Datasheet

ManualsBrandsANALOG DEVICES ManualsPMICsPMIC - system monitor Reset/power-on reset SC 70 5

Supervisory Circuits with Watchdog and

Manual Reset in 5-Lead SC70 and SOT-23

Data Sheet

ADM823/ADM824/ADM825

Rev. D Document Feedback

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FEATURES

Precision 2.5 V to 5 V power supply monitor

7 reset threshold options: 2.19 V to 4.63 V

140 ms (minimum) reset timeout

Watchdog timer with 1.6 sec timeout (ADM823, ADM824)

Manual reset input (ADM823, ADM825)

Push-pull output stages

RESET

(ADM823)

RESET

, RESET (ADM824/ADM825)

Low power consumption: 5 µA

Guaranteed reset output valid to V

= 1 V

Power supply glitch immunity

Specified over automotive temperature range

5-lead SC70 and SOT-23 packages

APPLICATIONS

Microprocessor systems

Computers

Controllers

Intelligent instruments

Portable equipment

FUNCTIONAL BLOCK DIAGRAM

ADM823

GND

WDI

RESET

GENERATOR

TCHDOG

DETEC

TOR

DEBOUNCE

REF

04534-001

Figure 1.

GENERAL DESCRIPTION

The ADM823/ADM824/ADM825 are supervisory circuits that

monitor power supply voltage levels and code execution integrity

in microprocessor-based systems. In addition to providing

power-on reset signals, an on-chip watchdog timer can reset the

microprocessor if it fails to strobe within a preset timeout

period. A reset signal can also be asserted by an external push-

button, through a manual reset input. The three parts feature

different combinations of watchdog input, manual reset input,

and output stage configuration, as shown in Table 1.

These parts are available in a choice of seven reset threshold

options ranging from 2.19 V to 4.63 V. The reset and watchdog

timeout periods are fixed at 140 ms (minimum) and 1.6 sec

(typical), respectively.

The ADM823/ADM824/ADM825 are available in 5-lead SC70

and SOT-23 packages and typically consume only 5 µA, making

them suitable for use in low power, portable applications.

Table 1. Selection Table

Part No. Watchdog Timer Manual Reset

Output Stage

RESET

ADM823 Yes Yes Push-Pull –

ADM824 Yes – Push-Pull Push-Pull

ADM825 – Yes Push-Pull Push-Pull

Summary of content (12 pages)

