LED1202: LED channel damage

[SunilHD]

Hi Team,

We have used LED1202 in our board where one LED driver is connected to Microprocessor and one LED driver is connected to MCU.
We are seeing random LED channel damages (with LED driver which is connected to MCU) while device is in running state, and LED channel damage issue is random that any or all channels get damage which are connected to LEDs only. LED turns ON permanent which channel got damaged.

We had debugged the operating voltage fluctuations, ground bounce effects but nothing happens during the LED channel failure.

We have limited LED channel current to 6mA and using LED function as ON and OFF only. No PWM functionality os being used here.

Could you please let us know what can be the root cause here behind LED channel damage?

Thank you

[SunilHD]

Hi,

Could you please confirm whether below connections are same what you are talking about?

Thank you

[AScha.3]

Hi,

Right, but the diodes to vcc have to be at the driver and it's vcc to stop any spike here going higher than vcc.

And you can use any fast diode for this, I used BAS 16H , because small package, SMD, cheap and high peak current.

And 1k is a bit high resistance, can only drive 3 or 4 mA to the LED.

That's why I recommended 330 ohms, so just select a resistance that will allow the current you need for your LED, in the range of 270....1k .

[SunilHD]

HI,

Driver IC supply and LED supply is common +3.3V

[AScha.3 · Accepted solution]

Yes, but you want prevent spike at driver, so diode has to be physically there and to vcc at driver. Only this position will prevent spike at driver. If you put it physically at the LED, it's totally useless.

[SunilHD]

Ok understood. We will take care of the same in layout.

Thank you for your quick support and assistance.