rev. c 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 that may result from its use. no license is granted by implication or otherwise under any patent or patent rights of analog devices. trademarks and registered trademarks are the property of their respective companies. one technology way, p.o. box 9106, norwood, ma 02062-9106, u.s.a. tel: 781/329-4700 www.analog.com fax: 781/326-8703 ? 2003 analog devices, inc. all rights reserved. adm811/adm812 microprocessor supervisory circuit in 4-lead sot-143 features superior upgrade for max811/max812 specified over temperature low power consumption (5 a typ) precision voltage monitor: 2.5 v, 3 v, 3.3 v, 5 v options reset assertion down to 1 v v cc 140 ms min power-on reset logic low reset output (adm811) logic high reset output (adm812) built-in manual reset applications microprocessor systems controllers intelligent instruments automotive systems safety systems portable instruments functional block diagram debounce reset /reset gnd v cc v ref adm811/adm812 reset generator mr general description the adm811/adm812 is a reliable voltage monitoring device suitable for use in most voltage monitoring applications. the adm811/adm812 is designed to monitor six different voltages, each allowing for a 5% or 10% degradation of standard psu voltages before a reset occurs. these voltages have been selected for the effective monitoring of 2.5 v, 3 v, 3.3 v, and 5 v supply vo lt age levels. included in this circuit is a debounced manual reset input. reset can be activated using an electrical switch (or an input from another digital device) or by a degradation of the supply voltage. the manual reset function is very useful, especially if the circuit in which the adm811/adm812 is operating enters into a state that can only be detected by the user. allowing the user to reset a system manually can reduce the damage or danger that could otherwise be caused by an out-of-control or locked system. v cc reset reset adm811 v cc mr gnd gnd microprocessor system 100k figure 1. typical adm811 operating circuit
rev. c e2e adm811/adm812especifications parameter min typ max unit test conditions/comments supply voltage 1.0 5.5 v t a = 0 reset e reset ? v cc vv cc > v th(max) , adm81_r/s/t/z an input falling below 0.25 v cc vv cc > v th(max) , adm81_r/s/t/z reset/ reset mrst tm s mm tm s mrstm v cc v 1.8 v < v cc < v th(min) , i source = 150 v cc vv cc > v th(max) , i source = 500
rev. c adm811/adm812 e3e caution esd (electrostatic discharge) sensitive device. electrostatic charges as high as 4000 v readily accumulate on the human body and test equipment and can discharge without detection. although the adm811/adm812 feature proprietary esd protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. therefore, proper esd precautions are recommended to avoid performance degradation or loss of functionality. absolute maximum ratings * (typical values are at t a = 25 mr reset t
rev. c adm811/adm812 e4e pin configuration 1 2 top view (not to scale) 4 3 gnd adm811/ adm812 reset /reset v cc mr pin function descriptions pin mnemonic function 1g nd 0 v. ground reference for all signals. 2 reset m reset mr reset mt resetm reset mr reset mr mrt
rev. c t ypical performance characteristics?adm811/adm812 e5e temperature e c 12 e40 10 8 6 4 2 0 e20 0 20 30 50 70 85 100 120 i dd e a i dd @ v cc = 5.5v i dd @ v cc = 3v i dd @ v cc = 1v tpc 1. supply current vs. temperature (adm81_r/s/t/z) 1000 power-down reset delay e s v od = 20mv v od = 200mv v od = 125mv 900 800 700 600 500 400 300 200 100 0 temperature e c e40 e20 0 20 30 50 70 85 100 120 tpc 2. power-down reset t rst erresettet rst teertre t rtt teertre t st er reset e teertre t reset t reresettres teertre t rtt
rev. c adm811/adm812 e6e circuit information reset thresholds a reset output is provided to the microprocessor whenever the v cc input is below the reset threshold. the actual reset thresh- old is dependent on whether an l, m, t, s, r, or z suffix is used. refer to table i. table i. reset threshold options reset model threshold (v) adm811lart 4.63 adm811mart 4.38 adm811tart 3.08 adm811-3tart 3.08 adm811sart 2.93 adm811rart 2.63 adm811zart 2.32 adm812lart 4.63 adm812mart 4.38 adm812tart 3.08 adm812sart 2.93 adm812rart 2.63 adm812zart 2.32 reset output on power-up and after v cc rises above the reset threshold, an internal timer holds the reset output active for 240 ms (typical). this is intended as a power-on reset signal for the processor. it allows time for both the power supply and the microprocessor to stabilize after power-up. if a power supply brownout or inter- ruption occurs, the reset output is similarly activated and remains active for 240 ms (typical) after the supply recovers. this allows time for the power supply and microprocessor to stabilize. the adm811 provides an active low reset output ( reset mreset m reset t mreset tmm t t t reset t tertterees t t eetserrteresettres reset e reset esrresettt t reset tms reset t ? reset
rev. c adm811/adm812 ? outline dimensions 4-lead small outline transistor package [sot-143] (rt-4) dimensions shown in millimeters 0.89 0.76 seating plane 0.45 0.30 0.15 0.05 3.04 2.80 1.22 0.80 pin 1 1.92 bsc 1 2 3 4 1.40 1.20 2.64 2.10 8 0 0.60 0.40 0.20 0.08 compliant to jedec standards to-253d 0.20 bsc
rev. c c00092e0e2/03(c) printed in u.s.a. e8e adm811/adm812 revision history location page 2/03
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