1 date: 09/10/04 sp6231 500ma, 3.3v linear regulator ?copyright 2004 sipex corporation features ?iny?dfn package offers excellent thermal characteristics (also available in nsoic) ?litch free?transition between two supplies 3.3v fixed ldo output voltage 400 a quiescent current @500ma load fast transient response current limit protection thermal shutdown protection with hysteresis auxiliary supply control internal 0.2 ? pfet switch eliminates external fets kelvin connection with 3.3v feedback 500ma, 3.3v linear regulator with auxiliary backup sp6231 description applications usb peripherals nic cards pcmcia/pci cards desktop computers dual power systems the sp6231 is a 500ma, 3.3v ldo with an integrated auxiliary voltage input switch. during normal operation, the sp6231 acts as a standard ldo with an output voltage of 3.3v delivering up to 500ma. when the 5v input drops below 4.4v, the 3.3v, v aux input is switched to the output through an internal pfet, maintaining a constant ?litch free?output voltage. the sp6231 is ideally suited for nic cards and portable battery powered equipment. when a desktop computer reverts to sleep mode, its 5v bus is removed, leaving only the 3.3v bus. the sp6231? auxiliary output passes the 3.3v bus through, keeping the nic card available for any wake-on-lan command. in battery powered applications, the sp6231 draws power from any available 5v usb connection and reverts to battery power when the usb power is removed. v out 3.3v @ 500ma sp6231 gnd out +5v usb v in v aux v sense +3.3v aux c2 2.2 f gnd gnd c1 2.2 f c3 10 f typical application circuit now available in lead free packaging 1 2 3 4 5 6 7 8 sp6231 8 pin nsoic v aux v in gnd gnd gnd gnd v sense v out
2 date: 09/10/04 sp6231 500ma, 3.3v linear regulator ?copyright 2004 sipex corporation v in ......................................................................................... 0.3v to 7v v out ..................................................................................... 0.3v to 6v v aux ..................................................................................... 0.3v to 7v storage temperature ........................ -65 c to 150 c power dissipation ............................ internally limited lead temperature (soldering) .... 60 sec. max above 183 c,230 c peak parameter units min typ max conditions linear regulator output voltage v 3.200 3.300 3.400 10ma < i out < 500ma line regulation mv 1 5 v in = 4.75v to 6v load regulation mv 5 25 v in = 5v, i out = 10ma to 500ma ground current a 110 i out = 10ma a 400 i out = 500ma current limit a 0.55 1.0 1.5 0v < v out < 3.2v thermal shutdown c 140 165 v in = 5v or v in = 0v thermal shutdown c15 hysteresis v sense pin current a15 auxiliary backup upper v in threshold v 4.35 4.5 4.65 v in increasing lower v in threshold v 4.25 4.4 4.55 v in decreasing v in threshold hysteresis mv 100 ground current a40v in < 4.25v, v aux = 3.3v, i out = 0ma r ds(on) ? 0.2 0.4 v in < 4.25v,v aux = 3.3v, i out = 500ma current limit a 1.1 0v < v out < 3.2v maximum junction c 125 temperature, t j(max) thermal resistance, ja c/w 57 dfn package unless otherwise specified: -40 c < t a < 85 c, 4.75v v in < 6v, c out 10 f with esr <1 ? , i out = 10ma, v aux = 3.3v these are stress ratings only and functional operation of the device at these ratings or any other above those indicated in the operation sections of the specifica- tions below is not implied. exposure to absolute maximum rating conditions for extended periods of time may affect reliability. absolute maximum ratings electrical characteristics
