LV14340 input 24v, the original design output 5V, but sometimes the actual output 18V or 24v, may I ask what the reason is? The following is the circuit design schematic diagram, and the R9 design USES 10K.

user5273056

Xiaojun,
how many boards did you test? all the boards show the same phenomenon?
When Vout is 5V, did you add some loading? If you add such as 1A loading, Vout 5V is stable or not?
Before get you answer, suggest do below test:
When Vout rising to 18V or 24V, test PIN5 voltage. If the voltage is <=0.75V, R4 has solder quality issue.

0 user5273056 over 7 years ago in reply to Jason Wang (BSR-MV)

Prodigy 210 points

The probability of damage is 1%. Now, another new phenomenon is that the input end of the constant current source will immediately drop to 8v after the abnormal power on the circuit, but sometimes the circuit can output normally.

0 Jason Wang (BSR-MV) over 7 years ago in reply to user5273056

TI__Genius 9550 points

Xiaojun,
please upload the layout for check.

0 user5273056 over 7 years ago in reply to Jason Wang (BSR-MV)

Prodigy 210 points

Jason
I will upload the layout.

0 user5273056 over 7 years ago in reply to user5273056

Prodigy 210 points

0 user5273056 over 7 years ago in reply to Jason Wang (BSR-MV)

Prodigy 210 points

Hi
Jason
Now there is a new phenomenon. The test found that the voltage of the dc source, which used 24V power supply, would drop sharply to about 8V at the output end after power up。
thanks

0 Andy Chen over 7 years ago in reply to user5273056

TI__Mastermind 34745 points

Hi

Can you test Vin waveform on EC2 at input trun-on? what's actual value of R7 and R9?

Power management

Power management forum

LV14340 input 24v, the original design output 5V, but sometimes the actual output 18V or 24v, may I ask what the reason is? The following is the circuit design schematic diagram, and the R9 design USES 10K.