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MIC5248 micrel august 2001 1 MIC5248 general description the MIC5248 is an efficient, precise cmos voltage regulator with power good output. the MIC5248 offers better than 3% initial accuracy, and constant ground current (typically 100 a)over load . the MIC5248 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 package, the MIC5248 is a fixed 1.2v regulator. typical application 15 2 34 c 47k out enable shutdown en v out MIC5248-x.xbm5 en (pin 3) may be connected directly to in (pin 1). v in pg low-noise regulator application MIC5248 150ma cap cmos ldo regulator w/power good final information features power good indicator load independent, ultralow ground current: 100 a 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 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 ittybitty is a trademark of micrel, inc. ordering information part number marking voltage junction temp. range* package MIC5248-1.2bm5 lv12 1.2 40 c to +125 c sot-23-5 other voltages available. contact micrel for details.
MIC5248 micrel MIC5248 2 august 2001 pin configuration in out pg en lvxx 1 3 45 2 gnd MIC5248-x.xbm5 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
MIC5248 micrel august 2001 3 MIC5248 electrical characteristics v in = 2.7v, v en = v in; i out = 100 a; t j = 25 c, bold values indicate 40 c t j +125 c; unless noted. symbol parameter conditions min typical max units v o output voltage accuracy i out = 100 a 33% 44 % ? v lnr line regulation v in = 2.7v to 6v 0.3 0 0.3 %/v ? v ldr load regulation i out = 0.1ma to 150ma, note 4 4.0 5.0 % i q quiescent current v en 0.4v (shutdown) 0.45 1 a i gnd ground pin current, note 5 i out = 0ma; v in = 6.0v 100 150 a i out = 150ma; v in = 6.0v 100 150 a psrr power supply rejection f = 120hz, c out = 4.7 f, i out = 150ma 60 db 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 i en enable input current v il 0.4v; v in = 5.5v 0.01 a 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 % of v out (pg on) 89.5 % high threshold % of v out (pg off) 96.5 % v ol pg output logic-low voltage i l = 100 a, fault condition 0.02 0.1 v i pg power good leakage current power good off, v pg = 5.5v 0.01 a v pg delay delay time to power good see timing diagram 1 5 ms 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. note 4. regulation is measured at constant junction temperature using low duty cycle pulse testing. parts are tested for load regulatio n in the load range from 0.1ma to 150ma. changes in output voltage due to heating effects are covered by the thermal regulation specification . note 5. ground pin current is the regulator quiescent current. the total current drawn from the supply is the sum of the load current p lus the ground pin current. note 6. the power good is a function of the output voltage being 5% low and the detection of one of the following: overcurrent, overtem perature or dropout. see applications information section for additional information. absolute maximum ratings (note 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 ) ...................................... +150 c storage temperature ............................... 65 c to +150 c lead temperature (soldering, 5 sec.) ....................... 260 c esd, note 3 operating ratings (note 2) input 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 ) ....................... 40 c to +125 c thermal resistance sot ?23( ja ) ...................................................... 235 c/w
MIC5248 micrel MIC5248 4 august 2001 block diagrams 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 1-5ms 1-5ms min - max 96.5% 96.5% 89.5% v out v en v pg indeterminable when v en low fault condition
MIC5248 micrel august 2001 5 MIC5248 95 97 99 101 103 105 107 109 111 113 2.5 3 3.5 4 4.5 5 5.5 6 6.5 ground current ( a) input voltage (v) ground current vs. input volta g e i out = 100 a i out = 150ma 98.2 98.4 98.6 98.8 99 99.2 99.4 0 20 40 60 80 100 120 140 160 ground current ( a) output current (ma) ground current vs. output current v in = 3.3v 85 90 95 100 105 110 -40 -20 0 20 40 60 80 100120140 ground current ( a) temperature ( c) ground current vs. temperature i out = 100 a i out = 150ma 260 270 280 290 300 310 320 330 340 350 360 2.6 3.1 3.6 4.1 4.6 5.1 5.6 6.1 short circuit current (ma) input voltage (v) short circuit current vs. input volta g e 260 270 280 290 300 310 320 -40 -20 0 20 40 60 80 100120140 short circuit current (ma) temperature ( c) short circuit current vs. temperature v in = 3.3v 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 2.6 3.1 3.6 4.1 4.6 5.1 5.6 6.1 power good delay (ms) input voltage (v) power good delay vs. input voltage i out = 100 a 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 -40 -20 0 20 40 60 80 100120140 power good delay (ms) temperature ( c) power good delay vs. temperature v in = 3.3v 0 0.5 1 1.5 2 2.5 3 3.5 0.001 0.01 0.1 1 10 100 1000 10000 power good (v) pull-up resistor (k ? ) power good pull-up resistor vs. power good power good power fail 1.17 1.175 1.18 1.185 1.19 1.195 2.6 3.1 3.6 4.1 4.6 5.1 5.6 6.1 output voltage (v) input voltage (v) output voltage vs. input voltage i out = 100 a i out = 150ma typical characteristics 1.16 1.165 1.17 1.175 1.18 1.185 1.19 1.195 0 20 40 60 80 100 120 140 160 output voltage (v) output current (ma) output voltage vs. output current v in = 3.3v 1.18 1.185 1.19 1.195 1.2 1.205 -40 -20 0 20 40 60 80 100120140 output voltage (v) temperature ( c) output voltage vs. temperature i out = 100 a 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 2.6 3.1 3.6 4.1 4.6 5.1 5.6 6.1 enable voltage (v) input voltage (v) enable voltage vs. input voltage i out = 100 a
