may 2003 1 mic8114 mic8114 micrel ordering information part number marking operating temp. range package mic8114tu nv ?0 c to +85 c 4-lead sot-143 mic8114 microprocessor reset circuit final information general description the mic8114 is an inexpensive microprocessor supervisory circuit that monitors the power supply in microprocessor based systems. the function of this device is to assert a reset if the power supply drops below a designated reset threshold level or /mr is forced low. the mic8114 has an active low /reset output. the reset output is guaranteed to remain asserted for a minimum of 790ms after v cc has risen above the designated reset threshold level. the mic1814 comes in a 4-pin sot-143 package. typical application v cc reset p reset v cc mic81 14 v cc mr features precision voltage monitor for 3.3v power supplies specifically tailored to the amd elan sc400/410 /reset remains valid with v cc as low as 1.4v <15 a supply current 1100ms minimum reset pulse width manual reset input available in 4-pin sot-143 package applications portable equipment intelligent instruments critical microprocessor power monitoring printers/computers embedded controllers micrel, inc. ?1849 fortune drive ?san jose, ca 95131 ?usa ?tel + 1 (408) 944-0800 ?fax + 1 (408) 944-0970 ?http://www.mic rel.com
mic8114 micrel mic8114 2 may 2003 pin description pin number pin name pin function 1 gnd ic ground pin 2 /reset /reset goes low if either v cc falls below the supply reset threshold voltage or if /mr is asserted. /reset remains asserted for one reset timeout period after both v cc exceeds the supply reset threshold voltage and /mr is deasserted. 3 /mr manual reset input. a logic low on /mr forces a reset. the reset will remain asserted as long as /mr is held low and for one reset timeout period after /mr goes high. this input can be shorted to ground via a switch or driven from cmos or ttl logic. pulled high internally through a 20k ? resistor. float if unused. 4v cc power supply input. pin configuration mr 1 2 4 v cc gnd mic81 14 reset 3 4-lead sot-143
may 2003 3 mic8114 mic8114 micrel electrical characteristics for typical values, v cc = 3.3v; t a = 25 c, bold values indicate ?0 c t a +85 c; unless noted symbol parameter condition min typ max units v cc operating voltage range t a = 0 c to 70 c 1.4 5.5 v t a = ?0 c to 85 c 1.6 5.5 v i cc supply current 9 15 a v th reset voltage threshold 3.00 3.08 3.15 v t rst reset timeout period 190 1200 1800 ms v oh /reset output voltage i source = 500 a 0.8 v cc v v ol /reset output voltage, v ol v cc = v th min, i sink = 1.2ma 0.3 v v cc = 1.4v, i sink = 50 a, t a = 0 c to 70 c 0.3 v v cc = 1.6v, i sink = 50 a, t a = ?0 c to +85 c 0.3 v /mr minimum pulse width 10 s /mr to reset delay 0.5 s /mr input threshold, v ih 0.7 v cc v /mr input threshold, v il 0.25 v cc /mr pull-up resistance 10 20 30 k ? /mr glitch immunity 100 ns note 1. exceeding the absolute maximum rating may damage the device. note 2. the device is not guaranteed to function outside its operating rating. note 3. devices are esd sensitive. handling precautions recommended. human body model, 1.5k in series with 100pf. absolute maximum ratings (note 1) terminal voltage (v cc ) ....................................................... ?.3v to +6.0v (/mr) ................................................ ?.3v (v cc + 0.3v) input current (v cc , /mr) ............................................ 20ma output current (/reset) ........................................... 20ma rate of rise (v cc ) ................................................ 100v/ s lead temperature (soldering, 10 sec.) ..................... 300 c storage temperature (t s ) ....................... ?5 c to +150 c operating ratings (note 2) operating temperature range mic8114tu ............................................ ?0 c to +85 c power dissipation (t a = +70 c) .............................. 320mw timing diagram v cc /mr / reset t rst t rst v th reset timing diagram
mic8114 micrel mic8114 4 may 2003 functional diagram + - reset threshold (v) v cc (4) reset (2) gnd (1) reset generator mr (3) v cc
may 2003 5 mic8114 mic8114 micrel applications information microprocessor reset the /reset pin is asserted whenever v cc falls below the reset threshold voltage. the reset pin remains asserted for a period of 790ms after v cc has risen above the reset threshold voltage. the reset function ensures the microprocessor is properly reset and powers up into a known condition after a power failure. /reset will remain valid with v cc as low as 1.4v. v cc transients the mic1815 is relatively immune to the negative-going v cc glitches below the reset threshold. typically, a negative- going transient 125mv belt the reset threshold with a duration of 50 s or less will not cause a reset. /reset valid at low voltage a resistor can be added from the /reset pin to ground to ensure the /reset output remains low with v cc down to 0v. a 100k ? resistor connected from /reset to ground is recommended. the resistor should be large enough not to load the /reset output and small enough to pull-down any stray leakage currents v cc reset p reset v cc mic81 14 v cc 100k /reset valid to v cc = 0v
mic8114 micrel mic8114 6 may 2003 package information 0.150 (0.0059) 0.089 (0.0035) 8 0 0.400 (0.016) typ 3 places 2.50 (0.098) 2.10 (0.083) 1.40 (0.055) 1.20 (0.047) 0.950 (0.0374) typ 3.05 (0.120) 2.67 (0.105) 0.800 (0.031) typ 1.12 (0.044) 0.81 (0.032) 0.10 (0.004) 0.013 (0.0005) dimensions: mm (inch) 0.41 (0.016) 0.13 (0.005) c l c l 4-lead sot-143 (ut) micrel, inc. 1849 fortune drive san jose, ca 95131 usa tel + 1 (408) 944-0800 fax + 1 (408) 944-0970 web http://www.micrel.com the information furnished by micrel in this datasheet is believed to be accurate and reliable. however, no responsibility is as sumed by micrel for its use. micrel reserves the right to change circuitry and specifications at any time without notification to the customer. micrel products are not designed or authorized for use as components in life support appliances, devices or systems where malfu nction of a product can reasonably be expected to result in personal injury. life support devices or systems are devices or systems that (a) are intend ed for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant inj ury to the user. a purchaser s use or sale of micrel products for use in life support appliances, devices or systems is at purchaser s own risk and purchaser agrees to fully indemnify micrel for any damages resulting from such use or sale. ? 2003 micrel, incorporated.
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