mic2785 dual supply voltage monitor with manual reset micro leadframe and mlf are registered trademark of amkor technology, inc. micrel inc. ? 2180 fortune drive ? san jose, ca 95131 ? usa ? tel +1 ( 408 ) 944-0800 ? fax + 1 (408) 474-1000 ? http://www.micrel.com march 2009 m9999-031709-a general description the mic2785 is a micropower voltage monitor that provides under-voltage monitoring and manual reset capability in a tiny 1.2mm x 1.2mm mlf ? package. the mic2785 provides a monitored voltage input (v in ) separate from the supply input (v dd ). this insures that the reset (/rst) output maintains a valid output state when the voltage being monitored ramps up or down. the device also includes a manual reset input (/mr). the /rst output is an active low push-pull output. the under-voltage detector compares the vin pin voltage against the factory-programmed threshold of 1.62v. the reset output is asserted any time the input voltage drops below the programmed threshold voltage. a reset can be generated at any time by asserting the manual reset input, /mr. this reset output will remain active until the release of /mr. the /mr input can also be used to daisy-chain the mic2785 onto existing power monitoring circuitry or other supervisors. hysteresis is in cluded to prevent chattering due to noise. the mic2785 consumes a minimum of quiescent current, only 5a, 1.5a from the main supply pin and 3.5a from the input pin. offered in a tiny, space saving 6-pin mlf ? (1.2mm x 1.2mm), package. (rohs lead-free compliant). datasheets and support documentation can be found on micrel?s web site at: www.micrel.com. features ? no external components ? monitors input voltage for under-voltage condition ? separate inputs for suppl y (vdd) and monitor (vin) ? + 1.5% vin threshold voltage accuracy ? valid /rst state with vin down to 0.0v ? valid /rst state with vdd down to 1.20v ? factory-programmed 1.62v reference ? manual reset input (/mr) ? active low reset (/rst) output ? ultra-low input current ? 5a total (vin and vdd) ? rejects brief input transients ? -25c to 85c operating temperature range ? rohs lead-free compliant ? available in tiny 6-pin 1.2mm x 1.2mm thin mlf ? package applications ? mobile phones ? pdas ? gps receivers ___________________________________________________________________________________________________________ typical application memory or microprocessor voltage monitor
micrel, inc. mic2785 march 2009 2 m9999-031709-a ordering information (1) part number typical application voltage nominal threshold voltage package mic2785-16yft 1.8v + 10% 1.62v 6-pin (1.2mm x 1.2mm) thin mlf ? note: 1. other voltage thresholds ava ilable. contact micrel for details. pin configuration 6-pin (1.2mm x 1.2mm) thin mlf ? (fl) pin description pin number pin name pin function 1 nc not internally connected. 2 vdd analog (input): independent supp ly input for internal circuitry. 3 gnd ground. 4 vin analog (input). monitored input voltage. an under-voltage condition will trigger a reset sequence. 5 /mr digital (input): asserting this pin low in itiates an immediate and unconditional reset. assuming vin is above the threshold when /mr is released (returns high), the reset output will be de-asserted. /mr may be driven by a logic signal or a mechanical switch. /mr has an internal pull-up to vdd and may be left floating if unused. 6 /rst digital (output): asserted low whenever the vin pin voltage falls below the reference voltage or manual reset pin (/mr) is asse rted. it will remain asserted until vin voltage rises above the threshold voltage and the /mr pin is released. the maximum output voltage of the /rst pin is vi n. /rst is a push-pull output.
