74LV123N 查看數據表（PDF） - Philips Electronics

零件编号

产品描述 (功能)

生产厂家

74LV123N

Dual retriggerable monostable multivibrator with reset

Philips Electronics 

Philips Semiconductors

Dual retriggerable monostable multivibrator

with reset

Product specification

74LV123

AC CHARACTERISTICS (Continued)

GND = 0V; tr = tf ≤ 2.5ns; CL = 50pF; RL =1 KΩ

SYMBOL

PARAMETER

WAVEFORM

CONDITION

LIMITS

–40 to +85°C

VCC(V)

1.2

MIN TYP MAX

10

1000

REXT

External timing

resistor

Figure 5

2.0

5

2.7

3

3.0 to 3.6

2

1000

1000

1000

4.5 to 5.5

2

1000

1.2

CEXT

External timing

capacitor

Figure 53

2.0

2.7

3.0 to 3.6

No limits

4.5 to 5.5

NOTES:

1. Unless otherwise stated, all typical values are at Tamb = 25°C.

2. Typical value measured at VCC = 3.3V.

3. Typical value measured at VCC = 5.0V.

4. For other REXT and CEXT combinations see Figure 5.

if CEXT > 10 nF, the next formula is valid:

tW = K x REXT x CEXT (typ.)

where, tW = output pulse width in ns;

REXT = external resistor in KΩ; CEXT = external capacitor in pF;

K = constant = 0.45 for VCC = 5.0V and 0.48 for VCC = 2.0V.

The inherent test jig and pin capacitance at pins 15 and 7 (nREXT/CEXT) is approximately 7 pF.

5. The time to retrigger the monostable multivibrator depends on the values of REXT and CEXT.

The output pulse width will only be extended when the time between the active-going edges of the

trigger pulses meets the minimum retrigger time.

If CEXT > 10 pF, the next formula (at VCC = 5.0V) for the set-up time of a retrigger pulse is valid:

trt = 30 + 0.19R x C-9 + 13 x R1.05 (typ.)

where, trt = retrigger time in ns;

CEXT = external capacitor in pF;

REXT = external resistor in KΩ.

The inherent test jig and pin capacitance at pins 15 and 7 (nREXT/CEXT) is approximately 7 pF.

6. When the device is powered up, initiate the device via a reset pulse, when CEXT < 50pF.

–40 to +125°C

MIN MAX

AC WAVEFORMS

VM = 1.5V at VCC w 2.7V; VM = 0.5 VCC at VCC t 2.7V; VOL and

VOH are the typical output voltage drop that occur with the output

load.

UNIT

ΚΩ

pF

nB INPUT

tW

nA INPUT

trt

tW

nQ OUTPUT

tW

tW

tW

SV00139

Figure 1.Output pulse control using retrigger pulse;

nRD = HIGH.

nB INPUT

nRD INPUT

tW

nQ OUTPUT

tW

tW

SV00140

Figure 2.Output pulse control using reset input nRD;

nA = LOW.

1998 Apr 28

8

Share Link: