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january 2000 1 lm4040/4041 lm4040/4041 micrel lm4040/4041 precision micropower shunt voltage reference final information general description ideal for space critical applications, the lm4040 and lm4041 precision voltage references are available in the subminia- ture (3mm 1.3mm) sot-23 surface-mount package. the lm4040 is the available in fixed reverse breakdown voltages of 2.500v, 4.096v and 5.000v. the lm4041 is available with a fixed 1.225v or an adjustable reverse break- down voltage. the lm4040 and lm4041? advanced design eliminates the need for an external stabilizing capacitor while ensuring stability with any capacitive load, making them easy to use. the minimum operating current ranges from 60 a for the lm4041-1.2 to 74 a for the lm4040-5.0. lm4040 versions have a maximum operating current of 15ma. lm4041 versions have a maximum operating current of 12ma. the lm4040 and lm4041 utilizes zener-zap reverse break- down voltage trim during wafer sort to ensure that the prime parts have an accuracy of better than 0.1% (a grade) at 25 c. bandgap reference temperature drift curvature correc- tion and low dynamic impedance ensure stable reverse breakdown voltage accuracy over a wide range of operating temperatures and currents. features small sot-23 package no output capacitor required tolerates capacitive loads fixed reverse breakdown voltages of 1.225, 2.500v, 4.096v and 5.000v adjustable reverse breakdown version contact micrel for parts with extended temperature range. key specifications output voltage tolerance (a grade, 25 c) .. 0.1% (max) low output noise (10hz to 100hz) lm4040 ................................................ 35 v rms (typ) lm4041 ................................................ 20 v rms (typ) wide operating current range lm4040 ................................................ 60 a to 15ma lm4041 ................................................ 60 a to 12ma industrial temperature range .................. ?0 c to +85 c low temperature coefficient ................ 100ppm/ c (max) applications battery-powered equipment data acquisition systems instrumentation process control energy management product testing automotive electronics precision audio components typical applications v s r s v r lm4041 adjustable r 1 r 2 v o v s r s v r i q + i l i q i l lm4040 lm4041 v o figure 2. lm4041 adjustable shunt regulator application figure 1. lm4040, lm4041 fixed shunt regulator application v o = 1.233 (r 2 /r 1 + 1) 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
lm4040/4041 micrel lm4040/4041 2 january 2000 part number * voltage accuracy, temp. coefficient lm4041aim3-1.2 1.225v 0.1%, 100ppm/ c lm4041bim3-1.2 1.225v 0.2%, 100ppm/ c lm4041cim3-1.2 1.225v 0.5%, 100ppm/ c lm4041dim3-1.2 1.225v 1.0%, 150ppm/ c lm4041cim3-adj 1.24v to 10v 0.5%, 100ppm/ c lm4041dim3-adj 1.24v to 10v 1.0%, 150ppm/ c pin configuration 1 2 3 fb + adjustable version sot-23 (m3) package top view fixed version sot-23 (m3) package top view 1 2 3 + pin 3 must float or be connected to pin 2. part number * voltage accuracy, temp. coefficient lm4040aim3-2.5 2.500v 0.1%, 100ppm/ c lm4040bim3-2.5 2.500v 0.2%, 100ppm/ c lm4040cim3-2.5 2.500v 0.5%, 100ppm/ c lm4040dim3-2.5 2.500v 1.0%, 150ppm/ c lm4040aim3-4.1 4.096v 0.1%, 100ppm/ c lm4040bim3-4.1 4.096v 0.2%, 100ppm/ c lm4040cim3-4.1 4.096v 0.5%, 100ppm/ c lm4040dim3-4.1 4.096v 1.0%, 150ppm/ c lm4040aim3-5.0 5.000v 0.1%, 100ppm/ c lm4040bim3-5.0 5.000v 0.2%, 100ppm/ c lm4040cim3-5.0 5.000v 0.5%, 100ppm/ c lm4040dim3-5.0 5.000v 1.0%, 150ppm/ c example field code _ _ a 3rd character a = 0.1% b = 0.2% c = 0.5% d = 1.0% example field code _ 2 _ 2nd character 1 = 1.225v 2 = 2.500v 4 = 4.096v 5 = 5.000v a = adjustable example: r2c represents reference, 2.500v, 0.5% (lm4040cim3-2.5) note: if 3rd character is omitted, container will indicate tolerance. sot-23 package markings example field code r _ _ 1st character r = reference ordering information
january 2000 3 lm4040/4041 lm4040/4041 micrel absolute maximum ratings reverse current ......................................................... 20ma forward current ......................................................... 10ma maximum output voltage lm4041-adjustable ................................................... 15v power dissipation at t a = 25 c (note 2) ................ 306mw storage temperature ............................... 65 c to +150 c lead temperature vapor phase (60 seconds) .............................. +215 c infrared (15 seconds) ...................................... +220 c esd susceptibility human body model (note 3) ................................. 2kv machine model (note 3) ...................................... 200v operating ratings (notes 1 and 2) temperature range (t min t a t max ) .......................... 40 c t a +85 c reverse current lm4040-2.5 .......................................... 60 a to 15ma lm4040-4.1 .......................................... 68 a to 15ma lm4040-5.0 .......................................... 74 a to 15ma lm4041-1.2 .......................................... 60 a to 12ma lm4041-adj ........................................ 60 a to 12ma output voltage range lm4041-adj .......................................... 1.24v to 10v + functional diagram lm4040, lm4041 fixed functional diagram lm4041 adjustable + fb v ref
lm4040/4041 micrel lm4040/4041 4 january 2000 lm4040-2.5 electrical characteristics boldface limits apply for t a = t j = t min to t max ; all other limits t a = t j = 25 c. the grades a, b, c, and d designate initial reverse breakdown voltage tolerance of 0.1%, 0.2%, 0.5%, and 1.0 respectively. lm4040aim3 lm4040bim3 lm4040cim3 symbol parameter conditions typical units (note 4) limits limits limits (limit) (note 5) (note 5) (note 5) v r reverse breakdown voltage i r = 100 a 2.500 v reverse breakdown voltage i r = 100 a 2.5 5.0 12 mv (max) tolerance 19 21 29 mv (max) i rmin minimum operating current 45 a 60 60 60 a (max) 65 65 65 a (max) ? v r / ? t average reverse breakdown i r = 10ma 20 ppm/ c voltage temperature i r = 1ma 15 100 100 100 ppm/ c (max) coefficient i r = 100 a 15 ppm/ c (max) ? v r / ? i r reverse breakdown voltage i rmin i r 1ma 0.3 mv change with operating 0.8 0.8 0.8 mv (max) current change 1.0 1.0 1.0 mv (max) 1ma i r 15ma 2.5 mv 0.6 0.6 0.6 mv (max) 8.0 8.0 8.0 mv (max) z r reverse dynamic impedance i r = 1ma, f = 120hz 0.3 ? i ac = 0.1 i r 0.8 0.8 0.9 ? (max) e n wideband noise i r = 100 a 10hz f 10khz 35 v rms ? v r reverse breakdown voltage t = 1000hrs long term stability t = 25 c 0.1 c 120 ppm i r = 100 a lm4040dim3 symbol parameter conditions typical units (note 4) limits (limit) (note 5) v r reverse breakdown voltage i r = 100 a 2.500 v reverse breakdown voltage i r = 100 a 25 mv (max) tolerance 49 mv (max) i rmin minimum operating current 45 a 65 a (max) 70 a (max) ? v r / ? t average reverse breakdown i r = 10ma 20 ppm/ c voltage temperature i r = 1ma 15 150 ppm/ c (max) coefficient i r = 100 a 15 ppm/ c (max) ? v r / ? i r reverse breakdown voltage i rmin i r 1ma 0.3 mv change with operating 1.0 mv (max) current change 1.2 mv (max) 1ma i r 15ma 2.5 mv 8.0 mv (max) 10.0 mv (max) z r reverse dynamic impedance i r = 1ma, f = 120hz 0.3 ? i ac = 0.1 i r 1.1 ? (max) e n wideband noise i r = 100 a 10hz f 10khz 35 v rms ? v r reverse breakdown voltage t = 1000hrs long term stability t = 25 c 0.1 c 120 ppm i r = 100 a
january 2000 5 lm4040/4041 lm4040/4041 micrel lm4040-4.1 electrical characteristics boldface limits apply for t a = t j = t min to t max ; all other limits t a = t j = 25 c. the grades a, b, c, and d designate initial reverse breakdown voltage tolerance of 0.1%, 0.2%, 0.5%, and 1.0% respectively. lm4040aim3 lm4040bim3 symbol parameter conditions typical units (note 4) limits limits (limit) (note 5) (note 5) v r reverse breakdown voltage i r = 100 a 4.096 v reverse breakdown voltage i r = 100 a 4.1 8.2 mv (max) tolerance 31 35 mv (max) i rmin minimum operating current 50 a 68 68 a (max) 73 73 a (max) ? v r / ? t average reverse breakdown i r = 10ma 30 ppm/ c voltage temperature i r = 1ma 20 100 100 ppm/ c (max) coefficient i r = 100 a 20 ppm/ c (max) ? v r / ? i r reverse breakdown voltage i rmin i r 1ma 0.5 mv change with operating 0.9 0.9 mv (max) current change 1.2 1.2 mv (max) 1ma i r 15ma 3.5 mv 7.0 7.0 mv (max) 10.0 10.0 mv (max) z r reverse dynamic impedance i r = 1ma, f = 120hz 0.5 ? i ac = 0.1 i r 1.0 1.0 ? (max) e n wideband noise i r = 100 a 10hz f 10khz 80 v rms ? v r reverse breakdown voltage t = 1000hrs long term stability t = 25 c 0.1 c 120 ppm i r = 100 a lm4040cim3 lm4040dim3 symbol parameter conditions typical units (note 4) limits limits (limits) (note 5) (note 5) v r reverse breakdown voltage i r = 100 a 4.096 v reverse breakdown voltage i r = 100 a 20 41 mv (max) tolerance 47 81 mv (max) i rmin minimum operating current 50 a 68 73 a (max) 73 78 a (max) ? v r / ? t average reverse breakdown i r = 10ma 30 ppm/ c voltage temperature i r = 1ma 20 100 150 ppm/ c (max) coefficient i r = 100 a 20 ppm/ c (max) ? v r / ? i r reverse breakdown voltage i rmin i r 1ma 0.5 mv change with operating 0.9 1.2 mv (max) current change 1.2 1.5 mv (max) 1ma i r 15ma 3.0 mv 7.0 9.0 mv (max) 10.0 13.0 mv (max) z r reverse dynamic impedance i r = 1ma, f = 120hz 0.5 ? i ac = 0.1 i r 1.0 1.3 ? (max) e n wideband noise i r = 100 a 10hz f 10khz 80 v rms ? v r reverse breakdown voltage t = 1000hrs long term stability t = 25 c 0.1 c 120 ppm i r = 100 a
lm4040/4041 micrel lm4040/4041 6 january 2000 lm4040-5.0 electrical characteristics boldface limits apply for t a = t j = t min to t max ; all other limits t a = t j = 25 c. the grades a, b, c, and d designate initial reverse breakdown voltage tolerance of 0.1%, 0.2%, 0.5%, and 1.0% respectively. lm4040aim3 lm4040bim3 symbol parameter conditions typical units (note 4) limits limits (limit) (note 5) (note 5) v r reverse breakdown voltage i r = 100 a 5.000 v reverse breakdown voltage i r = 100 a 5.0 10 mv (max) tolerance 38 