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NE56625-20 Datasheet PDF : 15 Pages
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Philips Semiconductors
System reset with Watchdog timer
Product data
NE56625-20
GENERAL DESCRIPTION
The NE56625-20 is comprised of a power-on reset, a Watchdog
timer and low battery detection circuit. The NE56625 is designed to
generate an Active-LOW reset signal for a variety of microprocessor
and logic systems. Accurate reset signals are generated during
momentary power interruptions or whenever power supply voltages
sag to intolerable levels. The built-in Watchdog timer monitors the
microprocessor and ensures it is operating properly. Any abnormal
system operations due to microprocessor malfunctions are
terminated by a system reset generated by the Watchdog. To
accommodate a wide range of system requirements, the Watchdog
Monitoring Time and power-on reset delay time are programmable
from 10 ms to 10 sec.
The NE56625-20 is designed for low voltage battery powered
applications with low battery detection threshold at 2.2 V. It is offered
in the 8-lead small outline surface mount package (SOP005).
FEATURES
• Accurate threshold detection voltages:
– Low battery: 2.2 V ±3%
– Power-on reset: 2.0 V ±3%
• Low hysteresis voltage (both low battery check and power-on
reset): 50 mV typ.
• Low supply current: 150 µA typ.
• Programmable power-on reset detection voltage
• Programmable power-on reset delay: 10 ms to 10 s
• Internal Watchdog timer programmable with external resistor and
capacitor: 10 ms to 10 s
• Reset assertion with VCC down to 0.8 VDC (typical)
• Few external components required
APPLICATIONS
• Microcomputer systems and logic systems
• 2 V cordless phones
• Various portable, battery operated equipment
SIMPLIFIED SYSTEM DIAGRAM
VCC
RCT
5
NE56625-20
VS
7
C
VREF
6 RCT
BATTERY
CHECK
RESET
GENERATOR
BC
2
RESET
8
PROGRAMMABLE
WATCHDOG
TIMER
CLK
3
LOGIC SYSTEM
NMI
RESET
CLK
GND
4 GND
1
CT
Figure 1. Simplified system diagram.
SL01593
2003 Oct 15
2
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