AD5100
Rev. A | Page 14 of 36
05
69
2-
0
06
V
1MON
V
2MON
V
1MON_OV*
V
1MON_UV*
V
2MON_OFF*
V
2MON_ON*
t
2SD_HOLD*
t
FD_DELAY
t
FD_DELAY
t
FD_DELAY
SHDNWARN
SHDN
AND RESET
NOTES
1. * = PROGRAMMABLE.
2. # = THE DURATION OF THE
t
MIN
MUST BE SHORTER THAN
t
VREG_OFF_DELAY
OR ELSE THE AD5100 WILL BE POWERED OFF.
t
GLITCH
t
GLITCH
t
2SD_HOLD*
t
1SD_HOLD*
t
1SD_HOLD*
t
1SD_DELAY*
t
1SD_DELAY*
t
FD_DELAY
t
2SD_DELAY*
t
MIN
#
t
2SD_DELAY*
Figure 7. V
1MON
and V
2MON
Shutdown Timing Diagrams in Level-Sensitive Mode (Note that RESET Follows SHDN)
V
2MON
V
2MON
is a high voltage monitoring input that controls the SHDN
and RESET functions of the external devices. V
2MON
monitors
inputs from 3 V to 30 V. It has a 16-level programmable turn-on
and turn-off (on, off) hysteresis thresholds (Register 0x03 and
Register 0x04), with an 8-step 0.07 ms to 200 ms shutdown hold
time (t
2SD_HOLD
) and 0.07 ms to 1200 ms shutdown delay
(t
2SD_DELAY
).
The V
2MON
pin is monitored by two comparators, one for turn-
on and one for turn-off detection, in the level-sensitive power-
up mode. Both are designed with 1.5% hysteresis. Only the
turn-on monitoring comparator is used if the rising edge
triggered wake-up mode is selected.
When the V
2MON
input goes above the programmed V
2MON
on
threshold, the comparator becomes active immediately, indicat-
ing that an on condition has occurred. Due to hysteresis, the
V
2MON
input must be brought below the programmed threshold
by 1.5% before the comparator becomes inactive, indicating that
the on condition has gone away (see Figure 8).
When the V
2MON
input drops below the programmed threshold,
the comparator becomes active immediately, indicating that a
V
2MON
off condition has occurred. Similarly, due to hysteresis,
the V
2MON
input must be brought above the programmed threshold
by 1.5% before the comparator becomes inactive, indicating that
the off condition has gone away.
0
569
2-
008
V
2MON
V
2MON_OFF
ON
COMPARATOR
ACTIVE
ON
COMPARATOR
INACTIVE
OFF
COMPARATOR
ACTIVE
OFF
COMPARATOR
INACTIVE
V
2MON_ON
HYSTERESIS
HYSTERESIS
Figure 8. V
2MON
Hysteresis
By default, V
2MON
is level sensitive and the on and off thresholds
are both monitored. The on threshold chosen must be greater
than the off threshold.
When the SHDN output is activated by the input reaching
the V
2MON_OFF
threshold, such fault condition is temporarily
recorded in the fault detection register. The SHDNWARN
output transitions low for signaling before the shutdown output,
SHDN, activates. The timing of the SHDN output is dependent
on how long the shutdown programmed delay (t
2SD_DELAY
) is set
relative to the SHDNWARN propagation delay (t
FD_DELAY
). This
feature allows the system to finish any critical housekeeping
tasks before shutting down the external device. SHDN activates
once the voltage on V
2MON
is outside the threshold for a time longer
than t
GLITCH
. RESET follows SHDN delay and hold timings when
triggered by V
2MON
.
The V
2MON
, shutdown, and shutdown warning timing diagrams
are shown in Figure 7.
