Retriggerable Resettable Multivibrator
54122 DM74122 Retriggerable Resettable Multivibrator
June 1989
54122 DM74122 Retriggerable Resettable Multivibrator
Ge...
Description
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...
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