DS1831AS-DS1831BS-DS1831S Fast Delivery |IC PHOENIX CO.,LIMITED

DS1831BS ,Multisupply MicroMonitor™DS1831/A/BMultisupply Micromonitor
DS1831C ,3.3V/2.5V Multisupply MicromonitorFEATURESPIN ASSIGNMENT 2.5V power-on resetDS1831C 3.3V power-on reset Two referenced comparators ..
DS1831CS , 3.3V/2.5V Multi-Supply MicroMonitor
DS1831S ,Multisupply MicroMonitor™PIN DESCRIPTIONIN 5V Power Supply Input MPBRST Master Pushbutton (DS1831)5VTD Watchdog Time Delay S ..
DS1832 ,3.3 Volt MicroMonitor ChipPIN DESCRIPTIONPBRST - Pushbutton Reset InputTD - Time Delay SetTOL - Selects 10% or 20% V DetectCC ..
DS1832S ,3.3 Volt MicroMonitor ChipPIN DESCRIPTIONPBRST - Pushbutton Reset InputTD - Time Delay SetTOL - Selects 10% or 20% V DetectCC ..
DZ23C10 ,Zener DiodesDZ23C2V7–DZ23C51Vishay Telefunken300 mW Dual Surface Mount Zener Diodes
DZ23C15-7-F , 300mW DUAL SURFACE MOUNT ZENER DIODE
DZ23C16-7-F , 300mW DUAL SURFACE MOUNT ZENER DIODE
DZ23C18 ,Zener DiodesAbsolute Maximum RatingsT = 25

DS1831AS-DS1831BS-DS1831S
Multisupply MicroMonitor™
FEATURES5V power-on reset3.3V power-on resetTwo referenced comparators with separate
outputs for monitoring additional suppliesInternal power is drawn from higher of either
the IN5V input or the IN3.3V inputExcellent for systems designed to operate
with multiple power suppliesAsserts resets during power transientsPushbutton reset input for system overrideMaintains reset for user configurable times
of 10ms, 100ms, or 1sWatchdog timer for software monitoring
(DS1831A)Precision temperature-compensated voltage
reference and voltage sensor16 pin DIP and 16 pin 150mil SO availableOperating Temperature of -40°C to +85°C
PIN ASSIGNMENT
DESCRIPTION
The DS1831 multisupply monitor and reset monitors up to four system voltages: 5V supply, 3.3V (or 3V)
supply, and two additional user configurable voltage monitors. DS1831 power for internal operation
DS1831/A/B
Multisupply Micromonitor

IN3.3V
RST3.3V
TOL3.3V
TD3.3V
PBRST3.3V
NMI1
NMI2
MPBRST
IN5V
RST5V
TOL5V
TD5V
PBRST5V
IN1
IN2
GND
DS1831
16-Pin (300mil) DIP
16-Pin (150mil) SO
IN3.3V
RST3.3V
TOL3.3V
TD3.3V
PBRST3.3V
NMI1
WDS
TDWD
IN5V
RST5V
TOL5V
TD5V
PBRST5V
IN1
GND
DS1831A
16-Pin (300mil) DIP
16-Pin (150mil) SO
IN3.3V
RST3.3V
TOL3.3V
TD3.3V
PBST
NMI1
NMI2
MPBRST
IN5V
RST5V
TOL5V
TD5V
PBRST5V
IN1
IN2
GND
DS1831B
16-Pin (300mil) DIP
16-Pin (150mil) SO
DS1831/A/B
3.3V reset or for all reset outputs by the master pushbutton. The DS1831A replaces one reference
comparator and the master pushbutton with watchdog and the DS1831B replaces the 3.3V PBRST with a
last reset status output.
TOL and TD inputs allow user configuration of the DS1831 for multiple applications. The TOL inputs
configure the tolerance for the specified output and the TD inputs configure the reset time delays.
