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ISO1540: Size of the pull up resistor

Intellectual 1660 points

Replies: 1

Views: 47

Part Number: ISO1540

Hello all,

my customer wants to use our ISO1540 to isolate four different device. Two times our INA220, one TMP112 and one of our LED driver.

He ask my what would be our recommendation for the pull up resistor on our device? He wants to use 1kOhm. Does this work?

Best regards


  • Hi Egon,

    Customer can choose any value for the pull-up resistor as long as it doesn't exceed the output sink current of ISO1540 channels. The current that can be sunk into Side1 & Side2 channels when operating as outputs is from 0.5mA to 3.5mA & 35mA, respectively. Based on the VCC1 & VCC2 voltages, customer can choose the pull-up resistor value such that IOL1 & IOL2 are in recommended operating range.

    Choosing higher resistance to keep currents to lower values makes the device power efficient but will increase rise and fall times. Similarly, choosing smaller values will give fast rise and fall times but will increase power consumption. Based on whether fast timings are important or power consumption, customer choose the resistor values accordingly. Thanks.

    Koteshwar Rao