TPS61087: Voltage Dip occuring with increased load

Baghiya Lakshmi

Part Number: TPS61087

Hi,

We are using the part TPS61087 in our design for a 5V to 12V boost converter with a current limit of around 1A. But, whenever we are trying to increase the load greater than 300mA, we are observing a voltage drop in the 12V rail (dropped to 7V for 8ms).

The 5V input can source up to 3A.

Please comment how to resolve this

Thanks in advance

Baghiya

over 1 year ago

0 Zack Liu over 1 year ago

TI__Mastermind 34201 points

Hi Baghiya,

Some information need you to provide:

1. Please share the output capacitor C12 part number.

2. Layout screenshot of this design.

3. Any switching waveform or Vout drop waveform.

0 Baghiya Lakshmi over 1 year ago in reply to Zack Liu

Intellectual 645 points

Hi Zack,

Please find the answers

1. Capacitor part number - 25SVPF27MX from Panasonic

3. Waveform

0 Baghiya Lakshmi over 1 year ago in reply to Baghiya Lakshmi

Intellectual 645 points

Hi Zack,

2 Layout

0 Zack Liu over 1 year ago in reply to Baghiya Lakshmi

TI__Mastermind 34201 points

Hi Baghiya,

1. For best output voltage filtering a low ESR output capacitor like ceramic capcaitor is recommended.

The selected output capacitor 25SVPF27MX is a polymer cap with big ESL, ESR. It's needed to add low ESR ceramic capacitor at output side and put it very close to rectifying diode cathode and IC PGDN pin.

2. Which node waveform are you sharing? What is the VIn/Vout/Iout condition?

Could you probe the VIn pin, SW pin, Vout pin at same time?

3. The layout is poor, which maybe the reason that this application board cannot output high enough current.

Please follow TI datasheet page 22 Layout Guidelines.

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TPS61087: Voltage Dip occuring with increased load