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help on uc2709

wutong feng
Prodigy 30 points
Other Parts Discussed in Thread: UC2709, UC1707

I connectted  the input of uc2709 to the output of a cpld. Both the uc2709 and the cpld was damaged.

I then placed a resistor of 51K between the cpld and uc2709. Uc2709 was damaged but cpld not.

i wonder if  i can apply a voltage on the input of uc2709. 

or I should use a open collector gate like 7406 (but without a pull up resistor) to drive it? 

  • 0
    TI__Mastermind 25486 points

    difficult to say, it could depend on many factors...

    you should check the voltage (if OVS are present), look at the continuity (to see which pair of pins is affected (which kind of damages are you talking about? I assume short circuit between pins): please clarify...

    Vincenzo.

  • 0 in reply to Vincenzo Pizzolante
    Prodigy 30 points

    thanks for your reply.

    The output of CPLD (xc95288xl) is 3.3V, there is no over voltage.

    when i applied 3.3V on the input of uc2709 directly, the UC2709 was exploded.

    Then I placed the Uc2709 on a breadboard, only connected the power and gnd. everything seems ok, so I'm sure there was no short circuit. 

    Then, I connected the input of UC2709 to a 3.3V,  the Uc2709 exploded again.

    I then inserted a resistor of 51K between the output of 95288xl and the input of Uc2709. After the 95288xl output a 3.3V,

    I saw there was a black point on the UC2709, it looked like the chip was burned from inside, but it did not explode.

    i saw a picture in uc1707's datasheet. so i guess if i should drive UC2709 with a open collector gate? 

    If I let the input pin float, output is low.  If I connect the input to gnd, output goes high.

    but i have not tested drive Uc2709 with a 7406. 

    Thanks!