LM3492HC: Contrast Ratio and Input Clamp Current Calculation

Ting Ye

Part Number: LM3492HC

Hello Team,

Could you help me check if below calculation to check if LM3492HC-Q1 contrast ratio and input clamping current meet the system specs?

LM3492HC-Q1 Contrast Ratio Calculation.xlsx

Via the calculation, the LED driver should meet the system specs.

1. 12S6P

2. LED VF Max of 3.7V

3. Iout per channel 0.13A

Thank you.

Regards,

Ting

over 5 years ago

0 Irwin Nederbragt over 5 years ago

TI__Mastermind 28655 points

Hello Ting,

"(1000:1 at 3-kHz LED dimming frequency, minimum pulse width of the dimming signal is 300 ns)." However: "The lowest contrast ratio is 1000:1. The finest pulse width of the dimming signal for the DIM1 and DIM2 pins is 300 ns."

I will check with a colleague on this.

Edit (adding): This is the LM3492HC part, it is good for 10,000:1 as long as the DIM1 and DIM2 pins are greater than 300 ns pulse width. Calculating Power is correct except what is the 1.2 for?

Regards,

0 Irwin Nederbragt over 5 years ago in reply to Irwin Nederbragt

TI__Mastermind 28655 points

Hello Ting,

From colleague; Contrast ratio will be higher with lower PWM frequency. What you are trying to achieve should be fine. He states 5000:1 at 200 Hz dimming should be achievable.

Regards,

0 Ting Ye over 5 years ago in reply to Irwin Nederbragt

TI__Genius 11800 points

Hello Irwin,

Thank you for helping confirm my calculation. The 1.2 for Pout calculation is to add margin for output power.

Thank you.
Regards,
Ting

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LM3492HC: Contrast Ratio and Input Clamp Current Calculation