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BQ78PL114 SMBus clock low extension

Other Parts Discussed in Thread: BQ78PL114

Hi there,

I have a problem with the BQ78PL114 clock low extension.

The SMBus Specification limits the SCL clock low period to 100us for every SMBus slave devices.

In our SMBus we have a clock low supervisor which trips after 200us when the SMBus SCL is permanently low.

In a first Prototype using the BQ78PL114 i've measured a clock low extension from the BQ78PL114 of 360us (100us is the allowed limit) for all 'read word' accesses:

 

To get the Smart batteries manufacturer name (SBS command 0x20) we have to use the SMBus 'block read' protocol.

The clock low extention i've measured now is 1100us !

 

Another SmartBattery Management chip worked fine, so these timings seems to be BQ78PL114 specific.

Is there a firmware update available to fix this timing issues or do you have any hint for me ?

 

Thanks