Harman Kardon HK 990/230, Service Manual

Page: 45 / 141

www.ti.com
DESCRIPTION/ORDERING INFORMATION (CONTINUED)
T o Eight Other Channels
1D
1Q
C
CLK
OE
CLR
1
1 1
14
13
2
R
1D
C1
23
SN74LVC823A
9-BIT BUS-INTERFACE FLIP-FLOP
WITH 3-STATE OUTPUTS
SCAS305I – MARCH 1993 – REVISED FEBRUARY 2005
A buffered output-enable (OE) input can be used to place the nine outputs in either a normal logic state (high or
low logic levels) or the high-impedance state. OE does not affect the internal operations of the latch. Previously
stored data can be retained or new data can be entered while the outputs are in the high-impedance state.
Inputs can be driven from either 3.3-V or 5-V devices. This feature allows the use of these devices as translators
in a mixed 3.3-V/5-V system environment.
This device is fully specified for partial-power-down applications using I
off
. The I
off
circuitry disables the outputs,
preventing damaging current backflow through the device when it is powered down.
To ensure the high-impedance state during power up or power down, OE should be tied to V
CC
through a pullup
resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.
FUNCTION TABLE
(EACH FLIP-FLOP)
INPUTS
OUTPUT
Q
OE CLR CLKEN CLK D
L L X X X L
L H L
↑
H H
L H L
↑
L L
L H H X X Q
0
H X X X X Z
LOGIC DIAGRAM (POSITIVE LOGIC)
4 3