P82B96: Sx Sy connect to multiple devices

Part Number: P82B96

Tool/software:

Hi TI Team,

We have a project is using P82B96 as following picture, previously only one sensor and the system working fine, now we need to increase sensor from 1 to 8 on the same PCBA, can we use the same P82B96?

VCC is 5V, the total PCB trace of I2C bus on the sensor board is around 10,000 - 15,000 mil. PCB trace capacitance: ~25pF, slave chip MCP3427-E/UN pin capacitance 10pF *8 = 80pF.

Please help review and advice will it work, thanks.

new:

2 months ago

0 Jack Guan 2 months ago

TI__Mastermind 41956 points

Hi AD,

Per section 5 of the datasheet, no more than two devices on Sx/Sy side should be connected at a time. I would recommend breaking the sensor configurations up, similar to the below (<2 devices).

Regards,

Jack

0 AD 2 months ago in reply to Jack Guan

Intellectual 300 points

Hi Jack,

Thansks for your response, I will add P82B96 for each slave, I have another quesiton, if all slaves are on the same board, should each P82B96 add pull up resistor,

Or only one set pull-up resistor for all P82B96 ?

0 Jack Guan 2 months ago in reply to AD

TI__Mastermind 41956 points

Hi AD,

Tx and Ty are open-collector outputs without ESD protection diodes to VCC. Each pin may be connected through a pullup resistor to a supply voltage in excess of VCC, as long as the 15-V rating is not exceeded.

The customer should determine the values of the pullup depending on the prop delay in their system, and explained further in section 10.1.1 of the P82B96 datasheet. This previously answered e2e thread walks through the example calculation: https://e2e.ti.com/support/interface-group/interface/f/interface-forum/1081658/p82b96-attempting-to-send-i2c-over-long-distance-twisted-pairs.

Regards,

Jack

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P82B96: Sx Sy connect to multiple devices