High-side switch overload detection

Abstract

This application relates to high-side switch overload detection. An apparatus includes a transistor (402) and a controller (210). The transistor (402) has a first terminal, a second terminal, and a control terminal. The controller (210) has an output coupled to the control terminal of the transistor (402) and an input coupled to the second terminal of the transistor (402). The controller (210) is capable of turning on the transistor (402) in response to an enable signal. The controller (210) is also capable of comparing a voltage at the input of the controller (210) to a threshold. The controller (210) is further capable of latching the transistor (402) off or turning the transistor (402) off for a time and then turning the transistor (402) back on in response to a result of the comparison.

Description

Technical Field

[0001] This disclosure generally relates to high-side switching circuits, and more specifically, to high-side switching overload detection. Background Technology

[0002] High-side switching circuits can be connected between a power supply and a load circuit to control the power supply to the load circuit. The switching device (or switch) in a high-side switching circuit can be a repeater or a semiconductor switching device, such as a transistor. Semiconductors offer many advantages over electromechanical switches in high-side switching applications. For example, compared to electromechanical switches, semiconductor switches reduce the risk of electrical sparks, reduce circuit area, and lower costs. Summary of the Invention

[0003] In one example, a device includes a transistor and a controller. The transistor has a first terminal, a second terminal, and a control terminal. The controller has an output coupled to the control terminal of the transistor and an input coupled to the second terminal of the transistor. The controller is capable of turning on the transistor in response to an enable signal. The controller is also capable of comparing the voltage at the controller's input with a threshold. The controller is further capable of, in response to the result of the comparison, latching the transistor into an off state or turning the transistor off for a period of time, and then turning the transistor back on.

[0004] In another example, a circuit includes a switch, a temperature sensor circuit system, a comparator, a logic circuit system, and a switch control circuit. The switch has a control input and a terminal. The temperature sensor circuit system has an output. The comparator has a first input coupled to the terminal of the switch, a reference input, and an output. The logic circuit system has an input coupled to the output of the comparator and an output. The switch control circuit has a first input coupled to the output of the temperature sensor circuit system, a second input coupled to the output of the logic circuit system, and an output coupled to the control input of the switch.

[0005] In another example, a system includes a battery, a load circuit, a processor, and a switching circuit. The battery has terminals. The load circuit has inputs. The processor has outputs. The switching circuit includes a temperature sensor, a transistor, and a controller. The temperature sensor has an output. The transistor has a first terminal coupled to the terminals of the battery, a second terminal coupled to the input of the load circuit, and a control terminal. The controller includes a comparator and a circuit system. The comparator has a first input, a second input, and an output coupled to the second terminal of the transistor. The comparator is capable of providing an output signal in response to comparing a voltage at its input with a reference voltage at its second input. The circuit system has a first input coupled to the output of the processor, a second input coupled to the output of the comparator, and an output coupled to the control terminal of the transistor. The circuit system of the controller is capable of turning on the transistor in response to a first enable signal at the output of the processor and turning off the transistor in response to a signal at the output of the temperature sensor. The controller is also capable of latching the transistor into an off state or turning the transistor off for a period of time and then turning it back on in response to the output signal from the comparator. Attached Figure Description

[0006] Figure 1 This is a block diagram of an example system that includes a high-side switching circuit.

[0007] Figure 2 This is a block diagram of an example high-side switching circuit based on overload severity control switch closure.

[0008] Figure 3 This is a flowchart of an example method for controlling the switching device in a high-side switching circuit.

[0009] Figure 4 yes Figure 2 A schematic diagram of an example high-side switching circuit shows the example internal circuit system.

[0010] Figure 5 This is a flowchart of an example method for controlling switch closure in a high-side switching circuit based on overload severity.

[0011] Figure 6 and 7 yes Figure 2 A graph of example signals in a high-side switching circuit illustrates switch closure control based on overload severity. Detailed Implementation

[0012] In various applications, high-side switching circuits can be used to control the power supply to a load circuit. If the current drawn from the load circuit by the high-side switching circuit exceeds an overload threshold, the high-side switching circuit can limit the current flowing to the load circuit to a selected current value. Control of the current flowing to the load circuit can be implemented by changing the control voltage supplied to a switching device, such as a field-effect transistor (FET). However, reducing the control voltage supplied to the switching device increases the power consumed by the switching device, which may lead to overheating (thermal failure).

[0013] The high-side switching circuit described herein detects overload conditions and selects a response based on the severity of the overload. If the overload exceeds a severity threshold, the high-side switching circuit can latch its internal switch in an open state until it closes in response to a signal received from an external controller. If the overload does not exceed the severity threshold, the high-side switch can temporarily open its internal switch and automatically reclose it after a retry interval. Therefore, the high-side switching circuit can provide a response (latching or automatic retry) selected to maintain switch operation while protecting the high-side switching circuit.

