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参数资料
| 型号： | SN74F168DR |
| 厂商： | TEXAS INSTRUMENTS INC |
| 元件分类： | 计数器 |
| 英文描述： | F/FAST SERIES, SYN POSITIVE EDGE TRIGGERED 4-BIT BIDIRECTIONAL DECADE COUNTER, PDSO16 |
| 封装： | PLASTIC, SO-16 |
| 文件页数： | 1/10页 |
| 文件大小： | 149K |
| 代理商： | SN74F168DR |
SN74F168
SYNCHRONOUS 4BIT UP/DOWN DECADE COUNTER
SDFS057A D2932, MARCH 1987 REVISED OCTOBER 1993
Copyright
1993, Texas Instruments Incorporated
21
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
POST OFFICE BOX 1443
HOUSTON, TEXAS 772511443
Fully Synchronous Operation for Counting
and Programming
Internal Look-Ahead Circuitry for Fast
Counting
Carry Output for N-Bit Cascading
Fully Independent Clock Circuit
Package Options Include Plastic
Small-Outline Packages and Standard
Plastic 300-mil DIPs
description
This synchronous, presettable, 4-bit up/down decade counter features an internal carry look-ahead circuitry for
cascading in high-speed counting applications. Synchronous operation is provided by having all flip-flops
clocked simultaneously so that the outputs change coincident with each other when so instructed by the
count-enable (ENP, ENT) inputs and internal gating. This mode of operation eliminates the output counting
spikes that are normally associated with asynchronous (ripple-clock) counters. A buffered clock (CLK) input
triggers the four flip-flops on the rising (positive-going) edge of the clock waveform.
This counter is fully programmable; that is, it may be preset to any number between 0 and its maximum count.
The load-input circuitry allows loading with the carry-enable output of cascaded counters. As loading is
synchronous, setting up a low level at the load (LOAD) input disables the counter and causes the outputs to
agree with the data inputs after the next clock pulse.
The carry look-ahead circuitry provides for cascading counters for n-bit synchronous application without
additional gating. Instrumental in accomplishing this function are two count-enable (ENP, ENT) inputs and a
ripple-carry (RCO) output. Both ENP and ENT must be low to count. The direction of the count is determined
by the level of the up/down (U/D) input. When U/D is high, the counter counts up; when low, it counts down. Input
ENT is fed forward to enable the RCO. RCO thus enabled will produce a low-level pulse while the count is zero
(all inputs low) counting down or maximum (9 or 15) counting up. This low-level overflow ripple-carry pulse can
be used to enable successive cascaded stages. Transitions at ENP or ENT are allowed regardless of the level
of the clock input. All inputs are diode clamped to minimize transmission-line effects, thereby simplifying system
design.
The SN74F168 features a fully independent clock circuit. Changes at control inputs (ENP, ENT, LOAD or U/D)
that will modify the operating mode have no effect on the contents of the counter until clocking occurs. The
function of the counter (whether enabled, disabled, loading, or counting) will be dictated solely by the conditions
meeting the setup and hold times.
The SN74F168 is characterized for operation from 0
°C to 70°C.
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
U/D
CLK
A
B
C
D
ENP
GND
VCC
RCO
QA
QB
QC
QD
ENT
LOAD
D OR N PACKAGE
(TOP VIEW)
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| SN74F169D | 功能描述:计数器 IC Sync 4-Bit Up/Down Binary Counter RoHS:否 制造商:NXP Semiconductors 计数器类型:Binary Counters 逻辑系列:74LV 位数:10 计数法: 计数顺序: 工作电源电压:1 V to 5.5 V 工作温度范围:- 40 C to + 125 C 封装 / 箱体:SOT-109 封装:Reel |
| SN74F169DE4 | 功能描述:计数器 IC Sync 4-Bit Up/Down Binary Counter RoHS:否 制造商:NXP Semiconductors 计数器类型:Binary Counters 逻辑系列:74LV 位数:10 计数法: 计数顺序: 工作电源电压:1 V to 5.5 V 工作温度范围:- 40 C to + 125 C 封装 / 箱体:SOT-109 封装:Reel |
| SN74F169DG4 | 功能描述:计数器 IC SYNC 4B Up Down Binary Counter RoHS:否 制造商:NXP Semiconductors 计数器类型:Binary Counters 逻辑系列:74LV 位数:10 计数法: 计数顺序: 工作电源电压:1 V to 5.5 V 工作温度范围:- 40 C to + 125 C 封装 / 箱体:SOT-109 封装:Reel |
| SN74F169DR | 功能描述:计数器 IC Sync 4-Bit Up/Down Binary Counter RoHS:否 制造商:NXP Semiconductors 计数器类型:Binary Counters 逻辑系列:74LV 位数:10 计数法: 计数顺序: 工作电源电压:1 V to 5.5 V 工作温度范围:- 40 C to + 125 C 封装 / 箱体:SOT-109 封装:Reel |
| SN74F169DRE4 | 功能描述:计数器 IC Sync 4-Bit Up/Down Binary Counter RoHS:否 制造商:NXP Semiconductors 计数器类型:Binary Counters 逻辑系列:74LV 位数:10 计数法: 计数顺序: 工作电源电压:1 V to 5.5 V 工作温度范围:- 40 C to + 125 C 封装 / 箱体:SOT-109 封装:Reel |
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