140) of an
amplification circuit (108); amplifying, using the amplification
circuit (108), the data signal (122) to produce an output signal
(152) through an output pin (154); attenuating, using a feedback
network (110), the output signal (152) to produce a feedback signal
(164); coupling the feedback signal (164) to a feedback input (138)
of the amplification circuit (108); detecting, using a control
circuit (104), a fault condition of the amplification circuit
(108); and decoupling, responsive to detecting the fault condition,
the feedback signal (164) from the feedback input (138) of the
amplification circuit (108), wherein detecting the fault condition
comprises detecting at least one of a high side current between a
high side transistor and the output pin during a falling edge
interval (308) of the output signal (152) or a low side current
between a low side transistor and the output pin during a rising
edge interval (304) of the output signal (152).
[0073] 23. The method of embodiment 22, wherein detecting the fault
condition further comprises detecting one or more oscillations in
the amplification circuit (108).
[0074] 24. The method of embodiment 22, further comprising:
transmitting, using the control circuit (104), a default condition
signal to an electronic control unit (116), responsive to detecting
the fault condition.
[0075] The embodiments described are illustrative and
non-limiting.
* * * * *