TPS54325: Problem with 5VIN and 4VOUT

FELIPE MARCONDES

Part Number: TPS54325

Hello,

I am using the TPS54325 switching power supply to power a 3G module model Telit UL865. The VIN is 5V and the VOUT is 4V (should be in 3.8V and 4.2 range as the module requirements). The 3G modem consums +- 500mA of average current with peaks of 2A and its very intolerant to power glitches.

I am facing a problem that when the modem starts to transmit the power supply is dropping below 3.5V and the 3G module is reseting. When I test with 6V of VIN at TPS54325 then the power supply remains stable and the modem works properly.

Checking the TPS54325 datasheet the specs for VIN are from 4.5-18V but its not clear if there is any relation between minimum VIN depending of VOUT (something like a "dropout" voltage). The datasheet curves are based in 1V of VOUT so its not very clear the behavior at my conditions (VIN-5V | VOUT-4V).

Please give me a feedback when possible. If any more informations are needed, I remain at disposal.

Thank you,
Regards.

over 5 years ago

0 Shawn Nie over 5 years ago

TI__Genius 10070 points

Hi,

This device can't support 5V-->4V, you can check the min VIN for your application (VOUT=4V, IOUT=2A).

Shawn

0 FELIPE MARCONDES over 5 years ago in reply to Shawn Nie

Prodigy 20 points

Hello Shawn,

Thank you for your answer. Can you please clarify to me where can I find this min VIN information as you recommended? I had searched at the datasheet more than once and cannot find it.

What is the minimum VIN that the TPS54325 requires in case I need to have an output with 4V/2A?

I will be waitiing your comments. Thank you very much.

Regards.

0 Shawn Nie over 5 years ago in reply to FELIPE MARCONDES

TI__Genius 10070 points

Hi,

There is no information in the datasheet, but you can simply calculate the max vout.

Shawn

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TPS54325: Problem with 5VIN and 4VOUT