ds1831bst-r Maxim Integrated Products, Inc., ds1831bst-r Datasheet - Page 3

• Manufacturer Part Number: ds1831bst-r
• Description: Ds1831, Ds1831a, Ds1831b Multisupply Micromonitor
• Manufacturer: Maxim Integrated Products, Inc.

DS1831/A/B
OPERATION—POWER MONITOR
The DS1831 provides the functions of detecting out-of-tolerance conditions on a 3.3V (or 3V) and 5V
power supply and warning a processor-based system of impending power failure. When an input is
detected as out-of-tolerance on either voltage input the
for that supply will be forced active low.
RST
When that input returns to a valid state the associated
will remain active for the time delay selected
RST
with the associated TD input and then return to an inactive state until the next input out-of-tolerance
condition.
On power-up both resets are kept active for the selected reset time after the associated power supply input
has reached the selected tolerance. This allows the power supply and system power to stabilize before
is released.
RST
All internal operating current for the DS1831 will be supplied by either the IN
or IN
input which
3.3V
5V
ever has the highest voltage level.
OPERATION—TOLERANCE SELECT
The DS1831 provides two TOL inputs for individual customization of the DS1831 to specific application
requirements. If the TOL for the 5V supply is tied to the 5V input a 5% tolerance is selected. If the TOL
is connected to ground a 10% tolerance is selected or if it is left unconnected a 15% tolerance is selected.
If the TOL for the 3.3V supply is tied to the 3.3V input a 5% tolerance is selected, a 10% tolerance is
selected if it is connected to ground, and a 20% tolerance is selected if the input is left unconnected.
These tolerance conditions are set at power up and can only be changed by power cycling the device.
OPERATION—RESET TIME-DELAY SELECT
The DS1831 provides two TD inputs for individual customization of reset time-delays and an additional
one for the DS1831A watchdog. TD inputs select time delays for the IN
and IN
resets outputs and
5V
3.3V
the Watchdog on the DS1831A. The reset time delays are shown in Table 1. These allow the selection of
minimum delays of 10ms, 100ms, and 1000ms.
Wiring an individual reset output to the push-button input of the other voltage reset allows custom reset
timings or allows for the sequencing of the reset outputs. See Figure 2.
These time-delays are set at power-up and cannot be changed after the device reaches an in-tolerance
condition.
TD INPUTS/RESET AND WATCHDOG TIME-DELAYS Table 1
RESET TIME-DELAY
TD
MIN
TYP
MAX
GND
10ms
16ms
20ms
Float
100ms
160ms
200ms
V
1000ms
1600ms
2000ms
CC
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