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參數(shù)資料
| 型號： | 74VHC161SJ |
| 廠商： | Fairchild Semiconductor |
| 文件頁數(shù)： | 4/11頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC COUNTER BINARY 4BIT 16SOP |
| 標(biāo)準(zhǔn)包裝： | 47 |
| 系列： | 74VHC |
| 邏輯類型： | 二進(jìn)制計數(shù)器 |
| 方向： | 上 |
| 元件數(shù)： | 1 |
| 每個元件的位元數(shù)： | 4 |
| 復(fù)位： | 異步 |
| 計時： | 同步 |
| 計數(shù)速率： | 125MHz |
| 觸發(fā)器類型： | 正邊沿 |
| 電源電壓： | 2 V ~ 5.5 V |
| 工作溫度： | -40°C ~ 85°C |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 16-SOIC（0.209"，5.30mm 寬） |
| 供應(yīng)商設(shè)備封裝： | 16-SOP |
| 包裝： | 管件 |
74VHC161
4-Bit
Binar
y
Counter
with
Async
hr
onous
Clear
1993 Fairchild Semiconductor Corporation
www.fairchildsemi.com
74VHC161 Rev. 1.4
2
Logic Symbols
IEEE/IEC
Functional Description
The VHC161 counts in modulo-16 binary sequence.
From state 15 (HHHH) it increments to state 0 (LLLL).
The clock inputs of all flip-flops are driven in parallel
through a clock buffer. Thus all changes of the Q outputs
(except due to Master Reset of the VHC161) occur as a
result of, and synchronous with, the LOW-to-HIGH tran-
sition of the CP input signal. The circuits have four fun-
damental modes of operation, in order of precedence:
asynchronous reset, parallel load, count-up and hold.
Five control inputs—Master Reset, Parallel Enable (PE),
Count Enable Parallel (CEP) and Count Enable Trickle
(CET)—determine the mode of operation, as shown in
the Mode Select Table. A LOW signal on MR overrides
all other inputs and asynchronously forces all outputs
LOW. A LOW signal on PE overrides counting and
allows information on the Parallel Data (Pn) inputs to be
loaded into the flip-flops on the next rising edge of CP.
With PE and MR HIGH, CEP and CET permit counting
when both are HIGH. Conversely, a LOW signal on
either CEP or CET inhibits counting.
The VHC161 uses D-type edge-triggered flip-flops and
changing the PE, CEP and CET inputs when the CP is in
either state does not cause errors, provided that the rec-
ommended setup and hold times, with respect to the ris-
ing edge of CP, are observed.
The Terminal Count (TC) output is HIGH when CET is
HIGH and counter is in state 15. To implement synchro-
nous multistage counters, the TC outputs can be used
with the CEP and CET inputs in two different ways.
Figure 1 shows the connections for simple ripple carry, in
which the clock period must be longer than the CP to TC
delay of the first stage, plus the cumulative CET to TC
delays of the intermediate stages, plus the CET to CP
setup time of the last stage. This total delay plus setup
time sets the upper limit on clock frequency. For faster
clock rates, the carry lookahead connections shown in
Figure 2 are recommended. In this scheme the ripple
delay through the intermediate stages commences with
the same clock that causes the first stage to tick over
from max to min to start its final cycle. Since this final
cycle requires 16 clocks to complete, there is plenty of
time for the ripple to progress through the intermediate
stages. The critical timing that limits the clock period is
the CP to TC delay of the first stage plus the CEP to CP
setup time of the last stage. The TC output is subject to
decoding spikes due to internal race conditions and is
therefore not recommended for use as a clock or asyn-
chronous reset for flip-flops, registers or counters.
Logic Equations:
Count Enable
= CEP CET PE
TC
= Q0 Q1 Q2 Q3 CET
Figure 1. Multistage Counter with Ripple Carry
Figure 2. Multistage Counter with Lookahead Carry
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參數(shù)描述 |
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| 74VHC161SJX | 功能描述:計數(shù)器移位寄存器 4-Bit Binary Counter RoHS:否 制造商:Texas Instruments 計數(shù)器類型: 計數(shù)順序:Serial to Serial/Parallel 電路數(shù)量:1 封裝 / 箱體:SOIC-20 Wide 邏輯系列: 邏輯類型: 輸入線路數(shù)量:1 輸出類型:Open Drain 傳播延遲時間:650 ns 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝:Reel |
| 74VHC16240 | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:16-BIT BUS BUFFER WITH 3-STATE OUTPUTS (INVERTED) |
| 74VHC16240TTR | 功能描述:緩沖器和線路驅(qū)動器 16-Bit Bus Buffer RoHS:否 制造商:Micrel 輸入線路數(shù)量:1 輸出線路數(shù)量:2 極性:Non-Inverting 電源電壓-最大:+/- 5.5 V 電源電壓-最小:+/- 2.37 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:MSOP-8 封裝:Reel |
| 74VHC16244 | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:16-BIT BUS BUFFER WITH 3-STATE OUTPUTS (NON INVERTED) |
| 74VHC16244TTR | 功能描述:緩沖器和線路驅(qū)動器 16-Bit Bus Buffer RoHS:否 制造商:Micrel 輸入線路數(shù)量:1 輸出線路數(shù)量:2 極性:Non-Inverting 電源電壓-最大:+/- 5.5 V 電源電壓-最小:+/- 2.37 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:MSOP-8 封裝:Reel |
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