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power management 1 SC631 fixed 4.4v output charge pump regulator ? 2008 semtech corporation features input voltage range 2.9v to 5.5v v out tolerance 4.4v 3% continuous output current 250ma peak output current 500ma three charge pump modes: 1x, 1.5x and 2x output ripple 30mv pp for i out 400ma short circuit, over-voltage, and over-temperature protection soft-start functionality shutdown current 0.1a, typical ultra thin package 2 x 2 x 0.6 (mm) fully weee and rohs compliant applications mobile phones multi-led backlit lcds pmps digital video cameras digital still cameras pdas led camera fl ash audio amplifi er power ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? description the SC631 is a high-current voltage regulator using semtechs proprietary low-noise charge pump technol- ogy. performance is optimized for use in single li-ion battery cell applications. the regulator provides the per- formance of a linear, low drop-out (ldo) voltage regulator when the input is greater than 4.4v. unlike an ldo, drop- out is avoided when the input is less than 4.4v. instead, a charge pump is activated to provide voltage boost and the head-room needed for voltage regulation. only two 2.2 f bucket capacitors are required to deliver the full output current. the charge pump provides a low emi solution compared to inductive boost regulators. the SC631s charge pump has three modes of operation: 2x, 1.5x, and 1x modes. the 2x and 1.5x modes deliver current to the load in each of two phases. the 1x mode turns off the charge pump, delivering current through an ldo. when active, the charge pump provides low-ripple operation at 200khz, which is typically less than 30mvpp at the output. the SC631 is capable of delivering 250ma continuous current, with peak current to 500ma. a 22 f output capacitor is used for decoupling the load and for smoothing mode transitions. hysteresis is provided to prevent chatter between charge pump modes. the micro lead-frame package is both small and thermally effi cient, measuring 2 x 2 x 0.6 (mm). SC631 v bat v out = 4.4v @ 250ma out c1+ in gnd en c1- c2+ c2- c in 22 f c out 22 f c 1 2.2 f c 2 2.2 f chip enable typical application circuit july 24, 2008 patents pending
SC631 2 pin confi guration marking information ordering information device package SC631ultrt (1)(2) mlpd-ut-8 2x2 SC631evb evaluation board notes: (1) available in tape and reel only. a reel contains 3,000 devices. (2) lead-free package only. device is weee and rohs compliant. top view t 1 2 4 5 6 3 7 8 c2+ c2- out en gnd c1+ c1- in 631 yw mlpd-ut-8; 2x2, 8 lead ja = 68c/w yw = datecode
SC631 3 exceeding the above specifi cations may result in permanent damage to the devic e or device malfunction. operation outside of the parameters specifi ed in the electrical characteristics section is not recommended. notes (1) calculated from package in still air, mounted to 3 x 4.5 (in), 4 layer fr4 pcb with thermal vias under the exposed pad p er jesd51 standards. (2) tested according to jedec standard jesd22-a114-b. absolute maximum ratings in (v) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to +6.0 out (v). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to +6.0 c1+, c2+ (v) . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to (v out + 0.3) pin voltage all other pins (v) . . . . . . . . . -0.3 to (v in + 0.3) out pin short circuit duration . . . . . . . . . . con tinuous esd protection level (2) (kv) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 recommended operating conditions ambient temperature range (c) . . . . . . . . -40 t a +85 in (v) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.9 v in 5.5 thermal information thermal resistance, junction to ambient (1) (c/w) . . . . 