[0014] Figure 1 This is a block diagram of example system 100. System 100 can be included in, for example, a vehicle, a computer, an industrial system, or any other system that uses high-side switching to control power. System 100 includes a voltage source 102, a voltage regulator 104, a processor 106, a high-side switching circuit 108, and a load circuit 110. Voltage source 102 can be a battery, a battery pack, or other voltage generating device. Voltage source 102 has an output at which a source voltage is provided. Voltage regulator 104 has an input coupled to the output of voltage source 102. Voltage regulator 104 converts the source voltage into a regulated voltage suitable for powering processor 106. For example, voltage regulator 104 is a step-down converter for converting the relatively high source voltage provided at the output of voltage source 102 into a lower regulated voltage suitable for powering processor 106. Voltage regulator 104 has an output at which a regulated voltage is provided.

[0015] Processor 106 is powered by a regulated voltage provided by voltage regulator 104. In one example, processor 106 is part of a microcontroller unit (MCU) for other operations of control system 100. When system 100 is an automobile, the MCU may control operations such as engine control, power steering, airbag deployment, infotainment system, advanced driver assistance system (ADAS), etc. The output of voltage regulator 104 is coupled to the input voltage terminal of processor 106. Processor 106 generates an enable signal 112 to trigger the operation of high-side switching circuit 108 (e.g., enabling and disabling current flowing through high-side switching circuit 108). Processor 106 has an output at which the enable signal 112 is provided. The output of processor 106 is coupled to the enable input of high-side switching circuit 108.

[0016] The input voltage terminal (VIN) of the high-side switching circuit 108 is coupled to the output of the voltage source 102. Under the control of an enable signal 112 received from the processor 106, the high-side switching circuit 108 switches the source voltage to the load circuit 110. The output terminal (VOUT) of the high-side switching circuit 108 is coupled to the input voltage terminal of the load circuit 110. The high-side switching circuit 108 provides an output voltage 114 at VOUT for powering the load circuit 110. The load circuit 110 can be any circuit that can be powered by the output voltage 114. For example, in automotive applications, the load circuit 110 may include ADAS circuitry, an automotive display module, or a main control module. The high-side switching circuit 108 can enable current flowing from VIN to VOUT in response to the enable signal 112 having a first state (e.g., logic high), and can disable current flowing from VIN to VOUT in response to the enable signal 112 having a second state (e.g., logic low).

[0017] High-side switching circuit 108 detects the current from VIN to VOUT. If the current exceeds a threshold, high-side switching circuit 108 may reduce current flow, causing the temperature of high-side switching circuit 108 to rise. If the temperature of high-side switching circuit 108 exceeds the threshold (over-temperature condition), high-side switching circuit 108 disables the current from VIN to VOUT. After disabling the current, high-side switching circuit 108 may select a response to the over-temperature condition based on the severity of the overcurrent condition that caused the over-temperature condition. If the overcurrent condition does not exceed the severity threshold, high-side switching circuit 108 may re-enable the current from VIN to VOUT after the retry interval expires. If the overcurrent condition does exceed the severity threshold, high-side switching circuit 108 may disable the current from VIN to VOUT until processor 106 toggles the enable signal. Toggling the enable signal may generally involve changing the state of the enable signal from a first state to a second state, and may more specifically involve changing the state of the enable signal from a first state to a second state and then back to the first state.

[0018] Therefore, the high-side switching circuit 108 can provide a response (latch or automatic retry) to over-temperature conditions based on the severity of the overload, reducing the management of the high-side switching circuit 108 by the processor 106. Because the high-side switching circuit 108 automatically selects the latch or retry operation, the input terminals or non-volatile memory associated with the selection of the latch or retry operation can be omitted, which can reduce package and / or circuit size. In some examples, the high-side switching circuit 108 may be part of an electronic fuse circuit.

[0019] Figure 2 This is a block diagram of an example high-side switching circuit 108 based on overload severity control switch closure. The high-side switching circuit 108 includes a switch 202 (also called a switching device), a controller 204, a temperature sensor 206, and a current sensor 208. Switch 202 can be opened or closed to disable or enable current from VIN to VOUT. Switch 202 has a first terminal coupled to VIN, a second terminal coupled to VOUT, and a control input (also called a control terminal) coupled to controller 204.

