SN74AHCT123ADE4 datasheet(8/24 Pages) TI

8 / 24 page

SN54AHCT123A, SN74AHCT123A

DUAL RETRIGGERABLE MONOSTABLE MULTIVIBRATORS

SCLS420G – JUNE 1998 – REVISED APRIL 2003

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

APPLICATION INFORMATION

retriggering data

The minimum input retriggering time (tMIR) is the minimum time required after the initial signal before retriggering

the input. After tMIR, the device retriggers the output. Experimentally, it also can be shown that to retrigger the

output pulse, the two adjacent input signals should be tMIR apart, where tMIR = 0.30 × tw. The retrigger pulse

duration is calculated as shown in Figure 3.

tMIR

tRT

tPLH

Input

Output

tRT = tw + tPLH = (K × RT × CT) + tPLH

Where:

tMIR = Minimum Input Retriggering Time

tPLH = Propagation Delay

tRT = Retrigger Time

= Output Pulse Duration Before Retriggering

Figure 3. Retrigger Pulse Duration

The minimum value from the end of the input pulse to the beginning of the retriggered output should be

approximately 15 ns to ensure a retriggered output (see Figure 4).

Input

Output

tMRT = Minimum Time Between the End of the Second Input Pulse and the Beginning of the Retriggered Output

tMRT = 15 ns

tMRT

Figure 4. Input/Output Requirements

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