PAGE 1
Supervisory Circuits with Watchdog and Manual Reset in 5-Lead SC70 and SOT-23 ADM823/ADM824/ADM825 Data Sheet FEATURES FUNCTIONAL BLOCK DIAGRAM Precision 2.5 V to 5 V power supply monitor 7 reset threshold options: 2.19 V to 4.63 V 140 ms (minimum) reset timeout Watchdog timer with 1.
PAGE 2
ADM823/ADM824/ADM825 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Reset Output ..................................................................................9 Applications ....................................................................................... 1 Manual Reset Input .......................................................................9 Functional Block Diagram .................................
PAGE 3
Data Sheet ADM823/ADM824/ADM825 SPECIFICATIONS VCC = 4.75 V to 5.5 V for ADM82xL, VCC = 4.5 V to 5.5 V for ADM82xM, VCC = 3.15 V to 3.6 V for ADM82xT, VCC = 3 V to 3.6 V for ADM82xS, VCC = 2.7 V to 3.6 V for ADM82xR, VCC = 2.38 V to 2.75 V for ADM82xZ, VCC = 2.25 V to 2.75 V for ADM82xY, TA = TMIN to TMAX, unless otherwise noted. Table 2. Parameter SUPPLY VCC Operating Voltage Range Min 1 1.
PAGE 4
ADM823/ADM824/ADM825 Parameter WATCHDOG INPUT (ADM823, ADM824) Watchdog Timeout Period WDI Pulse Width WDI Input Threshold, VIL WDI Input Current Data Sheet Min Typ Max Unit 1.12 50 0.7 × VCC 1.6 2.40 sec ns V µA µA −20 MANUAL RESET INPUT (ADM823, ADM825) MR Input Threshold MR Input Pulse Width MR Glitch Rejection MR Pull-Up Resistance MR to Reset Delay 120 −15 0.7 × VCC 1 35 0.3 × VCC 160 0.3 × VCC 100 52 500 75 Rev. D | Page 4 of 12 V µs ns kΩ ns Test Conditions/Comments VIL = 0.
PAGE 5
Data Sheet ADM823/ADM824/ADM825 ABSOLUTE MAXIMUM RATINGS TA = 25°C, unless otherwise noted. Table 3. Parameter VCC Output Current (RESET, RESET) All Other Pins Operating Temperature Range Storage Temperature Range θJA Thermal Impedance SC70 SOT-23 Lead Temperature Soldering (10 sec) Vapor Phase (60 sec) Infrared (15 sec) Rating −0.3 V to +6 V 20 mA −0.3 V to (VCC + 0.3 V) −40°C to +125°C −65°C to +150°C Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device.
PAGE 6
ADM823/ADM824/ADM825 Data Sheet PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS RESET 1 VCC GND 2 TOP VIEW (Not to Scale) MR 3 4 WDI 04534-002 GND 2 5 RESET 1 VCC ADM824 Figure 2. ADM823 Pin Configuration GND 2 TOP VIEW (Not to Scale) RESET 3 5 VCC 4 MR ADM825 4 WDI Figure 3. ADM824 Pin Configuration RESET 3 TOP VIEW (Not to Scale) 04534-004 5 ADM823 04534-003 RESET 1 Figure 4. ADM825 Pin Configuration Table 4. Pin Function Descriptions Pin No.
PAGE 7
Data Sheet ADM823/ADM824/ADM825 TYPICAL PERFORMANCE CHARACTERISTICS 100 10.0 9.5 90 9.0 80 VCC TO RESET DELAY (µs) 8.5 ADM823L 8.0 ICC (µA) 7.5 7.0 6.5 6.0 ADM824Y 5.5 5.0 70 60 50 40 30 20 4.5 ADM825R –20 0 10 20 40 60 TEMPERATURE (°C) 80 120 100 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10 5 0 0 60 20 40 TEMPERATURE (°C) 80 100 120 1.0 1.5 2.0 2.5 3.0 VCC (V) 3.5 4.0 4.5 5.0 5.5 Figure 6. Supply Current vs.
PAGE 8
Data Sheet 2.0 190 1.8 180 1.6 MR MINIMUM PULSE WIDTH (ns) 1.4 1.2 1.0 0.8 0.6 0.4 150 140 130 120 0 40 60 20 TEMPERATURE (°C) 80 100 120 100 –50 Figure 11. Watchdog Timeout Period vs. Temperature (ADM823/ADM824) 160 0 50 TEMPERATURE (°C) 04534-013 –20 04534-011 0 –40 100 Figure 13. Manual Reset Minimum Pulse Width vs. Temperature (ADM823/ADM825) 3.8 RESET OCCURS ABOVE GRAPH 3.6 140 MINIMUM PULSE WIDTH (ns) 120 100 VTH = 4.63V 80 60 40 20 3.4 NEGATIVE PULSE 3.2 3.0 2.8 2.6 2.
PAGE 9
Data Sheet ADM823/ADM824/ADM825 CIRCUIT DESCRIPTION The ADM823/ADM824/ADM825 provide microprocessor supply voltage supervision by controlling the reset input of the microprocessor. Code execution errors are avoided during power-up, power-down, and brownout conditions by asserting a reset signal when the supply voltage is below a preset threshold. Errors are also avoided by allowing supply voltage stabilization with a fixed timeout reset pulse after the supply voltage rises above the threshold.
PAGE 10
ADM823/ADM824/ADM825 Data Sheet APPLICATIONS INFORMATION WATCHDOG INPUT CURRENT WATCHDOG SOFTWARE CONSIDERATIONS To minimize the watchdog input current (and minimize overall power consumption), leave WDI low for the majority of the watchdog timeout period. When driven high, WDI can draw as much as 160 µA. Pulsing WDI low-high-low at a low duty cycle reduces the effect of the large input current.
PAGE 11
Data Sheet ADM823/ADM824/ADM825 OUTLINE DIMENSIONS 2.20 2.00 1.80 1.35 1.25 1.15 2.40 2.10 1.80 4 5 1 3 2 0.65 BSC 0.40 0.10 1.10 0.80 0.10 MAX COPLANARITY 0.10 SEATING PLANE 0.30 0.15 0.46 0.36 0.26 0.22 0.08 072809-A 1.00 0.90 0.70 COMPLIANT TO JEDEC STANDARDS MO-203-AA Figure 20. 5-Lead Thin Shrink Small Outline Transistor Package [SC70] (KS-5) Dimensions shown in millimeters 3.00 2.90 2.80 5 1.70 1.60 1.50 1 4 2 3.00 2.80 2.60 3 0.95 BSC 1.90 BSC 1.45 MAX 0.95 MIN 0.15 MAX 0.
PAGE 12
ADM823/ADM824/ADM825 Model 1 ADM823RYRJZ-R7 ADM823ZYKSZ-R7 ADM823YYKSZ-R7 ADM824LYRJZ-REEL7 ADM824SYKSZ-REEL7 ADM824RYKSZ-REEL7 ADM824SYRJZ-REEL7 ADM825LYRJ-R7 ADM825LYRJZ-R7 ADM825MYRJ-R7 ADM825TYKSZ-R7 ADM825TYRJ-R7 ADM825TYRJZ-R7 ADM825SYKSZ-R7 ADM825SYRJ-R7 ADM825SYRJZ-R7 ADM825RYRJ-R7 ADM825RYRJZ-R7 ADM825ZYKSZ-R7 1 Reset Threshold (V) 2.63 2.32 2.19 4.63 2.93 2.63 2.93 4.63 4.63 4.38 3.08 3.08 3.08 2.93 2.93 2.93 2.63 2.63 2.