DSDS1705/DS1706
DS1705/DS1706
3.3 and 5.0 Volt MicroMonitor
FEATURES
• Halts and restarts an out–of–control microprocessor
• Holds microprocessor in check during power tran-
sients
• Automatically restarts microprocessor after power
failure
• Monitors pushbutton for external override
• Accurate 5%, 10% or 20% resets for 3.3 systems and
5% or 10% resets for 5.0 volt systems
• Eliminates the need for discrete components
• 3.3 volt 20% tolerance for use with 3.0 volt systems
• Pin compatible with the MAXIM MAX705/MAX706 in
8–pin DIP and 8–pin SOIC
• 8–pin DIP, 8–pin SOIC and 8–pin µ–SOP packages
• Industrial temperature range –40°C to +85°C
DESCRIPTION
The DS1705/DS1706 3.3 or 5.0 Volt MicroMonitor moni-
tors three vital conditions for a microprocessor: power
supply, software execution, and external override. A
precision temperature compensated reference and
comparator circuit monitors the status of VCC at the
device and at an upstream point for maximum protec-
tion. When the sense input detects an out–of–tolerance
PIN ASSIGNMENT
PBRST
VCC
GND
IN
1
8
2
7
3
6
4
5
8–PIN DIP
(300 MIL)
WDS
RST
ST
NMI
PBRST
VCC
GND
IN
1
8
2
7
3
6
4
5
8–PIN SOIC
(150 MIL)
WDS
RST (*RST)
ST
NMI
PBRST 1
VCC 2
GND 3
IN 4
8 WDS
7 RST (*RST)
6 ST
5 NMI
8–PIN µ–SOP
(118 MIL)
See Mech. Drawings
Section
DS1705 and DS1706_/R/S/T (*DS1706L and DS1706P)
PIN DESCRIPTION
PBRST
– Pushbutton Reset Input
VCC
GND
– Power Supply
– Ground
IN
– Input
NMI
– Non–maskable Interrupt
ST
– Strobe Input
RST
– Active Low Reset Output
*RST
– Active High Reset Output
(DS1706P and DS1706L only)
WDS
– Watchdog Status Output
condition a non–maskable interrupt is generated. As
the voltage at the device degrades an internal power fail
signal is generated which forces the reset to an active
state. When VCC returns to an in–tolerance condition,
the reset signal is kept in the active state for a minimum
of 130 ms to allow the power supply and processor to
stabilize.
ECopyright 1995 by Dallas Semiconductor Corporation.
All Rights Reserved. For important information regarding
patents and other intellectual property rights, please refer to
Dallas Semiconductor data books.
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