ver: 1.1 jun 07, 2002 tel: 886-3-5788833 http://www.gmt.com.tw 1 g680/g681 global mixed-mode technology inc. microprocessor reset ic features ? high 2% voltage threshold accuracy ? independently adjustable high- and low- voltage thresholds ? fully specified over temperature ? available in three output configurations push-pull reset output (g680l) push-pull reset output (g680h) open-drain reset output (g681l) ? 140ms min power-on reset pulse width ? 4a supply current ? power supply transient immunity ? 5-pin sot23-5 packages applications ? computers ? controllers ? intelligent instruments ? critical p and c power monitoring ? portable / battery-powered equipment ? automotive general description the g680/g681 are microprocessor (p) supervisory circuits used to monitor the power supplies in p and digital systems. high- and low- voltage thresholds can be adjusted independently, allowing for wide hystere- sis. voltage detection thresholds are accurate to 2%. these circuits perform a single function: they assert a reset signal whenever the v cc supply voltage declines below the low-voltage threshold, keeping it asserted for at least 140ms after v cc has risen above the high-voltage threshold. the g681l has an open-drain output stage, while the g680 have push-pull outputs. the g681l?s open-drain reset output requires a pull-up resistor that can be connected to a voltage higher than v cc . the g680l have an active-low reset output, while the g680h has an active-high reset output. the reset com- parator is designed to ignore fast transients on thresh- old input. the ic?s power supply is separate from the detector inputs, allowing the g680/g681 to be powered from a down-stream supply. low supply current (4a, typical) makes the g680/g681 ideal for use in portable equipment. the g680/g681 are available in 5 pin sot 23-5 packages. ordering information part temp. range pin-package g680h(l)t1 -40c ~ +105c sot23-5 g681lt1 -40c ~ +105c sot23-5 pin configuration typical operating circuit vcc reset(reset) sot23-5 5 4 1 hth 2 3 gnd lth g680/g681 () is for g680h reset input gnd p v cc reset (reset) gnd g680/g681 v cc r pull-up v cc * *g681 only hth lth vcc reset(reset) sot23-5 5 4 1 hth 2 3 gnd lth g680/g681 () is for g680h vcc reset(reset) sot23-5 5 4 1 hth 2 3 gnd lth g680/g681 () is for g680h reset input gnd p v cc reset (reset) gnd g680/g681 v cc r pull-up v cc * *g681 only hth lth
ver: 1.1 jun 07, 2002 tel: 886-3-5788833 http://www.gmt.com.tw 2 g680/g681 global mixed-mode technology inc. absolute maximum ratings terminal voltage (with respect to gnd) v cc .???????????..?????-0.3v to +6.0v input voltage (v lth , v hth )?..???.-0.3v to (v cc + 0.3v) reset, reset (push-pull)....?......-0.3v to (v cc + 0.3v) reset (open drain)...?........?........?....-0.3v to +6.0v input current, v cc ............................??................20ma output current, reset, reset ..?.....................20ma continuous power dissipation (t a = +70c) sot23-5?????????????????.568mw operating temperature range ?....?.-40c to +105c storage temperature range..?...??.-65c to +150c lead temperature (soldering, 10s) ...?....?......+300c stresses beyond those listed under ?absolute maximum ratings? may cause permanent damage to the device. these are stress rat- ings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational se ctions of the specifications is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliab ility. electrical characteristics (v cc = full range, t a = -40c to +105c, unless otherwise noted. typical values are at t a = +25c, v cc = 3.3v (note 1) parameter symbol condition min typ max units v cc range 2.5 5.5 v supply current (sot23) i cc v cc <5.5v 4 7.5 a reset threshold v th 1.23 1.25 1.29 v reset threshold tempco 70 ppm/c v lth to reset delay (note 2) v lth = v th to v th ? 100mv 15 s v cc = 2.5v 80 250 550 reset active timeout period v cc = 5.5v 500 ms reset (reset) output current low i ol v cc = 2.5v, v reset (v reset ) = 0.5v, reset asserted or reset not asserted 8 ma reset output current high (push-pull g680) i oh v cc = 2.5v, v reset (v reset ) = 2v, reset not asserted or reset asserted. 2 ma note 1: production testing done at t a = +25c; limits over temperature guaranteed by design. note 2: reset output is for g680l/g681l; while reset output is for g680h. selector guide part / suffix output type top mark G680LT1 push-pull reset 680ax g680ht1 push-pull reset 680bx g681lt1 open-drain reset 681ax
