Dallas Semiconductor DS1817R-5-T-R, DS1817R-20-T-R, DS1817R-10-T-R, DS1817-5, DS1817-20 Datasheet
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FEATURES
Automatically restarts a microprocessor after
power failure
Maintains reset for 150 ms after VCC returns
to an in-tolerance condition
Reduces need for discrete components
Precision temperature-compensated voltage
reference and voltage sensor
Accurate 5%, 10% or 20% power monitoring
20% tolerance for use with 3.0-volt systems
Low-cost TO-92 or space saving surface
mount SOT-23 packages available
Push-pull active high output
Operating temperature -40°C to +85°C
PIN ASSIGNMENT
PIN DESCRIPTION
TO-92
1 RST Active High Reset Output
2 VCC Power Supply
3 GND Ground
SOT-23
1 RST Active High Reset Output
2 VCC Power Supply
3 GND Ground
DESCRIPTION
The DS1817 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 intern al power-fail
signal is generated which forces reset to t he active state. When V
CC
returns to an in-tolerance condition,
the reset signal is kept in the active state for approximately 150 ms to allow the power supply and
processor to stabilize.
DS1817
Active High 3.3V EconoReset
www.dalsemi.com
12
3
SOT-23 PACKAGE
See Mech. Drawing
1 2 3
1 2 3
TO-92 PACKAGE
See Mech. Drawing
DS1817
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OPERATION - POWER MONITOR
The DS1817 provides the function of detecting out-of-tolerance power supply conditions and warning a
processor based system of impending power failure. When VCC is detected as out-of-tolerance, the R ST
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 released.
BLOCK DIAGRAM (CMOS OUTPUT) Figure 1
APPLICATION EXAMPLE Figure 2
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