[0020] Controller 204 controls switch 202. Controller 204 has an output coupled to a control input of switch 202. Controller 204 provides a control signal at its output to enable or disable the current flowing through switch 202. Controller 204 has a connection to processor 106. Figure 1The controller 204 receives an enable signal 112 as a first input. The controller 204 has a second input coupled to a temperature sensor 206. The temperature sensor 206 measures the temperature of the high-side switching circuit 108 (e.g., the temperature of the die containing the high-side switching circuit 108). The temperature of the high-side switching circuit 108 is largely determined by the temperature of the switch 202. The temperature sensor 206 has an output coupled to the second input of the controller 204. The temperature sensor 206 provides a temperature sensing signal 210 at its output representing the measured temperature of the high-side switching circuit 108. In some examples, the temperature sensing signal 210 is a digital signal indicating whether the temperature of the high-side switching circuit 108 exceeds a threshold (over-temperature threshold). If the temperature of the high-side switching circuit 108 is less than the threshold, the temperature sensing signal 210 may have a first state (e.g., a logic low state). If the temperature of the high-side switching circuit 108 is greater than the threshold, the temperature sensing signal 210 may have a second state indicating an over-temperature condition (e.g., a logic high state).

[0021] Controller 204 has a third input coupled to current sensor 208. Current sensor 208 senses the current flowing through switch 202 and provides a current sensing signal representing the measured current to controller 204. In the example of high-side switching circuit 108, current sensor 208 may be coupled to a first or second terminal of switch 202. Controller 204 may identify overcurrent conditions based on the current sensing signal. For example, controller 204 may include an overcurrent circuit system 415. Overcurrent circuit system 415 may include a function to compare the current sensing signal with one or more current limits (e.g., I0). CL 2I CL The overcurrent circuit system 415 may include a comparator to identify overcurrent conditions (overloads). The overcurrent circuit system 415 may also include logic to turn transistor 402 on or off in response to the detection of an overcurrent condition. Such logic circuit system may include a timer to limit the time (retry interval) during which transistor 402 is turned off in response to an overcurrent condition. The logic circuit system may turn transistor 402 back on in response to the expiration of the retry interval.

[0022] Controller 204 has a fourth input coupled to VOUT. In some examples, controller 204 uses the output voltage 114 provided at VOUT as an indicator of overload severity to determine how to respond to an overtemperature event. If the output voltage 114 provided at VOUT is greater than a reference voltage (e.g., greater than 3 volts) or the inrush interval has not yet expired, controller 204 can respond to the overtemperature condition by opening switch 202 and reclosing it after a retry interval. The inrush interval can be a selected time that begins when switch 202 is closed. If the output voltage 114 provided at VOUT is less than a reference voltage and the inrush interval has expired, switch 202 can respond to the overtemperature condition by opening switch 202 and keeping it open until enable signal 112 switches.

[0023] Figure 3 This is a flowchart of an example method 300 for controlling switch closure in a high-side switching circuit based on overload severity control. Although depicted sequentially for convenience, at least some of the actions shown may be performed in a different order and / or in parallel. Additionally, some embodiments may perform only some of the shown actions. The operation of method 300 can be performed by an example of a high-side switching circuit 108.

[0024] In block 302, enable signal 112 changes the state from logic low to logic high to initiate the closing of switch 202. Enable signal 112 may be provided by circuitry external to the high-side switching circuit 108 (e.g., processor 106). In response to enable signal 112, controller 204 generates a control signal that closes switch 202.

[0025] In block 304, controller 204 determines whether an over-temperature condition has been detected. An over-temperature condition can be detected by temperature sensor 206. Temperature sensor 206 measures the temperature of high-side switching circuit 108 and provides a temperature sensing signal 210 indicating the presence of an over-temperature condition if the temperature of high-side switching circuit 108 exceeds a threshold.

[0026] If an overtemperature condition is detected, then in block 306, controller 204 sets a latching mode and generates a control signal to open switch 202. The latching mode indicates how controller 204 will respond to the overtemperature condition after switch 202 is opened. Controller 204 can set the latching mode based on output voltage 114 exceeding a threshold, where the relationship between output voltage 114 and the threshold indicates the severity of the overload causing the overtemperature condition. If output voltage 114 exceeds the threshold, the overload may be less severe, and the latching mode can be set to retry. If output voltage 114 is below the threshold, the overload may be more severe, and the latching mode can be set to latch.

[0027] In block 308, if the latch mode is set to retry, then controller 204 delays the retry time interval in block 310 and recloses switch 202 in block 302. The retry time interval may include a period of time sufficient for the temperature of the high-side switching circuit 108 to drop below the over-temperature threshold.

[0028] In block 308, if the latch mode is not set to retry (for example, the latch mode is set to latch), then in block 312, controller 204 keeps switch 202 open until enable signal 112 toggles. When enable signal 112 toggles, controller 204 closes switch 202 in block 302.

[0029] Figure 4 This is a schematic diagram of an example high-side switching circuit 400. High-side switching circuit 400 is an example of high-side switching circuit 108. High-side switching circuit 400 includes controller 204, temperature sensor 206, current sensor 208, and transistor 402. Transistor 402 is a switching device that implements switch 202. Transistor 402 acts as a pass transistor, conducting current between VIN and VOUT. Transistor 402 may be an n-channel metal-oxide-semiconductor field-effect transistor (NFET). Transistor 402 has a first terminal coupled to VIN (e.g., drain). Transistor 402 has a second terminal coupled to VOUT (e.g., source). Transistor 402 has a control terminal coupled to the output of controller 204 (e.g., gate). Current sensor 208 is coupled to the second terminal of transistor 402 and can be implemented using a sensing transistor or a sensing resistor in various examples. In the example of high-side switching circuit 400, current sensor 208 may be coupled to either the first or second terminal of transistor 402.

