Dallas DS1831C 3.3v/2.5v multi-supply micromonitor Datasheet

DS1831C/D/E
3.3V/2.5V Multi-Supply MicroMonitor
www.dalsemi.com
FEATURES
PIN ASSIGNMENT
2.5V power-on reset
3.3 (or 3V) power-on reset
2 referenced comparators with separate
outputs for monitoring additional supplies
Internal power is drawn from higher of either
the IN2.5V input or the IN3.3V input
Excellent for systems designed to operate
with multiple power supplies
Asserts resets during power transients
Pushbutton reset input for system override
Maintains reset for user configurable times
of 10 ms, 100 ms, or 1 sec
Watchdog timer for software monitoring
(DS1831D)
Precision temperature-compensated voltage
reference and voltage sensor
16 pin DIP & 16 pin 150 mil SOIC available
Operating Temperature of -40°C to +85°C
DS1831C
IN2.5V
1
16
IN3.3V
RST2.5V
2
15
RST3.3V
TOL2.5V
3
14
TOL3.3V
TD2.5V
4
13
TD3.3V
PBRST2.5V
5
12
PBRST3.3V
IN1
6
11
NMI1
IN2
7
10
NMI2
GND
8
9
MPBRST
16-Pin (300 mil) DIP
&
16-Pin (150 mil) SOIC
DS1831D
IN1
6
11
NMI1
ST
7
10
WDS
GND
8
9
TDWD
DS1831E
TD2.5V
4
13
TD3.3V
PBRST2.5V
5
12
PBST
IN1
6
11
NMI1
DESCRIPTION
The DS1831C Multi-Supply Monitor & Reset monitors up to 4 system voltages: 2.5 volt supply, 3.3 (or
3) volt supply, and 2 additional user configurable voltage monitors. DS1831 power for internal operation
comes from the higher voltage level of the 3.3 volt input or the 2.5 volt input. One of these inputs must
be greater than 1 volt for device operation. Pushbutton (manual reset) functionality is provided for the
2.5 volt reset, the 3.3 volt reset or for all reset outputs by the master pushbutton. The DS1831D replaces
one reference comparator and the master pushbutton with watchdog and the DS1831E replaces the
3.3-volt 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.
1 of 14
051100
DS1831C/D/E
PIN CONFIGURATION
1
IN2.5V
2.5V Power Supply Input
2
RST 2.5V
2.5V Reset Open Drain
Output
10
Selects 2.5V Input
Tolerance
Selects 2.5V Reset Time
Delay
PBRST 2.5V
2.5V Reset Pushbutton
IN1
IN2
ST
Sense Input 1
Sense Input 2 (DS1831C/E)
Watchdog Strobe Inputs
(DS1831D)
Ground
3
TOL2.5V
4
TD2.5V
5
6
7
8
GND
9
WDS
Master Pushbutton (DS1831C/E)
Watchdog Time Delay Select
(DS1831D)
Non Maskable Interrupt 2 (DS1831C/E)
Watchdog Status Output (DS1831D)
11
NM11
Non Maskable Interrupt 1
12
PBRST 3.3V
13 TD3.3V
3.3V Reset Pushbutton (DS1831C/E)
Pushbutton Status Output (DS1831E)
Select 3.3V Reset Time Delay
14 TOL3.3V
15 RST 3.3V
Selects 3.3V Input Tolerance
3.3V Reset Open Drain Output
16 IN3.3V
3.3V Power Supply Input
MPBRST
TDWD
NM12
PBST
BLOCK DIAGRAM Figure 1
IN2.5V
100 kΩ
PBRST2.5V
TD2.5V
VCC
TOL2.5V
TOLERANCE
BIAS
+
TIME
DELAY
1.25V T.C.
REFERENCE
-
100 kΩ
MPBRS
RST2.5V
Level Sense
&
Debounce
IN3.3V
100 kΩ
PBRST3.3V
TD3.3V
TOL3.3V
VCC
TOLERANCE
BIAS
TIME
DELAY
+
RST3 3V
-
IN
NMI
+
-
IN
NMI
+
GROUN
2 of 14
DS1831C/D/E
OPERATION – POWER MONITOR
The DS1831 provides the functions of detecting out-of-tolerance conditions on a 3.3 (or 3) volt and
2.5 volt 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 IN2.5V input which
ever has the highest voltage level.