3 date: 09/10/04 sp6231 500ma, 3.3v linear regulator ?copyright 2004 sipex corporation 8 pin nsoic 6 pin dfn pin name description v sense kelvin connection with 3.3v feedback. always tiethis pin to 1 4 the point of regulation 2 5 v in main 5v input. 3 6 v out v out = 3.3v when v in > 4.5v; v out = v aux when v in 4.4v 4 1 v aux 3.3v auxiliary backup supply that is switched in through an internal pmos when v in drops below 4.4v typically. 5-8 3 gnd 6 pin mlp is grounded. - 2 nc no connect functional diagram bandgap reference gnd v aux v in v in v out v sense (kelvin tied to v out ) gnd r4 + _ v ref v ref current limit 0.8a thermal shutdown 165 c r1 r2 enable 100mv hysteresis +3.3v v aux m2 m1 control logic r3 current limit 1.0a - + v ref enable ldo pin description
4 date: 09/10/04 sp6231 500ma, 3.3v linear regulator ?copyright 2004 sipex corporation general overview the sp6231 combines a linear regulator with an auxiliary backup. when the main supply volt- age is applied at v in , the sp6231 acts as a regulator. it supplies 3.3v at its output and sources up to 500ma with an overall accuracy of 3%. full protection with both current limit and thermal shutdown is provided. when the main supply drops below 4.4v, the output is switched through an internal pfet to the auxil- iary supply input. a typical application is a usb peripheral (for instance a digital camera) that in normal opera- tion draws power from a battery supply (v aux ) but when it is plugged into the usb port will recognize the main power supply availability (v in ) and draw its power from there, switching over from the battery to the main power supply. when the usb peripheral is removed from the usb port, the output is switched back ?litch free?to the battery supply so the peripheral sees no supply interruption. other applications in- clude nic cards, desktop computers, power supplies with multiple input sources and pcmcia/pci interface cards. modes of operation there are 2 modes of operation. the first mode is the ldo mode when the main supply (v in ) is above 4.5v. at this point (independent of what voltage the auxiliary supply is at) the sp6231 acts as an ldo with an output of 3.3v capable of delivering up to 500ma. in this mode all circuitry is powered off of the main supply v in . the second mode, the backup switch mode, occurs when v in drops below the auxiliary supply (and below the 4.4v ldo mode). in this mode the output is directly connected to the auxiliary input through an internal 0.2 ? pfet switch. all circuitry is powered off of the aux- iliary supply. when the main supply is below 4.4v but still greater then the auxiliary supply, the output is connected to the auxiliary supply but most internal circuitry is still powered off of the main supply. how this effects quiescent currents can be seen in figure 1. linear regulator mode when the main supply of the sp6231 (v in ) is above 4.5v, the part is in linear regulated ldo mode (regardless of the auxiliary supply level). it sources 3.3v ( 3%) up to 500ma. +3.3v auxiliary switch mode when the main supply falls below 4.4v, the output is connected to the auxiliary supply through an internal 0.2 ? pfet switch. sense pin in the ldo mode, a sense pin provides a kelvin connection with a 3.3v feedback (always tie this pin to the point of regulation). if an accurate 3.3v supply is needed some distance away from the sp6231, a drop in voltage might occur due to the resistance of the length of the trace from the sp6231 to where the supply is needed. for a 0.5 ? trace carrying 500ma the drop would be 0.25v leaving 3.05v at the supply destination. by kelvin connecting the sense pin to the supply destination the sp6231 will adjust its output voltage (to 3.55v) so that the voltage is 3.3v at the supply destination. if this accuracy is of no conc ern, the sense pin can simply be tied to the output pin. the sense pin draws 15 a of current. thermal and overcurrent protection both the ldo switch and the backup switch have overcurrent and thermal protection. the overcurrent protection will limit the output cur- rent to 1a for the ldo and 0.8a for the backup switch typically. when the sp6231 heats up above 165 c (due to power consumption in the chip), both switches will be opened so the part can cool down. once the temperature drops by 15 c, the sp6231 will turn on again. 0 20 40 60 80 100 120 0123456 v in (v) quiescent currents ( a) i in i aux figure 1. ground pin current vs. input voltage (v aux = 3.3v, no load) theory of operation
