BQ24640： BQ24640 output voltage

user5220139

Part Number: BQ24640

I designed a super capacitor charger based on BQ24640. The charger has adjustable charging voltage and current. The schematic diagram is basically the same as that provided by the official. It is powered by a DC stabilized power supply.

When the input voltage is 5v, the output voltage can be set normally. When the input voltage is greater than 5v, the output voltage remains around 1.7v and is not adjustable.

May I ask what causes this to happen?

over 4 years ago

0 HAOMING CHEN over 4 years ago

Prodigy 40 points

i have the same problem, the output voltage remains at 1.67v, but designed for 12v

0 Kedar Manishankar over 4 years ago

TI__Mastermind 24075 points

Hi,

There should be no issue. What is status of STAT? What is measure REGN voltage?

0 HAOMING CHEN over 4 years ago in reply to Kedar Manishankar

Prodigy 40 points

both of two led connecting to STAT and PG pin turn on. The voltage on REGN is 6v

0 Kedar Manishankar over 4 years ago in reply to HAOMING CHEN

TI__Mastermind 24075 points

Can you take a waveform capture of PH VCC and SRN?

0 HAOMING CHEN over 4 years ago in reply to Kedar Manishankar

Prodigy 40 points

this is waveform capture of VCC

PH waveform

SRN wave

0 user5220139 over 4 years ago in reply to Kedar Manishankar

Prodigy 20 points

Hi,

This is a schematic diagram. It works normally when the vcc is 5v, and the voltage is adjustable. When it is greater than 5v, it cannot work normally. The main performances are:

the output is about 1.7v, and it cannot be adjusted.

The PWM is abnormal.

Schematic_BQ24640-V3.0.pdf

0 HAOMING CHEN over 4 years ago in reply to Kedar Manishankar

Prodigy 40 points

this is my schematic documentschematic_bq24640.pdf

0 Kedar Manishankar over 4 years ago in reply to HAOMING CHEN

TI__Mastermind 24075 points

Hi All,

As there are 2 different customers with issue, please create a new post if you were not the origilanl creator of the post. It is possible that there are 2 different causes, but the information can be confusing to review. HAOMING, as original post creator was user5220139 I will answer his post on this thread. Feel free to create a new post or follow along. Thanks!

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BQ24640： BQ24640 output voltage