TPS61193: Abnormal state, Fault pin=High (normal state), SW pin=5Vdc (not switching)

Yusuke Mukuno

Expert 7395 points

Part Number: TPS61193

Hi Expert,

My customer found the issue of no LED current on some samples.(Abnormal sample# 3unit / 600units)

But, this issue is recovered by Vin restart.

Customer measured each pin status at this issue as below,

Vin =5V,

SW pin =5V(not switching)

OUT pin = around 0V

Fault pin = high (normal)

LDO pin = 4.3V (internal Vcc :OK)

Does TPS61193 have the any abnormal state with Fault pin= High and SW=Vin(not switching)?

Thanks

Muk

over 4 years ago

0 Yuting Shao over 4 years ago

TI__Genius 13001 points

Hi Yusuke-san,

I'm confused with one pint that SW is 5V while OUT is 0V since there is only a diode between them. Could you help check it?

Robin

0 Yusuke Mukuno over 4 years ago in reply to Yuting Shao

TI__Expert 7395 points

Hi Robin-san,

OUT pin voltage is LED Cathode side voltage. So There are the rectifier diode and LED between SW pin and OUT pin.

LED Vf is over 5V, And LED is not lighting at boost output voltage 5V(=Vin, in case of not-switching). So OUT pin is around 0V.

Thanks

Muk

0 Yuting Shao over 4 years ago in reply to Yusuke Mukuno

TI__Genius 13001 points

Hi Yusuke-san,

Sorry, I misunderstand your description about OUT which we think it's the boost output instead of LEDs' cathode.

I need you provide more application information:

1.What's the operation resulting in this abnormal phenomenon?

2.Could you provide the schematic for further analysis?

3.How about the quantity of LED in series? How many channel does customer use? How about current per channel?

Robin

0 Yusuke Mukuno over 4 years ago in reply to Yuting Shao

TI__Expert 7395 points

Hi Robin-san,

1. It had often occurred at high temp conditions. (suddenly)

2. I will send you schematics by e-mail.

3. Maybe 3pcs LED in series. LCD module requirement is Vf=9V (min) to 11.2V(max) .

Customer is using 2ch (OU1 and OUT2). OUT3 is connected to GND.

Both OUT1 and OUT2 is around 0V

Current setting : please refer the schematic.

Thanks

Muk

0 Yuting Shao over 4 years ago in reply to Yusuke Mukuno

TI__Genius 13001 points

Hi Muk-san,

I have already replied your email. Please check it and feel contact me if you have any further questions.

Robin

0 Yusuke Mukuno over 4 years ago in reply to Yuting Shao

TI__Expert 7395 points

Robin-san,

Thank you for your direct e-mail support.

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TPS61193: Abnormal state, Fault pin=High (normal state), SW pin=5Vdc (not switching)