LM3429: LM3429 Support the Value of PWM Frequency

jerry Yang

Part Number: LM3429

hi sir,

my customer use LM3429 to drive a 13.3 inch panel, now customer use a external PWM to Dimming , now customer wants to know what's MAX Frequency of PMW connected the pin 7(ndim),Tks.

over 5 years ago

0 Tuan Tran74 over 5 years ago

TI__Genius 17610 points

Hi Jerry,

Please read section 7.3.10 for PWM Dimming. The minimum ON time must be maintained and the equation is given as tpulse in equation (26). The frequency can by high but that relationship has to be maintained.

Thansk Tuan

0 jerry Yang over 5 years ago in reply to Tuan Tran74

Intellectual 470 points

hi sir,

thanks for your timely reply. now customer change the PWM to 23KHZ, duty cycle :6%-25%. but the panel will flash when the panel in the low brightness. could you please help to check what reason will result this issue,tks.

0 Tuan Tran74 over 5 years ago in reply to jerry Yang

TI__Genius 17610 points

Hi Jerry,

The equation (26) on page 21 of the data sheet for Tpulse has to be met. So Tpulse has to be greater than that time. What is Vin, ILED, Vo, and L that you are using?

Thanks Tuan

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LM3429: LM3429 Support the Value of PWM Frequency