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SN74LVC8T245: abnormal output during power up

Ruixin Feng
Intellectual 2205 points
Part Number: SN74LVC8T245

Tool/software:

Hi team,

In customer application, OE keep low, during power up, the output of buffer will show a pulse as below shown. And buffer application is shown in below.

Green is output of buffer. Yellow is VCCA(3.3V), Red is VCCB(5V), Blue is power enable.  Since buffer output is pulled up to 5V by a 10kohm resistor. For normal operation, output of buffer will increase by following 5V ramp up. But I don't know the reason why there was a pulse here. Could you pls give some comments for it? Thanks!

Rayna

  • 0
    Guru 295220 points

    Below the minimum recommended supply voltage of 1.65 V, correct operation is not guaranteed.

    To guarantee that all A/B outputs are disabled during power up, connect /OE to VCC with a pull-up, and force it down later with a GPIO from the CPU.