74HC123; 74HCT123

General description

The 74HC123; 74HCT123 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 74HC123; 74HCT123 are dual retriggerable monostable multivibrators with output pulse width control by three methods:

1. The basic pulse time is programmed by selection of an external resistor (R_EXT ) and capacitor (C_EXT ).
2. Once triggered, the basic output pulse width may be extended by retriggering the gated active LOW-going edge input (nA) or the active HIGH-going edge input (nB). By repeating this process, the output pulse period (nQ = HIGH, nQ = LOW) can be made as long as desired. Alternatively an output delay can be terminated at any time by a LOW-going edge on input nRD, which also inhibits the triggering.
3. An internal connection from nRD to the input gates makes it possible to trigger the circuit by a HIGH-going signal at input nRD as shown in the function table.

Schmitt-trigger action in the nA and nB inputs, makes the circuit highly tolerant to slower input rise and fall times.

The 74HC123; 74HCT123 is identical to the 74HC423; 74HCT423 but can be triggered via the reset input.

Features

• DC triggered from active HIGH or active LOW inputs
• Retriggerable for very long pulses up to 100 pct duty factor
• Direct reset terminates output pulse
• Schmitt-trigger action on all inputs except for the reset input
• ESD protection:
• HBM EIA/JESD22-A114-C exceeds 2000 V
• MM EIA/JESD22-A115-A exceeds 200 V
• Specified from -40 Cel to +85Cel and from -40 Cel to +125 Cel

Products/packages

Pricing/ordering/availability

Block diagrams/pinning

Design support

Application Notes

AN1998_2; An FM/IF system for DECT and other high speed GFSK applications (14-Jan-04)

Support Documents

HCT_USER_GUIDE; HC/T User Guide (1997-11-01)

75013486; Philips Logic Competitive Cross Reference Guide (2004-09-14)

Parametrics/similar products

Similar products
74HC123; 74HCT123 links to the similar products page containing an overview of products that are similar in function or related to the type number(s) as listed on this page. The similar products page includes products from the same catalog tree(s), relevant selection guides and products from the same functional category.

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