Datasheet DS1233M-5, DS1233M-3, DS1233MS-55, DS1233MS-5, DS1233MS-3 Datasheet (Dallas Semiconductor)

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

V

OL

t

RPD

t

F

V

CCTP

V

CC

RST

V

LTL

V

HTL

DS1233M

022698 3/4

TIMING DIAGRAM: POWER UP Figure 3

t

R

t

RPU

V

OH

V

CC

RST

V

CCTP

V

HTL

V

LTL

VOLTAGE TRIP LEVELS

PARAMETER SYMBOL MIN TYP MAX UNITS NOTES

Voltage High Trip Level V

HTL

4.75 V DS1233M–5,
DS1233M–55

Voltage Low T rip Level V

LTL

4.00 V DS1233M–5,
DS1233M–55

Voltage High T rip Level V

HTL

3.14 V DS1233M–3

Voltage Low T rip Level V

LTL

2.48 V DS1233M–3

TIMING DIAGRAM: POWER DOWN Figure 4

DS1233M

022698 4/4

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 V

CC

+ 0.5V
Operating Temperature –40°C to +85°C
Storage Temperature -55°C to +125°C
Soldering T emperature 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 V

CC

1.2 5.5 V 1

DC ELECTRICAL CHARACTERISTICS (–40°C to +85°C; V

CC

= 1.2V to 5.5V)

PARAMETER SYMBOL MIN TYP MAX UNITS NOTES

Output Voltage @ –500 µA V

OH

VCC–0.5V VCC–0.1V V 1

Output Current @ 0.4V I

OL

+8 mA 2, 3

Operating Current I

CC

50 µA 4

V

CC

Trip Point (DS1233M–5) V

CCTP

4.25 4.375 4.49 V 1

V

CC

Trip Point (DS1233M–55) V

CCTP

4.5 4.625 4.75 V 1

VCC Trip Point (DS1233M–3) V

CCTP

2.64 2.72 2.8 V 1

Output Capacitance C

OUT

10 pF

Internal Pull-Up Resistor R

P

3.75 5 6.50 KΩ

AC ELECTRICAL CHARACTERISTICS (–40°C to +85°C; VCC = 1.2V to 5.5V)

PARAMETER SYMBOL MIN TYP MAX UNITS NOTES

Reset Active Time t

RST

200 350 500 ms

VCC Detect to RST t

RPD

2 10 µs

VCC Slew Rate (V

HTL

– V

LTL

) t

F

300 µs

VCC Slew Rate (V

LTL

– V

HTL

) t

R

0 ns

VCC detect to RST t

RPU

200 350 500 ms 5

NOTES:

1. All voltages are referenced to ground.

2. Measured with V

CC

 2.7V.

3. A 1KΩ 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 µs.