[0030] Controller 204 includes switch control circuitry 404. Switch control circuitry 404 provides a control signal that turns transistor 402 on or off (e.g., opens or closes switch 202, as described with respect to high-side switch circuitry 108). Switch control circuitry 404 includes regulation circuitry 414 and retry timer 416. Regulation circuitry 414 sets the voltage of the control signal to regulate the current flowing through transistor 402. For example, if a sensing signal provided by current sensor 208 indicates that the current flowing through transistor 402 exceeds a threshold, then regulation circuitry 414 can decrease the voltage of the control signal to decrease the current flowing through transistor 402.

[0031] Retry timer 416 defines a retry interval for turning transistor 402 back on after it has been turned off due to an over-temperature condition. In some examples of the switch control circuit 404, the retry interval can be variable. For example, the retry interval can include an over-temperature interval defined by the temperature sensing signal 210, such that transistor 402 remains off until the temperature of the high-side switch circuit 400 is below an over-temperature threshold. Therefore, some examples of the switch control circuit 404 include an output coupled to the temperature sensor 206 to receive the input of the temperature sensing signal 210.

[0032] Based on the severity of the overload, controller 204 determines, in response to an over-temperature condition, whether switch control circuit 404 should retry turning on transistor 402 or latch transistor 402 into an off state. Controller 204 also includes comparator 420, voltage reference circuit 406, inrush timer 408, logic gate 410, and flip-flop 412. Comparator 420 compares the output voltage 114 at VOUT with a reference voltage (VREF) provided by voltage reference circuit 406. Comparator 420 has a first input (e.g., a non-inverting input) coupled to VOUT to receive the output voltage 114. Comparator 420 has a second input (e.g., an inverting input) coupled to the output of voltage reference circuit 406 to receive VREF. Comparator 420 has an output providing an output signal VOUT>VREF. VOUT>VREF is an indicator of overload severity. If the output voltage 114 is greater than VREF, then VOUT>VREF may have a first state (e.g., a logic high state), indicating that the overload is not severe. If the output voltage 114 is less than VREF, then VOUT>VREF may have a second state (e.g., a logic low state), indicating a severe overload.

[0033] Inrush timer 408 times an interval starting from the turn-on of transistor 402 (e.g., an inrush interval that begins when enable signal 112 transitions to a first logic state). Inrush timer 408 has an input coupled to EN to receive enable signal 112. Inrush timer 408 has an output providing an inrush timing signal 424. The inrush signal may have a first state (e.g., a logic high state) between the turn-on of transistor 402 and the end of the inrush interval. The inrush timing signal 424 may have a second state (e.g., a logic low state) after the end of the inrush interval. Inrush timer 408 may be reset in response to the enable signal having the second state or in response to the enable signal transitioning to the first state. The inrush interval defines a period during which the capacitor of load circuit 110 can be charged after transistor 402 is turned on and during which the current flowing through transistor 402 can be relatively high.

[0034] Logic gate 410 has a first input coupled to the output of inrush timer 408. Logic gate 410 has a second input coupled to the output of comparator 420. Logic gate 410 has an output at which a latch signal 418 is provided. Logic gate 410 combines the inrush signal and VOUT>VREF to produce latch signal 418. Latch signal 418 may have a first state (e.g., a logic low state) during the inrush interval or if VOUT>VREF is in a logic high state. If VOUT>VREF is in a logic low state, then latch signal 418 may have a second state (e.g., a logic high state) after the inrush interval.

[0035] Flip-flop 412 stores the state of latch signal 418 provided by logic gate 410 in response to temperature sensing signal 210 provided by temperature sensor 206. Flip-flop 412 has an output coupled to logic gate 410 to receive data input (D) of latch signal 418. Flip-flop 412 has a clock input (CLK) coupled to the output of temperature sensor 206. Flip-flop 412 has a reset input (CLRZ) coupled to EN to receive enable signal 112. Flip-flop 412 has an output (Q) at which latch mode signal 422 is provided. The output of flip-flop 412 is coupled to a first input of switch control circuit 404.

