Bidirectional current sensing with a window comparator circuit



This bidirectional current sensing solution uses a current-sense amplifier and a high-speed dual comparator with a rail-to-rail input common mode range to create over-current (OC) alert signals at the comparator outputs (OUTA and OUTB) if the input current (IG1) rises above 100 A or falls below -35 A. In this implementation, both over-current alert signals are active high, so when the 100 A or -35 A thresholds are crossed, the comparator outputs will go high. External hysteresis is implemented on both comparators so that the comparator outputs will return to logic low states when the current reduces by 10% (90 A and -31 A). While the circuit below has shunt resistor R8 connected to ground, the same circuit is applicable for high side current sensing up to the common mode voltage range of the INA.
System current levels:
  • Falling OC threshold : IG1 < -35 A
  • Falling OC recovery: IG1 > -31 A
  • Rising OC threshold: IG1 > 100 A
  • Rising OC recovery: IG1 < 90 A
  • V+ = 3.3 V
  • V- = 0 V
TLV3201-Q1 40ns, micro-Power, Rail-to-Rail Input, Single-Channel Comparator with Push-Pull Outputs TLV3202-Q1 Dual high speed, low power comparator
Analog current-sense amplifiers
INA240 -4 to 80V, bidirectional, ultra-precise current sense amplifier with enhanced PWM rejection
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Type Title Date
* Circuit design Bidirectional current sensing with a window comparator circuit 16 Sep 2019
E-book An Engineer's Guide to Current Sensing (Rev. B) 12 Apr 2022
Selection guide Current Sense Amplifiers (Rev. E) 20 Sep 2021
E-book Spacecraft Circuit Design Handbook 11 Aug 2021

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