ver: 1.1 jun 07, 2002 tel: 886-3-5788833 http://www.gmt.com.tw 3 g680/g681 global mixed-mode technology inc. timing diagram functional diagram v batt v reset v reset propagation delays not shown for clarity. v hth v lth 0v t rst t rst a v oh v ol v oh v ol v batt v reset v reset propagation delays not shown for clarity. v hth v lth 0v t rst t rst a v oh v ol v oh v ol + + high-voltage detect delay line rq sq one shot low-voltage detect + 1.24v bandgap reference gnd g680/g681 reset reset v dd lth hth + + high-voltage detect delay line rq sq one shot low-voltage detect + 1.24v bandgap reference gnd g680/g681 reset reset v dd lth hth
ver: 1.1 jun 07, 2002 tel: 886-3-5788833 http://www.gmt.com.tw 4 g680/g681 global mixed-mode technology inc. typical operating characteristics (v cc = full range, t a = -40c to +105c, unless otherwise noted. typical values are at t a = +25c, v cc = 5v for 463/438/400 versions, v cc = 3.3v for 308/293 versions, and v cc = 3v for 263 version.) power -down reset delay vs. temperature 0 10 20 30 40 50 60 70 -40-200 20406080 temperature(c) power-down reset delay( s) v od =10mv v od =v th- vlth v od =100mv v od =200mv supply current vs. temperature 0 0.5 1 1 .5 2 2.5 3 3.5 4 4.5 5 -40-200 20406080 temperature (c) supply current (ua) vcc=5v vcc=3.3v vcc=2.5v normalized reset threshold vs. temperature 0.986 0.988 0.99 0.992 0.994 0.996 0.998 1 1.002 -40-30-20-100 10202730405060708090 temperature (c) normalized reset threshold (v) reset timeout period vs. temperature 0 100 200 300 400 500 600 700 800 -40-30-20-100 102030405060708090 temperature (c) reset timeout period (ms) v cc =5.5v v cc =3v
ver: 1.1 jun 07, 2002 tel: 886-3-5788833 http://www.gmt.com.tw 5 g680/g681 global mixed-mode technology inc. pin description pin name function 1 hth high-voltage theshold (input): analog input to a comparator. when the level on this pin initially rises above v th , the delay generator cycles and the reset remains low or reset remains high for a minimum of 140ms. 2 gnd ground 3 lth low-voltage threshold (input): analog input to a comparator. this is the voltage monitor input assigned to detect a low voltage condition. when the level on this pin falls below v th , reset or reset is asserted and the condition is latched until v hth > v th . 4 reset (reset) reset (output): push-pull output. this output is asserted and latched when v lth v th . the polarity of this signal (active-high or low) is determined by the part number suffix. see ordering information. 5 v cc power supply (input): independent supply input for internal circuitry. detailed description a microprocessor?s (p?s) reset input starts the p in a known state. the g681l/g680l/g680h assert reset to prevent code-execution errors during power-up, power-down, or brownout conditions. they assert a reset signal whenever the threshold voltage declines below v th , keeping it asserted for at least 140ms after threshold voltage input has risen above the reset threshold. the g681l uses an open-drain output, and the g680l/g680h have a push-pull output stage. connect a pull-up resistor on the g681l?s reset out- put to any supply between 0 and 5.5v. battery voltage is monitored by a comparator via a voltage divider network. the divided voltage is com- pared to an internal reference voltage. when the volt- age at the lth input pin drops below the internal ref- erence voltage, the output is asserted. at this point, the voltage at hth is assumed to be below the refer- ence voltage. figure1. maximum transient duration without causing a reset pulse vs. reset com- parator overdrive applications information negative-going v cc transients in addition to issuing a reset to the p during power-up, power-down, and brownout conditions, the g681l/g680h/g680l are relatively immune to short- duration negative-going v lth transients (glitches). figure1. shows typical transient duration vs. reset comparator overdrive, for which the g681l/g680h/ g680l do not generate a reset pulse. the