[0036] If enable signal 112 is in a logic low state, then flip-flop 412 sets latch mode signal 422 to indicate that switch control circuit 404 should retry turning on transistor 402. If enable signal 112 is in a logic high state, then flip-flop 412 stores the state of latch signal 418 in response to a transition of temperature sensing signal 210 (e.g., a rising edge) and sets latch mode signal 422 to the state of latch signal 418. Therefore, if the inrush interval has expired and output voltage 114 is less than VREF, then in response to an over-temperature condition (caused by an over-current condition), latch mode signal 422 indicates that transistor 402 should be latched in an off state. During the inrush interval, or if output voltage 114 is greater than VREF, latch mode signal 422 indicates that transistor 402 should be retried.

[0037] Therefore, via latch mode signal 422, controller 204 instructs switch control circuit 404 to retry turning on transistor 402 during the inrush interval (when an overcurrent condition can be caused by the charging of the capacitor in load circuit 110) or when the severity of the overload is relatively low. After the inrush interval expires, if the severity of the overload is relatively high, controller 204 instructs switch control circuit 404 via latch mode signal 422 to latch transistor 402 in the off state until enable signal 112 switches. Controller 204 changes the state of latch mode signal 422 in response to temperature sensing signal 210.

[0038] Figure 5 This is a flowchart of an example method 500 for controlling switch closure in a high-side switching circuit based on overload severity. Although depicted sequentially for convenience, at least some of the actions shown may be performed in a different order and / or in parallel. Additionally, some embodiments may perform only some of the shown actions. The operation of method 500 can be performed by an example of a high-side switching circuit 400.

[0039] In block 502, enable signal 112 changes the state from logic low to logic high to initiate the activation of transistor 402. Enable signal 112 may be provided by circuitry external to the high-side switching circuit 400 (e.g., processor 106).

[0040] In block 504, controller 204 turns on transistor 402. Inrush timer 408 initiates the timing of inrush intervals in response to a change in state of enable signal 112 in block 502.

[0041] In block 506, controller 204 determines whether the current flowing through transistor 402 exceeds the current limit (I) based on the current sensing signal received from current sensor 208. CL (Controller 204 tests overcurrent conditions). If the current does not exceed the threshold, then in block 506, controller 204 continues to monitor the current.

[0042] If the current flowing through transistor 402 in block 506 exceeds the current limit, then in block 508, controller 204 initiates current regulation. Controller 204 (via regulation circuit 414) can adjust (e.g., reduce) the control voltage supplied to transistor 402 to regulate the current flowing through transistor 402.

[0043] In block 510, controller 204 determines whether the current flowing through transistor 402 has been regulated (e.g., the current has been reduced to below a threshold). If the current has not been regulated, then controller 204 sets the current flowing through transistor 402 against a second threshold (e.g., 2I). CLThe comparison is performed. If the current flowing through transistor 402 does not exceed the second threshold, the method returns to block 508 to check the regulation.

[0044] If the current flowing through transistor 402 in block 512 exceeds the second threshold, then in block 514, controller 204 turns off transistor 402. After turning off transistor 402, controller 204 may wait for a selected time (e.g., 50 microseconds), turn transistor 402 back on, and return to block 506 to test for overload.

[0045] The regulation of the current flowing through transistor 402 increases the voltage (drain-to-source voltage) across transistor 402, thereby increasing the power dissipated by transistor 402 and causing the temperature to rise. If the current flowing through transistor 402 has been regulated in block 510, then in block 516, controller 204 continues to regulate the current until the temperature sensing signal 210 provided by temperature sensor 206 indicates that the temperature of high-side switching circuit 400 exceeds a threshold (e.g., an over-temperature condition exists).

[0046] In block 518, controller 204 determines whether the output voltage 114 supplied at VOUT exceeds a threshold defined by VREF (e.g., 3 volts). If the output voltage 114 exceeds the threshold, controller 204 turns off transistor 402 in block 522 and starts retry timer 416. When the retry interval expires, controller 204 can turn transistor 402 back on and return to block 506 to continue method 500.

[0047] If the output voltage 114 provided at VOUT in block 518 does not exceed the threshold, then in block 520, controller 204 determines whether the inrush interval has expired. If the inrush interval has not expired, then controller 204 turns off transistor 402 in block 522 and starts retry timer 416. When the retry interval expires, controller 204 can turn transistor 402 back on and return to block 506 to continue method 500. Therefore, during the inrush interval, when the capacitor of load circuit 110 is charging and drawing a relatively high current, high-side switching circuit 400 can turn off and back on transistor 402 (retry) without external intervention.

[0048] If, in block 520, the inrush interval has expired when an over-temperature condition (in block 516) is detected, then in block 524, controller 204 turns off transistor 402 and latches (holds) transistor 402 in the off state until signal 112 switching is enabled in block 526. If signal 112 switching is enabled in block 526, then method 500 continues in block 504.

