Temperature-Compensated Current Monitoring

Abstract

Systems, methods and media for current monitoring are provided herein. An exemplary method may include: receiving a temperature of a power MOSFET, the temperature being sensed by a temperature sensor; determining a resistance of the power MOSFET using the received temperature; receiving a voltage across the power MOSFET, the voltage being measured by a differential amplifier; calculating a current provided to an electrical load by the power MOSFET using the determined resistance of the power MOSFET and the received voltage; comparing the calculated current to a predetermined threshold; and switching the power MOSFET to an off state in response to the calculated current exceeding the predetermined threshold.

What is claimed is: 
     
         1 . A system for monitoring current comprising:
 an electrical load;   a power MOSFET electrically coupled to the electrical load;   a differential amplifier electrically coupled to a source and a drain of the power MOSFET;   a temperature sensor thermally coupled to the power MOSFET;   a processor communicatively coupled to the differential amplifier and the temperature sensor; and   a memory communicatively coupled to the processor, the memory storing instructions executable by the processor to perform a method comprising:
 receiving a temperature of the power MOSFET, the temperature being sensed by the temperature sensor, 
 determining a resistance of the power MOSFET using the received temperature, 
 receiving a voltage across the power MOSFET, the voltage being measured by the differential amplifier, 
 calculating a current provided to the electrical load by the power MOSFET using the determined resistance of the power MOSFET and the received voltage, 
 comparing the calculated current to a predetermined threshold, and 
 switching the power MOSFET to an off state in response to the calculated current exceeding the predetermined threshold. 
   
     
     
         2 . The system of  claim 1  further comprising:
 a display, the display providing the notification to the user. 
 
     
     
         3 . The system of  claim 1  further comprising:
 a substrate, the power MOSFET and temperature sensor being disposed on the substrate. 
 
     
     
         4 . The system of  claim 1  further comprising:
 a heat sink, the heat sink being thermally coupled to the power MOSFET and the temperature sensor. 
 
     
     
         5 . The system of  claim 1  wherein the method further comprises:
 providing a notification to a user in response to the calculated current exceeding the predetermined threshold, the notification directing the user to service the electrical load. 
 
     
     
         6 . The system of  claim 1  wherein the MOSFET is an n-type MOSFET. 
     
     
         7 . The system of  claim 6  wherein the power MOSFET is in a high-side configuration. 
     
     
         8 . The system of  claim 1  wherein the MOSFET is a p-type MOSFET. 
     
     
         9 . The system of  claim 1  wherein the differential amplifier is a single-ended non-inverting op-amp. 
     
     
         10 . The system of  claim 1  wherein the differential amplifier is at least one of a current shunt monitor (CSM), difference amplifier (DA), and instrumentation amplifier (IA). 
     
     
         11 . The system of  claim 1  wherein the temperature sensor is an integrated silicon-based sensor. 
     
     
         12 . The system of  claim 1  wherein the temperature sensor is at least one of a thermocouple, resistive temperature device (RTD), and thermistor. 
     
     
         13 . A method for current monitoring by a processor comprising:
 receiving a temperature of a power MOSFET, the temperature being sensed by a temperature sensor;   determining a resistance of the power MOSFET using the received temperature;   receiving a voltage across a source and a drain of the power MOSFET, the voltage being measured by a differential amplifier;   calculating a current provided to an electrical load by the power MOSFET using the determined resistance of the power MOSFET and the received voltage;   comparing the calculated current to a predetermined threshold; and   switching the power MOSFET to an off state in response to the calculated current exceeding the predetermined threshold.   
     
     
         14 . The method of  claim 13  wherein receiving the temperature of the power MOSFET includes:
 receiving an analog voltage from the temperature sensor, the analog voltage representing the temperature of the power MOSFET; and 
 converting the analog voltage to a digital number by an analog to digital converter, the digital number representing the temperature of the power MOSFET. 
 
     
     
         15 . The method of  claim 13  wherein receiving a voltage across the power MOSFET includes:
 receiving an analog voltage from the differential amplifier, the analog voltage representing the temperature of the power MOSFET; and 
 converting the analog voltage to a digital number by an analog to digital converter, the digital number representing the voltage across the power MOSFET. 
 
     
     
         16 . The method of  claim 13  wherein determining the resistance of the power MOSFET includes using the received temperature to evaluate a second order polynomial. 
     
     
         17 . The method of  claim 13  wherein calculating the current includes using the determined resistance of the power MOSFET and the received voltage to evaluate Ohm's Law. 
     
     
         18 . The method of  claim 13  further comprising:
 providing a notification to a user in response to the calculated current exceeding the predetermined threshold, the notification directing the user to service the electrical load. 
 
     
     
         19 . A non-transitory computer-readable storage medium having embodied thereon instructions, the instructions being executable by a processor to perform a method for current monitoring, the method comprising:
 receiving a temperature of a power MOSFET, the temperature being sensed by a temperature sensor;   determining a resistance of the power MOSFET using the received temperature;   receiving a voltage across a source and a drain of the power MOSFET, the voltage being measured by a differential amplifier;   calculating a current provided to an electrical load by the power MOSFET using the determined resistance of the power MOSFET and the received voltage;   comparing whether the calculated current exceeds a predetermined threshold; and   switching the power MOSFET to an off state in response to the calculated current exceeding the predetermined threshold.   
     
     
         20 . The non-transitory computer-readable storage medium of  claim 19 , wherein the method further comprises:
 providing a notification to a user in response to the calculated current exceeding the predetermined threshold, the notification directing the user to service the electrical load.