rev. 0 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. a microprocessor supervisory circuits adm698/ADM699 one technology way, p.o. box 9106, norwood, ma 02062-9106, u.s.a. tel: 617/329-4700 fax: 617/326-8703 functional block diagram reset generator 4.65v v cc watchdog input wdi * adm698/ ADM699 reset watchdog output wdo * reset * * wdi (ADM699 only) reset (soic only) wdo (ADM699 soic only) watchdog transition detector (1 sec) typical application circuit * ADM699 only +5v v cc wdi * gnd adm698/ ADM699 reset ? power ? system i/o line ? reset features superior up grade for max698/max699 guaranteed reset assertion with v cc = 1 v low 0.6 ma supply current precision 4.65 v voltage monitor power ok/reset time delay watchdog timer minimum component count performance specified over temperature applications microprocessor systems computers controllers intelligent instruments automotive systems critical m p power monitoring general description the adm698/ADM699 supervisory circuits provide power supply monitoring and watchdog timing for microprocessor systems. the adm698 monitors the 5 v v cc power supply and gener- ates a reset pulse during power up, power down and during low voltage brown out conditions. the reset output is guaranteed to be functional (logic low) with v cc as low as 1 v. the ADM699 features an identical monitoring circuit as in the adm698 plus an additional watchdog timer input to monitor microprocessor activity. the reset output is forced low if the watchdog input is not toggled within the 1 second watchdog timeout period. both parts are available in 8-pin plastic dip and 16-lead soic packages. the 16-lead soic contains additional outputs reset (without inversion) and watchdog output wdo (ADM699 only).
adm698/ADM699Cspecifications parameter min typ max units test conditions/comments v cc operating voltage range 3.0 5.5 v supply current 0.6 1.95 ma power-down reset assertion 4.5 4.65 4.73 v power-up reset deassertion 4.73 v reset threshold hysteresis 40 mv reset active time 140 200 280 ms t a = +25 c, v cc = +5 v watchdog timeout period (ADM699) 1.0 1.6 2.25 s t a = +25 c, v cc = +5 v minimum wdi input pulse width 50 ns v il = 0.4, v ih = 3.5 v reset output voltage 0.4 v i sink = 1.6 ma, vcc = 4.4 v reset output voltage (v cc = 1 v) 4 200 mv i sink = 10 m a, v cc = 1.0 v 3.5 v i source = 1 m a, v cc = 5 v reset and wdo output voltage 0.4 v i sink = 1.6 ma, v cc = 5 v 3.5 v i source = 1 m a, v cc = 4.4 v reset output short circuit current 25 ma output sink current wdi input threshold (ADM699) logic low 0.8 v logic high 3.5 v wdi input current 20 50 m a wdi = v cc , t a = +25 c C50 C20 m a wdi = 0 v, t a = +25 c specifications subject to change without notice. rev. 0 C2C (v cc = +5 v 6 10%, t a = t min to t max unless otherwise noted) ordering guide temperature package model range option adm698an C40 c to +85 c n-8 adm698ar C40 c to +85 c r-16 adm698aq C40 c to +85 c q-8 adm698sq C55 c to +125 c q-8 ADM699an C40 c to +85 c n-8 ADM699ar C40 c to +85 c r-16 ADM699aq C40 c to +85 c q-8 ADM699sq C55 c to +125 c q-8 warning! esd sensitive device 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 adm698/ADM699 features 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* (t a = +25 c unless otherwise noted) v cc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C0.3 v to +6 v all other inputs . . . . . . . . . . . . . . . . . . . C0.3 v to v cc + 0.3 v power dissipation 8-pin dip . . . . . . . . . . . . . . . . . . . . 500 mw q ja , thermal impedance . . . . . . . . . . . . . . . . . . . . +120 c/w power dissipation 16-pin soic . . . . . . . . . . . . . . . . . 375 mw q ja , thermal impedance . . . . . . . . . . . . . . . . . . . . +110 c/w power dissipation 8-pin cerdip . . . . . . . . . . . . . . . . . . 500 mw q ja , thermal impedance . . . . . . . . . . . . . . . . . . . . +125 c/w operating temperature range industrial (a version) . . . . . . . . . . . . . . . . . C40 c to +85 c extended (s version) . . . . . . . . . . . . . . . . . C55 c to +125 c storage temperature range . . . . . . . . . . . . . C65 c to +150 c lead temperature (soldering, 10 secs) . . . . . . . . . . . . +300 c vapor phase (60 secs) . . . . . . . . . . . . . . . . . . . . . . . +215 c infrared (15 secs) . . . . . . . . . . . . . . . . . . . . . . . . . . . +220 c *stresses above those listed under absolute maximum ratings may cause perma- nent damage to the device. this is a stress rating only and functional operation of the device at these or any other conditions above those listed in the operational sections of this specification is not implied. exposure to absolute maximum ratings for extended periods of time may affect device reliability.