graph was generated using a negative-going pulse applied to v lth , starting 0.1v above the actual reset threshold and ending below it by the magnitude indicated (reset comparator overdrive). the graph indicates the maxi- mum pulse width a negative-going v lth transient can have without causing a reset pulse. as the magnitude of the transient increases (goes farther below the reset threshold), the maximum allowable pulse width de- creases. typically, a v lth transient that goes 100mv below the reset threshold and lasts 7s or less will not cause a reset pulse. a 0.1f bypass capacitor mounted as close as possible to the v lth pin provides additional transient immunity. programming the thresholds the low-voltage threshold is calculated using: r1+r2+r3 v bat (io) = v ref r2+r3 the low-voltage threshold is calculated using: r1+r2+r3 v bat (hi) = v ref r3 where, for both equations: v bat (hi) = 1.245v in order to provide the additional criteria needed to solve for the resistor values, the resistors can be se- lected such that they have a given total value, that is, r1 + r2 + r3 = r total . 0 50 100 150 200 250 300 350 1 10 100 1000 reset comparator overdrive, v th - v lth (mv) maximum transient duration (us) g680
ver: 1.1 jun 07, 2002 tel: 886-3-5788833 http://www.gmt.com.tw 6 g680/g681 global mixed-mode technology inc. a value such as 1m ? for r total is a reasonable value because it draws minimum battery current but has no measurable effect on accuracy. when working with large resistors, a small amount of leakage current can cause voltage offsets that degrade system accuracy. the maximum recommended total resistance from v bat to ground is 3m ? . figure 2. example circuit once the desired trip points are determined, set the v bat(hi) threshold first. for example, use a total of 1m = r1 + r2 + r3. for a typical single-cell lithium ion battery, 3.6v is a good ?high threshold? because at 3.6v the battery is moder- ately charged. solving for r3: 1m ? v bat (hi) = 1.245 r3 r3 = 344k ? once r3 is determined, the equation for v bat (lo) can be used to determine r2. a single lithium-ion cell should not be discharged below 2.5v. many applica- tions limit the drain to 3.1v. using 3.1v for the v bat (lo) threshold allows calculation of the two remaining re- sistor values. 1m ? v bat (lo) =3.1v = 1.245 r2+344k r2 = 56k ? r1 = 1m ? - r2 - r3 r 1=600k ? the accuracy of the resistors can be chosen based upon the accuracy required by the system. figure 3. interfacing to ps with bidirectional re set i/o interfacing to ps with bidirectional reset pins since the reset output on the g681l is open drain, this device interfaces easily with ps that have bidi- rectional reset pins, such as the motorola 68hc11. connecting the p supervisor?s reset output di- rectly to the microcontroller?s (c?s) reset pin with a single pull-up resistor allows either device to assert reset (figure 3). . v batt vcc lth hth reset reset r1 r2 r3 604k 1% 56k 1% 340k 1% g680/g681 v batt vcc lth hth reset reset r1 r2 r3 604k 1% 56k 1% 340k 1% g680/g681 reset input gnd p v cc reset gnd g681 v cc v cc motorola 68hcxx r pull-up reset input gnd p v cc reset gnd g681 v cc v cc motorola 68hcxx r pull-up
ver: 1.1 jun 07, 2002 tel: 886-3-5788833 http://www.gmt.com.tw 7 g680/g681 global mixed-mode technology inc. package information note: 1. package body sizes exclude mold flash protrusions or gate burrs 2. tolerance 0.1000 mm (4mil) unless otherwise specified 3. coplanarity: 0.1000mm 4. dimension l is measured in gage plane dimensions in millimeters symbols min nom max a 1.00 1.10 1.30 a1 0.00 ----- 0.10 a2 0.70 0.80 0.90 b 0.35 0.40 0.50 c 0.10 0.15 0.25 d 2.70 2.90 3.10 e 1.40 1.60 1.80 e ----- 1.90(typ) ----- e1 ----- 0.95 ----- h 2.60 2.80 3.00 l 0.37 ------ ----- 1 1o 5o 9o taping specification gmt inc. does not assume any res ponsibility for use of any circuitry described, no circuit patent licenses are implied and gmt inc. reserves the right at any t ime without notice to change said circuitry and specifications. e e d h 1 l c b a2 a1 a e1 e e d h 1 l c b a2 a1 a e1 feed direction sot23-5 package orientation feed direction sot23-5 package orientation
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