Philips Semiconductors
Product specification
4-bit parallel access shift register
74HC/HCT195
by the state of the parallel load enable (PE) input. Serial
data enters the first flip-flop (Q0) via the J and K inputs
when the PE input is HIGH and shifted one bit in the
direction Q0 → Q1 → Q2 → Q3 following each
LOW-to-HIGH clock transition. The J and K inputs provide
the flexibility of the JK type input for special applications
and by tying the pins together, the simple D-type input for
general applications. The “195” appears as four common
clocked D flip-flops when the PE input is LOW.
FEATURES
• Asynchronous master reset
• J, K, (D) inputs to the first stage
• Fully synchronous serial or parallel data transfer
• Shift right and parallel load capability
• Complement output from the last stage
• Output capability: standard
• ICC category: MSI
After the LOW-to-HIGH clock transition, data on the
parallel inputs (D0 to D3) is transferred to the respective
Q0 to Q3 outputs. Shift left operation (Q3 → Q2) can be
achieved by tying the Qn outputs to the Dn-1 inputs and
holding the PE input LOW.
GENERAL DESCRIPTION
The 74HC/HCT195 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.
All parallel and serial data transfers are synchronous,
occurring after each LOW-to-HIGH clock transition.
There is no restriction on the activity of the J, K, Dn and
PE inputs for logic operation other than the set-up and
hold time requirements. A LOW on the asynchronous
master reset (MR) input sets all Q outputs LOW,
independent of any other input condition.
The 74HC/HCT195 performs serial, parallel,
serial-to-parallel or parallel-to-serial data transfer at very
high speeds. The “195” operates on two primary modes:
shift right (Qo→Q1) and parallel load, which are controlled
QUICK REFERENCE DATA
GND = 0 V; Tamb = 25 °C; tr = tf = 6 ns
TYPICAL
SYMBOL
tPHL/ tPLH
PARAMETER
CONDITIONS
UNIT
ns
HC
15
HCT
15
propagation delay CP to Qn
maximum clock frequency
input capacitance
CL = 15 pF; VCC = 5 V
fmax
CI
57
57
MHz
pF
3.5
105
3.5
105
CPD
power dissipation capacitance per package
notes 1 and 2
pF
Notes
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
ORDERING INFORMATION
See “74HC/HCT/HCU/HCMOS Logic Package Information”.
December 1990
2
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