adm698/ADM699 rev. 0 C3C pin function description mnemonic function v cc +5 v power supply input. gnd 0 v. ground reference for all signals. reset logic output. reset goes low whenever v cc falls below the reset voltage threshold (4.65 v typ). reset remains low for a minimum of 140 ms after v cc returns to 5 v. reset also goes low for a minimum of 140 ms if the watchdog timer is enabled but not serviced within its time- out period. wdi watchdog input. wdi is a three level input. if wdi remains either high or low for longer than the watchdog timeout period, reset pulses low and wdo goes low. the timer resets with each transition on the wdi line. the watchdog timer may be disabled if wdi is left floating or is driven to midsupply. reset (soic packages only) logic output. reset is an active high output. it is the inverse of reset . wdo (soic ADM699 only) logic output. the watchdog output, wdo , goes low if wdi remains either high or low for longer than the watchdog timeout period. wdo is set high by the next transition at wdi. if wdi is unconnected or at midsupply, the watchdog timer is disabled and wdo remains high. pin configuration (dip) 1 2 3 4 8 7 6 5 top view (not to scale) o top view (not to scale) adm698/ ADM699 v cc v cc gnd gnd gnd nc (wdi) * nc * ( ) ADM699 only reset pin configuration (soic) 1 2 3 4 16 15 14 13 top view (not to scale) o 5 12 6 11 710 89 top view (not to scale) adm698/ ADM699 gnd v cc v cc gnd nc nc nc nc reset nc nc nc (wdi) * nc gnd reset nc (wdo) * *( ) ADM699 only typical performance curves 4.70 4.68 4.66 4.64 4.62 20 40 60 80 100 120 power up power down v cc = +5v temperature ? c reset voltage threshold ?v figure 3. reset voltage threshold vs. temperature 215 210 205 200 195 20 40 60 80 100 120 temperature ? c reset active time ?ms v cc = +5v figure 2. reset active time vs. temperature 10 90 100 0% 1v a4 500ms 3.36 v 1v aaa a a a a aaa a a aaa aaa a aaa aaa figure 1. reset output voltage vs. v cc
adm698/ADM699 rev. 0 C4C c1784C18C4/93 printed in u.s.a. circuit information power fail reset a precision voltage detector monitors v cc and generates a r eset output to hold the microprocessors reset line low when v cc falls below the reset threshold (4.65 v) (see figure 4). the reset voltage threshold is set to accommodate a 5% variation on v cc . the voltage detector has 40 mv hysteresis to ensure that glitches on v cc do not activate the reset output. on power up, an internal monostable holds reset low for 140 ms after v cc rises above the reset threshold. this allows the power supply to stabilize on power up and also prevents re- peated toggling of reset even if the 5 v power drops out and recovers with each power line cycle. in order to prevent mistriggering due to transient voltage spikes, it is recommended that a 0.1 m f capacitor be connected at the v cc pin. the reset output is guaranteed to remain low with v cc as low as 1 v. this holds the microprocessor in a stable shutdown condition as the power supply comes up. on the 16-lead soic package, an active high reset output is also provided. this is the complement of reset and is in- tended for microprocessors requiring an active high signal. v 2 v 2 v 1 v 1 v cc reset v 1 = reset voltage threshold v 2 = reset voltage threshold + threshold hysteresis t 1 = reset time t 1 t 1 figure 4. watchdog timeout period vs. temperature watchdog timer (ADM699 only) the watchdog timer input (wdi) monitors an i/o line from the m p system. the m p must toggle this input once every 1.6 sec- onds to verify correct software execution. failure to toggle the line indicates that the m p system is not correctly executing its program and may be tied up in an endless loop. if this happens, a reset pulse is generated to initialize the processor. the wdi input is a three level input and will recognize a low to- high or a high-to-low transition on its input. the watchdog timer is reset by each wdi transition and then begins its timeout period. if the wdi pin remains either high or low, reset pulses will be issued every 1.6 seconds typically. if the watch- dog timer is not needed, the wdi input should be left floating. the watchdog output ( wdo ) (soic package only) provides watchdog status information. it is driven low if wdi is not toggled within the watchdog timeout period. it goes high at the next wdi transition. it is also set high when v cc falls below the reset threshold. t 1 = reset time t 2 = watchdog time out period t 1 t 1 wdi reset t 1 wdo t 2 t 2 figure 5. wat chdog timeout period and reset active time outline dimensions dimensions shown in inches and (mm). 8-pin cerdip (q-8) pin 1 0.420 (10.67) max 0.060 (1.52) 0.015 (0.38) 0.150 (3.81) min 0.310 (7.87) 0.220 (5.59) 0.200 (5.08) max plane seating 0.070 (1.78) 0.30 (0.76) 0.100 (2.54) bsc 0.022 (0.558) 0.014 (0.356) 1 4 5 8 0.015 (0.381) 0.008 (0.204) 0.320 (8.13) 0.290 (7.37) 16-lead soic (r-16) 0.019 (0.49) 0.05 (1.27) ref 0.104 (2.65) 0.012 (0.3) 0.413 (10.50) 0.419 (10.65) 0.299 (7.60) 1 8 9 16 0.042 (1.07) 0.013 (0.32) 0.030 (0.75) 8-pin plastic dip (n-8)
|
