Hello,
While testing the TPS610985EVM-782 I have noticed that this device does not operate in active pass-thru mode when using a 3.6V or 4.2V AA battery as the input source. I have attached an ~1mA load (3k resistor) across the VMAIN (J4) output and GND (J8). When I apply a 4.2V battery across the Vin (J1) input and GND (J3) I observe that the VMAIN output is approximately 300mV less than the the VIN input, which indicates that the internal high side FET intrinsic diode is conducting and therefore this FET is not active. If I apply a short duration transient load to the VMAIN output, which causes the VMAIN output voltage to decrease to ~ 3V, I observe that the controller "corrects" itself and the pass-thru function now operates as it should with VIN equal to VMAIN (i.e. internal high side FET is active).
I have performed this test on a second TPS610985EVM-782 evaluation module and observed the same results.
I need this device to operate in active pass-thru mode with initial source voltages greater than the regulated 3V output.
Can you explain why this controller is behaving this way and how I can get it to operate as it should, in proper active pass-thru mode with 3.6V or 4.2V AA batteries.
thanks
