74HC237 datasheet(7/17 Pages) NXP

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74HC237

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Product data sheet

Rev. 4 — 10 January 2011

7 of 17

NXP Semiconductors

74HC237

3-to-8 line decoder, demultiplexer with address latches

[1]

tpd is the same as tPLH and tPHL.

[2]

tt is the same as tTHL and tTLH.

[3]

CPD is used to determine the dynamic power dissipation (PD in W).

PD =CPD  VCC2  fi  N+ (CL  VCC2  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;

(C

L  VCC

 f

o) = sum of outputs.

11. Waveforms

pulse width

LE HIGH; see Figure 9

VCC = 2.0 V

VCC = 4.5 V

VCC = 6.0 V

tsu

set-up time

An to LE; see Figure 9

VCC = 2.0 V

VCC = 4.5 V

VCC = 6.0 V

hold time

An to LE; see Figure 9

VCC = 2.0 V

VCC = 4.5 V

VCC = 6.0 V

CPD

power

dissipation

capacitance

CL =50pF;f= 1 MHz;

VI =GND to VCC

[3]

-60

Table 7.

Dynamic characteristics …continued

Voltages are referenced to GND (ground = 0 V); CL = 50 pF unless otherwise specified; for test circuit see Figure 10.

Symbol Parameter

Conditions

Tamb = 25 C

Tamb = 40 C

to +85

C

Tamb = 40 C

to +125

C

Unit

Min

Typ

Max

Min

Max

Min

Max

Measurement points are given in Table 8.

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

Fig 7.

Propagation delay input (An) and enable inputs (E2, LE) to output (Yn) and output transition time

001aab873

An, E2, LE

input

Yn output

tPHL

tTHL

tTLH

tPLH

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