june 2000 1 MIC5231 MIC5231 micrel general description the MIC5231 cap low-dropout voltage regulator is intended for low-output-current biasing applications. it features ex- tremely low ground current, not greater than 4 a under all load and temperature conditions, making it efficient and ideal for keep-alive applications in devices such as notebook computers. the MIC5231 offers better than 2% initial accuracy and low dropout (typically 150mv at 10ma output current). an output capacitor is not required for stable operation, decreasing cost and board space. tiny ceramic chip capacitors may be used to improve transient response. the MIC5231 also features a control pin which allows the regulator to be shut down when not required. its shutdown- state draws zero current, benefitting battery-powered appli- cations. the MIC5231 is available in fixed output voltages of 2.75v, 3.0v, 3.3v and 5v in the small sot-23-5 ittybitty package. contact micrel for other voltage options. micrel inc. 1849 fortune drive san jose, ca 95131 usa tel + 1 (408) 944-0800 fax + 1 (408) 944-0970 typical application in en out MIC5231-5.0bm5 gnd v in 6v v out 5v 5v linear regulator application ordering information part number marking voltage temperature range package MIC5231-2.75bm5 lm2h 2.75v 40 c to +125 c sot-23-5 MIC5231-3.0bm5 lm30 3.0v 40 c to +125 c sot-23-5 MIC5231-3.3bm5 lm33 3.3v 40 c to +125 c sot-23-5 MIC5231-5.0bm5 lm50 5.0v 40 c to +125 c sot-23-5 features extremely low quiescent current only 0.65 a no output capacitor requirement stable with ceramic or tantalum capacitors ittybitty sot-23-5 surface-mount package 10ma output drive low 150mv at 10ma dropout voltage tight load and line regulation low temperature coefficient logic-level enable input applications real-time clocks sram backup cellular telephones laptop, notebook and palmtop computers battery-powered equipment bar code scanners smps post-regulator and dc-to-dc modules MIC5231 micropower cap ldo regulator final information ittybitty is a trademark of micrel, inc.
MIC5231 2 june 2000 MIC5231 micrel pin description pin number pin name pin function 1 en enable (input): active high. logic high = enable; logic low = shutdown. do not float. 2 gnd ground 3 in supply input 4 out regulated output 5 nc not internally connected pin configuration part identification en nc out in lm50 1 3 45 2 gnd MIC5231-5.0bm5 absolute maximum ratings (note 1) supply voltage (v in ) .................................... 0.6v to +14v lead temperature (soldering, 5 sec.) ....................... 260 c storage temperature (t a ) ....................... 60 c to +150 c esd, note 3 .................................................................. 2kv operating ratings (note 2) input voltage (v in ) ........................................... 3.5v to 12v ambient temperature (t a ) ......................... 40 c to +85 c junction temperature (t j ) ....................... 40 c to +125 c thermal resistance, note 4
june 2000 3 MIC5231 MIC5231 micrel electrical characteristics v in = v out + 1v; i l = 100 a; c l = 0.47 f; t j = 25 c, bold values indicate 40 c t j +125 c; unless noted. symbol parameter conditions min typ max units v out output voltage accuracy variation from nominal v out 2+2% ? +3 % ? v out / ? t output voltage note 5 250 ppm/ c temperature coefficient ? v out /v out line regulation v in = 6v to 12v 0.2 0.25 % ? v out /v out load regulation i l = 10 a to 10ma, note 6 0.2 1 % v do dropout voltage, note 7 i l = 1ma 15 mv i l = 10ma 150 300 mv i q ground pin current v in = 6v, i l = 10ma 0.65 3 a v in = 12v, i l = 10ma 1.1 4 a psrr ripple rejection f = 100hz, i l = 100 a50db enable input v enl enable input voltage v en = logic low (regulator off) 0.4 0.18 v v en = logic high ((regulator on) 1.4 v i enl enable input current v enl 0.18v (regulator off) 1 na i enh enable input current v enh 1.4v (regulator on) 1 na 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: the maximum allowable power dissipation at any t a (ambient temperature) is p d(max) = (t j(max) t a ) ja . the jc of the MIC5231 is 130 c/w. mounted to a standard pc board, the ja is approximately 235 c/w. note 5: output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range. note 6: regulation is measured at constant junction temperature using low duty cycle pulse testing. note 7: dropout voltage is defined as the input to output differential at which the output voltage drops 2% below its nominal value mea sured at 1v differential. for outputs below 3.5v, dropout voltage is the input-to-output differential with the minimum input voltage 3.5v. minimum input operating voltage is 3.5v.
