Document
54122 DM74122 Retriggerable Resettable Multivibrator
June 1989
54122 DM74122 Retriggerable Resettable Multivibrator
General Description
The ’122 features positive and negative DC level triggering inputs complementary outputs an optional 10 kX internal timing resistor and an overriding Direct Clear (CD) input When the circuit is in the quasi-stable (delay) state another trigger applied to the inputs (per Truth Table) will cause the delay period to start again without disturbing the outputs This process can be repeated indefinitely and thus the output pulse period (Q HIGH Q LOW) can be made as long as desired Alternatively a delay period can be terminated by a LOW signal applied to CD which also prevents triggering An internal connection from CD to the input gate makes it possible to trigger the circuit by a positive-going signal on CD as shown in the Truth Table For timing capacitor values greater than 1000 pF the output pulse width is defined as follows tw e 0 32 RXCX (1 0 a 0 7 RX) Where tw is in ns RX is in kX and CX is in pF
Connection Diagram
Dual-In-Line Package
Logic Symbol
TL F 10212 – 2 TL F 10212 – 1
Order Number 54122DMQB 54122FMQB or DM74122N See NS Package Number J14A N14A or W14B
VCC e Pin 14 GND e Pin 7 NC e Pins 10 and 12
Pin Names A1 A2 B1 B2 CD Q Q
Description Trigger Inputs (Active Falling Edge) Trigger Inputs (Active Rising Edge) Direct Clear Inputs (Active LOW) Outputs
C1995 National Semiconductor Corporation
TL F 10212
RRD-B30M105 Printed in U S A
Absolute Maximum Ratings
(Note) Note The ‘‘Absolute Maximum Ratings’’ are those values beyond which the safety of the device cannot be guaranteed The device should not be operated at these limits The parametric values defined in the ‘‘Electrical Characteristics’’ table are not guaranteed at the absolute maximum ratings The ‘‘Recommended Operating Conditions’’ table will define the conditions for actual device operation
If Military Aerospace specified devices are required please contact the National Semiconductor Sales Office Distributors for availability and specifications Supply Voltage 7V Input Voltage 5 5V Operating Free Air Temperature Range b 55 C to a 125 C 54 DM74 0 C to a 70 C b 65 C to a 150 C Storage Temperature Range
Recommended Operating Conditions
Symbol VCC VIH VIL IOH IOL TA Parameter Min Supply Voltage High Level Input Voltage Low Level Input Voltage High Level Output Current Low Level Output Current Free Air Operating Temperature
b 55
54122 Nom 5 Max 55 Min 4 75 2 08
b0 8
DM74122 Nom 5 Max 55
Units V V 08
b0 8
45 2
V mA mA C
16 125
b 55
16 70
Recommended Operating Conditions VCC e a 5 0V
Symbol tw RX Parameter Trigger Pulse Width External Timing Resistor XC XM CX External Timing Capacitor Conditions
TA e a 25 C DM74 Min 40 Max ns 50 25 pF kX Units
Over Operating VCC and Temperature Range
50 50
No Restrictions
Electrical Characteristics over recommended operating free air temperature range (unless otherwise noted)
Symbol VI VOH VOL II IIH.