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[LTC1760] Weird SMBus level, The battery charger does not work

Question asked by JemsOn on Apr 26, 2018
Latest reply on May 15, 2018 by Zack

Hello everyone,

I am currently using a LTC1760 that communicates via SMBus with a microcontroller. I developed my own pcb  based on the reference design given in the datasheet.

 

design



The configuration:
I adapted the resistance bridges giving on the LOPWR pins, and DCDIV to my project.

Vmode = Vcc2 and Vdds> Vih_vdds (2.6V) -> Normal Operation on all, Charging is Allowed

The LTC1760 is connected either to the wall adapter or to a battery of (Smart Battery). The Power Switch works very well. If I feed the circuit with the wall adapter, the circuit is powered with the voltage supplied by the wall adapter and if I power with a smart battery the circuit is powered with the battery voltage.

My problem is on the side of the charge and the SMBus. The charger is not working and my SMBus levels are not consistent. let me explain :
The circuit detects well the battery or the wall adpateur but when both are present the charger is not working

 

SMBus Signal: SMBus ALERT = LOW SDA = 0.7V and SCL = 0.7V

 

Any ideas ???????

 

Thanks in advance !

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