OPERATION - TOLERANCE SELECT
The DS1831 provides 2 TOL inputs for individual customization of the DS1831 to specific application
requirements. If the TOL for the 2.5 volt supply is tied to the 2.5 volt 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 3.3 volt supply is tied to the 3.3 volt 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 2 TD inputs for individual customization of reset time delays and an additional one
for the DS1831D watchdog. TD inputs select time delays for the IN2.5V and IN3.3V resets outputs and the
Watchdog on the DS1831D. The reset time delays are shown in table 1. These allow the selection of
minimum delays of 10 ms, 100 ms, and 1000 ms.
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
TD
GND
Float
VCC
MIN
10 ms
100 ms
1000 ms
RESET TIME-DELAY
TYP
16 ms
160 ms
1600 ms
3 of 14
MAX
20 ms
200 ms
2000 ms
DS1831C/D/E
PUSHBUTTON RESET SEQUENCING Figure 2
3.3V Supply
2.5V Supply
IN2.5V
*
RST2.5V
TOL2.5V
TD2.5V
PBRST2.5V
16
1
2
15
DS1831C
14
3
4
13
5
12
IN3.3V
RST3.3V
TOL3.3V
TD3.3V
PBRST3.3V
GND
*NOTE:
The RST 2.5 volt output is connected to the IN3.3V via a 100 kΩ 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 3.3 volt power supply.
OPERATION - PUSHBUTTON RESET
The DS1831 provides 3 pushbutton inputs for manual reset of the device. Pushbutton inputs for the
3.3 volt reset, 2.5 volt reset, and a master pushbutton reset (DS1831C & DS1831D only) input; provide
multiple options for system control. The 3.3 volt pushbutton reset and 2.5 volt 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 2.5 volt reset pushbutton input and the 3.3 volt reset pushbutton input provide manual reset control
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 20 µs. 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 (IN2.5V, IN3.3V, IN1, or IN2) is
in tolerance and at least 1 output is active. A master pushbutton reset is generated by pulling the
MPBRST pin low for at least 20 µs. 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 100 kΩ pull up resistor and debounced via internal circuitry. See
figure 3 for an application example. Figures 4 and 5 for the timing diagram.
The 2.5 volt and 3.3 volt pushbutton reset inputs are pulled high through an internal 100 kΩ pull up
resistor to the voltage input, which is associated with that pushbutton. The master pushbutton is pulled to
the greater of the “IN2.5V” and “IN3.3V” inputs.
*Caution should be exercised to avoid pulling the pushbutton inputs above associated supply inputs.
Generally all pushbutton inputs should be driven low with open drain inputs.
4 of 14
DS1831C/D/E
PUSHBUTTON RESET Figure 3
2.5V Supply
IN2.5V
10 kΩ
1
16
2
DS1831C 15
3
14
4
13
5
12
RST2.5V
TOL2.5V
TD2.5V
PBRST2.5V
GND
TIMING DIAGRAM – MASTER PUSHBUTTON RESET Figure 4
tPB
MPBRST
tPDLY
VIH
VIL
tRST
RST2.5V and RST3.3V
VOH
NMI1 and NMI2
tNMI
VOH
TIMING DIAGRAM – 2.5V OR 3.3V PUSHBUTTON RESET Figure 5
tPB
PBRST2.5V
(or PBRST3.3V)
tPDLY
VIH
VIL
tRST
RST2.5V (or RST3.3V)
VOH
VIL
5 of 14
DS1831C/D/E
OPERATION – PUSHBUTTON STATUS
The DS1831E 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 10 kΩs (See Figure 6).
