74F169 Fairchild Semiconductor, 74F169 Datasheet - Page 2

• Manufacturer Part Number: 74F169
• Description: 4-Stage Synchronous Bidirectional Counter
• Manufacturer: Fairchild Semiconductor

www.fairchildsemi.com
Unit Loading/Fan Out
Functional Description
The 74F169 uses edge-triggered J-K type flip-flops and
has no constraints on changing the control or data input
signals in either state of the clock. The only requirement is
that the various inputs attain the desired state at least a
setup time before the rising edge of the clock and remain
valid for the recommended hold time thereafter. The paral-
lel load operation takes precedence over other operations,
as indicated in the Mode Select Table. When PE is LOW,
the data on the P
next rising edge of the clock. In order for counting to occur,
both CEP and CET must be LOW and PE must be HIGH;
the U/D input then determines the direction of counting.
The Terminal Count (TC) output is normally HIGH and goes
LOW, provided that CET is LOW, when a counter reaches
zero in the Count Down mode or reaches 15 for the
74F169 in the Count Up mode. The TC output state is not a
function of the Count Enable Parallel (CEP) input level.
Since the TC signal is derived by decoding the flip-flop
states, there exists the possibility of decoding spikes on
TC. For this reason the use of TC as a clock signal is not
recommended (see logic equations below).
1. Count Enable
2. Up: (74F169): TC
3. Down: TC
Q
Pin Names
0
0
CEP
CET
CP
P
PE
U/D
Q
TC
–P
• Q
CEP • CET • PE
0
0
–P
–Q
3
1
Q
inputs enters the flip-flops on the
• Q
3
3
0
• Q
2
• Q
1
• Q
Count Enable Parallel Input (Active LOW)
Count Enable Trickle Input (Active LOW)
Clock Pulse Input (Active Rising Edge)
Parallel Data Inputs
Parallel Enable Input (Active LOW)
Up-Down Count Control Input
Flip-Flop Outputs
Terminal Count Output (Active LOW)
3
• (Down) • CET
2
• Q
3
• (Up) • CET
Description
2
Mode Select Table
H
L
X
State Diagram
LOW Voltage Level
HIGH Voltage Level
Immaterial
PE CEP CET U/D
H
H
H
H
L
X
H
X
L
L
HIGH/LOW
50/33.3
50/33.3
X
X
H
1.0/1.0
1.0/2.0
1.0/1.0
1.0/1.0
1.0/1.0
1.0/1.0
L
L
U.L.
H
X
L
X
X
Output I
20 A/ 0.6 mA
20 A/ 1.2 mA
20 A/ 0.6 mA
20 A/ 0.6 mA
20 A/ 0.6 mA
20 A/ 0.6 mA
Input I
Load (P
Count Up (Increment)
Count Down (Decrement)
No Change (Hold)
No Change (Hold)
1 mA/20 mA
1 mA/20 mA
Action on Rising
Clock Edge
IH
OH
n
/I
/I
IL
OL
Q
n
)