TPS65133 Neg. Voltage cannot down to -5V

Shaquille Chen

Other Parts Discussed in Thread: TPS65133, OPA1622

Hi team,

One of customer facing a problem of TPS65133.

The Neg. voltage of TPS65133 cannot down to -5V.

Input: 3.3V

VPOS: 5V

VENG: -4.4V

The output of TPS65133 is several OP.

0 Diaara over 8 years ago

Hello Shaquille,

Is this happenning with the load connected? Could you please share the customer schematic and the values of the loads?

What do you mean with "The output of TPS65133 is several OP." ?

Best regards,

Diaara

0 Shaquille Chen over 8 years ago in reply to Diaara

Hi Diaara,

Thanks for your support.

What I mean is the output (VPOS and VNEG) connect with several OP.

Please refer to following block, customer use TPS65133 like this

I don't have any how many load and specific part number of op.

Please refer to the schematic below:

0 Ilona over 8 years ago in reply to Shaquille Chen

Hello Shaquille,

Thanks for sharing the information. I have view more question on the "cannot down to -5V" - concern:

How does the TPS65133 behave at the start-up? Does it ramp down to -5 V and then is chopped at -4 V or does it regulate directly to - 4 V?
Can you share the inductors you are using ?
Can you share the schematic for the OPA1622 (gain configuration)?
If possible, it would be helpful if you can share some scope plots showing how the output voltage/current and the switching nodes (SWN,SWP) are behaving.

Thank you.

Best Regards.

Ilona