BENEFITS AND FE ATURES
• Improves Reliability of Processor Operation
o Temperature-Compensated Voltage
Monitor for Precise, Automated Power-
Fail Detection
o Automatically Restarts a Microprocessor
After Power Failure
o Maintains Reset for 150ms After VCC
Returns to Tolerance for Processor
Stabilization
o Monitors Pushbutton for External
Override
o Active-Low Reset Output
• Efficient Open-Drain Output with Internal
5.5kΩ Pullup Resistor Saves Power and Space
o 35µA (max) Quiescent Current
• Allows for Easy Design with No Complicated
Settings
o Fixed 3.3V Reset Threshold
o 5%, 10%, and 20% Tolerance Versions
Available
• Operates in Most Commercial and Industrial
Environments
o -40°C to +85°C Operating Temperature
Range
• MXD1818 Offers Improved Performance over
the DS1818
PIN ASSIGNMENT
PIN DES CRIPTION
TO-92
1
RST
Active Low Reset Output
2 VCC Power Supply
3 GND Ground
SOT-23
1
RST
Active Low Reset Output
2 VCC Power Supply
3 GND Ground
DESCRIPTION
The DS1818 EconoReset uses a precision temperature-compensated reference and comparator circuit to
monitor the status of the power supply (VCC). When an out-of-tolerance co ndition is detected, an in ternal
power-fail si gnal is generated which fo rces reset to the active state. When VCC returns to an in-tolerance
condition, the reset signal is kept in the active state for approximately 150 ms to allow the power supply
and processor to stabilize.
The DS1818 also monitors a pushbutton on the reset output. If the reset line is pulled low, a reset is
generated upon release and the DS1818 output will be held in reset output low for typically 150 ms.
DS1818
3.3V Eco noReset with Pushbu tton
1
2
3
TOP VIEW
SOT-23 PACKAGE
See Mec h.
Drawings Section
On Website
1 2 3
1 2 3
BOTTOM VIEW
TO-92 PACKAGE
See Mec h.
Drawings Section
On Website
DALLAS
DS1818
Econo
Reset
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DS1818
OPERATION - POWER MONITOR
The DS1818 provides the functions of detecting out-of-tolerance power supply conditions and warning a
processor-based system of impending power failures. When VCC is detected as out-of-toleran ce, the
RST
signal i s assert ed. On p ower-up,
RST
is kept active for approximately 150 ms after the power supply has
reached t he selected t olerance. This allows the power s upply and mi croproces sor to stabi lize before
RST
is released.
BLOCK DIAGRAM (OPEN-DRAIN OUTPUT) Figure 1
APPLICATION EXAMPLE Figure 2
OPERATION - PUSHBUTTON RESE T
The DS1818 provides a pushbutton switch for manual reset control. When the DS1818 is not in a reset
cycle, a pushbutton reset can be generated by pulling the
RST
pin low for at least 1 µs. When the
pushbutton is held low, the
RST
is forced active low and will remain active low for about 150 ms after
the pushbutton is released. See Figure 2 for an application example and Figure 3 for the timing diagram.
TIMING DIAGRAM : PUS HBUTTON RESE T Figure 3
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DS1818
TIMING DIAGRAM : PO WE R-UP Figure 4
TIMING DIAGRAM : PO WE R-DOWN Figure 5
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DS1818
ABSOLUT E MAXIMUM RATINGS*
Voltage on VCC Pin Relative to Ground -0.5V to +7.0V
Voltage on
RST
Relative to Ground -0.5V to +5VCC +0.5V
Operating Temperature -40°C to +85°C
Storage Tem per at ure -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
1.0
5.5
V
1
DC ELECTRICAL CHARACTERISTICS (-40°C t o +85 °C; VCC=1.2V to 5.5V)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Output Current @ 0.4 V IOL +10 mA 2, 3
Voltage Input Low VIL 0.4 V 1
Voltage Input High
V
IH
0.7
*VCC
V
1
Operating Current V
CC
< 5.5V
I
CC
28
35
µA
4
VCC Trip Point (DS1818-5) VCCTP 2.98 3.06 3.15 V 1
VCC Trip Point (DS1818-10) VCCTP 2.80 2.88 2.97 V 1
V
CC
Trip Point (DS1818-20)
V
CCTP
2.47
2.55
2.64
V
1
Internal Pull-up Resistor RP 3.50 5.5 7.5 kΩ 7
Output Capacitance COUT 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
RST
100
150
250
ms
5
VCC Detect to
RST
tRPD 2 5 µs
VCC Slew Rate
(VCCTP (MAX) to VCCTP (MIN))
tF 300 µs 8
VCC Slew Rate
(VCCTP (MIN) to VCCTP (MAX))
tR 0 ns
VCC Detect to
RST
t
RPU
100
150
250
ms
5, 6
Pushbutton Detect to
RST
tPB 1 µs
Pushbutton Reset tPBRST 100 150 250 ms 5
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DS1818
NOTES:
1. All voltages are referenced to ground.
2. Measured with VCC ≥ 2.7V.
3. A 1 kΩ external pull-up resistor may be required in some applications for proper operation of the
microprocessor reset control circuit.
4. Measured w it h
RST
output open.
5. Measured with 2.7V ≤ VCC ≤ 3.3V.
6. tR = 5 µs.
7. VOH and IOH are a function of the value of RP and the associated output load conditions.
8. The tF value is for reference in defining values for tRPD and should not be considered a requirement for
proper operation or use of the device.
PART MARKING CODES
“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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DS1818
REVIS IO N HISTO RY
REVISION
NUMBER REVISION
DATE DESCRIPTION PAGES
CHANGED
1 3/15 Updated Benefits and Features section 1
For pricing, delivery, and ordering info r mation, p lease c ontact Ma xim Direct at 1-888-629-4642, or visit Ma xim Integrated’s website at www.maximintegrated.c om.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated re serves the right t o change the circuitry a nd specifications without notice at any time. The para metric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integ r a te d a nd t he M ax im In te gr at e d lo go are tr ad emark s of M axim Integrated Products, Inc. © 2015 Max im Integrated Products, Inc.
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