Nexperia

74HC21

Dual 4-input AND gate

10. Dynamic characteristics

Table 7. Dynamic characteristics

GND = 0 V; test circuit see Fig. 6.

25 °C

-40 °C to +85 °C -40 °C to +125 °C

Symbol Parameter

Conditions

Min Typ Max

Min

Max

Min

Max

Unit

nA, nB, nC or nD to nY;

see Fig. 5

[1]

VCC = 2.0 V

-

33

110

-

140

-

165

ns

VCC = 4.5 V

-

12

22

-

28

-

33

ns

VCC = 6.0 V

-

10

19

-

24

-

28

ns

tpd

propagation

delay

VCC = 5.0 V; CL = 15 pF

-

10

-

-

-

-

-

ns

nY output; see Fig. 5

[2]

VCC = 2.0 V

-

19

75

-

95

-

110

ns

VCC = 4.5 V

-

7

15

-

19

-

22

ns

tt

transition time

VCC = 6.0 V

-

6

13

-

16

-

19

ns

CPD

power

dissipation

capacitance

VI = GND to VCC

[3]

-

15

-

-

-

-

-

pF

[1] tpd is the same as tPHL and tPLH.

[2] tt is the same as tTHL and tTLH.

[3] CPD is used to determine the dynamic power dissipation (PD in μW):

PD = CPD x VCC 2 x fi x N + Σ(CL x VCC 2 x fo) where:

fi = input frequency in MHz;

fo = output frequency in MHz;

CL = output load capacitance in pF;

VCC = supply voltage in V;

N = number of inputs switching;

Σ(CL x VCC 2 x fo) = sum of outputs.

10.1. Waveforms and test circuit

001aab977

nA, nB, nC,

nD input

nY output

VM

VX

VI

tPHL

tTHL

tTLH

tPLH

VOH

VM

VY

VOL

GND

Measurement points are given in Table 8.

VOL and VOH are typical voltage output levels that occur with the output load.

Fig. 5. Waveforms showing the input (nA, nB, nC, nD) to output (nY) propagation delays and the output transition

times

74HC21

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© Nexperia B.V. 2023. All rights reserved

Product data sheet

Rev. 9 — 2 May 2023

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