43 mv (max) i rmin minimum operating current 54 a 74 74 a (max) 80 80 a (max) ? v r / ? t average reverse breakdown i r = 10ma 30 ppm/ c voltage temperature i r = 1ma 20 100 100 ppm/ c (max) coefficient i r = 100 a 20 ppm/ c (max) ? v r / ? i r reverse breakdown voltage i rmin i r 1ma 0.5 mv change with operating 1.0 1.0 mv (max) current change 1.4 1.4 mv (max) 1ma i r 15ma 3.5 mv 8.0 8.0 mv (max) 12.0 12.0 mv (max) z r reverse dynamic impedance i r = 1ma, f = 120hz 0.5 ? i ac = 0.1 i r 1.1 1.1 ? (max) e n wideband noise i r = 100 a 10hz f 10khz 80 v rms ? v r reverse breakdown voltage t = 1000hrs long term stability t = 25 c 0.1 c 120 ppm i r = 100 a lm4040cim3 lm4040dim3 symbol parameter conditions typical units (note 4) limits limits (limits) (note 5) (note 5) v r reverse breakdown voltage i r = 100 a 5.000 v reverse breakdown voltage i r = 100 a 25 50 mv (max) tolerance 58 99 mv (max) i rmin minimum operating current 54 a 74 79 a (max) 80 85 a (max) ? v r / ? t average reverse breakdown i r = 10ma 30 ppm/ c voltage temperature i r = 1ma 20 100 150 ppm/ c (max) coefficient i r = 100 a 20 ppm/ c (max) ? v r / ? i r reverse breakdown voltage i rmin i r 1ma 0.5 mv change with operating 1.0 1.3 mv (max) current change 1.3 1.8 mv (max) 1ma i r 15ma 3.5 mv 8.0 10.0 mv (max) 12.0 15.0 mv (max) z r reverse dynamic impedance i r = 1ma, f = 120hz 0.5 ? i ac = 0.1 i r 1.1 1.5 ? (max) e n wideband noise i r = 100 a 10hz f 10khz 80 v rms ? v r reverse breakdown voltage t = 1000hrs long term stability t = 25 c 0.1 c 120 ppm i r = 100 a
january 2000 7 lm4040/4041 lm4040/4041 micrel lm4040 typical characteristics +0.5 +0.4 +0.3 +0.2 +0.1 0 -0.1 -0.2 -0.3 -0.4 -0.5 -40 -22ppm/ c -51ppm/ c i r = 150a 12ppm/ c temperature ( c) v r change (%) temperature drift for different average temperature coefficient -200 20406080100 output impedance vs. frequency i r = i rmin + 100 a v r = 5v 2.5v 100 1k 10k 100k 1m frequency (hz) c l = 1f tantalum x cl 1k 100 10 1 0.1 impedance ( ? ) t j = 25 c, ? i r = 0.1 i r c l = 0 output impedance vs. frequency i r = 1ma t j = 25 c, ? i r = i r c l = 0 c l = 1f tantalum v r = 5v 2.5v 1k 100 10 1 0.1 100 1k 10k 100k 1m frequency (hz) impedance ( ? ) lm4040-5.0 r s = 30k t j = 25 c 10 0 6 4 2 0 0 100 200 300 400 response time (s) v r (v) v in (v) i j = 25 c lm4040-2.5 r s = 30k 0 20 40 60 80 5 0 6 4 2 0 response time (s) v r (v) v in (v) test circuit v in 1hz rate lm4040 r s v r reverse voltage (v) a , b, c, suffix d suffix reverse characteristics and minimum operating current 120 100 80 60 40 20 0 0 2 4 6 8 10 t j = 25 c typica l i rmin guaranteed 2.5v 4.1v 5v reverse current (a) 10.0 5.0 1 10 100 1k 10k 100k frequency (hz) 2.0 1.0 0.5 0.2 i r = 200a t j = 25 c 5v 2.5v noise voltage vs. frequency 0.1 noise (v/ hz )
lm4040/4041 micrel lm4040/4041 8 january 2000 lm4041-1.2 electrical characteristics boldface limits apply for t a = t j = t min to t max ; all other limits t a = t j = 25 c. the grades a, b, c, and d designate initial reverse breakdown voltage tolerance of 0.1%, 0.2%, 0.5%, and 1.0%, respectively. lm4041aim3 lm4041bim3 lm4041cim3 symbol parameter conditions typical units (note 4) limits limits limits (limit) (note 5) (note 5) (note 5) v r reverse breakdown voltage i r = 100 a 1.225 v reverse breakdown voltage i r = 100 a 1.2 2.4 6 mv (max) tolerance 9.2 10.4 14 mv (max) i rmin