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SN74LVC07A: Output Low fixed issue

user5163865
Genius 3395 points
Part Number: SN74LVC07A

Hi,

Please tell  me TI's point of view about following?

With the circuit configuration as shown in the figure,



Even though the input side (pin 11) is HI, the output side (pin 10) is stuck Lo and then toggling the input does not work.

Upon investigation, the power sequence was P1.8 → P3.3, and 1.8V was supplied to the pin 10 pull-up before supplying power to the SN74LVC07APWR.

Will this cause the SN74LVC07APWR to fail?
However, the same circuit is composed of 13 pins and 12 pins of the same SN74LVC07APWR, but for the H input to the input side (13 pin), the output side (12 pin) is also output to H, and it operates normally. .

(1) Is there a possibility that the SN74LVC07APWR will fail if a voltage load is applied to the output pin before power is supplied to the SN74LVC07APWR as described above?
(2) As mentioned above, is there a possibility that the same IC may malfunction or not malfunction depending on the pins?

Regarding the customer's complaint above, when I check the absolute maximum ratings in the data sheet, it seems that there is no problem in supplying voltage to the open-drain pull-up before the power supply.


Best regards,
Hiroshi

  • 0
    Guru 261430 points

    Applying a voltage to the output is allowed, in any situation.

    But the capacitor is rather large. When switching low, the discharge current might exceed the absolute maximum rating. A series resistor of at least 33 Ω between the output and the capacitor should limit the current to a safe value.

    It could be possible that the output was damaged by overvoltage (e.g., ESD), but this appears to be unlikely.