Features
• Buffered Inputs
• Asynchronous Parallel Load
• Fanout (Over Temperature Range)
- Standard Outputs . . . . . . . . . . . . . . . 10 LSTTL Loads
- Bus Driver Outputs . . . . . . . . . . . . . 15 LSTTL Loads
• Wide Operating Temperature Range . . . -55oC to 125oC
• Balanced Propagation Delay and Transition Times
• Significant Power Reduction Compared to LSTTL
Logic ICs
• HC Types
- 2V to 6V Operation
- High Noise Immunity: NIL = 30%, NIH = 30% of VCC
at VCC = 5V
• HCT Types
- 4.5V to 5.5V Operation
- Direct LSTTL Input Logic Compatibility,
VIL= 0.8V (Max), VIH = 2V (Min)
- CMOS Input Compatibility, Il ≤ 1μA at VOL, VOH

Description
The ’HC597 and CD74HCT597 are high-speed silicon gate
CMOS devices that are pin-compatible with the LSTTL 597
devices. Each device consists of an 8-flip-flop input register
and an 8-bit parallel-in/serial-in, serial-out shift register. Each
register is controlled by its own clock. A “low” on the parallel
load input (PL) shifts parallel stored data asynchronously into
the shift register. A “low” master input (MR) clears the shift
register. Serial input data can also be synchronously shifted
through the shift register when PL is high.