minimum operating current 45 a 60 60 60 a (max) 65 65 65 a (max) ? v r / ? t average reverse breakdown i r = 10ma 20 ppm/ c voltage temperature i r = 1ma 15 100 100 100 ppm/ c (max) coefficient i r = 100 a 15 ppm/ c (max) ? v r / ? i r reverse breakdown voltage i rmin i r 1ma 0.7 mv change with operating 1.5 1.5 1.5 mv (max) current change 2.0 2.0 2.0 mv (max) 1ma i r 15ma 4.0 mv 6.0 6.0 6.0 mv (max) 8.0 8.0 8.0 mv (max) z r reverse dynamic impedance i r = 1ma, f = 120hz 0.5 ? i ac = 0.1 i r 1.5 1.5 1.5 ? (max) e n wideband noise i r = 100 a 10hz f 10khz 20 v rms ? v r reverse breakdown voltage t = 1000hrs long term stability t = 25 c 0.1 c 120 ppm i r = 100 a lm4041dim3 lm4041eim3 symbol parameter conditions typical units (note 4) limits limits (limit) (note 5) (note 5) v r reverse breakdown voltage i r = 100 a 1.225 v reverse breakdown voltage i r = 100 a 12 25 mv (max) tolerance 24 36 mv (max) i rmin minimum operating current 45 a 65 65 a (max) 70 70 a (max) ? v r / ? t average reverse breakdown i r = 10ma 20 ppm/ c voltage temperature i r = 1ma 15 150 150 ppm/ c (max) coefficient i r = 100 a 15 ppm/ c (max) ? v r / ? i r reverse breakdown voltage i rmin i r 1ma 0.3 mv change with operating 2.0 2.0 mv (max) current change 2.5 2.5 mv (max) 1ma i r 15ma 2.5 mv 8.0 8.0 mv (max) 10.0 10.0 mv (max) z r reverse dynamic impedance i r = 1ma, f = 120hz 0.3 ? i ac = 0.1 i r 2.0 2.0 ? (max) e n wideband noise i r = 100 a 10hz f 10khz 35 v rms ? v r reverse breakdown voltage t = 1000hrs long term stability t = 25 c 0.1 c 120 ppm i r = 100 a
january 2000 9 lm4040/4041 lm4040/4041 micrel lm4041-adjustable electrical characteristics boldface limits apply for t a = t j = t min to t max ; all other limits t j = 25 c unless otherwise specified (sot-23, see note 7), i rmin i r < 12ma, v ref v out 10v. the grades c and d designate initial reverse breakdown voltage tolerance of 0.5% and 1%, respectively for v out = 5v. lm4041cim3 lm4041dim3 symbol parameter conditions typical units (note 4) limits limits (limit) (note 5) (note 5) v ref reference breakdown voltage i r = 100 a 1.233 v v out = 5v reference breakdown voltage i r = 100 a 6.2 12 mv (max) tolerance (note 8) 14 24 mv (max) i rmin minimum operating current 45 a 60 65 a (max) 65 70 a (max) ? v ref reference voltage i rmin i r 1ma 0.7 mv / ? i r change with operating sot-23: 1.5 2.0 mv (max) current change v out 1.6v 2.0 2.5 mv (max) (note 7) 1ma i r 15ma 2 mv sot-23: 4 6 mv (max) v out 1.6v 68 mv (max) (note 7) ? v ref reference voltage change i r = 1ma 1.3 mv/v / ? v o with output voltage change 2.0 2.5 mv/v (max) 2.5 3.0 mv/v (max) i fb feedback current 60 na 100 150 na (max) 120 200 na (max) ? v ref average reference v out = 5v / ? t voltage temperature i r = 10ma 20 ppm/ c coefficient i r = 1ma 15 100 150 ppm/ c (max) (note 8) i r = 100 a 15 ppm/ c (max) z out dynamic output impedance i r = 1ma, f = 120hz i ac = 0.1 i r v out = v ref 0.3 ? v out = 10v 2 ? (max) e n wideband noise i r = 100 a 10hz f 10khz 20 v rms ? v ref reference voltage t = 1000hrs long term stability t = 25 c 0.1 c 120 ppm i r = 100 a
