TPS25947: TPS25947

Bill Kury

Part Number: TPS25947

Tool/software:

I have my design back and it appears to be working ok but I have one issue. If I touch the input resistors, R901,R905, R907 in the layout, I can get the output to switch off. If I use a pencil or something else nothing happens. I think my body resistance is affecting the circuit when I do this. Can I lower the resistance values on the input side to eliminate this issues. Have you guys seen an issue like this before?

Bill

5 months ago

0 Arush Gupta 5 months ago

TI__Mastermind 38085 points

Hi Bill,

Can you reshare the schematic with updated numbering. I am assuming these three resistors are resistive ladder for EN and OVLO pins. If you think stronger pull up/down is required, yes please go ahead and reduce the resistor values. The values in the previous schematic should be fine. I am not sure what type of connection is happening when you are touching it.

Do you expect end application to have this scenario?

Best Regards,
Arush

0 Bill Kury 5 months ago in reply to Arush Gupta

Prodigy 220 points

Here you go.

0 Arush Gupta 5 months ago in reply to Bill Kury

TI__Mastermind 38085 points

Hi Bill,

So my assumption of them being the resistive ladder was correct.

Arush Gupta said:
Do you expect end application to have this scenario?

Best Regards,
Arush

0 Bill Kury 5 months ago in reply to Arush Gupta

Prodigy 220 points

Yes, I have it working in the lab. The problem that I have run into is that if you put your finger on the resistors R901, R905, R907, you can get the efuse device to turn off and on. I think this is due to the 115k resistor being a high value. If I can drop that resistor value, I believe this problem will go away. What do you think?

Bill

0 Arush Gupta 5 months ago in reply to Bill Kury

TI__Mastermind 38085 points

Hi Bill,

If you think stronger pull up/down is required, yes please go ahead and reduce the resistor values. Using stronger pull up/down will result in higher continuous current. I am not sure what type of connection is happening when you are touching it. Most likely, your hand is providing additional path.

Can you verify the voltages for EN and OVLO when you touch the resistors?

Do you expect this in the end application?

Best Regards,
Arush

0 Bill Kury 5 months ago in reply to Arush Gupta

Prodigy 220 points

The continuous current is not really an issue. The devices on my board are going to draw amps and this will draw mA at worst. I will rework the resistors. I will measure the voltages and get back to you.

Bill

0 Arush Gupta 4 months ago in reply to Bill Kury

TI__Mastermind 38085 points

Sure.

Best Regards,
Arush

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TPS25947: TPS25947