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LTC6803-1 Chain Communication Issue

Category: Hardware
Product Number: LTC6803-1


I'm developing a system which incorporates a 30 cell battery stack and 3 LTC6803-1 Battery Stack Monitor ICs for monitoring the cells.

The circuitry is based on the example provided on page 13 of the LTC6803-1/LTC6803-3 datasheet.

I can write commands to the first LTC6803-1 in the chain and read valid data back from it, e.g. write/read configuration data. However, I am unable to write or read from the other LTC6803-1 chips further up the chain.

When I probe the buffered SPI signals, CSB0, SDOI & SCK0, I can't seem to read a recognisable signal, even on SCKO (I currently don't have the capability to log current measurements at the magnitude indicated in the data sheet for current based logic levels and am assuming that some form of pulsed waveform would available to see on a scope).  

VMODE and TOS are set correctly for the three monitor chips and there's a 1K pullup resistor on SDO of the first LTC6803-1.

I would be most grateful for any help or guidance that anyone can provide on this matter.

Best regards