lm4040/4041 micrel lm4040/4041 10 january 2000 +0.5 +0.4 +0.3 +0.2 +0.1 0 -0.1 -0.2 -0.3 -0.4 -0.5 -40 -22ppm/ c -51ppm/ c i r = 150a lm4041-1.2 12ppm/ c temperature ( c) v r change (%) temperature drift for different average temperature coefficient -200 20406080100 c l = 1f tantalum output impedence vs. frequency 1k 100 10 1 0.1 100 1k 10k 100k 1m frequency (hz) t j = 25 c ? i r = 0.1i r lm4041-1.2 c l = 0 x c i r = 150a i r = 1ma impedance ( ? ) voltage impedance 1000 800 600 400 200 0 1 10 100 1k 10k 100k frequency (hz) i r = 200a t j = 25 c lm4041-1.2 lm4041-adj: v out = v ref noise (nv/ hz ) reverse characteristics and minimum operating current reverse voltage (v) 100 80 60 40 20 0 0 0.4 0.8 1.2 1.6 2.0 typical t j = 25 c lm4041-1.2 reverse current (a) reverse characteristics and minimum operating current reverse voltage (v) 100 80 60 40 20 0 0 0.4 0.8 1.2 1.6 2.0 typical t j = 25 c lm4041-1.2 reverse current (a) r s 30k v in 1hz rate lm4041-1.2 v r test circuit note 1. absolute maximum ratings indicate limits beyond which damage to the device may occur. operating ratings indicate conditions fo r which the device is functional, but do not guarantee specific performance limits. for guaranteed specification and test conditions, see the electrical characteristics. the guaranteed specifications apply only for the test conditions listed. some performance characteristics ma y degrade when the device is not operated under the listed test conditions. note 2. the maximum power dissipation must be derated at elevated temperatures and is dictated by t jmax (maximum junction temperature), ja (junction to ambient thermal resistance), and t a (ambient temperature). the maximum allowable power dissipation at any temperature is pd max = (t jmax t a )/ ja or the number given in the absolute maximum ratings, whichever is lower. for the lm4040 and lm4041, t jmax = 125 c, and the typical thermal resistance ( ja ), when board mounted, is 326 c/w for the sot-23 package. note 3. the human body model is a 100pf capacitor discharged through a 1.5k ? resistor into each pin. the machine model is a 200pf capacitor discharged directly into each pin. note 4. typicals are at t j = 25 c and represent most likely parametric norm. note 5. limits are 100% production tested at 25 c. limits over temperature are guaranteed through correlation using statistical quality control (sql) methods. note 6. the boldface (over temperature limit for reverse breakdown voltage tolerance is defined as the room temperature reverse breakdo wn voltage tolerance [( ? v r / ? t)(65 c)(v r )]. ? v r / ? t is the v r temperature coefficient, 65 c is the temperature range from 40 c to the reference point of 25 c, and v r is the reverse breakdown voltage. the total over temperature tolerance for the different grades follows: a-grade: 0.75% = 0.1% 100ppm/ c 65 c b-grade: 0.85% = 0.2% 100ppm/ c 65 c c-grade: 1.15% = 0.5% 100ppm/ c 65 c d-grade: 1.98% = 1.0% 150ppm/ c 65 c example: the a-grade lm4040-2.5 has an over temperature reverse breakdown voltage tolerance of 2.5 0.75% = 19mv. note 7. when v out 1.6v, the lm4041-adj must operate at reduced i r . this is caused by the series resistance of the die attach between the die ( ) output and the package ( ) output pin. see the output saturation curve in the typical performance characteristics section. note 8. reference voltage and temperature coefficient will change with output voltage. see typical performance characteristics curves. lm4040 and lm4041 electrical characteristic notes lm4041 typical characteristics
