Other Parts Discussed in Thread: , TPS63051, TPS62120
Hello,
I selected TPS62743 for a design, and found when the PCBs came back that the devices consume much more power than expected once the microcontroller is in deep sleep. Eventually I isolated the problem to the TPS62743.
So I bought the TPS62743EVM-689 to see if the problem persists on TI’s evaluation platform. It does.
Scenario: Set TPS62743EVM-689 jumpers to 3.3V output. Apply 3.0V supply on the input. The only load on the output is a voltmeter (standard 10MΩ input impedance).
The TPS62743 IC draws 294 uA, as seen in the photo attached, about 800 times the typical datasheet figure. The excess current draw occurs all the way down to the UVLO at VIN of 2.0V. I also tried providing a somewhat higher load of 1MΩ (closer to what I expect in the application when asleep), which did not alleviate the problem.
I did test with the 3.6V input used in most of the datasheet measurements, and found things in good agreement with datasheet specifications, drawing about 0.9uA with the voltmeter attached to the output and 0.4uA with the output open-circuit. This helped me validate my test setup and meter calibration.
In my application, the TPS62743 is being powered from a rechargeable Lithium cell, so this behavior is undesirable as it renders the product effectively unable to sleep.
It seems that this regulator was designed with such a cell in mind, and there do not seem to be any cautions against using TPS62743 with VIN below the output set point in the data sheet. So I suspect this is not performing as intended.
Any advice?