TPS92692-Q1: TIDA-01581 disconnect mirrored string, then reference string flicker

Sky Hsieh48

Part Number: TPS92692-Q1
Other Parts Discussed in Thread: TIDA-01581, TPS92692

Hi TI,

We use TIDA-01581 reference design for turn indicator which have 28 LEDs (3V*28pcs=84V), so we seperate 28 LEDs to 2 strings (15 & 13).

When we test open circuit of mirrored string, the reference string flicker.

Our customer cannot accept this flicker, do you have any suggestion to solve this problem?

Or do we have another reference design can avoid this?

over 1 year ago

0 Tuan Tran74 over 1 year ago

TI__Genius 17690 points

Hello Sky,

The issue with using the mirror string driver is that when you open circuit of the mirror string all of the current that is being controlled by the TPS92692 will go into the reference string and that's what you are seeing. You will need to design you own external circuit to sense that the string is open and disable the TPS92692 by pulling the SS pin to ground.

Thanks Tuan

0 Sky Hsieh48 over 1 year ago in reply to Tuan Tran74

Prodigy 100 points

Hi Tuan,

Do you have any suggestion or experiment for the external circuit of dual string topology?

Or any sulotion can handle this number of LED (VLED>60V)?

0 Tuan Tran74 over 1 year ago in reply to Sky Hsieh48

TI__Genius 17690 points

Hello Sky,

I am working with Yi-Hua Lin who is your local TI Application Engineer for this issue. He will present to you a recommended solution for this. For now it is best to work thru him for this request. I will close this thread and if there is an issue then you can always open the thread again.

Thanks Tuan

0 Sky Hsieh48 over 1 year ago in reply to Tuan Tran74

Prodigy 100 points

Hi Tuan,

Yes, my colleague and Andy is working on this issue. It seens there is a workaround for now.

I would like to know if there is a suitable IC solution or reference design can handle large number of LEDs.

I think IC solution like TPS929120 or TPS92662A are not suitable because the price are too high.

0 Tuan Tran74 12 months ago in reply to Sky Hsieh48

TI__Genius 17690 points

Sky,

Since your team is already working with Andy...It's best that you work thru him for your questions, requirements, and pricing. I cannot comment on pricing and that has to go thru you local TI contacts.

Thanks Tuan

0 Sky Hsieh48 11 months ago in reply to Tuan Tran74

Prodigy 100 points

Hi Tuan,

I think we could ignore these workarounds and TPS92692 for high voltage LED string application. Some functions is not working to use these solutions (eg., PWM dimming and output short circuit).

I would like to know if we have this requirement in the future, is there any good solution (IC or reference design) to handle it?

Protect feature we need: Output open circuit, short circuit without flicker.

0 Dave Yaeger 11 months ago in reply to Sky Hsieh48

TI__Intellectual 2925 points

Sky,

Our experts in China are on holiday this week. Please expect delay in response.

Best regards,

Dave

0 Tuan Tran74 11 months ago in reply to Dave Yaeger

TI__Genius 17690 points

Sky,

Currently we do not have a part that can support this high voltage. You'll have to limit the voltage going into the part.

Thanks Tuan

0 Sky Hsieh48 11 months ago in reply to Tuan Tran74

Prodigy 100 points

Hi Tuan,

Besides IC solution and TIDA-01581, is there any other reference design can handle this application?

For example, 28 pcs of turn indicator LED which VLED is 84V (3V*28).

0 Tuan Tran74 11 months ago in reply to Sky Hsieh48

TI__Genius 17690 points

Sky,

We do not have any other reference design that can handle this application as you mentioned.

Thanks Tuan

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TPS92692-Q1: TIDA-01581 disconnect mirrored string, then reference string flicker