LTC6993-1_15 Datasheet, PDF (14/26 Pages) Linear Technology – Monostable Pulse Generator

LTC6993-1/LTC6993-2
LTC6993-3/LTC6993-4
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
LTC6993-1
Rising-Edge
LTC6993-2
Rising-Edge
LTC6993-3
Falling-Edge
LTC6993-4
Falling-Edge
RETRIGGER
No
Yes
No
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).
TRIG
OUT
t_PD
t_OUT
t_WIDTH
t_PD
t_OUT
t_ARM
t_OUT
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Figure 3. Non-Retriggering Timing Diagram (LTC6993-1, POL = 0)
TRIG
OUT
t_WIDTH
t_PD
t_OUT
t_RETRIG
t_PD
t_PD
t_OUT
t_PD
t_OUT
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Figure 4. Retriggering Timing Diagram (LTC6993-2, POL = 0)
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