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TLV3492: Looking for low power low side current sense threshold interrupt to MCU

Vasudha Sundar
Prodigy 100 points
Part Number: TLV3492
Other Parts Discussed in Thread: LM321, TLV7041, TLV7031, LPV821

Hi,

I am looking for a compact circuit that will run on coin cell battery (power constrained app)

- need to measure a voltage a current sense resistor placed on a low-side of H-bridge 

- the circuit will generate a interrupt to the MCU 3.3v on exceeding a certain voltage across sense resistor

- currently have a LM321 & NCX2202 reference circuit is available but this will kill my battery due to poor design (see attachment0

- looking for a single package low power circuit to do that  function.

- I have located TLV3492 for this.. let me know if this is a good choice

- please provide any reference circuit to implement the same

I am also on a strict budget as it is a consumer product. so lowest cost is needed

Thank you

Vasudha

  • 0
    TI__Prodigy 600 points

    Hi Vasudha,

    TLV7031 seems to be a good fit to what you've described. It's a nano-power comparator (iQ=335nA) with push-pull output (the sister device TLV7041 has open-drain output).

    Here is an example for a low side current threshold detector (Load represents your circuit load, 100k is just a place holder)

    You could adjust the Vref and Rsense values to set the detection threshold. In the example, the current threshold is set to Vref/Rsense=100mV/1K = 100uA. To be precise, the hysteresis and input offset voltage should be included in the calculation.

    Best.

    -Jian Zhang
    LPAC Apps

  • 0 in reply to Jian Zhang5
    Prodigy 100 points
    Are you saying just a single TLV7031 will do the function of two op-amps in my previous circuit?
  • 0 in reply to Vasudha Sundar
    TI__Prodigy 600 points

    Yes, the original suggestion was using only a single TLV7031 for a simple case assuming your system can tolerant a voltage drop , say >100mV) over the sense resistor and the circuit noise is fairly low.

    Otherwise, a nano-power LPV821 amp can be used to boost the current sense voltage. LPV821 features a IQ of 650nA and has an Unity Gain-Bandwidth of 8 kHz.