1 date: 05/25/04 spx2431 precision adjustable shunt regulator ?copyrig ht 2003 sipex corporation precision adjustable shunt regulator spx2431 description features trimmed bandgap to 0.5% and 1.0% wide operating current 1ma to 100ma extended temp. range: 0 c to 105 c low temperature coefficient 30 ppm/ c offered in 3 pin sot-23 (m) replacement for tl431, as2431 low noise output the spx2431 is a 3-terminal adjustable shunt voltage regulator providing a highly accurate bandgap reference. the spx2431 acts as an open-loop error amplifier with a 2.5v temperature compensation reference. the spx2431 s thermal stability, wide operating current (100ma) and temperature range (0 c to 105 c) makes it suitable for a variety of applications that require a low cost, high performance solution. spx2431a tolerance of 0.5% is proven to be sufficient to overcome all of the other errors in the system to virtually eliminate the need for trimming in the power supply manufacturer's assembly line and contribute a significant cost savings. the output voltage may be adjusted to any value between v ref and 20 volts with two external resistors. in the standard shunt configuration, the combination of a low temperature coefficient, sharp turn on characteristics, low output impedance, and programmable output voltage makes this precision reference an excellent error amplifier. the spx2431 is available in sot-23-3 package. applications battery operating equipment adjustable supplies switching power supplies error amplifiers single supply amplifier monitors / vcrs / tvs personal computers functional diagram + - 2.5v reference (r) anode (a) cathode (k)
2 date: 05/25/04 spx2431 precision adjustable shunt regulator ?copyright 20 04 sipex corporation cathode-anode reverse breakdown v ka ....................................... 20v anode-cathode forward current, (<10ms) i ak ................................. 1a operating cathode current i ka .................................................. 100ma reference input current i ref ....................................................... 1.0ma continuos power dissipation at 25 c p d sot-23 .................................................................. 200 mw junction temperature t j ........................................................... 150 c storage temperature t stg .............................................. -65 to 150 c lead temperature (soldering 10 sec.) t l .................................. 300 c note: stresses greater than those listed under absolute maximum ratings may cause permanent damage to the device. this is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. exposure to absolute maximum rating condi- tions for extended periods may affect reliability. typical thermal resistances package 0 ja 0 jc typical derating sot-23 575 c/w 150 c/w 1.7 mw/ c typical deratings of the thermal resistances are given for ambient temperature >25 . electrical characteristics electrical characteristics at 25 c i k = 10ma v k = v ref , unless otherwise specified. parameter symbol figure conditions min typ max min typ max units spx2431a spx2431 reference voltage v ref 2 2.487 2.500 2.513 2.474 2.500 2.526 v 2t j = 0 c to 105 c 2.480 2.520 2.460 2.540 v ? v ref withtemp.* tc 2 0.07 0.20 0.07 0.20 mv/ c ratio of change in v ref ? v ref v ref to 10v -2.7 -1.01 -2.7 -1.01 mv/v to cathode voltage ? v k 3 10v to 20v -2.0 -0.4 0.3 -2.0 -0.4 0.3 reference input current i ref 3 0.7 4.0 0.7 4.0 a i ref temp deviation ? i ref 3t j = 0 c to 105 c 0.4 1.2 0.4 1.2 a min i k for regulation i k(min) 2 0.4 1.0 0.4 1.0 ma off state leakage i k(off) v ref = 0v, 0.04 0.04 500 na 4 v ka = 20v dynamic output z ka 2 z 1khz 0.15 0.5 0.15 0.5 ? impedance i k = 1 to 100ma recommended conditions parameter symbol rating unit cathode voltage v ka v ref to 20 v cathode current i k 10 ma absolute maximum ratings
3 date: 05/25/04 spx2431 precision adjustable shunt regulator ?copyrig ht 2003 sipex corporation 0 5000 ppm 0 0.5 % 27ppm/ c 0.0027% / c 0.0033mv / c 015 3045 6 0759 0 105 0 mv -5 ? t ? v ref junction temperature ( c) ? v ref (mv) ? t a ( ? v ref at 25 c ) ? t a ? v ref x 100 ? tc in % / c = ? tc in mv / c = ( ? v ref at 25 c ) ? t a ? v ref x 10 6 ? tc in ppm / c = calculating average temperature coefficient (tc) figure 1. v ref vs temperature test circuits i ref v ka = v ref v in i k i ref v ka v in i k (v ref ) r1 r2 v ka v in i k (off) figure 2. test circuit for v ka = v ref figure 3. test circuit for v ka > v ref figure 4. test circuit for i koff
