supply voltage monitor issue 2 ? january 2003 ZSM380 device description the ZSM380 is a three terminal under voltage monitor circuit for use in microprocessor systems. the threshold voltage of the device has been set to 3.8 volts making it ideal for 5 volt circuits. included in the device is a precise voltage reference and a comparator with built in hysteresis to prevent erratic operation. the ZSM380 features an open collector output capable of sinking at least l0ma which only requires a single external resistor to interface to following circuits. operation of the device is guaranteed from one volt upwards, from this level to the device threshold voltage the output is held low providing a power on reset function. should the supply voltage, once established, at any time drop below the threshold level then the output again will pull low. the device is available in a to92 package for through hole applications as well as sot223 for surface mount requirements. features ? sot223 and to92 packages ? power on reset generator ? automatic reset generation ? low standby current ? guaranteed operation from 1 volt ? wide supply voltage range ? internal clamp diode to discharge delay capacitor ? 3.8 volt threshold for 5 volt logic ? 20mv hysteresis prevents erratic operation applications ? microprocessor systems ? computers ? computer peripherals ? instrumentation ? automotive ? battery powered equipment schematic diagram 4-349
test conditions (t amb =25 c for typical values, t amb =-40 to 85 c for min/max values (note3)) comparator parameter symbol min typ. max. units threshold voltage high state output (v cc increasing) v ih 3.7 3.81 3.9 v threshold voltage low state output (v cc decreasing) v il 3.7 3.79 3.9 v hysteresis v h 0.01 0.02 0.05 v ouput output sink saturation: v ol (v cc =3.3v, i sink =8.0ma) 0.46 1.0 v (v cc =3.3v, i sink =2.0ma) 0.15 0.4 v (v cc =1.0v, i sink =0.1ma) 0.25 v onstate output sink current (v cc , output=3.3v) i sink 10 27 60 ma offstate output leakage current (v cc , output=5v) i oh 0.02 0.5 a clamp diode forward voltage (i f =10ma) v f 0.61.21.5v propagation delay (v in 5v to 3.3v, r l =10k, t amb =25c) t d 3 s total device operating input voltage range v cc 1.0 to 6.5 v quiescent input current (v cc =5v) i q 140 200 a note: 1. maximum package power dissipation must be observed. 2. maximum power dissipation for the sot223 package is calculated assuming that the device is mounted on a pcb measuring 2 inches square. 3. low duty cycle pulse techniques are used during test to maintain junction temperatures as close to ambient as possible. ZSM380 absolute maximum rating input supply voltage -1 to 10v offstate output voltage 10v onstate output sink current( note 1 ) internally limited clamp diode forward current( note 1 )100ma operating junction temperature 150 c operating temperature -40 to 85 c storage temperature -55 to 150 c power dissipation to92 780mw sot223 2w( note 2 ) 4-350
ZSM380 02 00.81.62.0 0.4 1.2 0 20 40 50 sink current (ma) 46810 2 4 6 8 10 0 output voltage (v) forward voltage (v) forward current (ma) input current ( a) input voltage (v) input current vs. input voltage output voltage vs. input voltage output i(sink) vs. output v(sat) clamp diode i(forward) vs. voltage input voltage (v) output saturation voltage (v) 30 10 200 0 100 300 400 500 0246810 20 0 10 30 40 50 0 0.4 0.8 1.2 1.6 2.0 85 c 25 c -40 c 85 c 25 c -40 c v in =0v t a =25 c r l =10k v in =3.3v 25 c -40 c 85 c threshold voltage (v) 3.77 3.78 3.79 3.81 3.80 3.82 threshold voltage vs. temperature -40 temperature ( c) -20 0 20 40 60 upper threshold 80 100 lower threshold v out (v) 0 2 4 3.3 5 r l =10k reset delay time 0 time ( s) 24 6 v in (v) typical characteristics 4-351
ZSM380 vcc threshold vol t ag e 1v output undefined output undefined output note 4: a time delayed reset can be accomplished with the additional cd. t dy = rcd ln 1 1 ? v th ( mpu ) v in timing diagram application circuit t dy =time (seconds) v th =microprocessor reset threshold v in =power supply voltage 4-352
sot223 package suffix ? g top view ? pin 4 floating or connected to pin 2 connection diagrams ordering information part number package part mark ZSM380g sot223 ZSM380 ZSM380c to92 ZSM380 to92 package suffix ? c bottom view ZSM380 4-353
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