Dear expert,
My customer use 3pcs SN74HC595 in series. IC1's Q7' working as IC2's DS SER. Likewise, IC2's Q7' working as IC3's SER.
The normal waveform was shown below: CH1: SRCLK CH2:RCLK CH3:SER of IC1. CH4: SER of IC2.
Abnormal waveform:CH1: SRCLK CH2:SER of IC1. CH3:SER of IC2. CH4: Output of IC2
By comparing the waveforms of channels 1, 3, and 4, when the data input of the No. 2 chip corresponds to a low level, its corresponding output pin outputs a high level, causing subsequent circuit malfunctions. Please kindly help check what causes it, thank you!