TPS25947: Protection Circuitry

Daniel De Sousa

Part Number: TPS25947

Hello,

We are using the TPS25947 and had some questions about protection circuitry. See Figure 10-1 below taken from the datasheet.

Our application:

VIN = 5V0

Iout = 1.5A peak - should theoretically be much lower

Questions:

In what case do we need D3 and D4? This section in the datasheet mentions 20V USB interface. Do you think it is applicable to our application?

D2 is a Schottky diode used for negative transients. How should we spec this diode? Current rating? Forward voltage? Would something like the MBR1H100SFT3G be okay?

over 3 years ago

0 Rakesh over 3 years ago

TI__Guru** 105361 points

Hi Daniel,

Thanks for reaching out!

We will get back on your questions by early next week.

Best Regards,

Rakesh

0 Kunal Goel over 3 years ago in reply to Rakesh

TI__Guru* 78941 points

Hi Daniel,

If your application like 20V USB port and wire can be plugged into port from output side then using D3 and D4 would be helpful. But it looks your application is different so you can skip using them.

For D2:

1. VR should be greater than VIN

2. VF should be around min abs max at VOUT(0.3V)

3. IFSM>1.5*2*ILIM=1.5*2*1.5=4.5A

MBR1H100SFT3G- VF is high. You can use this one B330A-13-F .

Regards

Kunal Goel

0 Daniel De Sousa over 3 years ago in reply to Kunal Goel

Intellectual 580 points

Hi there, looking at the datasheet, the absolute min on the output is actually -0.8V for a 1 us pulse.

Would that loosen the requirements for the system? ie. allow us to use the MBR diode above?

0 Kunal Goel over 3 years ago in reply to Daniel De Sousa

TI__Guru* 78941 points

Hi Daniel,

Thing is we don't know what pulse duration may be so to be on safer side I recommended B330A. . I think you can use MBR one , it should not be big concern.

Regards

Kunal Goel

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TPS25947: Protection Circuitry