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ADM1276 CML_Fault issue

Question asked by on Mar 19, 2014
Latest reply on Mar 20, 2014 by Ren

Customer use ADM1276 to do the POWER_CYCLE command to do loop test, meet CML_FAULT error. The steps of experiment show as below and all of results we find out within 3 cases.

(a) enable alert pin via set CML_ERROR_EN1 of ALERT_1_CONFIGURATION_REGISTER to 1

(b) In first console, keep issue STATUS_WORD command to read data recursively.

(c) In second console, issue POWER_CYCLE command recursively.

(d) At digital oscilloscope we set trigger pin as alert pin(CML_ERROR_EN1). Wait CML_FAULT error and get the waveform


Blue single : CLK

Red single : SDA

Yellow single : BMC Power

Green single : CML error


(1) CML_FAULT error at power-off moment (As attached waveform " CML_FAULT error at power-off moment_1 and CML_FAULT error at power-off moment_2)

(2-1) CML_FAULT error at power-on moment

(2-2) CML_FAULT error at power-on moment

(3)SDA locked and BMC recover SDA. And then BMC send first command to HSC. After first command, we see CML_FAULT error


Please refer attached waveform.


Some questions need help to clearly:

(a) Sometime CML_FAULT error at power-off moment and sometimes CML_FAULT error at power-on moment, Could you give us criterion of judged CML_FAULT??

(b) After power-on, why does the SDA lock to low?? Does CML_FAULT error cause by abnormal I2C single that BMC recover SDA?

Please help to find the root-cause and suggest the solution.