DS1831E APPLICATION EXAMPLE Figure 6
2.5V
3.3V Supply
IN2.5V
RST2.5V
VSENSE2
VSENSE1
1
16
IN3.3V
15
TOL2.5V
3
14
TOL3.3V
TD2.5V
4
13
TD3.3V
IN1
IN2
GND
DS1831E
5
12
6
11
7
10
8
9
10k
RST3.3V
2
PBRST2.5V
VCC
VCC
10 kΩ
PBST
NMI1
NMI2
MPBRST
OUTPUT VALID CONDITIONS
The DS1831 can maintain valid outputs as long as one input remains above 1.0 volt. Accurate voltage
monitoring additionally requires that either the 3.3 volt IN or 2.5 volt IN input be above 1.5 volts. If this
condition is not met and at least one of the supply inputs are at or above 1.0 volt 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 10 kΩs (See Figure 7).
6 of 14
DS1831C/D/E
APPLICATION DIAGRAM - OPEN DRAIN OUTPUTS Figure 7
3.3V Supply
2.5V Supply
IN2.5V
10 KΩ
RST2.5V
TOL2.5V
TD2.5V
PBRST2.5V
1
16
2
15
DS1831C
3
14
4
13
5
12
IN3.3v
10 KΩ
RST3.3V
TOL3.3V
TD3.3V
PBRST3.3V
GND
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 2 referenced comparator (DS1831D has only 1 referenced comparator) that can be used
to monitor upstream voltages or other system specific voltages. Each comparator is referenced to the
1.25 volt 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
10 µs. The comparator detection circuitry also has built-in hysteresis of 100 µV. The supply must be
below the voltage sense point for approximately 2 µs 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 1.25 volt 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 PBRST ’s 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.
The output associated with the specific input will be held low if the voltage on the input pin is less than
1.25 volts. If the voltage is above 1.25 volts the output will not sink current and will be pulled up by the
required pull up resistor. The value of the resistors 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 10 kΩs. If a NMI output is connected
to a pushbutton input an additional pull-up resistor can be used (to improve speed of transitions) but is not
required.
During a power-up, any detected IN pin levels above VTP by the comparator are disabled from generating
an inactive (high) interrupt until at least 1 supply on the VIN inputs rises above 1.5 volts. All NMI outputs
will be held active (low) until at least one VIN reaches 1.5 volts at which point the NMI outputs will be
based on the value of the associated IN input.
7 of 14
DS1831C/D/E
TIMING DIAGRAM - NON MASKABLE INTERRUPT Figure 8
VIN >1.25 V
VTP(max)
VTP
VTP(min)
VTP
VTP(min)
VTP(max)
tNMI
NMI
tIPD
VOH
VOL
NON MASKABLE INTERRUPT CIRCUIT EXAMPLE Figure 9
VSENSE1
VSENSE2
VCC
R1
PBRST3.3V
PBRST2.5V
IN1
R3
R2
NMI1
IN2
R4
10 kΩ
DS1831C
NMI2
GND
MPBRST
Example:
VSENSE1 = 11.50 volts trip point
Therefore:
11.50V =
R1 + 100 kΩ
100 kΩ
VSENSE1 =
X 1.25V
Resulting In: R1 = 820 kΩ
Repeat the same steps to solve for R3 and R4 with VSENSE2.
8 of 14
R1 + R2
R2
X 1.25V
DS1831C/D/E
OPERATION - WATCHDOG TIMER
The watchdog timer function (DS1831D only) forces the WDS signal active (low) when the ST input
does not have a transition (high-to-low or low-to-high) within the predetermined time period. The
time-out period is determined by the condition of the TDWD pin. If TDWD is connected to ground the
minimum watchdog time-out would be 10 ms, TD floating would yield a minimum time-out of 100 ms,
and TDWD connected to VCC would provide a time-out of 1000 ms minimum. Time-out of the watchdog
starts when at least one of the RST outputs becomes inactive (high). If a transition occurs on the ST input
pin prior to time-out, the watchdog timer is reset and begins to time-out again. If the watchdog timer is
allowed to time-out, then the WDS output is pulsed active for a minimum of 100 µs.
The WDS output is an open-drain output and must be pulled up externally. In most applications this
output would be connected to one of the Pushbutton inputs and would not require an external pull-up
resistor. The value of the resistors 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 10 kΩs. If a WDS output is connected to a pushbutton
input an additional pull-up resistor can be used (to improve speed of transitions) but is not required.