5 date: 09/10/04 sp6231 500ma, 3.3v linear regulator ?copyright 2004 sipex corporation typical performance characteristics v out figure 7. glitch free operation: switching from v aux to v in and vice versa. v aux = 3.3v, i load = 100ma. 0 10 20 30 40 50 60 70 80 90 0 100 200 300 400 500 600 700 output current (ma) ground current ( a) figure 6. ground pin current vs. load in backup switch mode, v aux = 3.3v, v in is floating. 0 10 20 30 40 50 60 70 0123456 v aux (v) i aux ( a) figure 5. ground pin current vs. v aux backup switch mode, v in is floating, no load. figure 4. v out over temperature, v in = 5v, i l = 10 a. 3.268 3.270 3.272 3.274 3.276 3.278 3.280 3.282 3.284 3.286 3.288 -60 -10 40 90 140 tem p erature ( c ) v out (v) figure 3. ground pin current vs. load in ldo mode, v in = 5v, v aux = 3.3v. figure 2. dc load regulation (includes thermal heating of the die), vin=5v 3.00 3.05 3.10 3.15 3.20 3.25 3.30 3.35 0 100 200 300 400 500 load current ( ma ) output voltage (v) 0 100 200 300 400 500 600 700 0 100 200 300 400 500 600 700 800 900 load current (ma) ground pin current ( a)
6 date: 09/10/04 sp6231 500ma, 3.3v linear regulator ?copyright 2004 sipex corporation typical performance characteristics figure 9. supply switching under full load, vaux=3.3v. ch 1=vin; ch 2=vout; ch 3=iload (500ma/div). figure 8. load transients. 1 - v out , 4 - i load (500ma/div) input capacitor a small capacitor 2.2 f or higher, is required from v in to gnd and v aux to gnd to create a high frequency bypass for the ldo amplifier. any ceramic or tantalum capacitor may be used at the inputs. capacitor esr (equivalent series resistance) should be smaller than 1 ? . output capacitor an output capacitor is required between v out and gnd to prevent oscillations. a 2.2 f ca- pacitor ensures unconditional stability from no load to full load over the entire input voltage and temperature range. larger capacitor values im- prove the regulator? transient response. the output capacitor value may be increased with- out limit. the output capacitor should have an esr below 3 ? and a resonant frequency above 1mhz. thermal considerations the sp6231 is designed to provide 500ma of continuous current. maximum power dissipa- tion can be calculated based on the output cur- rent and voltage drop across the device. to determine the maximum power dissipation in the package, use the junction-to-ambient ther- mal resistance of the device and the following basic equation: p d(max) = (t j(max) - t a ) / ja t j(max) is the maximum junction temperature of the die and is 125 c. t a is the ambient operating temperature. ja is the junction-to-ambient ther- mal resistance for the regulator and is layout and package dependent. the actual power dissipation of the regulator circuit can be determined using one simple equation: pd = (v in - v out ) * i out + v in * i gnd ? (v in - v out ) * i out substituting p d(max) for p d and solving for the operating conditions that are critical to the ap- plication gives the maximum operating condi- tions for the regulator circuit. for example if we are operating the sp6231 at room temperature, with a minimum footprint layout, we can deter- mine the maximum input voltage for a set output current. p d(max) = (125 c - 25 c) / 57 c/w = 1754mw ( ja = 57 c/w for the 3x3 mlp package) notice that the ldo in the mlp package has a much smaller ja than in comparable dimen- sions. for comparison, ja = 220 c/w for a sot-23 package. application information
