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FEATURES
§ Automatically restarts microprocessor after
power failure
§ Maintains reset for 350 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 package or surface mount
8-pin SOIC packages available
§ Internal 5 kW pullup resistor
§ Compatible with Motorola 68XXX series
and HC16 Microprocessors
§ Pin function compatible with the Motorola
MC33064, MC34064, MC33164, and
MC34164
§ Operating temperature of -40°C to +85°C
PIN ASSIGNMENT
1 2 3
PIN DESCRIPTIONS
TO-92
1 RST - Active Low Reset Output
2 VCC - Power Supply
3 GND - Ground
8-Pin SOIC
RST - Active Low Reset Output
VCC - Power Supply
NC - No Connect
GND - Ground
DESCRIPTION
The DS1233M EconoReset uses a precision temperature-compensated reference and comparator circuit to
monitor the status of the power supply (VCC). When an out-of-tolerance condition is detected, an internal
power-fail signal is generated which forces reset to the active (low) state. When VCC returns to an
intolerance condition, the reset signal is kept in the active state for approximately 350 ms to allow the
power supply and processor to stabilize.
DS1233M
EconoReset
www.maxim-ic.com
_
_ _
RST
V
CC
N
C
GND
N
C
N
C
N
C
N
C
1
2
3
4
8
7
6
5
DS1233M 8-Pin SOIC
(150mil)
See Mech. Drawings
Section on Website
BOTTOM VIE
W
TO-92 PACKAGE
See Mech.
Drawings Section
On Website
1 2 3
DALLAS
DS1233
Econo
Reset
DS1233M
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OPERATION - POWER MONITOR
The DS1233M 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, as
defined by the tolerance of the part selected, the RST signal is asserted. On power-up, RST is kept active
for approximately 350 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 Figure 1
APPLICATION EXAMPLE Figure 2
DS1233M
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TIMING DIAGRAM: POWER-UP Figure 3
VOLTAGE TRIP LEVELS
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Voltage High Trip Level VHTL 4.75 V DS1233M-5,
DS1233M-55
Voltage Low Trip Level VLTL 4.00 V DS1233M-5,
DS1233M-55
Voltage High Trip Level VHTL 3.14 V DS1233M-3
Voltage Low Trip Level VLTL 2.48 V DS1233M-3
TIMING DIAGRAM: POWER-DOWN Figure 4
DS1233M
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ABSOLUTE MAXIMUM RATINGS*
Voltage on VCC Pin Relative to Ground -0.5V to +7.0V
Voltage on I/O 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 VCC 1.2 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 Voltage @ -500 mAVOH VCC-0.5V VCC-0.1V V 1
Output Current @ 0.4V IOL +8 mA 2,3
Operating Current ICC 50 mA4
VCC Trip Point (DS1233M-5) VCCTP 4.25 4.375 4.49 V 1
VCC Trip Point (DS1233M-55) VCCTP 4.5 4.625 4.75 V 1
VCC Trip Point (DS1233M-3) VCCTP 2.64 2.72 2.8 V 1
Output Capacitance COUT 10 pF
Internal Pullup Resistor RP3.75 5 6.50 kW
AC ELECTRICAL CHARACTERISTICS (-40°C to +85°C; VCC = 1.2V to 5.5V)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Reset Active Time tRST 200 350 500 ms
VCC Detect to RST tRPD 210
ms
VCC Slew Rate (VHTL - VLTL )tF300 ms
VCC Slew Rate (VLTL - VHTL )t
R0ns
VCC Detect to RST tRPU 200 350 500 ms 5
NOTES:
1. All voltages are referenced to ground.
2. Measured with VCC ³ 2.7V.
3. A 1 kW external resistor may be required in some applications for proper operation of the
microprocessor reset control circuit.
4. Measured with outputs open.
5. tR = 5 ms.