68 maximum junction temperature (c) . . . . . . . . . . . . . . +150 storage temperature range (c) . . . . . . . . . . . . -65 to +150 peak ir reflow temperature (10s to 30s) (c) . . . . . . . +260 unless otherwise specifi ed: t a = +25c for typ, -40c to +85c for min and max; c 1 = c 2 = 2.2f (esr < 0.03); c in = c out = 22f; v in = 2.9v to 5.5v parameter symbol condition min typ max units output voltage v out v in = 4.2v, i out = 1ma 4.27 4.4 4.53 v output voltage ripple v pp i out 400ma 30 mv maximum output current i out peak load - thermally limited (1) , t j <150c, 3.33v v in 5.5v 500 ma continuous load, t a 55c, 2.92v v in 4.2v 325 ma continuous load 250 ma shutdown current i sd shutdown (en = gnd), v in = 3.6v 0.1 2 a total quiescent current i q en high, i out = 1ma 1.5 2.5 ma charge pump frequency f pump v in = 3.2v 200 khz start-up time t su (en transitions from low to high), 4.27v v out 4.53v, no load 400 s line regulation v line i out = 1ma, 2.85v v in 4.2v 21 mv load regulation v load v in =4.2v, 1ma i out 400ma 33 mv electrical characteristics
SC631 4 parameter symbol condition min typ max units en input high threshold v ih v in = 5.5v 1.6 v en input low threshold v il v in = 2.7v 0.4 v en input high current i ih v in = 5.5v 2 a en input low current i il v in = 5.5v 2 a open-loop output resistance r out 1x mode 0.25 1.5x mode, v in = 3.7v 2.85 2x mode, v in = 3.1v 2.9 mode transition voltage (2) v trans 1x i out = 200ma 4.41 v v trans 1.5x i out = 200ma 3.31 v fault protection short-circuit current i sc v out = 0v, i out = i in 300 600 980 ma input current limit i limit v out > 2v, 1x mode 0.6 1.2 2.0 a v out > 2v, 1.5x and 2x modes 1.2 2.0 2.8 a v out 2v, i out = i in 700 ma over temperature t otp rising threshold 165 c t hys hysteresis (3) 20 c electrical characteristics (continued) notes: (1) thermal limitation is dependent upon the thermal performance of the printed circuit board in support of the package standar d of 68 c/w. (2) voltage at the in pin where a mode transition takes place in the charge pump with v in falling. (3) guaranteed by design - not tested in production.
SC631 5 typical characteristics load regulation 25 20 15 10 5 0 0 90 180 270 360 450 output current (ma) v out = 4.4v, v in = 4.2v t a =85c t a =25c t a =-40c output voltage variation ? v load (mv) -15 -10 -5 0 5 10 15 20 25 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 output voltage variation ? v line (mv) v out = 4.4v, i out = 1ma input voltage (v) 3.6v, 0mv 85c 25c -40c line regulation psrr versus frequency 2x mode psrr versus frequency 1.5x mode -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 100 1000 10000 frequency [hz] gain [db] v in = 3.6v, v out = 4.4v, i out = 50ma c in =c out =22f (0805) c 1 =c 2 =2.2f (0603) -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 100 1000 10000 frequency [hz] gain [db] v in = 2.9v, v out = 4.4v, i out = 50ma c in =c out =22f (0805) c 1 =c 2 =2.2f (0603)
SC631 6 typical characteristics (continued) effi ciency 10ma effi ciency 50ma effi ciency 200ma effi ciency 100ma effi ciency 400ma effi ciency 300ma 50 60 70 80 90 100 2.7 3.0 3.3 3.6 3.9 4.2 v in (v) efficiency(%) v out = 4.4v, i out = 10ma 1.5x mode 2x mode mode transition hysteresis 50 60 70 80 90 100 2.7 3.0 3.3 3.6 3.9 4.2 efficiency(%) v out = 4.4v, i out = 50ma v in (v) 1.5x mode 2x mode mode transition hysteresis 50 60 70 80 90 100 2.7 3.0 3.3 3.6 3.9 4.2 efficiency(%) v in (v) v out = 4.4v, i out = 100ma 1.5x mode mode transition hysteresis 2x mode 50 60 70 80 90 100 2.7 3.0 3.3 3.6 3.9 4.2 efficiency(%) v out = 4.4v, i out = 200ma v in (v) 2x mode 1.5x mode mode transition hysteresis 50 60 70 80 90 100 2.7 3.0 3.3 3.6 3.9 4.2 efficiency(%) v out = 4.4v, i out = 300ma 1.5x mode mode transition hysteresis 2x mode v in (v) 50 60 70 80 90 100 2.7 3.0 3.3 3.6 3.9 4.2 v in (v) efficiency(%) v out = 4.4v, i out = 400ma 1.5x mode 2x mode
SC631 7 ripple 1x mode time (10s/div) v in -pp (20mv/div) v out -pp (20mv/div) i out (200ma/div) v in = 5.2v, v out = 4.4v, i out = 400ma c in =c out =22f (0805) c 1 =c 2 =2.2f (0603) ripple 1.5x mode ripple 2x mode v in -pp (100mv/div) v out -pp (100mv/div) i out (200ma/div) v in -pp (50mv/div) v out -pp (50mv/div) i out (200ma/div) time (10s/div) time (10s/div) c in =c out =22f (0805) c 1 =c 2 =2.2f (0603) c in =c out =22f (0805) c 1 =c 2 =2.2f (0603) 0ma 400ma v in = 4.2v, v out = 4.4v, i out = 400ma v in = 3.2v, v out = 4.4v, i out = 400ma 0ma 400ma 0ma 400ma startup (no load) v in = 3.6v, i out = 0ma v en (2v/div) C 0v v out (2v/div) C 0v 0v i out (200ma/div) startup (400ma) v in = 3.6v, i out = 400ma v en (2v/div) C 0v v out (2v/div) C 0v 0v i out (200ma/div) C typical characteristics (continued) time (200s/div) time (200s/div) quiescent current v out = 5v, i out = 1ma 0.5 1.0 1.5 2.0 2.5 2.90 3.16 3.42 3.68 3.94 4.20 -45c 25c 85c v in (v) i q (ma) c in =c out =22f (0805) c 1 =c 2 =2.2f (0603) c in =c out =22f (0805) c 1 =c 2 =2.2f (0603)
