Dallas Semiconductor DS1233M-5, DS1233M-3, DS1233MS-55, DS1233MS-5, DS1233MS-3 Datasheet
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DS1233M
EconoReset
DS1233M
022698 1/4
FEATURES
• Automatically restarts microprocessor after power
failure
• Maintains reset for 350 ms after V
CC
returns to an
in-tolerance condition
• Reduces need for discrete components
• Precision temperature-compensated voltage refer-
ence and voltage sensor
• Low-cost TO-92 package or surface mount 8–pin
SOIC packages available
• Internal 5 KΩ pull-up 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
DALLAS
123
123
DS1233
Econo
Reset
DS1233M
TO-92 Package
See Mech. Drawings
Section
8
7
6
5
1
2
3
4
RST
V
CC
NC
GND
NC
NC
NC
NC
DS1233M 8–PIN SOIC
(150 MIL)
See Mech. Drawings
Section
PIN DESCRIPTIONS
TO–92
1 RST – Active Low Reset Output
2V
CC
– Power Supply
3 GND – Ground
8–Pin SOIC
RST – Active Low Reset Output
V
CC
– 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 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.
DS1233M
022698 2/4
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 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.
BLOCK DIAGRAM Figure 1
Vcc TOLERANCE
AND BIAS
T.C. REFERENCE
350 ms
DELAY
GROUND
RST
V
CC
5KΩ
APPLICATION EXAMPLE Figure 2
V
CC
MICROPROCESSOR
RST
RESET
DS1233M
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