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TPS61177A: I2C Communication_ device address '2C'

Ji Li
Prodigy 10 points
Part Number: TPS61177A

I have a design with TPS61177a, following the reference design. 

there's another device on i2C bus with address '5d'. 

after asserting the 'ENB' pin, I can find two devices on I2C line with address '2C' and '5d'. 

the address of TPS61177a is '58'. 

another device cannot be disconnected. I'm not sure this is right? any idea? thanks, 

- Ji

  • 0
    TI__Genius 12915 points

    Hi Ji,

    58h is the chip address plus write bit (8'b 0101 1000). The address is actually 2C (7'b 010 1100). I think your recognition is right.

  • 0 in reply to Hardy Wu
    Prodigy 10 points

    Thanks Hardy, 

    one more question about the supply voltage. 

    I have 3V VINB designed. but I found the chip working not stable. I increased the voltage to 5V. it became stable.

    (stable means, with 3V input voltage, I tested on 3 my customized boards, I see TPS61177a was not on the I2C bus on one of them, and increase the voltage to 5V, it shows up.)

    I may have some problem with layout, but just want to know the supply voltage can impact the operation or not? 

    I'm thinking to change the supply voltage to 5V. any advices? Thanks. 

    - Ji

  • 0 in reply to Ji Li
    TI__Genius 12915 points

    Hi Ji,

    What level your SCL and SDA pulled up? VIH for interface pin is a absolute value 1.75V and I do not think VINB value would influence the communication. Did you measure the voltage on VINB pin to see if the voltage dropped?