SC631 8 pin descriptions pin pin name pin function 1 gnd ground connect to ground plane with multiple vias 2 c1+ positive terminal of bucket capacitor 1 3 c1- negative terminal of bucket capacitor 1 4 in input supply voltage 5en chip enable active-high 6 out output 7 c2+ positive terminal of bucket capacitor 2 8 c2- negative terminal of bucket capacitor 2 t thermal pad this pad is for heat sinking and is not connected internally. it must be connected to a ground plane using multiple vias.
SC631 9 block diagram charge pump 200khz logic control reference voltage generator ldo c1+ c1- c2- out in en gnd c2+ 5 7 4 2 3 8 6 1
SC631 10 general description the SC631 is a 4.4v output charge pump regulator designed to support up to 325ma (t a 55c, 2.92v v in 5.5v) and 250ma (t a 85c, 2.90v v in 5.5v) of continu- ous current. SC631 applications include power for leds and audio amplifi ers in portable handheld equipment. SC631 may be used in conjunction with regulated current sink devices such as the sc620 octal led driver or with ballast resistors. the SC631 has three operating modes 1x, 1.5x, and 2x. the 1x mode is a linear series regulation mode with a low open-loop output resistance of only 250m . the 1x mode functions as a low-noise linear regulator. the 1.5x and 2x modes are a low noise, constant frequency, constant duty cycle switch mode, using two bucket capacitors. one bucket supports the full output current while the other bucket charges from the input. the two buckets exchange roles in the next phase, supplying continuous output current in both phases and reducing the need for a large output decoupling capacitor. the constant frequency, constant duty cycle operation also produces predictable constant frequency harmonics. mode transition hysteresis hysteresis is provided to prevent chatter between charge pump modes for input steps of up to 120mv. for optimum transient performance, it is recommended for the supply decoupling capacitance be large enough to prevent steps greater than 120mv. normally c in = 22uf is suffi cient to minimize supply transients during the charge pump mode transitions. thermal resistance the SC631 package is thermally effi cient when the circuit board layout connects the thermal pad through multiple vias to the ground plane. the thermal resistance rating is dependent upon the connection between the thermal pad and the ground plane. a layout that is done correctly should keep the junction temperature below the over- temperature limit while operating the SC631 within the specifi ed electrical conditions. a poor layout may allow the junction temperature to reach the over temperature limit, so it is important to maintain adequate ground plane around the device to maximize heat transfer to the pcb. temperature derating the v in supply range and ambient temperature range of the application should be compared with the following derating curve to determine the maximum safe continu- ous load current. the dc operating points beneath each curve are in the safe opera ting temperature range of the mlp package. 150 200 250 300 350 400 450 35 45 55 65 75 85 ambient temp (c) i out (ma) derating for v in < 4.2v derating for v in < 5.5v maximum continuous output protection circuitry the SC631 also provides protection circuitry that pre- vents the device from operating in an unspecifi ed state. these functions include: over-current protection (ocp) short-circuit current protection (sccp) over-temperature protection (otp) ? ? ? applications information
