functional block diagram v cc reset adm709 v th reset generator gnd reset adm709 gnd gnd ? reset v cc v cc typical operating circuit ordering guide reset temperature package model threshold range option* adm709lan 4.65 v C40 c to +85 c n-8 adm709lar 4.65 v C40 c to +85 c so-8 adm709man 4.40 v C40 c to +85 c n-8 adm709mar 4.40 v C40 c to +85 c so-8 adm709tan 3.08 v C40 c to +85 c n-8 adm709tar 3.08 v C40 c to +85 c so-8 ADM709SAN 2.93 v C40 c to +85 c n-8 adm709sar 2.93 v C40 c to +85 c so-8 adm709ran 2.63 v C40 c to +85 c n-8 adm709rar 2.63 v C40 c to +85 c so-8 *n = plastic dip; so = soic. 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 power supply monitor with reset adm709 ? analog devices, inc., 1995 one technology way, p.o. box 9106, norwood. ma 02062-9106, u.s.a. tel: 617/329-4700 fax: 617/326-8703 general description the adm709 contains a power supply monitor which generates a system reset during power-up, power-down and brownout conditions. when v cc falls below the reset threshold, reset goes low and holds the m p in reset. on power-up the reset output is held low for 140 ms after v cc rises above the thresh- old. the reset output remains operational with v cc as low as 1 v. three supply-voltage threshold levels are available suitable for +5 v, +3.3 v and for +3 v supply monitoring. the actual reset voltage threshold is given below. the adm709 is available in 8-pin dip and soic packages. table i. reset threshold suffix voltage (v) l 4.65 m 4.40 t 3.08 s 2.93 r 2.63 features precision supply voltage monitor +5 v, +3.3 v, +3 v power supply monitor 35 m a quiescent current 140 ms (min) power-on reset pulse low cost 8-pin dip/so packages upgrade for max709 applications microprocessor systems computers controllers intelligent instruments critical m p monitoring automotive systems critical m p power monitoring
rev. 0 C2C (v cc = full operating range, t a = t min to t max unless otherwise noted) absolute maximum ratings* (t a = +25 c unless otherwise noted) v cc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C0.3 v to +6 v reset output . . . . . . . . . . . . . . . . . . . C0.3 v to v cc + 0.3 v v cc input current . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 ma reset output current . . . . . . . . . . . . . . . . . . . . . . . . 20 ma power dissipation, n-8 dip . . . . . . . . . . . . . . . . . . . . 727 mw q ja thermal impedance . . . . . . . . . . . . . . . . . . . . . 135 c/w power dissipation, so-8 soic . . . . . . . . . . . . . . . . . . 470 mw q ja thermal impedance . . . . . . . . . . . . . . . . . . . . . 110 c/w operating temperature range industrial ( a version) . . . . . . . . . . . . . . . . . C40 c to +85 c lead temperature (soldering, 10 secs) . . . . . . . . . . . . +300 c vapor phase (60 secs) . . . . . . . . . . . . . . . . . . . . . . . . . +215 c infrared (15 secs) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +220 c storage temperature range . . . . . . . . . . . . . C65 c to +150 c esd rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . >5 kv * stresses above those listed under absolute maximum ratings may cause permanent 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. pin function description mnemonic pin no. function nc 1, 4, 5, 6, 8 no connect pins. v cc 2 +5 v, +3.3 v, +3 v power supply input. reset 7 logic output. it remains low while v cc is below the reset threshold voltage and for 280 ms (typ) after v cc rises above the threshold. gnd 3 ground, 0 v. adm709Cspecifications parameter min typ max units test conditions/comments v cc operating voltage range 1.0 5.5 v t a = 0 c to +70 c 1.2 5.5 v t a = C40 c to +85 c supply current 35 85 m av cc < 3.6 v, t a = 0 c to +70 c 35 110 m av cc < 3.6 v, t a = C40 c to +85 c 65 150 m av cc < 5.5 v, t a = 