When the input signals of SN74ABT541 are different, the output is disturbed

syn222

When the input signals of SN74ABT541 are different, the output is disturbed [Copy link]

As shown in the figure below, only A1, A2, and A3 are input. A1 inputs a PWM signal with a duty cycle of 0.2, A2 and A3 input high level, Y1 outputs normal, Y2 and Y3 outputs seem to be affected by Y1 and interfered, outputting the waveforms 2 and 3 below (originally should be high level), the input end has been tested and it is a normal waveform, please help

maychang

"A2 and A3 input high level" How is this "high level" applied? Directly connected to the positive terminal of the power supply? Through a resistor? Are the three wires A1, A2, and A3 long and close to each other?

syn222

maychang posted on 2018-6-16 12:38 "A2 and A3 input high level" How is this "high level" applied? Directly connected to the positive terminal of the power supply? Through a resistor? A1, A2, A3...

This high level and PWM are directly connected to the input terminal of ABT541 through the output of the arm chip, without passing through a resistor. The arm chip and ABT541 are relatively close, and the line spacing is also large. Is my power supply voltage too small?

maychang

syn222 posted on 2018-6-16 13:46 This high level and PWM are directly connected to the ABT541 input terminal through the arm chip output without passing through the resistor. The arm chip and ABT541 are relatively close, and the line...

Is my power supply voltage too small? This is very likely the case. The rated working voltage of this buffer/driver is 5V, and the minimum is 4.5V.

syn222

Changed to 5V power supply and still the same

maychang

syn222 posted on 2018-6-17 12:13 Changed to 5V power supply and still the same

It is recommended to use 74HC574 or something like that. The buffer/driver supply voltage of this model can be as low as 2V and as high as 6V.