LP55231: I2C stalls after re-enable the EN pin

Zhaohong Zhang1

Part Number: LP55231

In our design, we use 4 LP55231 with MSP430. After power on, the EN is set to high and everything works fine. In order to save power, we would like the disable LP55231 when MSP430 goes into low power mode. What we did is to set the EN pin low before MSP430 enters low power mode and set the EN pin high again when MSP430 exists the low power mode. From the LP55231 datasheet, this process should work.

The issue is that after we set EN pin high again, the I2C is stalling. It seems that LP55231 is holding the I2C SCL line low. Our first I2C write is to the MISC register (0x36). Do I miss something in this process?

Would you please help?

Thanks,

Zhaohong

over 4 years ago

0 Hardy Wu over 4 years ago

TI__Genius 12915 points

Hi Zhaohong,

Can you help try write chip enable register(00h) firstly after toggling EN pin? When chip_en = L, I2C commands cannot be written correctly.

0 Zhaohong Zhang1 over 4 years ago in reply to Hardy Wu

Intellectual 300 points

Hardy,

I fixed the issue in a different way. Before I disable the LED EN signal, there is an I2C write to turn off the LED. I added a short delay for LP55231 to complete its internal operation before being shut down. Everything works fine after adding the delay.

Thank you every much for the support.

Zhaohong

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LP55231: I2C stalls after re-enable the EN pin