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ADM1064 I2C returns a NACK for address FA00

Category: Hardware
Product Number: ADM1064

I have a new batch of cards that use the ADM1064. Some of this batch always return a NACK for address read FA00.

This is when the read is part of a 2 byte read sequence that starts from F800 and is meant to read the whole EEPROM from 0xF800 to 0xFBFF.

The failing access 'target W address' gets ACK. '1st Address word = FA' gets ACK. '2nd Address word = 00' gets NACK.

The preceding accesses to the ADM1064 completed correctly, which are "target W - F9 - FE" - "target R - Data".

Does anyone have any idea why multiple parts might have an issue reading FA00? 

Clock speed is 100KHz.. voltage levels and signals look ok on a scope.

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