PIN DESCRIPTION
IN5V5V Power Supply InputMPBRSTMaster Pushbutton (DS1831)
TDWDWatchdog Time Delay Select (DS1831A)
RST5V5V Reset Open Drain OutputNMI2Non-maskable Interrupt 2 (DS1831)
WDSWatchdog Status Output (DS1831A)
TOL5VSelects 5V Input ToleranceNMI1Non-maskable Interrupt 1
TD5VSelects 5V Reset Time DelayPBRST3.3V3.3V Reset Pushbutton
PBSTPushbutton Status Output (DS1831B)
PBRST5V5V Reset PushbuttonTD3.3VSelect 3.3V Reset Time Delay
IN1Sense Input 1TOL3.3VSelects 3.3V Input Tolerance
IN2
Sense Input 2 (DS1831)
Watchdog Strobe Inputs
(DS1831A)
RST3.3V3.3V Reset Open Drain Output
GNDGroundIN3.3V3.3V Power Supply Input
DS1831 BLOCK DIAGRAM Figure 1
RST3.3V
VCC
TOLERANCE
BIAS
IN5V
TIME
DELAY
1.25V T.C.
REFERENCE
TOL5V
VCC
TOLERANCE
BIAS
IN3.3V
TOL3.3V
TIME
DELAY
Level
Sense
MPBRST
100k
TD5V
TD3.3V
100k
PBRST3.3V
PBRST5V
100k
IN1
IN2
NMI1
NMI2
RST5V
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 RST for that supply will be forced active low.
When that input returns to a valid state the associated RST will remain active for the time delay selected
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
RST is released.
All internal operating current for the DS1831 will be supplied by either the IN3.3V or IN5V input which
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 IN5V and IN3.3V resets outputs and
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-DELAYMINTYPMAX
GND10ms16ms20ms
Float100ms160ms200ms
VCC1000ms1600ms2000ms
DS1831/A/B
PUSHBUTTON RESET SEQUENCING Figure 2
NOTE: The RST5V output is connected to the IN3.3V via a 100 k resistor in the push-button input and
therefore does not require a pull-up resistor (an addition pull up can be used to accelerate responses). If an
external pull up is used in this example it must be connected to the 3.3V power supply.
OPERATION—PUSHBUTTON RESET
The DS1831 provides three pushbutton inputs for manual reset of the device. Pushbutton inputs for the
3.3V reset, 5V reset, and a master pushbutton reset (DS1831 and DS1831B only) input; provide multiple
options for system control. The 3.3V pushbutton reset and 5V pushbutton resets provide a simple manual
reset for the associated reset output; while the master pushbutton reset forces all resets and NMI outputs
active low.
The 5V reset pushbutton input and the 3.3V reset pushbutton input provide manual reset control input for
each associated reset output. When the output associated with a pushbutton input is not active, a
pushbutton reset can be generated by pulling the associated PBRST pin low for at least 20µs. When the
pushbutton is held low the reset will be forced active and will remain active for a reset cycle after the
pushbutton is released. See Figure 2 for an application example that allows a user to sequence the reset
outputs.
A master pushbutton reset cycle can be started if at least one voltage input (IN5V, IN3.3V, IN1, or IN2) is in
tolerance and at least one output is active. A master pushbutton reset is generated by pulling the MPBRST
pin low for at least 20µs. When the pushbutton is held low all outputs are forced active and will remain
active for a reset or NMI time delay after the pushbutton is released. The Master Pushbutton input is
pulled high through an internal 100k pull up resistor and debounced via internal circuitry. See Figure 3
for an application example. Figures 4 and 5 for the timing diagram.
The 5V and 3.3V pushbutton reset inputs are pulled high through an internal 100k pull up resistor to the
voltage input, which is associated with that pushbutton. The master pushbutton is pulled to the greater of
the IN5V and IN3.3V inputs.