january 2000 11 lm4040/4041 lm4040/4041 micrel lm4041 typical characteristics lm4041-adj 85 c 25 c -40 c -40 c 85 c reference voltage vs. output voltage and temperature 1.244 1.240 1.236 1.232 1.228 1.224 1.220 0 2 4 6 8 10 output voltage (v) reference voltage (v) reference voltage vs. temperature and output voltage 1.244 1.240 1.236 1.232 1.228 1.224 1.220 -40 -20 0 20 40 60 80 100 temperature ( c) lm4041-adj v out = v ref v out = 5v v out = 10v i r = 1ma reference voltage (v) t j = 85 c lm4041-adj t j = 25 c, -40 c feedback current vs. output voltage and temperature 0 2 4 6 8 10 output voltage (v) 100 80 60 40 20 0 feedback (na) output saturation 0 2 4 6 8 10 12 output current (ma) 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1.0 lm4041-adj v adj = v ref + 5v -40 c 85 c 25 c output saturation (v) lm4041-adj t j = 25 c i r = 1ma ? i r = 0.1i r c l = 0 c l =1f x c v out = 10v 5v 2.5v 1.23v output impedence vs. frequency * 1k 100 10 1 0 100 1k 10k 100k 1m frequency (hz) impedance ( ? ) c l = 0 c l =1f x c 5v 2.5v 1.23v frequency (hz) 100 1k 10k 100k 1m 1k 100 10 1 0 output impedence vs. frequency * impedance ( ? ) v out = 10v lm4041-adj t j = 25 c i r = 1ma ? i r = 0.1 i r fb steps (v) 0 2 4 6 8 10 t j = 25 c lm4041-adj 0 2 4 6 8 100 80 60 40 20 0 reverse characteristics ? output voltage (v) reverse current (a) lm4041-adj t j = -40 c 25 c 85 c 0 10 20 30 40 -40 c output input -40 c large signal response 10 8 6 4 2 0 response time (s) voltage (v) * output impedance vs. freq. test circuit large signal response test circuit ? reverse characteristics test circuit fb 2v / step v ou t i r ( + ) ( ) lm4041-adj v v out lm4041 - adj ( + ) fb ( - ) 100k input + 15v 5.1k + c l 120k fb i r
lm4040/4041 micrel lm4040/4041 12 january 2000 applications information the lm4040 and lm4041 have been designed for stable operation without the need of an external capacitor con- nected between the (+) and ( ) pins. if a bypass capacitor is used, the references remain stable. schottky diode lm4040-x.x and lm4041-1.2 in the sot-23 package have a parasitic schottky diode between pin 2 ( ) and pin 3 (die attach interface connect). pin 3 of the sot-23 package must float or be connected to pin 2. lm4041-adjs use pin 3 as the ( ) output. conventional shunt regulator in a conventional shunt regulator application (see figure 1), an external series resistor (r s ) is connected between the supply voltage and the lm4040-x.x or lm4041-1.2 reference. r s determines the current that flows through the load (i l ) and the reference (i q ). since load current and supply voltage may vary, r s should be small enough to supply at least the minimum acceptable i q to the reference even when the supply voltage is at its minimum and the load current is at its maximum value. when the supply voltage is at its maximum and i l is at its minimum, r s should be large enough so that the current flowing through the lm4040-x.x is less than 15ma, and the current flowing through the lm4041-1.2 or lm4041-adj is less than 12ma. r s is determined by the supply voltage (v s ), the load and operating current, (i l and i q ), and the reference s reverse breakdown voltage (v r ). r s = (v s v r ) / (i l + i q ) adjustable regulator the lm4041-adj s output voltage can be adjusted to any value in the range of 1.24v through 10v. it is a function of the internal reference voltage (v ref ) and the