8-bit serial-in/serial or parallel-out shift
register with output latches; 3-state
• 8-bit serial input
• 8-bit serial or parallel output
• Storage register with 3-state outputs
• Shift register with direct clear
• 100 MHz (typ) shift out frequency
• Output capability:
– parallel outputs; bus driver
– serial output; standard
• ICC category: MSI.
• Serial-to-parallel data conversion
• Remote control holding register.
The 74HC/HCT595 are high-speed Si-gate CMOS devices
and are pin compatible with low power Schottky TTL
(LSTTL). They are specified in compliance with JEDEC
standard no. 7A.
The “595” is an 8-stage serial shift register with a storage
register and 3-state outputs. The shift register and storage
register have separate clocks.
Data is shifted on the positive-going transitions of the
SHCP input. The data in each register is transferred to the
storage register on a positive-going transition of the STCP
input. If both clocks are connected together, the shift
register will always be one clock pulse ahead of the
The shift register has a serial input (DS) and a serial
standard output (Q7’) for cascading. It is also provided with
asynchronous reset (active LOW) for all 8 shift register
stages. The storage register has 8 parallel 3-state bus
driver outputs. Data in the storage register appears at the
output whenever the output enable input (OE) is LOW.
QUICK REFERENCE DATA
GND = 0 V; Tamb = 25 °C; tr = tf = 6 ns.
SHCP to Q7’
STCP to Qn
MR to Q7’
maximum clock frequency SHCP, STCP
power dissipation capacitance per package
CL = 15 pF; VCC = 5 V
notes 1 and 2
1. CPD is used to determine the dynamic power dissipation (PD in µW):
PD = CPD × VCC2 × fi + ∑ (CL × VCC2 × fo) where:
fi = input frequency in MHz
fo = output frequency in MHz
∑(CL × VCC2 × fo) = sum of outputs
CL = output load capacitance in pF
VCC = supply voltage in V
2. For HC the condition is VI = GND to VCC; for HCT the condition is VI = GND to VCC − 1.5 V.
1998 Jun 04