TPS546B24A: COMM error

Hailiang Zhang 

Other Communications Errors are generally violations of the SMBus or PMBus specification, such as

1) Sending too few bits or bytes

2) Sending too many bytes

3) SMBus time-out (holding CLK low longer than 25ms) 

What was the customer trying to do before the communications error was reported?

Hi Peter，

It seems that none of the events you cited occurred. During the startup of the customer's switch, before loading the driver, the host got this communication error while reading the fault register via I2C with no other commands. Can this communication error be ignored?

Regards，
Hailiang

Hi Peter,

Customer tested the system. The I2C pull-up level is only 14.5ms later than TPS546B24A power-on, which is shorter than 25ms. And the customer tried to use external pull-up source for experiments and found that even if the pull-up source was provided in advance, communication errors would still be reported. 

Are there any other suggestions? Would it be helpful to have the customer monitor the 12Vin, clock and data lines of PMbus?

Regards,
Hailiang

Hailiang Zhang 

Ask the customer to monitor ALERT, CLK and DAT and see when ALERT is pulled low, and what traffic was on CLK and DAT when ALERT is asserted low.