Dual JK ﬂip-ﬂop with set and reset;
• J, K inputs for easy D-type flip-flop
• Toggle flip-flop or “do nothing” mode
• Output capability: standard
• ICC category: flip-flops
The 74HC/HCT109 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 74HC/HCT109 are dual positive-edge triggered, JK
flip-flops with individual J, K inputs, clock (CP) inputs, set
(SD) and reset (RD) inputs; also complementary Q and Q
The set and reset are asynchronous active LOW inputs
and operate independently of the clock input.
The J and K inputs control the state changes of the
flip-flops as described in the mode select function table.
The J and K inputs must be stable one set-up time prior to
the LOW-to-HIGH clock transition for predictable
The JK design allows operation as a D-type flip-flop by
tying the J and K inputs together.
Schmitt-trigger action in the clock input makes the circuit
highly tolerant to slower clock rise and fall times.
QUICK REFERENCE DATA
GND = 0 V; Tamb = 25 °C; tr = tf = 6 ns
nCP to nQ, nQ
nSD to nQ, nQ
nRD to nQ, nQ
maximum clock frequency
capacitance per ﬂip-ﬂop
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.
See “74HC/HCT/HCU/HCMOS Logic Package Information”.
1997 Nov 25