7 date: 09/10/04 sp6231 500ma, 3.3v linear regulator ?copyright 2004 sipex corporation v out 3.3v sp6231 gnd v in v aux v sense v aux +3.3v c5 2.2 f c4 10 f v out gnd c3 2.2 f v in 5v gnd 1 2 3 4 +5v usb connector gnd lx v batt shdn j1 10 h v out shdn c2 100 f schottky diode d1 1 2 3 c1 100 f 5 4 1 2 3 v batt sp6641b j3 1 2 3 6 5 4 sp6231 500ma, 3.3v cmos ldo with auxiliary backup sp6641b two cell boost to prevent the device from entering thermal shutdown, maximum power dissipation can not be exceeded. using the output voltage 3.3v and an output current of 500ma, the maximum input voltage can be determined. ground pin current can be taken from the electrical characteristics table (i gnd = 400 a at i out = 500ma). the maximum input voltage is determined as fol- lows: 1754mw = (v in - 3.3v) * 500ma + v in * 0.4 ma solving for v in , we get: v in = (1754mw + 1650mw) / 500.2ma after calculations, we find that the maximum input voltage of a 500ma application in a 3x3 mlp package, with a minimum footprint lay- out, is 6.8v. application information this application circuit is available as the evaluation board sp6231eb and is described in detail in the sp6231 evaluation board manual. portable application circuit: sp6231 and sp6641b sp6231 with sp6641 in a portable application in a portable application, the power sources are often switched between batteries and usb 5v supplies. utilizing usb power eliminates the loading on the batteries when the device is connected to computers, and thus can signifi- cantly increase battery life. when the device is powered by single or dual alkaline batteries, a boost regulator, such as sp6641a/b, converts the battery voltages to a regulated 3.3v. sp6641a/b is packaged in a tiny sot-23 pack- age and requires less than 10 a quiescent cur- rent. when the output of sp6641a/b is con- nected to sp6231 as an auxiliary supply, sp6231 will automatically disconnect its load when the presence of usb power is detected. however, when the portable device is disconnected from usb, sp6231 seamlessly reconnects sp6641a/ b output to the load.
8 date: 09/10/04 sp6231 500ma, 3.3v linear regulator ?copyright 2004 sipex corporation package: 6 pin dfn k 6 pin dfn jedec mo-229c (veea-2) variation dimensions in (mm) symbol min nom max a a1 a3 b d d2 e2 e l 0.80 0.90 1.00 0 0.02 0.05 0.20 3.00 bsc 2.20 2.60 0.30 0.40 0.50 1.40 1.75 0.23 0.25 0.30 0.50 e 3.00 bsc - - - -- - 0.20 - - to p v iew bottom view a a3 a1 d e e/2 d/2 l k d2 e2 1 e b side view
9 date: 09/10/04 sp6231 500ma, 3.3v linear regulator ?copyright 2004 sipex corporation see view c 1 1.65 a a2 a1 seating plane side view l1 l 1 1 seating plane gauge plane l2 view c top view e e e/2 e1 a index area (d/2 x e1/2) e1/2 d b 1 8 pin nsoic p ackage: c with plating base metal b contact area dimensions minimum/maximum (mm) 8 pin nsoic (jedec ms-012, aa - variation) common height dimension a a1 a2 b c l e e1 e l2 l1 1.35 4.90 bsc 0.40 0.31 0.51 symbol min nom max 0.10 - 0 . 2 5 d 1.75 1.25 0.17 0.25 6.00 bsc 3.90 bsc 1.27 bsc 1.27 1.04 ref 0.25 bsc 0 5 8 15 - - - - - - - package: 8 pin nsoic
10 date: 09/10/04 sp6231 500ma, 3.3v linear regulator ?copyright 2004 sipex 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. corporation sipex corporation headquarters and sales office 233 south hillview drive milpitas, ca 95035 tel: (408) 934-7500 fax: (408) 935-7600 ordering information part number temperature range package type sp6231er-3.3 ...................................... -40 c to 85 c .............................................. 6 pin dfn sp6231er-3.3/tr ................................ -40 c to 85 c ............................................. 6 pin dfn sp6231en-3.3 ...................................... -40 c to 85 c .......................................... 8 pin nsoic sp6231en-3.3/tr ................................ -40 c to 85 c ......................................... 8 pin nsoic available in lead free packaging. to order add "-l" suffix to part number. example: sp6231er-3.3/tr = standard; sp6231er-l-3.3/tr = lead free /tr = tape and reel pack quantity is 2,500 for nsoic and 3,000 for dfn.
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