RST5V
PBRST3.3V
GND
TD5V
IN3.3VIN5V
RST3.3V
TOL3.3V
PBRST5V
TOL5VDS1831
TD3.3V
5V Supply3.3V Supply
DS1831/A/B
PUSHBUTTON RESET Figure 3
TIMING DIAGRAM—MASTER PUSHBUTTON RESET Figure 4
RST5V
GND
TD5V
IN5V
PBRST5V
TOL5V
5V Supply
DS1831
10 k
VIH
VIL
tPDLY
tPB
tRST
MPBRST
RST5V and RST3.3V
VOH
tNMINMI1 and NMI2
VOH
DS1831/A/B
TIMING DIAGRAM—5V OR 3.3V PUSHBUTTON RESET Figure 5
OPERATION—PUSHBUTTON STATUS
The DS1831B provides a master pushbutton status open drain output. The PBST output indicates the
status of the most recent reset condition. If the last reset was generated by the master pushbutton input it
would maintain a low condition until cleared by another event (except the master pushbutton) generating
a reset. Once cleared it will remain high until the master pushbutton is pulled low generating a reset
condition. The PBST output is open drain and will require a pull-up resistor on the output to maintain a
valid condition. The value of the pull up resistor is not critical in most cases but must be set low enough
to pull the output to a high state. A common value used is 10k (see Figure 6).
DS1831B APPLICATION EXAMPLE Figure 6
VIH
VIL
tPDLY
tPB
tRST
PBRST5V
(or PBRST3.3V)
RST5V (or RST3.3V)
VOH
VIL
5V Supply
PBRST5V
GND
NMI2
IN1NMI1
VSENSE1
IN2
MPBRST
VSENSE2
VCC
10k
DS1831B
RST5V
TD5V
IN5V
TOL5V
PBST
IN3.3V
RST3.3V
TOL3.3V
TD3.3V
3.3V Supply
VCC
10 k
DS1831/A/B
OUTPUT VALID CONDITIONS
The DS1831 can maintain valid outputs as long as one input remains above 1.0V. Accurate voltage
monitoring additionally requires that either the 3.3V IN or 5V IN input be above 1.5V. If this condition is
not met and at least one of the supply inputs are at or above 1.0V all outputs are maintained in the active
condition. The DS1831 requires pull-up resistors on the outputs to maintain a valid output. The value of
the pull up resistor is not critical in most cases but must be set low enough to pull the output to a high
state. A common pull-up resistor value used is 10k (see Figure 7).
APPLICATION DIAGRAM—OPEN DRAIN OUTPUTS Figure 7
NOTE: If outputs are at different voltages the outputs can not be connected to form a wired AND.
OPERATION—NON-MASKABLE INTERRUPT
The DS1831 has two referenced comparator (DS1831A has only one referenced comparator) that can be
used to monitor upstream voltages or other system specific voltages. Each comparator is referenced to the
1.25V internal band gap reference and controls an open-drain output. When a voltage being monitored
decays to the voltage sense point, the DS1831 pulses the NMI output to the active state for a minimum
10µs. The comparator detection circuitry also has built-in hysteresis of 100µV. The supply must be below
the voltage sense point for approximately 2µs before a low NMI will be generated. In this way, power
supply noise is minimized in the monitoring function, reducing false interrupts. See Figure 8 for the non-
maskable timing diagram.
Versatile trip voltages can be configured by the use of an external resistor divider to divide the voltage at
a sense point to the 1.25V trip levels of the referenced comparators. See Figure 9 for an example circuit
diagram and sample equations. The equations demonstrate a design process to determine the resistor
values to use.
Connecting one or both NMI outputs to one of the reset specific PBRSTs allows the non-maskable
interrupt to generate an automatic reset for the reset time period when an out-of-tolerance condition
occurs in a monitored supply. An example is shown in Figure 9.
RST5V
PBRST3.3V
GND
TD5V
IN3.3vIN5V
RST3.3V
TOL3.3V
PBRST5V
TOL5V
DS1831
TD3.3V
5V Supply3.3V Supply
10 k10K

Partno	Mfg	Dc	Qty	Available	Descript
DS1831AS		N/a	5	avai	Multisupply MicroMonitor™
DS1831BS	MAXIM	N/a	175	avai	Multisupply MicroMonitor™
DS1831S	DS	N/a	7	avai	Multisupply MicroMonitor™