4538

Dual retriggerable precision monostable multivibrator with reset


1CEXT	1 •	16	Vcc
1REXT/CEXT	2	15	2CEXT
1CD	3	14	2REXT/CEXT
1B	4	13	2CD
1A	5	12	2B
1Q	6	11	2A
1Q	7	10	2Q
GND	8	9	2Q

Pin	Symbol	Description
1	1CEXT	external capacitor connection (connect to capacitor and ground)
2	1REXT/CEXT	external capacitor/resistor connection
3	1CD	clear direct input (active low)
4	1B	input (low-to-high triggered)
5	1A	input (high-to-low triggered)
6	1Q	output
7	1Q	complementary output
8	GND	ground
9	2Q	complementary output
10	2Q	output
11	2A	input (high-to-low triggered)
12	2B	input (low-to-high triggered)
13	2CD	clear direct input (active low)
14	2REXT/CEXT	external capacitor/resistor connection
15	2CEXT	external capacitor connection (connect to capacitor and ground)
16	Vcc	supply voltage

Specifications

(typical values under recommended operating conditions, unless specified)

Parameter	Value	Unit
External timing resistor R_EXT	5 (min)	kΩ
External timing capacitor C_EXT	2000 (min)	pF
Pulse width variation, Vcc = 5V	±0.2	%

Notes

Connect a timing capacitor C_EXT between nCEXT and nREXT/CEXT.
Connect a resistor R_EXT between nREXT/CEXT and Vcc.
A high-to-low transition on nA when nB is low causes a pulse on nQ and nQ.
A low-to-high transition on nB when nA is high causes a pulse on nQ and nQ.
Setting nCD low inhibits pulses.
Output pulse width = R_EXT × C_EXT.
(74HC4538) Output pulse width = 0.7 × R_EXT × C_EXT.

Note: Data is maintained by an independent source and accuracy is not guaranteed. Check with the manufacturer's datasheet for up-to-date information.