參數(shù)資料
型號(hào): SNJ54LV163AJ
廠商: Texas Instruments, Inc.
英文描述: Small Signal General Purpose Transistor; Package: SOT-23 (TO-236) 3 LEAD; No of Pins: 3; Container: Tape and Reel; Qty per Container: 3000
中文描述: 4位同步二進(jìn)制
文件頁數(shù): 2/18頁
文件大?。?/td> 461K
代理商: SNJ54LV163AJ
SCLS405E APRIL 1998 REVISED DECEMBER 2004
2
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
description/ordering information (continued)
The ’LV163A devices are 4-bit synchronous binary counters designed for 2-V to 5.5-V V
CC
operation.
These synchronous, presettable counters feature an internal carry look ahead for application in high-speed
counting designs. The ’LV163A devices are 4-bit binary counters. Synchronous operation is provided by having
all flip-flops clocked simultaneously so that the outputs change coincident with each other when instructed by
the count-enable (ENP, ENT) inputs and internal gating. This mode of operation eliminates the output counting
spikes normally associated with synchronous (ripple-clock) counters. A buffered clock (CLK) input triggers the
four flip-flops on the rising (positive-going) edge of the clock waveform.
These counters are fully programmable; that is, they can be preset to any number between 0 and 9 or 15. As
presetting is synchronous, setting up a low level at the load input disables the counter and causes the outputs
to agree with the setup data after the next clock pulse, regardless of the levels of the enable inputs.
The clear function for the ’LV163A devices is synchronous. A low level at the clear (CLR) input sets all four of
the flip-flop outputs low after the next low-to-high transition of CLK, regardless of the levels of the enable inputs.
This synchronous clear allows the count length to be modified easily by decoding the Q outputs for the maximum
count desired. The active-low output of the gate used for decoding is connected to CLR to synchronously clear
the counter to 0000 (LLLL).
The carry look-ahead circuitry provides for cascading counters for n-bit synchronous applications without
additional gating. ENP, ENT, and a ripple-carry output (RCO) are instrumental in accomplishing this function.
Both ENP and ENT must be high to count, and ENT is fed forward to enable RCO. Enabling RCO produces a
high-level pulse while the count is maximum (9 or 15 with Q
A
high). This high-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 CLK.
These counters feature a fully independent clock circuit. Changes at control inputs (ENP, ENT, or LOAD) that
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) is dictated solely by the conditions meeting the
stable setup and hold times.
These devices are fully specified for partial-power-down applications using I
off
. The I
off
circuitry disables the
outputs, preventing damaging current backflow through the devices when they are powered down.
FUNCTION TABLE
INPUTS
OUTPUTS
FUNCTION
CLR
LOAD
ENP
ENT
CLK
QA
QB
QC
QD
L
X
X
X
X
L
L
L
L
Reset to “0”
H
L
X
X
A
B
C
D
Preset data
H
H
X
L
No change
No count
H
H
L
X
No change
No count
H
H
H
H
Count up
Count
H
X
X
X
No change
No count
相關(guān)PDF資料
PDF描述
SNJ54LV163AW Small Signal General Purpose Transistor; Package: SOT-23 (TO-236) 3 LEAD; No of Pins: 3; Container: Tape and Reel; Qty per Container: 3000
SNJ54LV174AFK HEX D-TYPE FLIP-FLOPS WITH CLEAR
SNJ54LV174AJ HEX D-TYPE FLIP-FLOPS WITH CLEAR
SNJ54LV174AW HEX D-TYPE FLIP-FLOPS WITH CLEAR
SNJ54LV367AFK HEX BUFFERS AND LINE DRIVERS WITH 3-STATE OUTPUTS
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