The ST input can be derived from many microprocessor outputs. The most typical signals used are the
microprocessor address signals, data signals, or control signals. When the microprocessor functions
normally, these signals would, as a matter of routine, cause the watchdog to be reset prior to time-out. To
guarantee that the watchdog timer does not time-out, a transition must occur at or less than the minimum
times shown in Table 1. A typical circuit example is shown in Figure 10. The watchdog timing is shown
in Figure 11.
The DS1831A watchdog function cannot be disabled. The watchdog strobe input must be strobed to avoid
a watchdog time-out however the watchdog status output can be disconnected yielding the same result.
WATCHDOG CIRCUIT EXAMPLE Figure 10
VSENSE1
VCC
R1
PBRST3.3V
PBRST2.5V
IN1
µP
R2
NMI1
10 kΩ
DS1831D
ST
WDS
GND
TDWD
9 of 14
DS1831C/D/E
TIMING DIAGRAM-STROBE INPUT Figure 11
INVALID
EDGES
VALID
EDGES
INDETERMINATE
EDGES
ST
MIN.
tST
MAX.
tTD
WDS
RESET TIMING DIAGRAM - POWER UP Figure 12
tR
VINTP (MAX)
VINTP (MIN)
VINTP
IN2.5V (or IN3.3V)
tRPU
VOH
RST2.5V (or RST3.3V)
10 of 14
DS1831C/D/E
RESET TIMING DIAGRAM - POWER DOWN Figure 13
tF
IN2.5V (or IN3.3V)
VINTP (MAX)
VINTP
RST2.5V (or RST3.3V)
VINTP (MIN)
tRPD
VOL
11 of 14
DS1831C/D/E
ABSOLUTE MAXIMUM RATINGS*
Voltage on IN2.5V or IN3.3V
Pins Relative to Ground
Voltage on either RST Relative to Ground
Voltage on PBRST3.3V Relative to Ground
Voltage on PBRST2.5V Relative to Ground
Voltage on MPBRST Relative to Ground
Operating Temperature
Storage Temperature
Soldering Temperature
-0.5V to +7.0V
-0.5V to the greater of IN2.5V + 0.5V or IN3.3V + 0.5V
-0.5V to IN3.3V + 0.5V
-0.5V to IN2.5V + 0.5V
-0.5V to the greater of IN2.5V + 0.5V or IN3.3V + 0.5V
-40°C to +85°C
-55°C to +125°C
See J-STD-020A specification
*
This is a stress rating only and functional operation of the device at these or any other conditions
above those indicated in the operation sections of this specification is not implied. Exposure to
absolute maximum rating conditions for extended periods of time may affect reliability.
** The voltage input on IN and ST inputs can be exceeded if the input current is less than 10 mA.
RECOMMENDED DC OPERATING CONDITIONS
PARAMETER
SYMBOL
MIN
IN2.5V (Supply Voltage)
V IN
1.0
IN3.3V (Supply Voltage)
V IN
1.0
2
ST and MPBRST input
VIH
VINT-0.4
High Level
VIH
2
PBRST 3.3V input High Level
VIH
2
PBRST 2.5V input High Level
ST, PBRST 3.3V, PBRST 2.5V and
VIL
-0.3
MPBRST input Low Level
* VINT is the greater voltage level of the IN2.5V or IN3.3V.