4 date: 05/25/04 spx2431 precision adjustable shunt regulator ?copyright 20 04 sipex corporation -2 -1 0 1 2 3 150 125 100 75 50 25 0 -25 -50 -75 -100 v ka cathode voltage (v) i k cathode current (ma) v ka = v ref 0 c to 105 c -60 -30 0 30 60 90 120 2.53 2.52 2.51 2.50 2.49 2.48 2.47 2.46 2.45 t a ambient temperature ( c) v ref reference voltage (v) v ka = v ref i k = 10ma typical performance characteristics figure 5. high current operating characteristics figure 6. reference voltage vs ambient tempetature -1.0 0 1.0 2.0 3.0 900 800 700 600 500 400 300 200 100 0 -100 -200 v ka cathode voltage (v) i k cathode current ( a) v ka = v ref 0 to 105 c 105 c 25 c -0 c -60 -30 0 30 60 90 120 3.0 2.5 2.0 1.5 1.0 0.5 0 t a ambient temperature ( c) i ref reference input current ( a) r1 = 10k ? r2 = i k = 10ma figure 7. low current operating characteristics 10 100 1k 10k 100k 70 60 50 40 30 20 10 0 f frequency (hz) noise voltage n/ hz v ka = v ref i k = 10ma t a = 25 c 0 36912 15 18 21 24 27 30 0 -10 -20 -30 -40 -50 v ka cathode voltage (v) ? v ref (mv) 0 c 25 c 75 c 125 c i ka = 10ma figure 9. reference voltage line regulation vs cathode voltage and t ambient figure 10. noise voltage vs frequency figure 8. reference input current vs ambient temperature
5 date: 05/25/04 spx2431 precision adjustable shunt regulator ?copyrig ht 2003 sipex corporation v in v out v in v out typical performance characteristics: continued -60 -30 0 30 60 90 120 0.150 0.125 0.100 0.075 0.050 0.025 0.0 t a free air temperature z ka dynamic impedance ( ? ) v ka = v ref i k = 1 to 100ma f 1khz figure 11. low frequency dynamic output impedance vs t ambient 10 100 1k 10k 100k 1m 10m start 10.000hz stop 50 000 000.000hz ref level 60.000db 0.0deg /div 10.000db 45.000deg marker 25 297 mag (a/r) marker 25 297 phase (a/r) 698.000 hz -0.025 db 698.000 hz 93.320 deg gain phase 60db 50db 40db 30db 20db 10db 0db -10db -20db -30db -40db 215 180 135 90 45 0 -45 -90 -135 -180 -215 figure 12. small signal gain and phase vs frequency; i k = 10ma, t a = 25 c i k v in 9 f 15k ? 8.25k ? v out gnd 230 ? figure 13. test circuit for gain and phase frequency response figure 14. frequency = 100khz, i k = 10ma, t a = 25 c figure 15. test circuit for pulse response figure 16. stability boundary conditions i k v out gnd 250 ? 50 ? v in f p = 100khz 10 0 10 1 10 2 10 3 10 4 10 5 10 6 10 7 100 90 80 70 60 50 40 30 20 10 0 c l load capacitance (pf) i k cathode current (ma) a: v ka = v ref b: v ka = 5v at i k =10ma c: v ka =10v at i k =10ma d: v ka =15v at i k =10ma c d b a stable stable t a = 25 c
6 date: 05/25/04 spx2431 precision adjustable shunt regulator ?copyright 20 04 sipex corporation typical performance characteristics: continued figure 17. test circuit for stability figure 18. dynamic output impedance t a = 25 c, i k = 1 to 100ma figure 19. off state leakage figure 20. shunt regulator v out = (1+r1/r2)v ref 150 ? 10k ? i k c l r 0.01 0.1 1 10 100 -50 0 50 100 150 t a ambient temperature ( c) i k off cathode current (na) v ka = 20v v ref = 0v 1k 10k 100k 1m 10m 100 10 1.0 0.1 0.01 f frecuency (hz) z ka dynamic impedance ( ? ) t a = 25 c i k = 1 to 100ma r2 0.1% v in r3 r1 0.1% v out v ref spx2431 figure 21. constant current, sink, i sink = v ref /r1 figure 22. reference amplifier for isolated feedback in off-line dc-dc converters q1 v in r2 r1 0.1% i sink spx2431 r2 0.1% r3 r1 0.1% v out spx2431 c2 c1 isolated feedback v out rtn + r3 sets feedback gain, c1 provides feedback compensation opto isolator
7 date: 05/25/04 spx2431 precision adjustable shunt regulator ?copyrig ht 2003 sipex corporation typical performance characteristics: continued figure 23. precision high current series regulator v out = (1+r1/r2)v ref figure 25. single supply comparator with temperature compensated threshold. v in threshold = 2.5v v in r1 0.1% spx2431 r3 r2 0.1% c1 r5 r4 v out v in r1 0.1% spx2431 r3 r2 0.1% q1 v out v cc r2 spx2431 v in v out r1 * resistor values are chosen such that the effect to i ref is negligible . figure 24. high current shunt regulator v out = (1+r1/r2)v ref
8 date: 05/25/04 spx2431 precision adjustable shunt regulator ?copyright 20 04 sipex corporation packages: 3 pin sot-23 a a2 a1 side view a a seating plane c c with plating base metal b e e1 e e1 d b 1 2 3 l1 l gauge plane view c see view c b b 0.89 - 1.12 0.01 - 0.10 dimensions in (mm) 3 pin sot-23 jedec to-236 (ab) variation 0.88 0.95 1.02 0.30 - 0.50 0.08 - 0.20 0.40 0.50 0.60 0.54 ref 0? - 8 a a1 a2 b c d e e1 l l1 min nom max 2.80 2.90 3.04 2.10 - 2.64 1.20 1.30 1.40 e e1 0.95 bsc 1.90 bsc section b-b view a-a seating plane 3 pin sot-23
9 date: 05/25/04 spx2431 precision adjustable shunt regulator ?copyrig ht 2003 sipex corporation corporation analog excellence sipex corporation reserves the right to make changes to any products described herein. sipex does not assume any liability aris ing out of the application or use of any product or circuit described herein; neither does it convey any license under its patent rights nor t he rights of others. sipex corporation headquarters and sales office 22 linnell circle billerica, ma 01821 tel: (978) 667-8700 fax: (978) 670-9001 e-mail: sales@sipex.com part number acc output voltage packages spx2431am ...................... 0.5% ...................... 2.5v ......................... 3 pin sot-23 spx2431am/tr ................ 0.5% ...................... 2.5v ......................... 3 pin sot-23 spx2431m ........................ 1.0% ...................... 2.5v ......................... 3 pin sot-23 spx2431m/tr .................. 1.0% ...................... 2.5v ......................... 3 pin sot-23 ordering information /tr = tape and reel pack quantity is 2,500 for sot-23.
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