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參數資料
| 型號： | DM74LS191 |
| 廠商： | Fairchild Semiconductor Corporation |
| 元件分類： | 通用總線功能 |
| 英文描述： | Synchronous 4-Bit Up/Down Binary Counter with Mode Control(帶模式控制的同步4位二進制加/減計數器) |
| 中文描述： | 同步4位向上/向下二進制計數器模式控制（帶模式控制的同步4位二進制加/減計數器） |
| 文件頁數： | 1/6頁 |
| 文件大小： | 72K |
| 代理商： | DM74LS191 |
August 1986
Revised February 1999
D
1999 Fairchild Semiconductor Corporation
DS006405.prf
www.fairchildsemi.com
DM74LS191
Synchronous 4-Bit Up/Down Counter with Mode Control
General Description
The DM74LS191 circuit is a synchronous, reversible, up/
down counter. Synchronous operation is provided by hav-
ing all flip-flops clocked simultaneously, so that the outputs
change simultaneously when so instructed by the steering
logic. This mode of operation eliminates the output count-
ing spikes normally associated with asynchronous (ripple
clock) counters.
The outputs of the four master-slave flip-flops are triggered
on a LOW-to-HIGH level transition of the clock input, if the
enable input is LOW. A HIGH at the enable input inhibits
counting. Level changes at either the enable input or the
down/up input should be made only when the clock input is
HIGH. The direction of the count is determined by the level
of the down/up input. When LOW, the counter counts up
and when HIGH, it counts down.
The counter is fully programmable; that is, the outputs may
be preset to either level by placing a LOW on the load input
and entering the desired data at the data inputs. The output
will change independent of the level of the clock input. This
feature allows the counters to be used as modulo-N divid-
ers by simply modifying the count length with the preset
inputs.
The clock, down/up, and load inputs are buffered to lower
the drive requirement; which significantly reduces the num-
ber of clock drivers, etc., required for long parallel words.
Two outputs have been made available to perform the cas-
cading function: ripple clock and maximum/minimum count.
The latter output produces a high-level output pulse with a
duration approximately equal to one complete cycle of the
clock when the counter overflows or underflows. The ripple
clock output produces a low-level output pulse equal in
width to the low-level portion of the clock input when an
overflow or underflow condition exists. The counters can be
easily cascaded by feeding the ripple clock output to the
enable input of the succeeding counter if parallel clocking
is used, or to the clock input if parallel enabling is used.
The maximum/minimum count output can be used to
accomplish look-ahead for high-speed operation.
Features
I
Counts binary
I
Single down/up count control line
I
Count enable control input
I
Ripple clock output for cascading
I
Asynchronously presettable with load control
I
Parallel outputs
I
Cascadable for n-bit applications
I
Average propagation delay 20 ns
I
Typical clock frequency 25 MHz
I
Typical power dissipation 100 mW
Ordering Code:
Devices also available in Tape and Reel. Specify by appending the suffix letter “X” to the ordering code.
Order Number
DM74LS191M
DM74LS191N
Package Number
M16A
N16E
Package Description
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150” Narrow Body
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300” Wide
相關PDF資料 |
PDF描述 |
|---|---|
| DM74LS191N | Synchronous 4-Bit Up/Down Counter with Mode Control |
| DM74LS191MX | Synchronous Up/Down Counter |
| DM74LS193M | Synchronous 4-Bit Binary Counter with Dual Clock |
| DM74LS193 | Synchronous 4-Bit Binary Counter with Dual Clock(帶雙時鐘的同步4位二進制計數器) |
| DM74LS193N | Synchronous 4-Bit Binary Counter with Dual Clock |
相關代理商/技術參數 |
參數描述 |
|---|---|
| DM74LS191 WAF | 制造商:Fairchild Semiconductor Corporation 功能描述: |
| DM74LS191M | 功能描述:計數器 IC Syn 4-Bit Counter RoHS:否 制造商:NXP Semiconductors 計數器類型:Binary Counters 邏輯系列:74LV 位數:10 計數法: 計數順序: 工作電源電壓:1 V to 5.5 V 工作溫度范圍:- 40 C to + 125 C 封裝 / 箱體:SOT-109 封裝:Reel |
| DM74LS191MX | 功能描述:計數器 IC Syn 4-Bit Counter RoHS:否 制造商:NXP Semiconductors 計數器類型:Binary Counters 邏輯系列:74LV 位數:10 計數法: 計數順序: 工作電源電壓:1 V to 5.5 V 工作溫度范圍:- 40 C to + 125 C 封裝 / 箱體:SOT-109 封裝:Reel |
| DM74LS191N | 功能描述:計數器 IC Syn 4-Bit Counter RoHS:否 制造商:NXP Semiconductors 計數器類型:Binary Counters 邏輯系列:74LV 位數:10 計數法: 計數順序: 工作電源電壓:1 V to 5.5 V 工作溫度范圍:- 40 C to + 125 C 封裝 / 箱體:SOT-109 封裝:Reel |
| DM74LS193 WAF | 制造商:Fairchild Semiconductor Corporation 功能描述: |
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