ADM13307
Rev. 0 | Page 10 of 12
THEORY OF OPERATION
The ADM13307 devices are triple voltage supervisors designed
to monitor up to three supplies and provide a reset signal to
DSP and microprocessor-based systems.
There are five models available, all of which feature a combina-
tion of internally pretrimmed undervoltage threshold options
for monitoring 1.8 V, 2.5 V, 3.3 V, and 5 V supplies. There are
also adjustable input options with threshold voltages of either
0.6 V or 1.25 V.
ADM13307-18, ADM13307-25, and ADM13307-33 models
have two internally fixed thresholds and one externally
programmable threshold, via a resistor string, while the
ADM13307-4 and ADM13307-5 offer one internally fixed
threshold and two externally programmable thresholds via a
resistor string. See the Ordering Guide for a list of all available
options.
INPUT CONFIGURATION
The ADM13307 is powered through V
DD
. To increase noise
immunity in noisy applications, place a 0.1 μF capacitor
between the V
DD
input and ground.
The SENSEv inputs are resistant to short power supply glitches.
Do not allow unused SENSEv inputs to float or to be grounded,
instead connect it to a supply voltage greater than its specified
threshold voltage.
Typically, the threshold voltage at an adjustable SENSEv input
is either 0.6 V or 1.25 V. Refer to the Ordering Guide for details.
For example, to monitor a voltage greater than 1.25 V, con-
nect a resistor divider network to the device as depicted in
Figure 13, where,
⎟
⎠
⎞
⎜
⎝
⎛
+
=
R2
R2R1
V
MONITERED
V25.1
06923-012
R1
R2
MONITORED VOLTAGE
V
REF
= 1.25V
Figure 13. Setting the Adjustable Monitor
RESET OUTPUT
The reset outputs are guaranteed to be in the correct state for
V
DD
down to 1.1 V. During power up,
RESET
is asserted when
the supply voltage becomes greater than 1.1 V.
Once the supplies monitored at the SENSEv pins rise above their
associated threshold level, the
RESET
signal remains low for the
reset timeout period before deasserting. Subsequently, if a supply
monitored by the SENSEv pins falls below its associated thresh-
old, the
RESET
output reasserts.
06923-013
SENSEv
V
(NOM)
0
1
V
IT–
RESET
t
d
t
d
t
t
Figure 14. Reset Timing Diagram
The ADM13307 features both an active-low push-pull
RESET
output and active-high push-pull RESET output.
MANUAL RESET (MR)
The ADM13307 features a manual reset input, which when driven
low, asserts the reset output, as shown in Figure 15. When
MR
transitions from low to high, the reset remains asserted for the
duration of the reset active timeout period before deasserting.
An external push-button switch can be connected between
MR
and ground to allow the user to generate a reset.
06923-015
0
1
RESET
t
d
t
0
1
t
MR
Figure 15. Manual Reset Timing Diagram
