TPS62813-Q1: Vin = 3.3V, Vout = -1.2V/1.3A?

Hello Steve,

It is unlike that TPS6281x-Q1 devices will work on inverting Buck Boost configuration because output will not be able to regulate with negative voltage on VFB pin. Anyway, I will check internally to confirm my theory.

Keep you posted.

Best regards,

Excel

There wouldn't be negative voltage on feedback fin; the GND pad of the part would be tied to VOUT per the usual IBB connection.

Hi Steve,

The main concern here is Ground connection. Could you provide the schematic diagram? 

It is possible to generate the negative output but the input & output grounding should not have common grounding.

Best regards,

Tanvee

I'm not sure what the confusion is here- seems like a pretty simple question?

Do you see any problem using TPS62813 in the Inverting Buck Boost configuration as commonly outlined in various app notes such as SLYT286?

I realize that the "ground" connection/thermal pad of the device will need to be connected to Vout, etc... the question is whether or not it's ever been tried with this device and/or whether there could be any issues with the internal compensation that could prevent it from being stable. 

I would try to simulate it except most of these devices the SPICE models are internally wired in a way that prevents them from simulating correctly even if the part works in this configuration in the real world.

Hi Steve,

There is no confusion. The device can be used as an inverting converter and the recommendation was to give more attention to the grounding of the device as suggested in the app note. Unfortunately, models are not designed for this topology and can not be simulated.

Best regards,

Tanvee

OK, thanks.  Any concern with the output current of 1.3A at -1.2V?

-Steve