[0049] Figure 6 and 7This is a graph of an example signal in the high-side switching circuit 400, illustrating control based on overload severity. Figure 6 and 7 The following signals are shown: enable signal 112, output voltage 114, current 614 through transistor 402, gate-source voltage 616 of transistor 402, VOUT>VREF, inrush time signal 424, latch signal 418, and temperature sensing signal 210. Figure 6 The retry operation in response to a less severe overload is illustrated. At time 602, enable signal 112 transitions, and controller 204 turns on transistor 402 (VGS rises) and starts inrush timer 408. The output voltage 114 rises to approximately 13.5 volts with a current of approximately 135 mA. Inrush time signal 424 is logic high during the inrush interval. If the inrush signal is logic high or the output voltage 114 exceeds a threshold voltage (e.g., 3 volts), then latch signal 418 is logic low. At time 604, the inrush interval expires, and inrush time signal 424 transitions from logic high to logic low.

[0050] At time 606, the load resistance decreases, and the current through transistor 402 increases to approximately 1 ampere. This current exceeds the current limit of the high-side switching circuit 400. The high-side switching circuit 400 senses the overcurrent condition, turns off transistor 402, and the output voltage 114 drops to zero. In response to the decrease in output voltage 114, VOUT>VREF transitions from logic high to logic low.

[0051] At time 608, controller 204 turns on transistor 402, where the gate voltage decreases to limit the current flowing through transistor 402, and output voltage 114 rises to approximately 6 volts. In response to the increase in output voltage 114, VOUT>VREF transitions from logic low to logic high. The temperature of the high-side switching circuit 400 increases in response to the current flowing through transistor 402, and at time 610, the temperature of the high-side switching circuit 400 exceeds an over-temperature threshold. Temperature sensing signal 210 transitions from logic low to logic high to indicate the over-temperature condition. At time 610, output voltage 114 exceeds a reference voltage (e.g., output voltage 116 is greater than 3 volts), and the inrush interval expires. Therefore, latch signal 418 is logic low, controller 204 sets the latch mode to retry, and controller 204 turns off transistor 402.

[0052] At time 612, the temperature of the high-side switching circuit 400 has dropped below the over-temperature threshold. Controller 204 is set to retry, and controller 204 re-energizes transistor 402. The output voltage 114 rises again to approximately 6 volts. Therefore, if the output voltage 114 of the high-side switching circuit 400 indicates a relatively minor overload, then the high-side switching circuit 400 operates in retry mode.

[0053] Figure 7 The latching operation in response to a relatively severe overload is illustrated. At time 702, the enable signal 112 transitions, and the controller 204 turns on transistor 402 (gate-to-source voltage 716 rises) and starts the inrush timer 408. With a current 714 of approximately 135 mA, the output voltage 114 rises to approximately 13.5 volts. The inrush time signal 424 is logic high during the inrush interval. If the inrush signal is logic high or the output voltage 114 exceeds a threshold voltage (e.g., 3 volts), then the latch signal 418 is logic low. At time 704, the inrush interval expires, and the inrush time signal 424 transitions from logic high to logic low.

[0054] At time 706, the load resistance decreases, and the current 714 through transistor 402 increases to approximately 1.76 amps. This current 714 exceeds the current limit of the high-side switching circuit 400. The high-side switching circuit 400 senses the overcurrent condition, turns off transistor 402, and the output voltage 116 drops to zero. In response to the decrease in output voltage 114, VOUT>VREF transitions from logic high to logic low.

[0055] At time 708, controller 204 turns on transistor 402, where the gate-to-source voltage 716 decreases to limit the current 714 flowing through transistor 402, and the output voltage 114 rises to approximately 1.36 volts. The output voltage 114 is less than the reference voltage (VREF) provided by voltage reference circuit 406, and VOUT>VREF remains logic low. The temperature of high-side switching circuit 400 increases in response to the current flowing through transistor 402, and at time 710, the temperature of high-side switching circuit 400 exceeds the over-temperature threshold. Temperature sensing signal 210 transitions from logic low to logic high to indicate the over-temperature condition. With VOUT>VREF logic low and the inrush signal logic low, controller 204 latches transistor 402 in an off state until enable signal 112 transitions from logic low to logic high. Therefore, after temperature sensing signal 210 transitions from logic high to logic low at time 712, transistor 402 remains off until the enable signal switches.

[0056] In this description, the term "coupled" may encompass a connection, communication, or signaling path that enables the functional relationship to be consistent with this specification. For example, if device A generates a signal to control device B to perform an action, then: (a) in a first example, device A is coupled to device B via a direct connection; or (b) in a second example, device A is coupled to device B via an intermediate component C, provided that the intermediate component C does not alter the functional relationship between device A and device B, such that device B is controlled by device A via the control signal generated by device A.

[0057] As used herein, the terms “terminal,” “node,” “interconnect,” “pin,” and “lead” are used interchangeably. Unless otherwise specified, these terms are generally used to refer to interconnects or terminals between device elements, circuit elements, integrated circuits, devices, or other electronic or semiconductor components.

