ST HCF4538B User Manual

HCF4538B

DUAL MONOSTABLE MULTIVIBRATOR

■RETRIGGERABLE/RESETTABLE CAPABILITY

■TRIGGER AND RESET PROPAGATION DELAYS INDEPENDENT OF RX, CX

■TRIGGERING FROM LEADING OR TRAILING EDGE

■Q AND Q BUFFERED OUTPUT AVAILABLE

■SEPARATE RESETS

■WIDE RANGE OF OUTPUT PULSE WIDTHS

■QUIESCENT CURRENT SPECIFIED UP TO 20V

■5V, 10V AND 15V PARAMETRIC RATINGS

■SCHMITT TRIGGER INPUT ALLOWS UNLIMITED RISE AND FALL TIMES ON +TR AND -TR INPUTS

■INPUT LEAKAGE CURRENT

II = 100nA (MAX) AT VDD = 18V TA = 25°C

■100% TESTED FOR QUIESCENT CURRENT

■MEETS ALL REQUIREMENTS OF JEDEC JESD13B " STANDARD SPECIFICATIONS FOR DESCRIPTION OF B SERIES CMOS DEVICES"

DESCRIPTION

The HCF4538B is a monolithic integrated circuit fabricated in Metal Oxide Semiconductor technology available in DIP and SOP packages.

The HCF4538B dual precision monostable multivibrator provides stable retriggerable/ resettable one-shot operation for any fixed voltage

	DIP	SOP
ORDER CODES
PACKAGE	TUBE	T & R
DIP	HCF4538BEY
SOP	HCF4538BM1	HCF4538M013TR

timing application. An external resistor (RX) and an external capacitor (CX) control the timing and accuracy for the circuit. Adjustment of RX and CX provides a wide range of output pulse widths from the Q and Q terminals. The time delay from trigger input to output transition (trigger propagation delay) and the time delay from reset input to output transition (reset propagation delay) and the time delay from reset input to output transition (reset propagation delay) are independent of RX and CX. Precision control of output pulse width is achieved through linear CMOS techniques. Leading edge triggering (+TR) and trailing edge triggering (-TR) inputs are provided for triggering

PIN CONNECTION

September 2001

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HCF4538B

from either edge of an input pulse. An unused +TR input should be tied to VSS. An unused -TR input should be tied to VDD . A RESET (on low level) is provided for immediate termination of the output pulse or to prevent output pulses when power is turned on. An unused RESET input should be tied to VDD . However, if an entire section of the HCF4538B is not used, its inputs must be tied to either VDD or VSS (see table 1). In normal operation the circuit triggers (extends the output

IINPUT EQUIVALENT CIRCUIT

FUNCTIONAL DIAGRAM

pulse one period) on the application of each new trigger pulse. For operation in the non-retiggerable mode, Q is connected to -TR when leading edge triggering (+TR) is used or Q is connected to +TR when trailing edge triggering (-TR) is used. The time period (T) for this multivibrator can be calculated by : T = RX CX. The min. value of external resistance, RX, is 4KΩ. The max. and min. values of external capacitance, CX, are 100 μF and 5nF, respectively.

PIN DESCRIPTION

	PIN No	SYMBOL					NAME AND FUNCTION
	4, 12		+TR				Trigger Inputs (Low to
							High, Edge-Triggered)
	5, 11		-TR				Trigger Inputs (High to
							Low, Edge-Triggered)
	3, 13	RESET					Direct Reset Inputs
							(Active Low)
	1, 15	CX1, CX2					External Capacitor Con-
							nections
	2, 14		RXCX1				External Resistor/Capaci-
			RXCX2				tor Connections
	6, 10		Q1, Q2				Pulse Outputs
							Complementary Pulse
	7, 9		Q1, Q2
							Outputs
	8		VSS				Negative Supply Voltage
	16		VDD				Positive Supply Voltage

Terminals 1, 8, 15 are electrically connected internally

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HCF4538B

TABLE 1 : Functional Terminal Connections

	VDD to Term. N°		VSS to Term. N°		Input Pulse to		Other Connections
FUNCTION					Term. N°
	Mono (1)	Mono (2)	Mono (1)	Mono (2)	Mono (1)	Mono (2)	Mono (1)	Mono (2)
Leading Edge Trigger/	3, 5	11, 13			4	12
Retriggerable
Leading Edge Trigger/Non	3	13			4	12	5, 7	11, 9
Retriggerable
Trailing Edge Trigger/	3	13	4	12	5	11
Retriggerable
Trailing Edge Trigger/Non	3	13			5	11	4, 6	12, 10
Retriggerable

A Retriggerable one-shot multivibrator has an output pulse width which is extended on full time period (T) after application of the last trigger pulse.

A Non-Retriggerable one-shot multivibrator has a time period (T) referenced from the application of the firs trigger pulse.

LOGIC DIAGRAM

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