micrel, inc. mic2785 march 2009 3 m9999-031709-a absolute maximum ratings (1) supply voltage (v dd )........................................-0.3v to +6v monitor input (v in ) ............................................-0.3v to +6v input voltage (v /mr ) ..........................................-0.3v to +6v /rst curre nt .............................................................20ma lead temperature (solde ring, 20sec .) ....................... 260c junction temperature (t j ) .........................-40c to +125c storage temperature (t s ) ..........................-65c to +150c esd rating (3) (human body model) ............................. 1.5kv operating ratings (2) supply voltage (v dd ).................................... +1.5v to +5.5v monitor input (v in ) ......................................... ?0.3v to + v dd input voltage (v /mr ) ..................................... ?0.3v to + 5.5v ambient temperature (t a ) .......................... ?40c to +85c junction thermal resistance mlf ? ( ja ).....................................................140. 7c/w electrical characteristics (4) v dd = 3.1v; v in = v dd = 3.1v t a = 25c, bold values indicate ?40c< t a < +85c, unless noted. symbol parameter condition min typ max units i dd supply current (v dd ) v in = v th +1.6%, /mr & /rst open 1.0 a i in supply current (v in ) v in = v th +1.6%, /mr & /rst open 3.5 a v th accuracy -1.5 +1.5 % v hyst hysteresis voltage 1.5 % t prop_th propagation delay v in = v th 1 .5%, 100mv 5 25 s v ol output voltage low v in ? v th -1.5%, i sink = 100a, v dd > 1.2v 0.3 v v oh output voltage high v in > v th +1.5%, i source = 500a 0.8 * v in v /mr input v ih input high voltage v dd = 3.1v 1.7 v v il input low voltage v dd = 3.1v 0.4 v t prop_mr propagation delay v /mr < (v il ?100mv) 0.5 25 s t min minimum input pulse width v /mr < v il reset occurs 33 ns i pu internal pull-up current 100 na notes: 1. exceeding the absolute maximum rating may damage the device. 2. the device is not guaranteed to function outside its operating rating. 3. devices are esd sensitive. hand ling precautions recommended. human body model, 1.5k in series with 100pf. 4. specification for packaged product only.
micrel, inc. mic2785 march 2009 4 m9999-031709-a timing diagram
micrel, inc. mic2785 march 2009 5 m9999-031709-a functional diagram application information design and product advantages the mic2785?s tiny 1.2mm x 1.2mm thin mlf ? package combined with no external components offers several advantages compared to conventional voltage supervisors. tremendous savings are captured with decreased board size, reduced circuit complexity, and decreased bill of material (bom) cost. power supply input (vdd) the vdd pin provides a stable input power for the internal circuitry. this insure s that the reference circuitry and monitoring circuitry have a stable voltage over the entire operating voltage range. supply bypassing is not required. however, bypassing may be valuable depending on the quality of the system voltage to which the vdd pin is connected. if bypassing is added, connect the capacitor(s) as closely as possible to the vdd pin. place the lowest value capacitors closest to the vdd pin. under-voltage detector input (vin) the largest portion of the monitoring circuitry is the vin comparator. the vin pin is connected to the non- inverting terminal of the comparator. the internal reference is connected to the inverting terminal of the comparator. a reset is triggered when vin falls below v ref . the vin pin circuitry includes hysteresis to prevent /rst pin chattering due to noise. the vin pin is relatively immune to very brief negative-going transients. reset output (/rst) the /rst pin is a complementary push-pull output, which source and sink current. the reset output is asserted any time the vin pin voltage is less than the threshold voltage (v in < v th ) or the /mr pin is asserted. the /rst pin responds very quickly to reset conditions, typically asserting within 5s of v in < v th . the mic2785 securely monitors the supply voltage of critical components lik e microcontrollers and microprocessors. with the mic2785?s /rst pin connected to the p?s reset pin, the processor will be properly reset at power on and during power-down and brown-out conditions. manual reset input (/mr) the /mr pin provides the ability to initiate a reset via external logic or a manual switch. this is in addition to the mic2785?s automatic voltage monitoring function. asserting the /mr input to a logic low causes an immediate and unconditional reset. assuming the vin pin voltage is within tolerance when /mr is released (returns high), the re set output will be de-asserted. /mr is internally pulled-up to vdd and may be left floating/ open if unused.
micrel, inc. mic2785 march 2009 6 m9999-031709-a package information 6-pin (1.2mm x 1.2mm) thin mlf ? (fl) micrel, inc. 2180 fortune drive san jose, ca 95131 usa tel +1 (408) 944-0800 fax +1 (408) 474-1000 web http://www.micrel.com the information furnished by micrel in this data sheet is belie ved to be accurate and reliable. however, no responsibility is a ssumed 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 authori zed for use as components in life support app liances, devices or systems where malfu nction of a product can reasonably be expected to result in pers onal injury. life support devices or system s are devices or systems that (a) are in tended 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 significan t injury to the user. a purchaser?s use or sale of micrel produc ts for use in life support app liances, devices or systems is a purchaser?s own risk and purchaser agrees to fully indemnify micrel for any damages resulting from such use or sale. ? 2009 micrel, incorporated.
micrel, inc. mic2785 march 2009 7 m9999-031709-a revision history date edits by: revision number
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