MIC5231 4 june 2000 MIC5231 micrel 0 0.5 1 0110 ground current ( a) output current (ma) ground current vs. output current 0.2 0.3 0.4 0.5 0.6 0.7 0.8 24681012 ground current ( a) supply voltage (v) ground current vs. supply voltage 0 0.2 0.4 0.6 0.8 1 -40 0 40 80 120 ground current ( a) temperature ( c) ground current vs. temperature 2.90 2.95 3.00 3.05 3.10 -50 -20 10 40 70 100 130 output voltage (v) temperature ( c) ground current vs. temperature 0 50 100 150 -50 -20 10 40 70 100 130 short circuit current (ma) temperature ( c) short circuit current vs. temperature
june 2000 5 MIC5231 MIC5231 micrel applications information input capacitor a 0.1 f (or larger) capacitor should be placed from the in (supply input) to gnd (ground) if there is more than 20 cm of wire between in and the ac filter capacitor or if supplied from a battery. output capacitors the MIC5231 does not require an output capacitor for stabil- ity. a 1 f or larger capacitor is recommended between out (output) and gnd to improve the regulator s transient re- sponse. a 0.1 f capacitor can be used to reduce overshoot recovery time at the expense of overshoot amplitude. the esr (effective series resistance) of this capacitor has no effect on regulator stability, but low-esr capacitors improve high frequency transient response. the value of this capaci- tor may be increased without limit, but values larger than 10 f tend to increase the settling time after a step change in input voltage or output current. the MIC5231 has no minimum load current; it will remain stable and in regulation with no load (other than the internal voltage divider). this is especially important in real-time clock and cmos ram keep-alive applications. minimum load current the MIC5231 does not require a minimum load for proper operation. this allows the device to operate in applications where very light output currents are required for keep-alive purposes. this is important for powering sram or flash memory in low-power modes for handheld devices. safe operating conditions the MIC5231 does not incorporate current limit or thermal shutdown in the design. the output pass element is approxi- mately 15 ? , therefore, when a short occurs from the output to ground, the current is self-limited. the pass element has a positive temperature coefficient, such that when the device gets hot, the output impedance goes up, limiting the current even further. the maximum junction temperature for the device is +125 c, and it is important that this is not exceeded for any length of time. thermal considerations the MIC5231 is not intended for sourcing currents that would cause a large power loss in the device, but since it is not current limited, it is possible to source more than the rated 10ma. at this point, it is important to ensure that the die temperature does not exceed +125 c. power dissipation in the regulator is calculated as follows: p d = (v in v out )i out + v in i gnd the MIC5231 consumes only 0.65 a over load and does not need to consider that contribution in the power dissipation equation, therefore the equation is simplified. p d = (v in v out )i out the MIC5231, in the ittybitty sot-23-5 package, has a thermal resistance, junction-to-ambient, of 235 c/w. using this number, the power dissipation capability of that package, without exceeding a +125 c junction temperature rating, can easily be calculated. p tt d(max) j(max) a ja = = ? ? p 125 c t 235 c/w d(max) a = = ? ? if the device is being operated at +85 c, the maximum power dissipation allowed can easily be determined. p 125 c 85 c 235 c/w d(max) = = ? ? = = = =? ? ( () ) = =? ? ( () ) i 170mw 8.7v out = = i 19.5ma out = = therefore, the device can source almost 20ma at an ambient of +85 c before the die temperature exceeds +125 c. block diagram in out gnd en MIC5231 bandgap reference
MIC5231 6 june 2000 MIC5231 micrel 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 (m5)
june 2000 7 MIC5231 MIC5231 micrel
MIC5231 8 june 2000 MIC5231 micrel micrel inc. 1849 fortune drive san jose, ca 95131 usa tel + 1 (408) 944-0800 fax + 1 (408) 944-0970 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. ? 2000 micrel incorporated
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