LM36922: LED fails due to LM36922 default state.

Praveen N1

Intellectual 420 points

Part Number: LM36922

Hi Team,

We are using LM36922 LED driver. Due to the default state of led driver the LED got spoiled.

Our maximum led current is about 15mA.

If I2C fails, the led gets a maximum current from the driver. Because the default state of the driver is high.

So, What shall we do for avoid this problem. Even the I2C fails driver should not deliver more than 15mA. Will you please give your suggestion for this.

over 1 year ago

0 Dave Yaeger over 1 year ago

TI__Intellectual 2925 points

Hi Praveen,

Our experts for this issue are currently celebrating the Chinese Golden Week holiday, they will respond to you next week.

Regards,

Dave

0 Patrick Yao over 1 year ago

TI__Mastermind 23850 points

Hi Praveen,

Except for I2C, you can use an external PWM input to control the brightness as well.

With your concern, you can set the maximum PWM duty as 60%, then when I2C fails, the total maximum current is no more than 15mA.

You can find the reference at page 18-19 on datasheet.

LM36922 datasheet

Patrick

0 Praveen N1 over 1 year ago in reply to Patrick Yao

Intellectual 420 points

Hi Patrick

Thanks lot.

We are using this LED for imaging application. If we use PWM control that will create a noise issue in the board.

Because of that only we are using a I2C control.

0 Patrick Yao over 1 year ago in reply to Praveen N1

TI__Mastermind 23850 points

Hi Praveen,

1. Is it possible to drive HWEN high and write registers with I2C first, then supply Vin?

2. In my understanding, your LED can only tolerate 15mA as maximum current, right? So is there any possibility to change the LED with those have more current tolerance?

If I2C fails, I don't think device can limit the maximum current to 15mA without PWM.

Patrick

Power management

Power management forum

LM36922: LED fails due to LM36922 default state.