DS1233D
5V EconoReset
www.maxim-ic.com
FEATURES
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Automatically restarts microprocessor after
power failure
Maintains reset for 350 ms after V
CC
returns
to an in-tolerance condition
Accurate 5%, 10% or 15% microprocessor 5V
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 5 kW pull-up resistor
Compatible with Motorola 68XXX series and
HC16 Microprocessors
Operating temperature of -40°C to +85°C
PIN ASSIGNMENT
DALLAS
DS1233
Econo
Reset
1
2
4
3
1 2 3
1 2 3
BOTTOM VIEW
TO-92 PACKAGE
See Mech.
Drawings Section
On Website
TOP VIEW
SOT-23 PACKAGE
See Mech.
Drawings Section
On Website
PIN DESCRIPTION
PIN 1
PIN 2
PIN 3
PIN 4
GROUND
RESET
V
CC
GROUND (SOT-223 ONLY)
DESCRIPTION
The DS1233D EconoReset uses a precision temperature-compensated reference and comparator circuit to
monitor the status of the power supply (V
CC
). When an out-of-tolerance condition is detected, an internal
power-fail signal is generated which forces reset to the active state. When V
CC
returns to an in-tolerance
condition, the reset signal is kept in the active state for approximately 350 ms to allow the power supply
and processor to stabilize.
OPERATION - POWER MONITOR
The DS1233D provides the functions of detecting out-of-tolerance power supply conditions and warning
a processor-based system of impending power failure. When V
CC
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.
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041002
DS1233D
ABSOLUTE MAXIMUM RATINGS*
Voltage on V
CC
Pin Relative to Ground
Voltage on I/O Relative to Ground
Operating Temperature
Storage Temperature
Soldering Temperature
*
-0.5V to +7.0V
-0.5V to V
CC
+0.5V
-40°C to +85°C
-55°C to +125°C
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
PARAMETER
Supply Voltage
SYMBOL
V
CC
MIN
1.2
TYP
5.0
MAX
5.5
(-40°C to +85°C)
UNITS
V
NOTES
1
DC ELECTRICAL CHARACTERISTICS
PARAMETER
Low Level @
RST
Output Current @ 0.4V
Operating Current
V
CC
Trip Point 5%
V
CC
Trip Point 10%
V
CC
Trip Point 15%
Output Capacitance
Internal Pull-Up Resistor
SYMBOL
V
OL
I
OL
I
CC
V
CCTP1
V
CCTP2
V
CCTP3
C
OUT
R
P
4.5
(-40°C to +85°C; V
DD
=5V
±
10%)
MIN
+8
50
4.625
4.375
4.125
5
4.74
4.49
4.24
10
3.75
6.25
4.25
4.0
TYP
MAX
0.4
UNITS
V
mA
mA
V
V
V
pF
kW
1
1
1
NOTES
1
2
AC ELECTRICAL CHARACTERISTICS
PARAMETER
Reset Active Time
V
CC
Detect to
RST
V
CC
Slew Rate (4.75V - 4.00V)
V
CC
Slew Rate (4.00V - 4.75V)
V
CC
Detect to RST
SYMBOL
t
RST
t
RPD
t
F
t
R
t
RPU
(-40°C to +85°C; V
CC
=5V
±
10%)
MIN
250
300
0
250
350
450
TYP
350
MAX
450
100
UNITS
ms
ns
ms
ns
ms
NOTES
NOTES:
1. All voltages are referenced to ground.
2. A 1 kW external resistor may be required for proper operation of the microprocessor reset control
circuit.
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