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TPS7A4701-EP: Output voltage at -40°C

Part Number: TPS7A4701-EP
Other Parts Discussed in Thread: TPS7A47

I am using TPS7A4701-EP in ANY-OUT mode. Some of ANY-OUT pins are grounded using 0 ohms so that the output voltage will be 9.1V (1.4+6.4+0.8+0.4+0.1). The output voltage is 9.1V at room temperature as expected but it drops to 8.8V at -40°C.  What can be the reason of this much drop?

  • HI,

    Is this happening on our EVM or on your board? I am just wondering if at -40C the board is warping and adding stress to the package. Also, any contamination or condensation on the board may affect the output. One place I would look is the NR capacitor. if there is additional leakage on this, it might lower the output voltage. 

    I hope this gives you some ideas.

  • Not EVM and I think that the contamination and warping cannot be the reason because  I faced with this problem on several boards. 

    I realized that the voltage drop increases with decreasing temperature. For example, output voltage at -10°C was approximately 8.9V. Also, the connection between SENSE and OUT is done near the LDO and the load is far from the LDO (in a different board). Could this causes to the voltage drop?

  • Hi,

    Yes. the TPS7A47 regulates to the Sense pin. So if the load is a long distance from the LDO across a board connector, the characteristic impedance of the traces both in the output and the GND return could impact the actual voltage seen at the load. 

    Can you measure the output of the LDO from VOUT to GND under these same conditions?