TPS2490: Load Discharge and Timer Queries

Gaurav Agrawal

Part Number: TPS2490
Other Parts Discussed in Thread: CSD18537NQ5A

Hi,

We use TPS2490 in a load switch configuration for switching a voltage of 40-50V with a drain current requirement is max 1A. The output load cap is 3000uF. The MOSFET used is CSD18537NQ5A.

We noticed that the device does not have a quick load discharge functionality. With 3000uF cap, its close to 0.15C charge at the output that needs to be dissipated in less than 2sec. Is their any other way we can achieve the same around this IC? We wish to avoid using a bleed resistor with a FET/BJT outside the IC.

Regards

Gaurav

over 4 years ago

0 Rakesh over 4 years ago

TI__Guru** 105661 points

Hi Gaurav,

We need to use external components to facilitate load cap discharge like you mentioned by using a bleed resistor with a FET/BJT outside the IC

Best Regards, Rakesh

0 Gaurav Agrawal over 4 years ago in reply to Rakesh

Intellectual 735 points

Thanks Rakesh.

Is there any other IC from TI which has this inbuilt and supports 50V?

Regards

Gaurav

0 Rakesh over 4 years ago in reply to Gaurav Agrawal

TI__Guru** 105661 points

Sorry. No Gaurav.

Best Regards, Rakesh

0 Gaurav Agrawal over 4 years ago in reply to Rakesh

Intellectual 735 points

Hi Rakesh,

OK we shall implement the output discharge separately.

Another query that I have is related to sequence below:

1) IC enabled and working at 50V, with output 3000uF caps charged.

2) IC is disabled

3) IC is enabled again (from the same 50V source, or another source at a lower or higher voltage in range), before the output discharges.

As I understand there shall be a period when the output voltage shall reflect to the input through the N-FET body diode, till the diode stops to conduct, and then the IC shall raise the output voltage till Vds is in range of no fault.

Please confirm if this is correct, or there can be any other issue.

Regards

Gaurav

0 Rakesh over 4 years ago in reply to Gaurav Agrawal

TI__Guru** 105661 points

Hi Gaurav,

No issue as long as the body diode of the FET can handle the discharge current from OUT to IN when IC is disabled.

Best Regards, Rakesh

0 Rakesh over 4 years ago in reply to Rakesh

TI__Guru** 105661 points

Hi Gaurav,

Do you have any follow up questions ? let us know

Best Regards, Rakesh

0 Gaurav Agrawal over 4 years ago in reply to Rakesh

Intellectual 735 points

Hi Rakesh,

Thanks for your support, you can close the thread as of now. If something comes up, we shall post afresh.

Regards

Gaurav

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TPS2490: Load Discharge and Timer Queries