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DS1233M
EconoReset
www.maxim-ic.com
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
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
DALLAS
DS1233
Econo
Reset
RST
V
CC
NC
GND
1
2
3
4
8
7
6
5
NC
NC
NC
NC
DS1233M 8-Pin SOIC
(150mil)
See Mech. Drawings
Section on Website
1
2
3
_
1
_
2
_
3
BOTTOM VIEW
TO-92 PACKAGE
See Mech.
Drawings Section
On Website
PIN DESCRIPTIONS
TO-92
1
RST
2 V
CC
3 GND
- Active Low Reset Output
- Power Supply
- Ground
8-Pin SOIC
RST
V
CC
NC
GND
- Active Low Reset Output
- Power Supply
- No Connect
- Ground
DESCRIPTION
The DS1233M 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 (low) state. When V
CC
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.
1 of 4
041002
DS1233M
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
APPLICATION EXAMPLE
Figure 2
2 of 4
DS1233M
TIMING DIAGRAM: POWER-UP
Figure 3
VOLTAGE TRIP LEVELS
PARAMETER
Voltage High Trip Level
SYMBOL
MIN
TYP
MAX
UNITS
V
HTL
V
LTL
V
HTL
V
LTL
4.75
4.00
3.14
2.48
V
V
V
V
Voltage Low Trip Level
Voltage High Trip Level
Voltage Low Trip Level
NOTES
DS1233M-5,
DS1233M-55
DS1233M-5,
DS1233M-55
DS1233M-3
DS1233M-3
TIMING DIAGRAM: POWER-DOWN
Figure 4
3 of 4
DS1233M
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
PARAMETER
Output Voltage @ -500
m
A
Output Current @ 0.4V
Operating Current
V
CC
Trip Point (DS1233M-5)
V
CC
Trip Point (DS1233M-55)
V
CC
Trip Point (DS1233M-3)
Output Capacitance
Internal Pullup Resistor
SYMBOL
V
CC
MIN
1.2
TYP
MAX
5.5
(-40°C to +85°C)
UNITS
V
NOTES
1
NOTES
1
2,3
4
1
1
1
DC ELECTRICAL CHARACTERISTICS
(-40°C to +85°C; V
CC
= 1.2V to 5.5V)
TYP
MAX
V
CC
-0.1V
UNITS
V
mA
m
A
V
V
V
pF
k
W
UNITS
ms
m
s
m
s
ns
ms
SYMBOL MIN
V
CC
-0.5V
V
OH
I
OL
+8
I
CC
V
CCTP
4.25
V
CCTP
4.5
V
CCTP
2.64
C
OUT
R
P
3.75
SYMBOL MIN
t
RST
200
t
RPD
t
F
300
t
R
0
t
RPU
200
4.375
4.625
2.72
5
TYP
350
2
50
4.49
4.75
2.8
10
6.50
MAX
500
10
AC ELECTRICAL CHARACTERISTICS
PARAMETER
Reset Active Time
V
CC
Detect to RST
V
CC
Slew Rate (V
HTL
- V
LTL
)
V
CC
Slew Rate (V
LTL
- V
HTL
)
V
CC
Detect to RST
(-40°C to +85°C; V
CC
= 1.2V to 5.5V)
NOTES
350
500
5
NOTES:
1. All voltages are referenced to ground.
2. Measured with V
CC
³
2.7V.
3. A 1 k
W
external resistor may be required in some applications for proper operation of the
microprocessor reset control circuit.
4. Measured with outputs open.
5. t
R
= 5
m
s.
4 of 4
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