Q: TPS6223x VIN Open condition by 1158565
Is there any problem with the following conditions?

*DCDC INPUT:Open
*DCDC OUTPUT:Voltage Biased
*EN:High, Low (both cases)


I guess that some currents flow from output to input through parasitic diode in Hi side FET.  Does this flow cause any problem?


A: Re: TPS6223x VIN Open condition by 1559531

The parasitic diode in the high side FET will allow current to flow from Vout (output) to Vin (input).  This current flow will not damage the TPS62233 provided current is kept low.  But there is a possibility it will cause a problem depending on the application and what is connected to Vin (e.g. a battery). Enable has no control of the parasitic diode.

Two tests were run using the standard EVM.

The first test biased Vout with 3V through a 1k resistor, a 100 ohm resistor from Vin to GND and EN = High.  Measurements were Vin = 0.237V and Vout = 0.712V, showing approximately 0.5V drop across the parasitic diode.  It was again tested with EN = Low and the results were identical.

With Vin open and EN = High: Vin = 2.411 V and Vout = 2.412 V showing that the input and output are not isolated but there is no current flow.  Then setting EN = Low: Vin = 2.789V and Vout = 3.00V, again showing no isolation but some voltage drop across the parasitic diode and therefore some current flow.