TPS61163A: Do not switching

daniel

Part Number: TPS61163A
Other Parts Discussed in Thread: TPS61163

Hi Team,

It is a smartphone application, and we face an issue that chip do not switch, the LX pin always bypass the VPH_PWR.

We check the schematic, and probe the EN/VIN/PWM pins, they are all good.

We also have tried adjust the PWM voltage or frequency, but not help. Please kindly give us some suggestions that we can try.

Attached schematic, inductor and diode P/N . Please kindly help if maybe there are any component limitation.

Inductor: MRSC252A10-4R7M

Diode: WSB5539N

Thanks

over 5 years ago

0 daniel over 5 years ago

Genius 5095 points

0 Sean Zhou over 5 years ago in reply to daniel

TI__Mastermind 22745 points

Hi
What are LR103, LR105? Why you add this? have you tried to remove those? The Schematic seems ok, I think you need remove LR103 and LR105 first, then have a try.
Sean

0 daniel over 5 years ago in reply to Sean Zhou

Genius 5095 points

Dear Sean,

LR103 and LR105 are non-mount, so it wouldn't affect the schematic.
If we give valid VIN and EN, the chip should start switching, right? Does the PWM affect the switch or not?

Thanks

0 Sean Zhou over 5 years ago in reply to daniel

TI__Mastermind 22745 points

Hi Daniel,
have you add the LED load to do the test? What's your load?
Sean

0 daniel over 5 years ago in reply to Sean Zhou

Genius 5095 points

Dear Sean,

If there is no load, the switch behavior won't activate?

Thanks

0 Sean Zhou over 5 years ago in reply to daniel

TI__Mastermind 22745 points

Hi Daniel,
Yes, you need to connect the load to give a full feedback loop, so it will switch.
Sean

0 daniel over 5 years ago in reply to Sean Zhou

Genius 5095 points

Dear Sean,

Many thanks for your support.

We find the root cause: The RF de-sense capacitors on FB pin.

But why the capacitors would cause no switching issue?

Thanks

0 Sean Zhou over 5 years ago in reply to daniel

TI__Mastermind 22745 points

Hi,
TPS61163 is the BOOST+Current Sink Topology, the current sink will turn on/off with fixed frequency, if you put a large capacitor on the FB pins, it will definitely have big effect on the topology. Because the voltage will decrease very slowly with this big capacitor. Thanks.
Sean

0 Sean Zhou over 5 years ago in reply to daniel

TI__Mastermind 22745 points

Hi daniel,
I'll close this thread due to inactivity and if you have more questions please reply to it directly and it will open again. Please help to click "Resolve" if the problem is solved.
Sean

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TPS61163A: Do not switching