DS1233A Datasheet by Maxim Integrated

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DALLAS ' SEMICONDUCTOR power failure I Monitors pushbutton for external override I Internal circuitry debounces pushbutton switch I Maintains reset for 350ms after Vcc returns to an inItolerance condition or pushbutton 1 2 a released I Accurate 10% or 15% microprocessor 3.3V power supply monitoring I Reduces need for discrete components I Precision temperatureecompensated voltage reference and Voltage sensor I Lowicost T0792 package or surface mount SOT7223 package I Intemal SkQ pullIup resistor I Operating temperature of 740°C to +85°C PIN DESCRIPTION PIN l GROUND PIN 2 RESET PIN 3 Vcc PIN 4 GROUND (SOTIZ DESCRIPTION The DSIZ33A EconoReset monitors two vital conditions for a microprocessor: power s override. A precision temperatureicompensated reference and comparator circuit are u status of the power supply (Vcc). When an outiofrtolerance condition is detected, an signal is generated which forces reset to the active state. When Vcc returns to an into the reset signal is kept in the active state for approximately 350ms to allow the processor to stabilize. The second function of the DSIZ33A is pushbutton reset contr debounces a pushbutton closure and will generate a 350ms reset pulse upon release. OPERATION — POWER MONITOR The DSIZ33A provides the functions of detecting outIofrtolerance power supply cond a processorrbased system of impending power failure. When Vcc is detected as 0 defined by the tolerance of the part selected, the E signal is asserted. On powerrup, for approximately 350ms after the power supply has reached the s supply and microprocessor to stabilize before RST is released. lofS
DS1233A
3.3V EconoReset
www.maxim-ic.com
FEATURES
Automatically restarts microprocessor after
power failure
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Monitors pushbutton for external override
Internal circuitry debounces pushbutton
switch
Maintains reset for 350ms after VCC returns to
an in-tolerance condition or pushbutton
released
Accurate 10% or 15% microprocessor 3.3V
power supply monitoring
Reduces need for discrete components
Precision temperature-compensated voltage
reference and voltage sensor
Low-cost TO-92 package or surface mount
SOT-223 package
Internal 5kpull-up resistor
Operating temperature of -40C to +85C
PIN ASSIGNMENT
DALLAS
DS1233A
Econo
Reset
1
PIN DESCRIPTION
PIN 1 GROUND
PIN 2 RESET
PIN 3 VCC
PIN 4 GROUND (SOT-223 ONLY)
DESCRIPTION
The DS1233A EconoReset monitors two vital conditions for a microprocessor: power supply and external
override. A precision temperature-compensated reference and comparator circuit are used 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 state. When VCC returns to an in-tolerance condition,
the reset signal is kept in the active state for approximately 350ms to allow the power supply and
processor to stabilize. The second function of the DS1233A is pushbutton reset control. The DS1233A
debounces a pushbutton closure and will generate a 350ms reset pulse upon release.
OPERATION — POWER MONITOR
The DS1233A 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 350ms after the power supply has reached the selected tolerance. This allows the power
supply and microprocessor to stabilize before RST is released.
1 2 3
1 2 3
2 3
4
TOP VIEW
SOT-223 PACKAGE
BOTTOM VIEW
TO-92 PACKAGE
Vcc RST MONITOR *—<:i w="" vcc="" tolerance="" and="" bias="" 350="" ms="" delay="" ground="" t.c.="" reference="" vcc="" w="" microprocessoh="" 03123:“="" ’——i="" w="" pushbutton="" capncitor="" v="">
DS1233A
OPERATION — PUSHBUTTON RESET
The DS1233A provides for a pushbutton switch to be connected to the RST output pin. When the
DS1233A is not in a reset cycle, it continuously monitors the RST signal for a low-going edge. If an edge
is detected, the DS1233A will debounce the switch by pulling the RST line low. After the internal timer
has expired, the DS1233A will continue to monitor the RST line. If the line is still low, the DS1233A will
continue to monitor the line looking for a rising edge. Upon detecting a release, the DS1233A will force
the RST line low and hold it low for 350ms.
NOTE:
For proper operation with an external pushbutton, a capacitor between 100pF and 0.01F must be
connected between RST and ground. In applications where additional reset current is required, a
minimum capacitance of 500 pF should be used, along with a parallel external pull-up resistor of 1k
minimum.
BLOCK DIAGRAM Figure 1
APPLICATION EXAMPLE Figure 2
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W
DS1233A
PUSHBUTTON RESET Figure 3
POWER-UP Figure 4
POWER-DOWN Figure 5
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DS1233A
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 Range -40°C to +85°C
Storage Temperature Range -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 (-40C to +85C)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Supply Voltage VCC 1.2 3.3 5.5 V 1
DC ELECTRICAL CHARACTERISTICS (-40C to +85C; VDD = 3.3V 10%)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Low Level @ RST VOL 0.4 V 1
Output Current @ 0.4V IOL +8 mA
Operating Current ICC 50
A
VCC Trip Point 10% VCCTP1 2.80 2.88 2.97 V 1
VCC Trip Point 15% VCCTP2 2.64 2.72 2.80 V 1
Output Capacitance COUT 10 pF
Pushbutton Detect PBDV 0.8 2.0 V 1
Pushbutton Release PBRD 0.3 0.8 V 1, 2
Internal Pull-Up Resistor RP 3.75 5 6.25
k
AC ELECTRICAL CHARACTERISTICS (-40C to +85C; VCC = 3.3V 10%)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Reset Active Time tRST 250 350 450 ms
VCC Detect to RST tRPD 100 ns
VCC Slew Rate (2.85V - 2.3V) tF 300 s
VCC Slew Rate (2.3V - 2.85V) tR 0 ns
Pushbutton Debounce PBDB 250 350 450 ms
VCC Detect to RST tRPU 250 350 450 ms
NOTES:
1) All voltages are referenced to ground.
2) With a 100pF to 0.01F capacitor connected from RST to ground.
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ECONORESET SELECTION GUIDE to www.muxnmc com/packages 21-0248 21-0250 21-0264
DS1233A
ECONORESET SELECTION GUIDE
VCC TRIP POINT PUSHBUTTON DETECT
MIN TYP MAX MIN TYP MAX
DS1233-15 4.0 4.125 4.24 1.8 - 3.3
DS1233-10 4.25 4.375 4.49 1.8 - 3.3
DS1233-5 4.5 4.625 4.75 1.8 - 3.3
DS1233D-15 4.0 4.125 4.24 N/A N/A
DS1233D-10 4.25 4.375 4.49 N/A N/A
DS1233D-5 4.5 4.625 4.75 N/A N/A
DS1833-15 4.0 4.125 4.24 N/A N/A
DS1833-10 4.25 4.375 4.49 N/A N/A
5V
DS1833-5 4.5 4.625 4.75 N/A N/A
DS1233A-15 2.64 2.72 2.80 0.8 - 2.0
3.3V DS1233A-10 2.8 2.88 2.97 0.8 - 2.0
PACKAGE INFORMATION
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages.
PACKAGE TYPE PACKAGE CODE DOCUMENT NO.
TO 92 Q3+1 21-0248
TO 92 Q3+4 21-0250
SOT 223 K3+1 21-0264
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