Copyright 1995 by Dallas Semiconductor Corporation.
All Rights Reserved. For important information regarding
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DS1813
5V EconoReset with Pushbutton
DS1813
082196 1/5
FEATURES
•Automatically restarts a microprocessor after power
failure
•Monitors pushbutton for external override
•Maintains reset for typically 150 ms after VCC returns
to an in–tolerance condition
•Reduces need for discrete components
•Precision temperature–compensated voltage
reference and voltage sensor
•Low–cost TO–92 or space saving surface–mount
SOT–23 packages available
•Efficient open–drain output with internal 5.5KΩ
pull–up resistor
•Operating temperature –40°C to +85°C
PIN ASSIGNMENT
123
TO–92 PACKAGE
See Mech. Drawings
Section
12
3
SOT–23 PACKAGE
123
PIN DESCRIPTIONS
TO–92
1 RST Active Low Reset Output
2V
CC Power Supply
3 GND Ground
SOT–23
1 RST Active Low Reset Output
2V
CC Power Supply
3 GND Ground
DESCRIPTION
The DS1813 EconoReset uses a precision temperature
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 state. When
VCC returns to an in–tolerance condition, the reset sig-
nal is kept in the active state for approximately 150 ms to
allow the power supply and processor to stabilize.
The DS1813 also monitors a pushbutton on the reset
output. If the reset line is pulled low , a reset is generated
upon release and will be held in reset output low for typi-
cally 150 ms.
DS1813
082196 2/5
OPERATION – POWER MONITOR
The DS1813 provides the functions of detecting out–of–
tolerance power supply conditions and warning a pro-
cessor–based system of impending power failure.
When VCC is detected as out–of–tolerance, the RST
signal is asserted. On power–up, RST is kept active for
approximately 150 ms after the power supply has
reached the selected tolerance. This allows the power
supply and microprocessor to stabilize before RST is re-
leased.
OPERATION – PUSHBUTTON RESET
The DS1813 provides for a pushbutton switch for
manual reset control. When the DS1813 is not in a reset
cycle, a pushbutton reset can be generated by pulling
the RST pin low for at least 1 µs. When the pushbutton is
held low , the RESET is forced active low and will remain
active low for about 150 ms after the pushbutton is
released. See Figure 2 for an application example and
Figure 3 for the timing diagram.
BLOCK DIAGRAM (OPEN-DRAIN OUTPUT) Figure 1
Vcc TOLERANCE
T.C. REFERENCE
150 ms
GROUND
RESET
RST
MONITOR
DELAY
AND BIAS
5.5KΩ
VCC
+
–
APPLICATION EXAMPLE Figure 2
DS1813 MICROPROCESSOR
RST
RESET
VCC
DS1813
082196 3/5
TIMING DIAGRAM: PUSHBUTTON RESET Figure 3
RST VIH
tRST
VIL
tPB
TIMING DIAGRAM: POWER UP Figure 4
tR
tRPU
VOH
VCC
RST
VCCTP
VCCTP(MAX)
VCCTP(MIN)
TIMING DIAGRAM: POWER DOWN Figure 5
VOL
tRPD
tF
VCCTP
VCC
RST
VCCTP(MAX)
VCCTP(MIN)
DS1813
082196 4/5
ABSOLUTE MAXIMUM RATINGS*
Voltage on VCC Pin Relative to Ground –0.5V to +7.0V
Voltage on RST Relative to Ground –0.5V to +5VCC + 0.5V
Operating Temperature –40°C to +85°C
Storage Temperature –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 (–40°C to +85°C)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Supply Voltage VCC 0.0 5.5 V 1
DC ELECTRICAL CHARACTERISTICS (–40°C to +85°C; VCC = 1.2V to 5.5V)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Output Current @ 0.4 volts IOL +10 mA 2, 3
Operating Current VCC < 5.5 ICC 30 40 µA 4
VCC T rip Point (DS1813–5) VCCTP 4.50 4.62 4.75 V 1
VCC T rip Point (DS1813–10) VCCTP 4.25 4.35 4.49 V 1
VCC Trip Point (DS1813–15) VCCTP 4.00 4.13 4.24 V 1
Internal Pull–Up Resistor RP3.50 5.5 7.5 K
Output Capacitance COUT 10 pF
AC ELECTRICAL CHARACTERISTICS (–40°C to +85°C; VCC = 1.2V to 5.5V)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
RESET Active Time tRST 100 150 300 ms
VCC Detect to RST tRPD 2 5 µs
VCC Slew Rate
(VCCTP (MAX) – VCCTP (MIN)) tF300 µs
VCC Slew Rate
(VCCTP (MIN) – VCCTP (MAX)) tR0 ns
VCC Detect to RST tRPU 100 150 300 ms 5
Push–button Detect to RST tPB 1µs
Push–button Reset tPBRST 100 150 300 ms
NOTES:
1. All voltages are referenced to ground.
2. Measured with VCC > 2.7 volts.
3. A 1KΩ external resistor may be required in some applications for proper operation of the microprocessor
reset control circuit.
4. Measured with RST output open.
5. tR = 5 µs.
DS1813
082196 5/5
PART MARKING CODES
12
3
ABCD
“A”, “B”, &“C” represent the device type. “D” represents the device tolerance.
810 DS1810. . . .
811 DS1811. . . .
812 DS1812. . . .
813 DS1813. . . .
815 DS1815. . . .
816 DS1816. . . .
817 DS1817. . . .
818 DS1818. . . .
A5%. . . . . .
B 10%. . . . . .
C 15%. . . . . .
D 20%. . . . . .
