74HC123 데이터 시트보기 (PDF) - NXP Semiconductors.

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74HC123

Dual retriggerable monostable multivibrator with reset

NXP Semiconductors. 

NXP Semiconductors

74HC123; 74HCT123

Dual retriggerable monostable multivibrator with reset

12. Application information

12.1 Timing component connections

The basic output pulse width is essentially determined by the values of the external timing

components REXT and CEXT.

(1) CEXT

REXT

VCC

GND nCEXT nREXT/CEXT

8

14 (6) 15 (7)

123

1 (9)

nA

nB

2 (10)

13 (5)

nQ

4 (12)

nQ

3 (11)

nRD

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(1) For minimum noise generation it is recommended to ground pins 6 (2CEXT) and 14 (1CEXT)

externally to pin 8 (GND).

Fig 13. Timing component connections

12.2 Power-up considerations

When the monostable is powered-up it may produce an output pulse, with a pulse width

defined by the values of REXT and CEXT. This output pulse can be eliminated using the

circuit shown in Figure 14.

CEXT

REXT

VCC

GND nCEXT nREXT/CEXT

8

14 (6)

15 (7)

123

nA

1 (9)

nB

2 (10)

13 (5)

nQ

4 (12)

nQ

3 (11)

nRD

RESET

VCC

Fig 14. Power-up output pulse elimination circuit

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74HC_HCT123

Product data sheet

All information provided in this document is subject to legal disclaimers.

Rev. 8 — 16 December 2011

© NXP B.V. 2011. All rights reserved.

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