DC ELECTRICAL CHARACTERISTICS
PARAMETER
Input Leakage
Output Current @ 2.4V
Output Current @ 0.4V
Operating Current @ ⇐5.5V
Operating Current @ ⇐3.6V
IN3.3V Trip Point (TOL3.3V = IN3.3V)
IN3.3V Trip Point (TOL3.3V = GND)
IN3.3V Trip Point (TOL3.3V = Float)
IN2.5V Trip Point (TOL2.5V =
IN2.5V)
IN2.5V Trip Point (TOL2.5V = GND)
IN2.5V Trip Point (TOL2.5V = Float)
IN Input Trip Points
(-40° to 85°C)
MAX
5.5
5.5
IN3.3V + 0.3
IN2.5V +0.3
UNITS
V
V
V
V
V
V
NOTES
1
1
1,2*
1,3*
1
1
.5
V
1
VINT + 0.3
(-40° to 85°C, VCC = 1.0V TO 5.5V)
SYMBOL
IIL
IOH
IOL
ICC
ICC
VINTP
VINTP
VINTP
MIN
-1.0
TYP
MAX
+1.0
UNITS
µA
2.98
2.80
2.47
80
60
3.06
2.88
2.55
100
80
3.15
2.97
2.64
mA
µA
µA
V
V
V
NOTES
4
5
6
7
8
1
1
1
VINTP
2.250
2.312
2.375
V
1
VINTP
VINTP
VTP
2.125
2.000
1.20
2.187
2.062
1.25
2.250
2.125
1.30
V
V
V
1
1
1
+10
12 of 14
DS1831C/D/E
CAPACITANCE
PARAMETER
Input Capacitance
Input Capacitance
(tA = 25°C)
SYMBOL
CIN
COUT
MAX
5
7
AC ELECTRICAL CHARACTERISTICS
PARAMETER
RESET Active Time (TD=Low)
RESET Active Time (TD=Float)
RESET Active Time (TD=High)
VCC Detect to RST
VCC Detect to RST
VIN Detect to NMI
NMI Active Time
PBRST = VIL
PBRST Stable Low to Reset
Active
Watchdog Timeout (TD(WD)=Low)
Watchdog Timeout (TDWD=Float)
Watchdog Timeout (TDWD=High)
ST Pulse Width
Vin Slew Rate (V INTP(MAX) to V
INTP(MIN))
Vin Slew Rate (V INTP(MAX) to V
INTP(MIN))
SYMBOL
tRST
tRST
tRST
tRPU
tRPD
tIPD
tNMI
tPB
UNITS
pF
pF
NOTES
(-40° to 85°C, VCC = 1.0V TO 5.5V)
MIN
TYP
MAX
10
16
20
100
160
200
1000
1600
2000
See RESET Active Time
2
10
2
10
20
20
tPDLY
16
160
1600
UNITS
ms
ms
ms
ms
µs
µs
µs
µs
50
µs
20
200
2000
ms
ms
ms
ns
tTD
tTD
tTD
tST
10
100
1000
10
tF
300
µs
tR
0
ns
NOTES
8
8
8
8
9
9
NOTES:
1.
2.
3.
4.
5.
6.
7.
8.
9.
All voltages are referenced to ground.
Measured with both IN3.3V & IN2.5V ≥ 2.7V.
Measured with both IN3.3V & IN2.5V ≤ 2.7V.
All Pushbutton inputs are internally pulled to the associated Supply IN input or the greatest Supply IN
input for the MPBRST with an internal Impedance of 100 kΩ.
All outputs are Open Drain and output IOH would be determined by the external pull-up resistor.
Measured with outputs open and IN3.3V or IN2.5V ≤ 5.5V.
Measured with outputs open and IN3.3V or IN2.5V ≤ 3.6V.
Measured using tR = 5 µs.
Noise immunity - pulses <2 µs at a trip level will not cause a RST or NMI .
13 of 14
DS1831C/D/E
Ordering Information
Ordering Part
Package Type
Description
Number
DS1831C
16 Pin DIP 300 mil
2.5V/3.3V MultiSupply Monitor
DS1831CS
16 Pin SO 150 mil
2.5V/3.3V MultiSupply Monitor
DS1831D
16 Pin DIP 300 mil
2.5V/3.3V MultiSupply Monitor w/Watchdog
DS1831DS
16 Pin SO 150 mil
2.5V/3.3V MultiSupply Monitor w/Watchdog
DS1831E
16 Pin DIP 300 mil
2.5V/3.3V MultiSupply Monitor w/Pushbutton Status
DS1831ES
16 Pin SO 150 mil
2.5V/3.3V MultiSupply Monitor w/Pushbutton Status
* Add “/T&R” for tape and reeling of surface mount packages.
14 of 14
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