ratio of the external feedback resistors as shown in figure 2. the output is found using the equation (1) v o = v ref [ (r2/r1) + 1 ] where v o is the desired output voltage. the actual value of the internal v ref is a function of v o . the corrected v ref is determined by (2) v ref = v o ( ? v ref / ? v o ) + v y where v o is the desired output voltage. ? v ref / ? v o is found in the electrical characteristics and is typically 1.3mv/v and v y is equal to 1.233v. replace the value of v ref in equation (1) with the value found using equation (2). note that actual output voltage can deviate from that pre- dicted using the typical ? v ref / ? v o in equation (2); for c- grade parts, the worst-case ? v ref / ? v o is 2.5mv/v and v y = 1.248v. the following example shows the difference in output voltage resulting from the typical and worst case values of ? v ref / ? v o : let v o = +9v. using the typical values of ? v ref / ? v o , v ref is 1.223v. choosing a value of r1 = 10k ? , r2 = 63.272k ? . using the worst case ? v ref / ? v o for the c-grade and d- grade parts, the output voltage is actually 8.965v and 8.946v respectively. this results in possible errors as large as 0.39% for the c-grade parts and 0.59% for the d-grade parts. once again, resistor values found using the typical value of ? v ref / ? v o will work in most cases, requiring no further adjustment. figure 4. voltage level detector r1 120 k r2 1m fb + lm4041-adj d1 < 12v led on r3 200 5v d1 lm4041- adj r1 120k r2 1m fb + r3 330 > 12v led on 5v figure 3. voltage level detector
january 2000 13 lm4040/4041 lm4040/4041 micrel figure 8. bidirectional adjustable clamp 2.4 to 6v v in r1 i lm4041-adj d2 1n457 r3 1m r2 330k v out lm4041-adj fb + fb + d1 1n457 r4 330k v in r1 r2 390k r3 500k fb + lm4041-adj d1 1n457 r4 390k d2 1n457 lm4041-adj fb + i v out figure 7. bidirectional adjustable clamp 18v to 2.4v 0 to 20ma r1 390 ? 2% 1n4002 d2 lm4041-adj + fb d1* 1 2 3 6 5 4 4n28 n.c. i threshold = + = 3.2ma 1.24v r1 5a 4n28 gain n.c. r2 470k cmos + 5v figure 9. floating current detector d1 1n457 r3 510k lm4041-adj d2 1n457 v out r2 510k v in r1 i + fb fb lm4041-adj + figure 6. bidirectional clamp 2.4v figure 5. fast positive clamp 2.4v + ? v d1 v in v out d1 1n914 d2 1n914 r3 240k r4 240k r1 i r2 50a lm4041-adj fb +
lm4040/4041 micrel lm4040/4041 14 january 2000 +15v r1 2n2905 2n 3964 r2 120k lm4041-adj fb + 1.24v r1 i out = 1a < i out = 100ma +5v r3 100k cmos r4 10m 1 2 3 6 5 4 4n28 n.c. r2 22k lm4041-adj + r1 332 ? 1% fb 1n914 2n2222 d1* i threshold = = 3.7ma 2% 1.24v r1 d2 1n4002 0 to 20 ma figure 10. current source figure 11. precision floating current detector * d1 can be any led, v f = 1.5v to 2.2v at 3ma. d1 may act as an indicator. d1 will be on if i threshold falls below the threshold current, except with i = o.
january 2000 15 lm4040/4041 lm4040/4041 micrel package information 0.15 (0.006) 0.076 (0.0030) 0.41 (0.016) 0.13 (0.005) 3.05 (0.120) 2.67 (0.105) 8 0 0.445 (0.0175) typ 3 places 2.50 (0.098) 2.10 (0.083) 1.40 (0.055) 1.19 (0.047) 0.10 (0.004) 0.013 (0.0005) 1.15 (0.045) 0.76 (0.030) dimensions: mm (inch) 2.36 (0.093) 2.28 (0.090) c l c l sot-23 (m3)
lm4040/4041 micrel lm4040/4041 16 january 2000 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. ? 2000 micrel incorporated

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