ADM9690 Analog Devices, ADM9690 Datasheet

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ADM9690

Manufacturer Part Number
ADM9690
Description
Power Supply and Watchdog Timer Monitoring Circuit
Manufacturer
Analog Devices
Datasheet

Specifications of ADM9690

Batt-backup-flg
No
Manual Reset Capability
No
Package
SOIC
Power Fail Indicator
No
Reset Threshold Summary
4.31V
Reset Output-stage
Active-Low/Push-Pull
Min Reset Timeout (ms)
10,50
Typ Watchdog Timeout (ms)
0.75,1.5,12.5,25
Watchdog Timer
Yes

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a
GENERAL DESCRIPTION
The ADM9690 contains a voltage monitoring comparator and a
watchdog timer monitor. It is designed to monitor the 5 V
power supply to a microprocessor and the microprocessor opera-
tion via a watchdog function.
The voltage monitoring comparator monitors the voltage on
V
power-fail, two reset signals are generated. Both reset signals go
active (low) simultaneously. They will remain active while
V
60 ms (RESET(2)) after V
old. RESET(1) is intended to provide a power-on reset signal
for the µP while RESET(2) is used to hold additional circuitry
in a reset state until the µP has regained control following a
power-up. The voltage monitoring circuitry remains operational
with V
REV. A
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
MON
MON
FEATURES
Precision Voltage Monitor (4.31 V)
Watchdog Timeout Monitor
Selectable Watchdog Timeout—0.75 ms, 1.5 ms,
Two RESET Outputs
APPLICATIONS
Microprocessor Systems
Computers
Printers
Controllers
Intelligent Instruments
12.5 ms, 25 ms
. If it drops outside tolerance, as will happen during a
is below the threshold, and for 50 ms (RESET(1)) or
CC
as low as 2 V.
MON
climbs above the reset thresh-
Power Supply and Watchdog Timer
The watchdog timer monitoring circuit is designed to monitor
the activity on the WDI input. This input is normally connected
to an output line on the µP. Its function is to check that the
microprocessor has not stalled in an infinite loop. If there is a
period of inactivity for the watchdog timeout period, both reset
outputs are activated. As above, RESET(1) remains low for
50 ms while RESET(2) remains low for an additional 10 ms.
The watchdog timer is restarted when RESET(1) goes inactive.
The actual watchdog timeout period is adjustable using two
select inputs SEL1 and SEL2.
The ADM9690 is available in an 8-lead SOIC package. It is
specified over the industrial temperature range.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
Fax: 781/326-8703
WATCHDOG
INPUT (WDI)
OSC SEL2
OSC SEL1
V
MON
FUNCTIONAL BLOCK DIAGRAM
4.31V
WATCHDOG
TIMEBASE
WATCHDOG
TRANSITION
DETECTOR
World Wide Web Site: http://www.analog.com
Monitoring Circuit
V
CC
GND
RESET(1)
RESET(2)
TIMER
TIMER
ADM9690
© Analog Devices, Inc., 2000
ADM9690
RESET(1)
RESET(2)

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ADM9690 Summary of contents

Page 1

... The watchdog timer is restarted when RESET(1) goes inactive. The actual watchdog timeout period is adjustable using two select inputs SEL1 and SEL2. The ADM9690 is available in an 8-lead SOIC package specified over the industrial temperature range. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. ...

Page 2

... ADM9690–SPECIFICATIONS Parameter V OPERATING VOLTAGE RANGE CC SUPPLY CURRENT RESET AND WATCHDOG TIMER Reset Voltage Threshold Reset Threshold Hysteresis Reset Timeout Delay ( RESET(2) Timeout Delay ( WATCHDOG TIMEOUT PERIOD (TWD) WDI INPUT PULSEWIDTH RESET(1)/(2) Output Voltage WDI INPUT THRESHOLD Logic Low ...

Page 3

... Logic Output. RESET(1) goes low if V falls below the Reset Threshold or the Watch- dog timer is not serviced within its timeout period. The reset threshold is typically 4.4 V for the ADM9690. RESET(1) remains low for 50 ms after V returns above the thresh- CC old. RESET(1) also goes low for the Watchdog Timer is not serviced within its timeout period ...

Page 4

... Figure 3. Watchdog and Reset Timeout Period vs. Supply @ –40 ° 120 V CC 4.31V RESET(2) RESET(2) TIMER WATCHDOG TIMEBASE RESET(1) RESET(1) TIMER WATCHDOG WATCHDOG ADM9690 INPUT (WDI) TRANSITION DETECTOR GND Figure 5. Typical Application Circuit –4– 100 RESET2/TIMEOUT RESET1/TIMEOUT WATCHDOG TIMEOUT PERIOD 10 2.5 3.0 3.5 4.0 4.5 5 ...

Page 5

... POWER SUPPLY AND WATCHDOG MONITORING CIRCUIT The ADM9690 contains a power supply voltage monitoring comparator and a watchdog timer monitor. Either V ping outside tolerance or the watchdog timer timing out results in a reset sequence as discussed below. Two reset outputs are provided. RESET(1) and RESET(2). ...

Page 6

... ADM9690 OUTLINE DIMENSIONS Dimensions shown in inches and (mm). 8-Lead Narrow Body SOIC (SO-8) 0.1968 (5.00) 0.1890 (4.80 0.1574 (4.00) 0.2440 (6.20 0.1497 (3.80) 0.2284 (5.80) PIN 1 0.0688 (1.75) 0.0196 (0.50) 0.0098 (0.25) 0.0532 (1.35) 0.0099 (0.25) 0.0040 (0.10) 8° 0.0500 0.0192 (0.49) 0° SEATING 0.0098 (0.25) 0.0500 (1.27) (1.27) 0.0138 (0.35) PLANE BSC 0.0075 (0.19) 0.0160 (0.41) –6– x 45° ...

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