MIC5248 micrel MIC5248 6 august 2001 0.8 0.85 0.9 0.95 1 1.05 1.1 1.15 1.2 -40 -20 0 20 40 60 80 100120140 enable voltage (v) temperature ( c) enable voltage vs. temperature v in = 3.3v v in = 12v v out = 5v power good characteristic time (250 s/div) power good (2v/div) output (1v/div) enable (2v/div)
MIC5248 micrel august 2001 7 MIC5248 applications information enable/shutdown the MIC5248 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 this 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 indetermi- nate state on the output. input capacitor an input capacitor is not required for stability. a 1 f input capacitor is recommended when the bulk ac supply capaci- tance is more than 10 inches away from the device, or when the supply is a battery. output capacitor the MIC5248 requires an output capacitor for stability. the design requires 1 f or greater on the output to maintain stability. the capacitor can be a low-esr ceramic chip capacitor. the MIC5248 has been designed to work specifi- cally with the low-cost, small chip capacitors. tantalum capacitors can also be used for improved capacitance over temperature. the value of the capacitor can be increased without bound. x7r dielectric ceramic capacitors are recommended be- cause of their temperature performance. x7r-type capaci- tors change capacitance by 15% over their operating tem- perature 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 with y5v dielectric, the value must be much higher than an x7r ceramic or a tantalum capacitor to ensure the same minimum capacitance value over the operating temperature range. tantalum capacitors have a very 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 come back up once the output has reached 96.5% of its nominal value and a 1ms to 5ms delay has passed. see timing diagram. the MIC5248 s internal circuit intelligently monitors overcurrent, overtemperature and dropout conditions and ors thes outputs together ti 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 MIC5248 implements a unique output stage to dramati- cally 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 prevents the output voltage from overshooting when a heavy load is removed. this feature helps to speed up the transient re- sponse by significantly decreasing transient response recov- ery time during the transition from heavy load (100ma) to light load (100 a). active shutdown the MIC5248 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 dis- charge, de-energizing the load. thermal considerations the MIC5248 is designed to provide 150ma of continuous current in a very small package. maximum power dissipation can be calculated 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 ther- mal resistance of the device and the following basic equation: p tt d(max) j(max) a ja = ? ? ? ? ? ? ? c, and t a is the ambient operating temperature. ja is layout dependent; table 1 shows examples of junction-to- ambient thermal resistance for the MIC5248. package ja recommended ja 1" square jc minimum footprint copper clad sot-23-5 (m5) 235 c/w 185 c/w 145 c/w table 1. sot-23-5 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 operating the MIC5248-1.2bm5 at 50 c with a minimum footprint layout, the maximum input voltage for a set output current can be determined as follows: p 125 c 5 c 235 c/w d(max) = ? ? ? ? ? ? ? 0 p d(max) = 315mw the junction-to-ambient thermal resistance for the minimum footprint is 235 c/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 100 a over the load range, the power dissipation contributed by the
MIC5248 micrel MIC5248 8 august 2001 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 application 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 regu- lators 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.
MIC5248 micrel august 2001 9 MIC5248 package information 0.20 (0.008) 0.09 (0.004) 0.60 (0.024) 0.10 (0.004) 3.02 (0.119) 2.80 (0.110) 10 0 3.00 (0.118) 2.60 (0.102) 1.75 (0.069) 1.50 (0.059) 0.95 (0.037) ref 1.30 (0.051) 0.90 (0.035) 0.15 (0.006) 0.00 (0.000) dimensions: mm (inch) 0.50 (0.020) 0.35 (0.014) 1.90 (0.075) ref sot-23-5 (m)
MIC5248 micrel MIC5248 10 august 2001
MIC5248 micrel august 2001 11 MIC5248
MIC5248 micrel MIC5248 12 august 2001 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 this information is believed to be accurate and reliable, however no responsibility is assumed by micrel for its use nor for an y infringement of patents or other rights of third parties resulting from its use. no license is granted by implication or otherwise under any patent or pat ent right of micrel inc. ? 2001 micrel incorporated

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