Q: TPS61241 : 　Pre-bias is applicable? by 569213

Can I apply pre-bias to the TPS61241 output through current limiting resister and diode from an LDO, while VIN equals to Zero voltage and is powered on/off keeping Enable to Low.

 

Also, is the low side switch FET state on or off when TPS61241 is not powered?


A: Re: TPS61241 : 　Pre-bias is applicable? by 1559531

Pre-biasing the output will not cause any issues.  Also the low side switch FET will be off when the TPS61241 is not powered.  This was confirmed with three tests, all pre-biasing VOUT with 2.5V through a 1k resistor.

-VIN = 0 (floating) and Enable = Low.  This resulted in no current from the 2.5V into the device and voltage on input capacitor did not increase.

-VIN = 0 (floating) and Enable = High.  Same as first test.

-VIN = 3V, start up voltages and currents were observed after setting Enable = High. Normal start up with no current flowing into the device from VOUT