mic5268 150ma cap cmos ldo regulator w/power good ittybitty is a trademark of micrel, inc. micrel inc. ? 2180 fortune drive ? san jose, ca 95131 ? usa ? te l +1 (408) 944-0800 ? fax + 1 (408) 474-1000 ? http://www.micre l.com september 2006 1 m9999-91506 general description the mic5268 is an efficient, precise cmos voltage regulator with power good output. the mic5268 offers better than 3% initial accuracy, and constant ground current (typically 100a) over load. the mic5268 also works with low-esr ceramic capacitors, reducing the amount of board space necessary for power applications, critical in hand-held wireless devices. key features include current limit, thermal shutdown, a push-pull output for faster transient response, and an active clamp to speed up device turnoff. available in the ittybitty? sot-23-5 pa ckage, the mic5268 is a fixed 1.2v regulator. data sheets and support doc umentation can be found on micrel?s web site at www.micrel.com. features ? power good indicator ? load independent, ultra-low ground current: 100a ? 150ma output current ? current limiting ? thermal shutdown ? tight load and line regulation ? ?zero? off-mode current ? stability with low-esr capacitors ? fast transient response ? ttl-logic-controlled enable input applications ? processor power-up sequencing ? laptop, notebook, and palmtop computers ? pcmcia v cc and v pp regulation/switching ordering information part number marking standard pb-free standard pb-free voltage junction temp. range (1) package mic5268-1.2bm5 mic5268-1.2ym5 l512 l51 2 1.2v ?40 to +125c 5-pin sot-23 note: 1. other voltage available. c ontact micrel marketing for details. typical application 15 2 34 c 47k ou t enable shutdown en v out mic5268-x.xbm5/ym5 v in pg 1.2v regulator with power good
micrel, inc. mic5268 september 2006 2 m9999-091506 pin configuration mic5268-x.x-bm5/ym5 5-pin sot-23 (m5) pin description pin number pin name pin function 1 in supply input 2 gnd ground 3 en enable/shutdown (input): cmos compatible input. logic high = enable; logic low = shutdown. do not leave open. 4 pg power good output 5 out regulator output
micrel, inc. mic5268 september 2006 3 m9999-091506 absolute maximum ratings (1) supply input voltage (v in ).................................... 0v to +7v enable input voltage (v en )..................................... 0v to v in flag output voltage (v pg ) ...................................... 0v to v in junction temperature (t j ) ....................................... +150c lead temperature (solde ring, 5sec .) ......................... 260c storage temperature (t s ) .........................?65c to +150c eds rating (3) operating ratings (2) supply voltage (v in ) ........................................ +2.7v to +6v enable input voltage (v en )..................................... 0v to v in flag output voltage (v pg ) ...................................... 0v to v in junction temperature (t j ) ........................ ?40c to +125c thermal resistance sot-23 ( ja )....................................................235 c/w electrical characteristics v in = xx; r l =xx; t a = 25c, bold values indicate ?40c< t a < +85c, unless noted. symbol parameter condition min typ max units v o output voltage accuracy i out = 100a ?3 ?4 3 4 % % ? v lnr line regulation v in = 2.7v to 6v ?0.3 0.3 %/v ? v lnr load regulation i out = 0.1ma to 150ma, note 4 3 5 % i q quiescent current v en 0.4v (shutdown) pg = nc 0.45 1 a i out = 0ma; v in = 6.0v 110 150 a i gnd ground pin current, note 5 i out = 150ma; v in = 6.0v 110 150 a i lim current limit v out = 0v 160 350 ma enable input v il enable input logic-low voltage v in = 5.5v, regulator shutdown 0.4 v v ih enable input logic-high voltage v in = 5.5v, regulator enabled 1.6 v v il 0.4v; v in = 5.5v 0.01 a i en enable input current v ih 1.6v; v in = 5.5v 0.01 a thermal protection thermal shutdown temperature 150 c thermal shutdown hysteresis 10 c power good, note 6 v pg low threshold high threshold % of v out (pg on) % of v out (pg off) 88 97 % % v ol pg output logic-low voltage i l = 10ma 250 500 mv i pg power good leakage cu rrent power good off, v pg = 5.5v 0.01 a v pg delay delay time to power good see timing diagram 1 5 ms 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. handling precautions recommended. 4. regulation is measured at constant junction temperature using lo w duty cycle pulse testing. parts are tested for load regul ation in the load range from 0.1ma to 150ma. changes in output voltage due to heating effects are covered by the thermal regulation specification. 5. ground pin current is the regulator quiescent current. the tota l current drawn from the supply is the sum of the load curre nt plus the ground pin current. 6. the power good is a function of the output voltage being 5% low and the detection of one of the following: overcurrent, ove rtemperature or dropout. see ?applications informati on? section for additional information.
