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DS1811
5V EconoReset with Open Drain Output
FEATURES
§ Automatically restarts a microprocessor after
power failure
§ Maintains reset for 150 ms after VCC returns
to an in-tolerance condition
§ Reduces need for discrete components
§ Precision temperature-compensated voltage
reference and voltage sensor
§ Low-cost TO-92 or space saving SOT-23
packages available
§ Efficient open-drain output with internal
5.5 kW pull-up resistor
§ Operating temperature -40°C to +85°C
PIN ASSIGNMENT
DALLAS
DS1811
Econo
Reset
12
TOP VIEW
SOT-23 PACKAGE
See Mech.
Drawings Section
1 2 3
1 2 3
BOTTOM VIEW
TO-92 PACKAGE
See Mech.
Drawings Section
On Website
On Website
PIN DESCRIPTION
TO-92
1 RST Active Low Reset Output
2 VCC Power Supply
3 GND Ground
SOT-23
1 RST Active Low Reset Output
2 V
Power Supply
CC
3 GND Ground
DESCRIPTION
The DS1811 EconoReset uses a precision temperature reference and comparator circuit to monitor the
status of the power supply (V
signal is generated which forces reset to the active state. When V
the reset signal is kept in the active state for approximately 150 ms to allow the power supply and
processor to stabilize.
). When an out-of-tolerance condition is detected, an internal power-fail
CC
returns to an in-tolerance condition,
CC
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DS1811
OPERATION - POWER MONITOR
The DS1811 provides the functions of detecting out-of-tolerance power supply conditions and warning a
processor-based system of impending power failure. When VCC is detected as out-of-tolerance, the RST
signal is asserted. On power-up, RST is kept active for approximately 150 ms after the power supply has
reached the selected tolerance. This allows the power supply and microprocessor to stabilize before RST
is released.
BLOCK DIAGRAM (OPEN-DRAIN OUTPUT) Figure 1
APPLICATION EXAMPLE Figure 2
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TIMING DIAGRAM: POWER-UP Figure 3
TIMING DIAGRAM: POWER-DOWN Figure 4
DS1811
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DS1811
ABSOLUTE MAXIMUM RATINGS*
Voltage on VCC Pin Relative to Ground -0.5V to +7.0V
Voltage on RST Relative to Ground -0.5V to VCC +0.5V
Operating Temperature -40°C to +85°C
Storage Temperature -55°C to +125°C
Soldering Temperature 260°C for 10 seconds
* 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.
RECOMMENDED DC OPERATING CONDITIONS (-40°C to +85°C)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Supply Voltage V
CC
0.0 5.5 V 1
DC ELECTRICAL CHARACTERISTICS (-40°C to +85°C; VCC=1.2V to 5.5V)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Output Current @ 0.4 volts I
Operating Current VCC < 5.5 volts I
VCC Trip Point (DS1811-5) V
VCC Trip Point (DS1811-10) V
VCC Trip Point (DS1811-15) V
Internal Pull-Up Resistor R
Output Capacitance C
OL
CC
CCTP
CCTP
CCTP
P
OUT
+10 mA 2, 3
30 40
mA
4
4.50 4.62 4.75 V 1
4.25 4.35 4.49 V 1
4.00 4.13 4.24 V 1
3.5 5.5 7.5
kW
10 pF
AC ELECTRICAL CHARACTERISTICS (-40°C to +85°C; VCC=1.2V to 5.5V)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
RESET Active Time t
VCC Detect to RST
RST
t
RPD
100 150 300 ms
25
ms
V
Slew Rate
CC
(V
(MAX) to V
CCTP
VCC Slew Rate
(V
(MIN) to V
CCTP
VCC Detect to RST
CCTP
CCTP
(MIN))
(MAX))
t
RPU
t
t
F
R
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300
ms
0ns
100 150 300 ms 5
NOTES:
1. All voltages are referenced to ground.
2. Measured with VCC ³ 2.7 volts.
3. A 1kW external resistor may be required in some applications for proper operation of the
microprocessor reset control circuit.
4. Measured with RST output open.
5. tR = 5 ms.
PART MARKING CODES
DS1811
“A”, “B”, &“C” represent the device type.
810 . . . . DS1810
811 . . . . DS1811
812 . . . . DS1812
813 . . . . DS1813
815 . . . . DS1815
816 . . . . DS1816
817 . . . . DS1817
818 . . . . DS1818
“D” represents the device tolerance.
A . . . . . . 5%
B . . . . . . 10%
C . . . . . . 15%
D . . . . . . 20%
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