[0058] The circuits or devices described herein as containing certain components can conversely be adapted to be coupled to components used to form the described circuit system or device. For example, a structure described as containing one or more semiconductor elements (e.g., transistors), one or more passive elements (e.g., resistors, capacitors, and / or inductors), and / or one or more sources (e.g., voltage sources and / or current sources) may substantially contain only semiconductor elements within a single physical device (e.g., a semiconductor die and / or integrated circuit (IC) package) and may be adapted to be coupled to at least some of the passive elements and / or sources to form the described structure during or after manufacturing, for example, by an end user and / or a third party.

[0059] While the use of specific transistors is described herein, other transistors (or equivalent devices) may be used alternatively with minimal alteration to the rest of the circuit system. For example, field-effect transistors (“FETs”) (e.g., n-channel FETs (NFETs) or p-channel FETs (PFETs)), bipolar junction transistors (BJTs, such as NPN or PNP transistors), insulated-gate bipolar transistors (IGBTs), and / or junction field-effect transistors (JFETs) may be used in place of or in combination with the devices described herein. Transistors may be depletion-mode devices, drain-extended devices, enhancement-mode devices, natural transistors, or other types of device structure transistors. Furthermore, the devices may be implemented in or on a silicon (Si) substrate, a silicon carbide (SiC) substrate, a gallium nitride (GaN) substrate, or a gallium arsenide (GaAs) substrate.

[0060] The claims may refer to the control input and current terminals of a transistor. In the context of a FET, the control input (or transistor control terminal) is the gate, and the current terminals are the drain and source. In the context of a BJT, the control input is the base, and the current terminals are the collector and emitter.

[0061] In this article, "FET on" means that a conductive channel exists in the FET and drain current can flow through it. "FET off" means that no conductive channel exists, and therefore drain current does not flow through the FET. However, an "off" FET can still have current flowing through the body diode of the transistor.

[0062] The circuits described herein are reconfigurable to include additional or different components to provide functionality at least partially similar to that available before the component replacement. Unless otherwise stated, components shown as resistors generally represent any one or more elements coupled in series and / or parallel to provide a certain amount of impedance represented by the resistor shown. For example, a resistor or capacitor shown and described herein as a single component can actually be multiple resistors or capacitors respectively coupled in parallel between the same nodes. Conversely, a resistor or capacitor shown and described herein as a single component can be multiple resistors or capacitors respectively coupled in series between the same two nodes as a single resistor or capacitor.

[0063] While some elements in the described examples are included in the integrated circuit and others are external to the integrated circuit, in other example embodiments, additional or fewer features may be incorporated into the integrated circuit. Additionally, some or all features shown as being external to the integrated circuit may be included in the integrated circuit, and / or some features shown as being internal to the integrated circuit may be incorporated externally. As used herein, the term "integrated circuit" means one or more circuits that are: (i) incorporated in / on a semiconductor substrate; (ii) incorporated in a single semiconductor package; (iii) incorporated in the same module; and / or (iv) incorporated in / on the same printed circuit board.

[0064] The use of the phrase "grounding" in the foregoing description includes chassis grounding, earth grounding, floating grounding, virtual grounding, digital grounding, common grounding, and / or any other form of grounding connection applicable to or suitable for the teachings of this specification. In this specification, unless otherwise stated, "about," "approximately," or "substantially" preceding a parameter means a difference of no more than + / - 10% from the parameter, or, if the parameter is zero, a reasonable range near zero.

[0065] Within the scope of the claims, the described embodiments may be modified, and other embodiments are possible.

Claims

1. An apparatus comprising: A transistor having a first terminal, a second terminal, and a control terminal; as well as A controller having an output coupled to the control terminal of the transistor and an input coupled to the second terminal of the transistor, the controller being capable of: In response to the enable signal, the transistor is turned on; Compare the voltage at the input of the controller with a threshold; as well as In response to the result of the comparison, the transistor is either latched into an off state or turned off for a period of time, and then the transistor is turned back on.

2. The device of claim 1, wherein the controller is capable of latching the transistor in an off state in response to the voltage being less than the threshold.

3. The device of claim 1, wherein the controller is capable of turning off the transistor for the time specified, and then turning the transistor back on in response to the voltage exceeding the threshold.

4. The device according to claim 1, wherein: The input is the first input; The controller has a second input; and The controller includes a timer capable of timing the influx interval; and the controller is capable of: In response to the influx interval not yet having expired: Delay the selected time; and A control signal is provided at the output of the controller, the control signal having a first state selected to turn on the transistor; and In response to the expiration of the inflow interval: The control signal is provided with a second state, which is selected to turn off the transistor until an enable signal received at the second input of the controller switches on. and In response to the enable signal switching, a control signal is provided having the first state selected to turn on the transistor.

5. The device of claim 4, wherein the controller is capable of activating the timer in response to a change in the enable signal.

