External LED schematics available?

Hi all,

I am designing a drone for using pixhawk and need to retrofit the external USB and LED for my own design.

So I draw schematics and circuit board for both USB and LEDs. 

USB works just fine however LED circuit does not work as expected. 

I tried to copy from the original LED indicator from 3DR and used following parts.

TCA62724 (i2c LED driver)




Schematics as follows.


The circuit is very straight forward and nothing special by any respect.

When plugged in the I2C connector in Pixhawk, LED is not working and only RED LED is lit. 

No change in color and no blinking. 

Oscilloscope shows I2C protocol is flowing into the chip. 

Should I put protection resister between 5V rail to the RGB LED?

Does anyone can help me solving this problem here? 

Any comments will be much appreciated.

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  • Late reply but might help someone else. This sounds like a power supply issue based on the RED LED only lighting. Check the voltage going into the circuit, should be 4.7V or more.- ted

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