TPS51386: Schematic Review Request: No output with 12V input. Zero current draw

Jonah Mikesell

Prodigy 50 points

Part Number: TPS51386

Tool/software:

10 months ago

0 Jonah Mikesell 10 months ago

Prodigy 50 points

The output voltage is supposed to be 5V. I am getting no output on VCC, which should be an internal 5V LDO output.

+1 Aurora Tie 10 months ago

TI__Genius 16740 points

Hi Jonah,

I checked the schematic, this is a problem. Pls don't use VCC to power EN. You can use Vin with voltage divider resistors to power EN, or use another power rail. Because the chip needs VIN and EN to be powered normally before it can work, and then VCC will have 5V output. Thanks.

Aurora

0 Jonah Mikesell 10 months ago in reply to Aurora Tie

Prodigy 50 points

Hi Aurora,

Thank you! I put together a makeshift voltage divider and supplied the enable pin with 7.89V (which I believe is too high). But I did achieve a voltage output of 6V with a 12V input, which is near what I need (5V). Thanks!

0 Aurora Tie 10 months ago in reply to Jonah Mikesell

TI__Genius 16740 points

Hi Jonah,

Yes, 7.89V is too high. Pls ensure the voltage of EN pin is lower than 6V(abs max value), but higher than 1.5V. Thanks.

Aurora

0 Jonah Mikesell 9 months ago in reply to Aurora Tie

Prodigy 50 points

Hi Aurora,

Could you please check once more? Here is the planned final schematic.

0 Aurora Tie 9 months ago in reply to Jonah Mikesell

TI__Genius 16740 points

Hi Jonah,

This schematic looks good to me. Thanks.

Aurora

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TPS51386: Schematic Review Request: No output with 12V input. Zero current draw