Philips N74F191N, N74F191D Datasheet

INTEGRATED CIRCUITS

74F191

Up/down binary counter with reset and ripple clock

Product specification IC15 Data Handbook

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1995 Jul 17

Philips Semiconductors Product specification

74F191Up/Down binary counter with reset and ripple clock

FEA TURES

•High speed –125MHz typical f

MAX

•Synchronous, reversible counting

•4-Bit binary

•Asynchronous parallel load capability

•Cascadable without external logic

•Single up/down control input

DESCRIPTION

The 74F191 is a 4-bit binary counter. It contains four edge-triggered master/slave flip-flops with internal gating and steering logic to provide asynchronous preset and synchronous count-up and count-down operations.

Asynchronous parallel load capability permits the counter to be preset to any desired number. Information present on the parallel data inputs (D outputs when the Parallel Load (PL overrides the counting function. Counting is inhibited by a High level on the count enable (CE) input. When CE is Low, internal state changes are initiated. Overflow/underflow indications are provided by two types of outputs, the Terminal Count (TC) and Ripple Clock (RC

The TC output is normally Low and goes High when: 1) the count reaches zero in the countdown mode or 2) reaches “15” in the count up mode. The TC output will remain High until a state change occurs, either by counting or presetting, or until U output should not be used as a clock signal because it is subject to decoding spikes. The TC signal is used internally to enable the RC output. When TC is High and CE is Low, the RC follows the clock pulse. The RC width, although delayed in time by two gate delays.

- D3) is loaded into the counter and appears on the

) input is Low. This operation

/D is changed. TC

output essentially duplicates the Low clock pulse

PIN CONFIGURATION

U/D

5 6

GND

TYPE TYPICAL f

MAX

74F191 125MHz 40mA

11 10

SF00729

TYPICAL

SUPPLY CURRENT

(TOTAL)

ORDERING INFORMATION

COMMERCIAL RANGE

DESCRIPTION

16-pin plastic DIP N74F191N SOT38-4

16-pin plastic SO N74F191D SOT109-1

VCC = 5V ±10%,

= 0°C to +70°C

amb

PKG DWG #

INPUT AND OUTPUT LOADING AND FAN-OUT TABLE

PINS DESCRIPTION

D0 - D

Data inputs 1.0/1.0 20µA/0.6mA

74F(U.L.)

HIGH/LOW

CE Count enable input (active Low) 1.0/3.0 20µA/1.8mA CP Clock pulse input (active rising edge) 1.0/1.0 20µA/0.6mA PL Asynchronous parallel load control input (active Low) 1.0/1.0 20µA/0.6mA U/D Up/down count control input 1.0/1.0 20µA/0.6mA Q0 - Q

Flip-flop outputs 50/33 1.0mA/20mA RC Ripple clock output (active low) 50/33 1.0mA/20mA TC Terminal count output 50/33 1.0mA/20mA

NOTE: One (1.0) FAST Unit Load (U.L.) is defined as: 20µA in the High state and 0.6mA in the Low state.

1995 Jul 17 853–0352 15459

LOAD VALUE

HIGH/LOW

Philips Semiconductors Product specification

74F191Up/Down binary counter with reset and ripple clock

LOGIC SYMBOL

VCC=Pin 16 GND=Pin 8

LOGIC DIAGRAM

15 1 10 9

D0D

LOGIC SYMBOL (IEEE/IEC)

4 5

Q2Q

7623

15 1 10 9

SF00730

15 1 10 9

EN1 M2[DOWN]

M3[UP]

1,2–/1,3+ G4

C5 [LOAD]

CTR DIV 10

[1] [2] [4] [8]

2(CT=0)Z6

3(CT=15)Z6

6, 4, 1

+ –

3 2 6 7

SF00731

U/D

VCC= Pin 16 GND = Pin 8

TCRC

76231213

SF00732

1995 Jul 17

Philips Semiconductors Product specification

74F191Up/Down binary counter with reset and ripple clock

MODE SELECT — FUNCTION TABLE

INPUTS OUTPUTS OPERATING MODE

PL U/D CE CP D

L L

H L l ↑ X Count up Count up H H l ↑ X Count down Count down H X H X X No change Hold (do nothing)

X X

TC AND RC FUNCTION T ABLE

INPUTS TERMINAL COUNT STATE OUTPUTS

U/D CE CP Q

H H X H H H H L H L H X H H H H H H

L L H H H H H L H X L L L L L H H H X L L L L H H

H L L L L L H

H = High voltage level steady state L = Low voltage level steady state X = Don’t care

= Low pulse ↑ = Low-to-High clock transition l = Low voltage level one set-up time prior to the Low-to-High clock transition

L H

Parallel load

TC RC

1995 Jul 17

Philips Semiconductors Product specification

74F191Up/Down binary counter with reset and ripple clock

APPLICATIONS

DIRECTION CONTROL

ENABLE

CLOCK

ENABLE

CLOCK

U/D

RC RC RC CE CP

U/D CE CP

a. N-Stage Counter Using Ripple Clock

ENABLE

CLOCK

U/D

RC RC RC CE CP

U/D CE CP

b. Synchronous N-Stage Counter with Common Clock Using Ripple/Clock

U/D CE CP

* = Carry Gate

U/D CE

TC TC TC

U/D CE CP

c. Synchronous N-Stage Counter with Common Clock and Terminal Count

SF00733

Figure 1.

The 74F191 simplifies the design of multi-stage counters, as indicated in Figure 1, each RC

output is used as the clock input for the next higher stage. When the clock source has a limited drive capability this configuration is particularly advantageous, since the clock source drives only the first stage. It is only necessary to inhibit the first stage to prevent counting in all stages, since a High signal on CE

inhibits the RC output pulse as indicated in the Mode Select Table. The timing skew between state changes in the first and last stages is represented by the cumulative delay of the clock as it ripples through the preceding stages. This is a disadvantage of the configuration in some applications.

Figure 1b shows a method of causing state changes to occur simultaneously in all stages. The RC

output signals propagate in

ripple fashion and all clock inputs are driven in parallel. The Low state duration of the clock in this configuration must be long enough to allow the negative-going edge of the RC to the last stage before the clock goes High. Since the RC

signal to ripple through

output of any package goes High shortly after its clock input goes High, there is no such restriction on the High state duration of the clock.

In Figure 1c, the configuration shown avoids ripple delays and their associated restrictions. The combined TC signals from all the preceding stages forms the CE

input signal for a given stage. An enable signal must also be included in each carry gate in order to inhibit counting. The TC output of a given stage is not affected by its own CE

, therefore, the simple inhibit scheme of Figure 1a and 1b

does not apply.

1995 Jul 17

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