Datasheet for the SN74HC595, the 8-bit serial-in, parallel-out shift register with output latches from the 74HC logic family. The 477 KB PDF gives pinout, timing diagrams, supply range and output drive limits. Technicians use it when tracing LED driver chains, display boards and port expanders, checking the serial data, shift clock, latch clock, output enable and clear lines. Cascaded chips pass data through the QH' output, a useful probing point when one stage stops responding.
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