micrel, inc. mic5268 september 2006 4 m9999-091506 typical characteristics
micrel, inc. mic5268 september 2006 5 m9999-091506 block diagram reference voltage en quickstart under- voltage lockout thermal sensor in fault gnd active shutdown pull up pull down overcurrent dropout detection out of regulation detection pg out current amplifier startup/ shutdown control error amplifier delay timing diagram
micrel, inc. mic5268 september 2006 6 m9999-091506 application information enable/shutdown the mic5268 comes with an active-high enable pin that allows the regulator to be disabled. forcing the enable pin low disables the regulator and sends it into a ?zero? off-mode-current state. in th is state, current consumed by the regulator goes nearly to zero. forcing the enable pin high enables the output voltage. this part is cmos and the enable pin cannot be left floating; a floating enable pin may cause an indeterminate state on the output. input capacitor an input capacitor is not required for stability. a 1f input capacitor is recommended when the bulk ac supply capacitance is more than 10 inches away from the device, or when the supply is a battery. output capacitor the mic5268 require s an output capacitor for stability. the design requires 1f or greater on the output to maintain stability. the c apacitor can be a low-esr ceramic chip capacitor. the mic5268 has been designed to work specifically with the low-cost, small chip capacitors. tantalum capacitors can also be used for improved capacitance overtemperature. the value of the capacitor can be increased without bound. x7r dielectric ceramic capacitors are recommended because of their temperatur e performance. x7r-type capacitors change capacitance by 15% over their operating temperature range and are the most stable type of ceramic capacitors. z5u and y5v dielectric capacitors change value by as much 50% and 60% respectively over their operating temperature ranges. to use a ceramic chip capacitor withy5v dielectric, the value must be much higher than an x7rceramic or a tantalum capacitor to ensure the same minimum capacitance value over the operating temperature range. tantalum capacitors have a ve ry stable dielectric (10% over their operating temperature range) and can also be used with this device. power good the power good output is an open-drain output. it is designed essentially to work as a power-on reset generator once the regulated voltage was up and/or a fault condition. the output of the power good drives low when a fault condition and an undervoltage detection occurs. the power good output comes back up once the output has reached 97% of its nominal value and a 1ms to 5ms delay has passed. see timing diagram . the mic5268?s internal circuit intelligently monitors overcurrent, overtemperature and dropout conditions and ors these outputs together indicate some fault condition. this output is fed into an on-board delay circuitry that drives the open drain transistor to indicate a fault. transient response the mic5268 implements a unique output stage to dramatically improve transient response recovery time. the output is a totem-pole configuration with a p- channel mosfet pass device and an n-channel mosfet clamp. the n-channel clamp is a significantly smaller device that prevent s the output voltage from overshooting when a heavy load is removed. this feature helps to speed up the transient response by significantly decreasing transient response recovery time during the transition from heavy load (100ma) to light load (100a). active shutdown the mic5268 also features an active shutdown clamp, which is an n-channel mosfet that turns on when the device is disabled. this allows the output capacitor and load to discharge, de-energizing the load. thermal considerations the mic5268 is designed to provide 150ma of continuous current in a very small package. maximum power dissipation can be calc ulated based on the output current and the voltage drop across the part. to determine the maximum power dissipation of the package, use the junction-to- ambient thermal resistance of the device and the fo llowing basic equation: ? ? ? ? ? ? ? ? ? = ja a j(max) d(max) t t p t j(max) is the maximum junction temperature of the die, 125c, and t a is the ambient operating temperature. ja is layout dependent; table 1 shows examples of junction-to-ambient thermal re sistance for the mic5268. package ja recommended minimum footprint ja 1? square copper clad jc sot-23-5 (m5) 235c/w 185c/w 145c/w table 1. thermal resistance the actual power dissipation of the regulator circuit can be determined using the equation: p d = (v in ? v out ) i out + v in i gnd substituting p d(max) for p d and solving for the operating conditions that are critical to the application will give the maximum operating conditions for the regulator circuit. for example, when operat ing the mic5268-1.2bm5 at 50c with a minimum footprint layout, the maximum input voltage for a set output current can be determined as follows: ? ? ? ? ? ? ? = c 235 c 50 c 125 p d(max) p d(max) = 315mw
micrel, inc. mic5268 september 2006 7 m9999-091506 the junction-to-ambient thermal resistance for the minimum footprint is 235c/w, from table 1. the maximum power dissipation must not be exceeded for proper operation. using the output voltage of 1.2v and an output current of 150ma, the maximum input voltage can be determined. because this device is cmos and the ground current is typically 100a over the load range, the power dissipati on contributed by the ground current is < 1% and can be ignored for this calculation. 315mw = (v in ? 1.2v) 150ma 315mw = v in 150ma ? 195mw 510mw = v in 150ma v in (max) = 3.4v therefore, a 1.2v applicati on at 150ma of output current can accept a maximum input voltage of 3.4v in a sot- 23-5 package. for a full discussion of heat sinking and thermal effects on voltage regulators, refer to the regulator thermals section of micrel?s designing with low-dropout voltage regulators handbook. dual-supply operation when used in dual supply systems where the regulator load is returned to a negative supply, the output voltage must be diode clamped to ground.
micrel, inc. mic5268 september 2006 8 m9999-091506 package information 5-pin sot-23 (m5) 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 personal injury. life suppo rt devices or systems 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. ? 2002 micrel, incorporated.
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