Dallas Semiconductor DS1233-5, DS1233-15, DS1233-10, DS1233Z-5, DS1233Z-15 Datasheet
...
www.dalsemi.com
3
DS1233
5V EconoReset
FEATURES
PIN ASSIGNMENT
Automatically restarts microprocessor after
power failure
Monitors pushbutton for external override
Internal circuitry debounces pushbutton
DALLAS
DS1233
Econo
Reset
switch
Maintains reset for 350 ms after VCC returns
to an in-tolerance condition or pushbutton
released
Accurate 5%, 10% or 15% microprocessor 5V
power supply monitoring
1 2 3
1
Reduces need for discrete components
Precision temperature-compensated voltage
reference and voltage sensor
Low-cost TO-92 package or surface-mount
SOT-223 package
1 2 3
TO-92 PACKAGE
See Mech.
Drawings Section
4
2
SOT-223 PACKAGE
See Mech.
Drawings Section
Internal 5kΩ=pull-up resistor
Operating temperature of -40°C to +85°C
PIN DESCRIPTION
PIN 1 GROUND
PIN 2 RESET
PIN 3 V
CC
PIN 4 GROUND (SOT-223 ONLY)
DESCRIPTION
The DS1233 EconoReset monitors two vital conditions for a microprocessor: power supply and external
override. A precision temperature compensated ref erence and comparator cir cuit are used to monit or the
status of the power supply (V
signal is generated which forces reset to t he active 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. The second function of the DS1233 is pushbutton reset control. The DS1233
debounces a pushbutton closure and will generate a 350 ms reset pulse upon release.
). When an out-of-tolerance condition is detected, an internal power-fail
CC
OPERATION - POWER MONITOR
The DS1233 provides the functions 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, as
defined by the tolerance of the part selected, the
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.
RST signal is asserted. On power-up, RST is kept active
1 of 5 111899
DS1233
OPERATION - PUSHBUTTON RESET
The DS1233 provides for a pushbutton switch to be connected to the RST output pin. When the DS1233
is not in a reset cycle, it continuously monitors the RST signal for a low going edge. If an edge is
detected, the DS1233 will debounce the switch by pulling the RST line low. After the internal timer has
expired, the DS1233 will continue to monitor the RST line. If the line is still low, the DS1233 will
continue to monitor the line looking for a rising edge. Upon detecting a release, the DS1233 will force the
RST line low and hold it low for 350 ms.
NOTE:
For proper operation with an external pushbutton, a capacitor between 100 pF and 0.01 µF must be
connected between
minimum capacitance of 500 pF should be used, along with a parallel external pull-up resistor of 1
kΩ=minimum.
RST and ground. In applications where additional reset current is required, a
BLOCK DIAGRAM Figure 1
APPLICATION EXAMPLE Figure 2
2 of 5
Loading...