Data Sheet
CLR
C
ext
R
ext
/C
ext
R
B
A
Q
Q
SN54LV123A, SN74LV123A
SCLS393P –APRIL 1998–REVISED OCTOBER 2013
www.ti.com
This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more
susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.
DESCRIPTION (CONTINUED)
Pulse triggering occurs at a particular voltage level and is not directly related to the transition time of the input
pulse. The A, B, and CLR inputs have Schmitt triggers with sufficient hysteresis to handle slow input transition
rates with jitter-free triggering at the outputs.
Once triggered, the basic pulse duration can be extended by retriggering the gated low-level-active (A) or high-
level-active (B) input. Pulse duration can be reduced by taking CLR low. The input/output timing diagram
illustrates pulse control by retriggering the inputs and early clearing.
During power up, Q outputs are in the low state, and Q outputs are in the high state. The outputs are glitch free,
without applying a reset pulse.
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 device when it is powered down.
Pin assignments for these devices are identical to those of the 'AHC123A and 'AHCT123A devices for
interchangeability, when allowed.
Table 1. FUNCTION TABLE
(EACH MULTIVIBRATOR)
INPUTS OUTPUTS
CLR A B Q Q
L X X L H
X H X L
(1)
H
(1)
X X L L
(1)
H
(1)
H L ↑
H ↓ H
↑ L H
(1) These outputs are based on the assumption that the indicated
steady-state conditions at the A and B inputs have been set up long
enough to complete any pulse started before the setup.
Figure 1.
LOGIC DIAGRAM, EACH MULTIVIBRATOR (POSITIVE LOGIC)
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Product Folder Links: SN54LV123A, SN74LV123A