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OPA170: Alternative with different ESD structure?

Part Number: OPA170
Other Parts Discussed in Thread: TLV2450

Hi team,

I have a customer using the OPA170 in a design, and during prototype testing they ran into the below issue:

We are using the TI OPA170 on a new controller board for the purpose of battery cell measurement. In order to reduce power consumption while the system is asleep, we have a circuit to turn off V+ under MOSFET control. V- supply and a bias voltage into VIN+ remain powered, while VIN- is not.

During final engineering testing, we discovered that there is a negative leakage path across the ESD protection diode structure and the pass diode in the FET to the cell voltage that normally powered V+.  This can cause an imbalance between the cells over time.

The OPA170's data sheet shows the diode protection structure below:

We would like to know if there are other pin-compatible TI op-amps (SOT-23) with a different type of ESD clamp that does not pass current from VIN+ to V+.  We understand that the TLV2450 uses a different type of clamp, but that op-amp is not compatible.

Thanks guys,

Brian Antheunisse


  • Brian,

    Almost all of the op amps include ESD protection diode between each pin and the rails but not between the input terminals as shown in the simplified diagram of OPA170. Please provide the circuit schematic showing configuration details under sleep conditions when the leakage occurs that drains the battery cell - these include the input and supply voltages as well as resistors used.  What is the Roff value of the FET switch used to disconnect (V+)?