0 c to +70 c 65 200 m av cc < 5.5 v, t a = C40 c to +85 c reset threshold 4.5 4.65 4.75 v adm709l 4.25 4.40 4.50 v adm709m 3.00 3.08 3.15 v adm709t 2.85 2.93 3.00 v adm709s 2.55 2.63 2.70 v adm709r v cc to reset delay 20 m sv cc = reset threshold maxCmin reset active time-out period 140 280 380 ms v cc = reset threshold max, v cc rising reset output voltage 0.3 v adm709r/s/t, i sink = 1.2 ma. v cc = reset threshold min 0.4 v adm709l/m, i sink = 3.2 ma. v cc = reset threshold min 0.3 v i sink = 50 m a. v cc 3 1.0 v 0.4 v i sink = 100 m a. v cc 3 1.2 v 0.8 v cc v adm709r/s/t, i source = 500 m a, v cc 3 reset threshold max v cc C1.5 v v adm709l/m, i source = 800 m a, v cc 3 reset threshold max specifications subject to change without notice. pin configuration v cc reset 1 2 3 4 8 7 6 5 top view (not to scale) adm709 nc gnd nc nc nc nc nc = no connect
adm709 rev. 0 C3C reset at voltages < 1 v the adm709 reset output is guaranteed to operate with supply voltages as low as 1 v. if it is desired that the reset output remains low below 1 v, then a pull-down resistor should be connected between the reset output and gnd. a resistor of 100 k w is suitable. this is illustrated in figure 5. r1 reset adm709 gnd figure 5. reset valid @ v cc < 1 v glitch immunity the adm709 is immune to short transients which may occur on the v cc line. this is important so that spurious resets are not generated as a result of minor glitches on the power supply. additional glitch immunity may be obtained by connecting a capacitor (0.1 m f or greater) as close as possible to the v cc pin on the device. microprocessors with bidirectional i-o some microprocessors or microcontrollers such as the mc68hc11 have bidirectional reset lines. in order to avoid signal contention, a resistor of 4.7 k w should be connected between the adm709 reset output and the microcontroller reset line. this arrangement is shown in figure 6. reset adm709 gnd gnd ? buffered reset +5v reset v cc figure 6. interfacing to microprocessors with bidirectional reset v cc reset adm709 v th reset generator gnd figure 1. functional block diagram reset adm709 gnd gnd ? reset v cc v cc figure 2. typical operating circuit circuit information reset output reset is an active low output which provides a reset signal to the microprocessor whenever the v cc supply voltage is below the reset threshold. an internal timer holds reset low for 140 ms after the voltage on v cc rises above the threshold. this is intended as a power-on reset signal for the processor. it allows time for the power supply and microprocessor to stabilize after power up. similarly a power supply brownout will initiate a pro- cessor reset. on power-down, the reset output remains low with v cc as low as 1 v. this ensures that the microprocessor is held in a stable shutdown condition as the power supply drops. vrt vrt t rs v cc reset figure 3. power off/on reset timing v cc reset 400ms/div figure 4. reset output vs. v cc
rev. 0 C4C adm709 outline dimensions dimensions shown in inches and (mm). 8-lead plastic dip (n-8) pin 1 0.280 (7.11) 0.240 (6.10) 4 5 8 1 seating plane 0.060 (1.52) 0.015 (0.38) 0.130 (3.30) min 0.210 (5.33) max 0.160 (4.06) 0.115 (2.93) 0.430 (10.92) 0.348 (8.84) 0.022 (0.558) 0.014 (0.356) 0.070 (1.77) 0.045 (1.15) 0.100 (2.54) bsc 0.325 (8.25) 0.300 (7.62) 0.015 (0.381) 0.008 (0.204) 0.195 (4.95) 0.115 (2.93) 8-lead soic (so-8) 0.0098 (0.25) 0.0075 (0.19) 0.0500 (1.27) 0.0160 (0.41) 8 0 0.0196 (0.50) 0.0099 (0.25) x 45 pin 1 0.1574 (4.00) 0.1497 (3.80) 0.2440 (6.20) 0.2284 (5.80) 4 5 1 8 0.0192 (0.49) 0.0138 (0.35) 0.0500 (1.27) bsc 0.0688 (1.75) 0.0532 (1.35) 0.0098 (0.25) 0.0040 (0.10) 0.1968 (5.00) 0.1890 (4.80) printed in u.s.a. c2022C18C4/95
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