6. The device according to claim 4, further comprising: A temperature sensor having an output, the temperature sensor being able to provide a temperature sensing signal at the output of the temperature sensor; The controller has a third input coupled to the output of the temperature sensor; and the controller is capable of providing a control signal having a second state in response to the temperature sensing signal indicating an overtemperature condition, the second state being selected to turn off the transistor.

7. The device of claim 6, wherein the controller comprises: A voltage reference circuit with an output; A comparator having a first input coupled to the second terminal of the transistor, a second input coupled to the output of the voltage reference circuit, and an output; A logic gate having a first input coupled to the output of the comparator, a second input coupled to the output of the timer, and an output; as well as A trigger having a data input coupled to the output of the logic gate, a clock input coupled to the output of the temperature sensor, and an output, wherein a mode signal provided at the output of the trigger has a first state indicating a retry operation and a second state indicating a latch operation.

8. A circuit comprising: A switch, which has control inputs and terminals; A temperature sensor circuit system with an output; A comparator having a first input, a reference input, and an output coupled to the terminal of the switch; A logic circuit system having inputs and outputs coupled to the output of the comparator; as well as A switch control circuit having a first input coupled to the output of the temperature sensor circuit system, a second input coupled to the output of the logic circuit system, and an output coupled to the control input of the switch.

9. The circuit according to claim 8, wherein: The input of the logic circuit system is the first input; The logic circuit system has a second input; and The circuit includes a timer with an output coupled to the second input of the logic circuit system.

10. The circuit of claim 9, wherein the logic circuit system comprises a logic gate having a first input coupled to the output of the comparator, a second input coupled to the output of the timer, and an output.

11. The circuit of claim 10, wherein the logic circuit system comprises a flip-flop having a data input coupled to the output of the logic gate, a clock input coupled to the output of the temperature sensor circuit system, and an output coupled to the second input of the switch control circuit.

12. The circuit according to claim 11, wherein: The temperature sensor circuit system is capable of detecting over-temperature conditions; The comparator can compare the output voltage provided by the switch with a threshold. The switch control circuit is capable of: In response to the over-temperature condition, the switch is disconnected; as well as After the switch is opened, the switch is closed in response to the output voltage exceeding the threshold.

13. The circuit of claim 12, further comprising an inflow timer capable of timing the inflow interval that begins when the switch is closed; in: The logic circuit system is able to determine whether the inflow interval has expired in response to the disconnection of the switch; The switch control circuit is capable of: In response to the fact that the inflow interval has not expired and the retry interval has expired after the switch is opened, the switch is closed; as well as In response to the expiration of the inrush interval, the output voltage not exceeding the threshold and the receipt of an enable signal, the switch is closed.

14. The circuit of claim 12, wherein the temperature sensor circuit system is capable of: Measure the temperature of the switch; and Compare the stated temperature with the over-temperature threshold; and A temperature sensing signal is provided to indicate that the temperature exceeds the over-temperature threshold.

15. A system comprising: A battery having terminals; A load circuit having an input; A processor that has output; as well as A switching circuit, comprising: Temperature sensor with output; A transistor having a first terminal coupled to the terminal of the battery, a second terminal coupled to the input of the load circuit, and a control terminal; The controller includes: A comparator having a first input, a second input, and an output coupled to the second terminal of the transistor, the comparator being able to provide an output signal in response to comparing a voltage at its input with a reference voltage at its second input; A circuit system having a first input coupled to the output of the processor, a second input coupled to the output of the comparator, and an output coupled to the control terminal of the transistor, the circuit system of the controller being capable of: In response to a first enable signal at the output of the processor, the transistor is turned on; In response to a signal at the output of the temperature sensor, the transistor is turned off; as well as In response to the output signal from the comparator, the transistor is latched into an off state or turned off for a period of time, and then turned back on.

16. The system according to claim 15, wherein: The controller has a third input; and The controller is capable of: The transistor is turned off until an enable signal is received at the third input of the controller; as well as In response to the enable signal switching, the transistor is turned on.

17. The system of claim 15, wherein the controller includes a timer with an output, the timer being capable of timing inrush intervals; and the controller being able to: Delay the selected time; and Turn on the transistor.

18. The system of claim 17, wherein the controller is capable of: In response to the expiration of the inrush interval, the transistor is turned off until an enable signal received at the second input of the controller switches off; and In response to the enable signal switching, the transistor is turned on.

19. The system of claim 18, wherein the controller is capable of activating the timer in response to a change in the enable signal.

20. The system of claim 17, wherein the circuit system comprises: A logic gate having a first input coupled to the output of the comparator, a second input coupled to the output of the timer, and an output; and A trigger having a data input coupled to the output of the logic gate, a clock input coupled to the output of the temperature sensor, and an output, wherein a mode signal provided at the output of the trigger has a first state indicating a retry operation and a second state indicating a latch operation.

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