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LP5018: I2C Bus noise issue

Part Number: LP5018


my customer is currently working on a design and he plans to use the LP5018 but he is facing some issues.

He is using the LP5018 chip to drive 18 LEDs. The current limit is set using an external resistor on the iref pin to a maximum of around 11mA per channel. Using this chip he is driving 6 RGB LEDs and sometimes he has some issues with the data signals of the I2C bus. The bus gets very noisy. Sometimes this noise is so high that other I2C commands can't be read anymore. This happens usually when all the LEDs are activated at once.

The functionality is fine for each color at a time at every intensity but gets damaged when all the colours are activated at once at full power. After that last activation the bus can't read signals anymore.

If he lowers the current limiting resistor, thus a higher current through the LEDs, the issue happens more frequently. So not only at full power on all the LEDs but also if he activates for example only red and blue at full power on each LED.

Below are some of the images showing the noise:

  • noise on bus at 100% 18LEDs 11mA

  • noise on bus at 100% 18LEDs 15mA

Hopefully all these details help understand the issue. I can send you the schematic shot internally.

Best regards,