Philips 74HCT161U, 74HCT161PW, 74HCT161NB, 74HCT161N, 74HCT161D Datasheet

INTEGRATED CIRCUITS

DATA SHEET

For a complete data sheet, please also download:

∙The IC06 74HC/HCT/HCU/HCMOS Logic Family Specifications

∙The IC06 74HC/HCT/HCU/HCMOS Logic Package Information

∙The IC06 74HC/HCT/HCU/HCMOS Logic Package Outlines

74HC/HCT161

Presettable synchronous 4-bit binary counter; asynchronous reset

Product specification			December 1990
File under Integrated Circuits, IC06

Philips Semiconductors	Product specification

Presettable synchronous 4-bit binary

74HC/HCT161

counter; asynchronous reset

FEATURES

·Synchronous counting and loading

·Two count enable inputs for n-bit cascading

·Positive-edge triggered clock

·Asynchronous reset

·Output capability: standard

·ICC category: MSI

input (PE) disables the counting action and causes the data at the data inputs (D0 to D3) to be loaded into the counter on the positive-going edge of the clock (providing that the set-up and hold time requirements for PE are met). Preset takes place regardless of the levels at count enable inputs (CEP and CET).

A LOW level at the master reset input (MR) sets all four outputs of the flip-flops (Q0 to Q3) to LOW level regardless

of the levels at CP, PE, CET and CEP inputs (thus providing an asynchronous clear function).

GENERAL DESCRIPTION

The 74HC/HCT161 are high-speed Si-gate CMOS devices and are pin compatible with low power Schottky TTL (LSTTL). They are specified in compliance with JEDEC standard no. 7A.

The 74HC/HCT161 are synchronous presettable binary counters which feature an internal look-ahead carry and can be used for high-speed counting.

Synchronous operation is provided by having all flip-flops clocked simultaneously on the positive-going edge of the clock (CP).

The outputs (Q0 to Q3) of the counters may be preset to a HIGH or LOW level. A LOW level at the parallel enable

QUICK REFERENCE DATA

The look-ahead carry simplifies serial cascading of the counters. Both count enable inputs (CEP and CET) must be HIGH to count. The CET input is fed forward to enable the terminal count output (TC). The TC output thus enabled will produce a HIGH output pulse of a duration approximately equal to a HIGH level output of Q0. This pulse can be used to enable the next cascaded stage.

The maximum clock frequency for the cascaded counters is determined by the CP to TC propagation delay and CEP to CP set-up time, according to the following formula:

		1
fmax =	--------------------------------------------------------------------------------------------------
	tP(max)	(CP to TC) + tSU (CEP to CP)

GND = 0 V; Tamb = 25 °C; tr = tf = 6 ns

	SYMBOL	PARAMETER			CONDITIONS	TYPICAL		UNIT
						HC	HCT
	tPHL/ tPLH	propagation delay			CL = 15 pF;
			CP to Qn		VCC = 5 V	19	20	ns
			CP to TC			21	24	ns
			MR	to Qn		20	25	ns
			MR	to TC		20	26	ns
			CET to TC			10	14	ns
	fmax	maximum clock frequency				44	45	MHz
	CI	input capacitance				3.5	3.5	pF
	CPD	power dissipation			notes 1 and 2	33	35	pF
		capacitance per package

Notes

1.CPD is used to determine the dynamic power dissipation (PD in mW):

PD = CPD ´ VCC2 ´ fi +

å (CL ´ VCC2 ´ fo) where:

fi = input frequency in MHz

fo = output frequency in MHz

å (CL ´ VCC2 ´ fo) = sum of outputs

CL = output load capacitance in pF

VCC = supply voltage in V

2. For HC the condition is VI = GND to VCC

For HCT the condition is VI = GND to VCC - 1.5 V

December 1990

2

Philips Semiconductors	Product specification

Presettable synchronous 4-bit binary

74HC/HCT161

counter; asynchronous reset

ORDERING INFORMATION

See “74HC/HCT/HCU/HCMOS Logic Package Information”.

PIN DESCRIPTION

PIN NO.		SYMBOL			NAME AND FUNCTION
1					asynchronous master reset (active LOW)
		MR
2		CP			clock input (LOW-to-HIGH, edge-triggered)
3, 4, 5, 6		D0 to D3			data inputs
7		CEP			count enable input
8		GND			ground (0 V)
9					parallel enable input (active LOW)
		PE
10		CET			count enable carry input
14, 13, 12, 11		Q0 to Q3			flip-flop outputs
15		TC			terminal count output
16		VCC			positive supply voltage

Fig.1 Pin configuration.		Fig.2 Logic symbol.		Fig.3 IEC logic symbol.

December 1990

3

Philips Semiconductors	Product specification

Presettable synchronous 4-bit binary

74HC/HCT161

counter; asynchronous reset

Fig.4

Functional diagram.

FUNCTION TABLE

OPERATING MODE

INPUTS

OUTPUTS

MR

CP

CEP

CET

PE

Dn

Qn

TC

reset (clear)

L

X

X

X

X

X

L

L

parallel load

H

−

X

X

I

I

L

L

H

−

X

X

I

h

H

(1)

count

H

−

h

h

h

X

count

(1)

hold

H

X

I

X

h

X

qn

(1)

(do nothing)

H

X

X

I

h

X

qn

L

Note

1.The TC output is HIGH when CET is HIGH and the counter is at terminal count (HHHH). H = HIGH voltage level

h = HIGH voltage level one set-up time prior to the LOW-to-HIGH CP transition L = LOW voltage level

I = LOW voltage level one set-up time prior to the LOW-to-HIGH CP transition

q = lower case letters indicate the state of the referenced output one set-up time prior to the LOW-to-HIGH CP transition

X = don’t care

− = LOW-to-HIGH CP transition

December 1990

4