LM3429: Confirmation of feasibility

Dice-K

Mastermind 6968 points

Part Number: LM3429
Other Parts Discussed in Thread: TPS92691, TPS92692

Hi support team,

Is it feasible with the boost of LM3429 with the following specifications?

- Vin: 8 ~ 36.5V

- LED IF: 55mA

- LED VF: 2.85V

- Number of LEDs: 18

- Dimming signal: Duty 0~100％, 11±3V, 190Hz±20%

LED: NICHIA, NFSW757GT-V3

https://www.nichia.co.jp/specification/products/led_spec/NFSW757GT-V3-E(5466)Rs030.pdf

Regards,

Dice-K

over 4 years ago

0 Caroline Fuschino over 4 years ago

TI__Intellectual 1675 points

Hi Dice-K,

Thank you for reaching out for support. Our engineers are looking into this and will get back to you by the end of the day.

Best Regards,

Caroline

0 Tuan Tran74 over 4 years ago in reply to Caroline Fuschino

TI__Mastermind 18890 points

Hi Dice-K,

From you specification, the best part for you is the TPS92691 or TPS92692. These parts have external Dimming FET capability and can do PWM dimming to narrower duty cycle than the LM3429. The only issue is really narrow dimming pulse of less than 3% from the 190HZ PWM dimming frequency. This is because when you PWM dimming it's still a control system with sampling when PWM on and you need the some ON time and sampling to satisfy the control loop.

Thanks Tuan

0 Dice-K over 4 years ago in reply to Tuan Tran74

Mastermind 6968 points

Hi Tuan,
Thank you for your reply.

TPS92691 has a small withstand voltage of the PWM terminal, but it is a candidate.

Best regards,
Dice-K

0 Tuan Tran74 over 4 years ago in reply to Dice-K

TI__Mastermind 18890 points

Hi,

Thanks and hope you can use the part.

Thanks Tuan

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LM3429: Confirmation of feasibility