MC74AC299 Datasheet, PDF (3/11 Pages) ON Semiconductor – 8−Input Universal Shift/Storage Register with Common Parallel I/O Pins

MC74AC299, MC74ACT299
FUNCTIONAL DESCRIPTION
The MC74AC299/74ACT299 contains eight edge−triggered
D−type flip−flops and the interstage logic necessary to
perform synchronous shift left, shift right, parallel load and
hold operations. The type of operation is determined by S₀
and S₁, as shown in the Truth Table. All flip−flop outputs are
brought out through 3−state buffers to separate I/O pins that
also serve as data inputs in the parallel load mode. Q₀ and Q₇
are also brought out on other pins for expansion in serial
shifting of longer words.
A LOW signal on MR overrides the Select and CP inputs
and resets the flip−flops. All other state changes are initiated
by the rising edge of the clock. Inputs can change when the
clock is in either state provided only that the recommended
setup and hold times, relative to the rising edge of CP, are
observed.
A HIGH signal on either OE₁ or OE₂ disables the 3_-state
buffers and puts the I/O pins in the high impedance state. In
this condition the shift, hold, load and reset operations can
still occur. The 3−state buffers are also disabled by HIGH
signals on both S₀ and S₁ in preparation for a parallel load
operation.
TRUTH TABLE
Inputs
MR S₁ S₀ CP
Response
L X X X Asynchronous Reset; Q₀−Q₇ = LOW
HHH
Parallel Load; I/O_n → Q_n
HLH
Shift Rights; DS₀ → Q₀, Q₀ → Q₁, etc.
HH L
Shift Left; DS₇ → Q₇, Q₇ → Q₆, etc.
H L L X Hold
H = HIGH Voltage Level
L = LOW Voltage Level
X = Immaterial
= LOW-to-HIGH Transition
MAXIMUM RATINGS*
Symbol
Parameter
Value
Unit
V_CC
V_IN
V_OUT
I_IN
I_OUT
I_CC
T_stg
DC Supply Voltage (Referenced to GND)
DC Input Voltage (Referenced to GND)
DC Output Voltage (Referenced to GND)
DC Input Current, per Pin
DC Output Sink/Source Current, per Pin
DC V_CC or GND Current per Output Pin
Storage Temperature
−0.5 to +7.0
V
−0.5 to V_CC +0.5
V
−0.5 to V_CC +0.5
V
±20
mA
±50
mA
±50
mA
−65 to +150
°C
*Maximum Ratings are those values beyond which damage to the device may occur. Functional operation should be restricted to the
Recommended Operating Conditions.
RECOMMENDED OPERATING CONDITIONS
Symbol
Parameter
Min
Typ
Max
V_CC
Supply Voltage
′AC
′ACT
2.0
5.0
6.0
4.5
5.0
5.5
V_IN, V_OUT DC Input Voltage, Output Voltage (Ref. to GND)
0
t_r, t_f
Input Rise and Fall Time (Note 1)
′AC Devices except Schmitt Inputs
V_CC @ 3.0 V
−
V_CC @ 4.5 V
−
V_CC @ 5.5 V
−
t_r, t_f
Input Rise and Fall Time (Note 2)
′ACT Devices except Schmitt Inputs
V_CC @ 4.5 V
−
V_CC @ 5.5 V
−
−
V_CC
150
−
40
−
25
−
10
−
8.0
−
T_J
Junction Temperature (PDIP)
T_A
Operating Ambient Temperature Range
I_OH
Output Current − High
I_OL
Output Current − Low
−
−
140
−40
25
85
−
−
−24
−
−
24
1. V_IN from 30% to 70% V_CC; see individual Data Sheets for devices that differ from the typical input rise and fall times.
2. V_IN from 0.8 V to 2.0 V; see individual Data Sheets for devices that differ from the typical input rise and fall times.
Unit
V
V
ns/V
ns/V
°C
°C
mA
mA
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