Datasheet

LTC6993-1/LTC6993-2
LTC6993-3/LTC6993-4
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OPERATION
Monostable Multivibrator (One Shot)
The LTC6993 is a monostable multivibrator. A trigger
signal on the TRIG input will force the output to the active
(unstable) state for a programmable duration. This type
of circuit is commonly referred to as a one-shot pulse
generator.
Figures 3 details the basic operation. A rising edge on
the TRIG pin initiates the output pulse. The pulse width
(t
OUT
) is determined by the N
DIV
setting and by the resis-
tor (R
SET
) connected to the SET pin. Subsequent rising
edges on TRIG have no affect until the completion of the
one shot and for a short rearming time (t
ARM
) thereafter.
To ensure proper operation, positive and negative TRIG
pulses should be at least t
WIDTH
wide.
The LTC6993-2 and LTC6993-4 allow the output pulse to
be
“retriggered”. As shown in Figure 4, the output pulse
will stay high until t
OUT
after the last rising-edge on TRIG.
Successive trigger signals can extend the pulse width in-
definitely. Consecutive trigger signals must be separated
by t
RETRIG
to be recognized.
Negative Trigger Versions
In addition to the retrigger option, the LTC6993 family also
includes negative input (falling-edge) versions. These four
combinations are detailed in
Table 2.
Table 2. Retrigger and Input Polarity Options
DEVICE INPUT POLARITY RETRIGGER
LTC6993-1 Rising-Edge No
LTC6993-2 Rising-Edge Yes
LTC6993-3 Falling-Edge No
LTC6993-4 Falling-Edge Yes
Output Polarity (POL Bit)
Each variety of LTC6993 also offers the ability to invert
the output, producing negative pulses. This option is
programmed, along with N
DIV
, by the choice of DIVCODE.
(The previous section describes how to program DIVCODE
using the DIV pin).
Figure 3. Non-Retriggering Timing Diagram (LTC6993-1, POL = 0)
Figure 4. Retriggering Timing Diagram (LTC6993-2, POL = 0)
t
PD
t
WIDTH
t
RETRIG
TRIG
OUT
t
OUT
t
PD
t
PD
t
PD
t
OUT
t
OUT
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t
PD
TRIG
OUT
t
PD
t
ARM
t
WIDTH
t
OUT
t
OUT
t
OUT
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