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SN75451B: I used SN75451B in my project , when I test the board ,the chip very hot

chen chen35
Intellectual 875 points
Part Number: SN75451B

Hi 

    I used SN75451B in my project , when I test the board ,the chip very hot ,please help to review my design ,is it  have some mistake? Thanks a lot .

  • 0
    TI__Genius 10855 points

    Hi Chen Chen,

    Thanks for reaching out on E2E!

    Can you elaborate on the temperature conditions? What temperature does the part reach, and under what conditions? What current are you driving through the device? 

    Thanks,

    Arthur Huang

  • 0 in reply to Alpha H
    Intellectual 875 points
    Hi Arthur,
    It is tested at room temperature about 26℃.The chip temperature about 65℃.The current through the device about 50mA. Thanks a lot.
  • 0 in reply to chen chen35
    TI__Genius 10855 points

    Hi Chen Chen, 

    Do you have a bypass capacitor on VCC? The datasheet mentions adding a 0.1uF bypass cap to prevent power disturbances/glitches.

    Are you tying the input 2 channel, pin3, to VCC or GND?

    Which package of the SN75451B are you using? If you look at the thermal calculations, 65C seems reasonable. Since you're dissipating 5V @ 50mA, your average power dissipation is 0.25W. Looking at the thermal information on page 4, if you're using the D or PS package, you could be dissipating ~120C/W * 0.25W = 30C of heat, which would be similar to the 65C that you're measuring on the package.

    Thanks,

    Arthur Huang