CIRCUIT060035

Bidirectional current sensing with a window comparator circuit

CIRCUIT060035

Overview

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.
Features
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
Supply:
  • V+ = 3.3 V
  • V- = 0 V
Comparators
TLV3201-Q1 40ns, micro-Power, Rail-to-Rail Input, Single-Channel Comparator with Push-Pull Outputs TLV3202-Q1 Dual high speed, low power comparator
Current sense amplifiers analog output
INA240 -4 to 80V, bidirectional, ultra-precise current sense amplifier with enhanced PWM rejection

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Technical documentation

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Type Title Date
* Application note Bidirectional current sensing with a window comparator circuit Sep. 16, 2019
Selection guide Current Sense Amplifiers (Rev. E) Sep. 20, 2021
E-book Simplifying Current Sensing (Rev. A) Jan. 09, 2020

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