SC631 11 over-current protection over-current protection is provided to limit the output current. when v out is greater than 2v, ocp limits the output to 1a typical. the 2v threshold allows the device to recover from excessive voltage droop during an over- current event. short-circuit current protection short-circuit current protection is provided to limit the current that can be sourced when the output is shorted to ground. when a short circuit forces v out to drop below 2v, the sccp detects the condition and limits the output current to 600ma (typical). over-temperature protection the over-temperature circuit helps prevent the device from overheating and experiencing a catastrophic failure. when the junction temperature exceeds 165c, the device is disabled. it remains disabled until the junction tempera- ture drops below this threshold. hysteresis is included that prevents the device from re-enabling until the junc- tion temperature is reduced by 20c. capacitor selection the SC631 is designed to use low-esr ceramic capacitors for the input and output bypass capacitors as well as the charge pump bucket capacitors. ideal performance is achieved when the bucket capacitors are exactly equal. the value of input and output decoupling capacitors will vary with system requirements. for best ripple perfor- mance c in and c out are normally 22f and the bucket capacitors c 1 and c 2 are 2.2f. for low profi le designs, two 10f capacitors may be used in place of each 22f. applications information (continued) when selecting capacitors for the application, the dc voltage characteristic of the capacitor should be consid- ered. the value of capacitance at the dc operating voltage may be considerably lower than the rated value. the fol- lowing table lists recommended capacitor values which have been chosen to minimize the impact of this limitation. table 1 recommended capacitors capacitor value f case size notes c in , c out 22 0805 typical output v pp 20mv in all charge pump modes typical input ripple 100mv in all charge pump modes c bucket 2.2 0603 required for the full rated output current c bucket 2.2 0402 useful for load current up to 300ma note: use only x5r type capacitors, with a 6.3v rating or higher the highest capacitance values in the smallest package sizes tend to have poor dc voltage characteristics. the highest value 0402 size capacitor retains as little as 35% of its rated value at 5vdc. the same value chosen in the next larger package size (0603) retains about 60% of its rated value at 5vdc.
SC631 12 applications information (continued) pcb layout considerations poor layout can degrade the performance of the regula- tor and can be a contributory factor in emi problems, ground bounce, thermal issues, and resistive voltage losses. poor regulation and instability can result. the following design rules are recommended: place the bucket capacitors as close to the device as possible and on the same side of the board. use short wide copper areas between the capacitor pins and the device pins. 1. place the input and output decoupling capacitors as close as possible to the device and connect these capacitors ground pads together to the ground plane using multiple vias through a short wide copper area. connect pin 1 directly to the copper area under the thermal pad. the thermal pad at the center of the device is not electrically connected. connect this pad to the ground plane using multiple vias. use a ground plane to further reduce noise interference on sensitive circuit nodes. 2. 3. 4. 5. c out en v in c in SC631 v out c2+ c2- c1+ c1- gnd c 2 gnd en c 1
SC631 13 outline drawing mlpd-ut-8 2x2 2.00 .079 pin 1 indicator (laser mark) a1 seating plane c b a aaa c 1 n e 2.10 2.10 1.90 1.90 .083 .083 .075 .075 2 a2 d e/2 e bxn bbb c a b coplanarity applies to the exposed pad as well as the terminals. 2. d1 .061 .067 .071 1.55 1.70 1.80 e1 .026 .031 .035 0.65 0.80 0.90 d/2 e/2 e lxn d1 e1 inches .020 bsc b .007 bbb aaa n l e d .012 dim a1 a2 a min .000 .020 0.30 0.18 .012 0.25 .010 0.40 0.30 .004 .003 8 .014 .079 .016 0.08 0.10 8 0.35 2.00 0.50 bsc millimeters max 0.05 0.60 dimensions min 0.00 nom (.006) - - max .002 .024 nom 0.50 - (0.1524) - controlling dimensions are in millimeters (angles in degrees). notes: 1. a
semtech corporation power management products division 200 flynn road, camarillo, ca 93012 phone: (805) 498-2111 fax: (805) 498-3804 www.semtech.com contact information SC631 14 land pattern mlpd-ut-8 2x2 inches dimensions p z x y c g dim millimeters failure to do so may compromise the thermal and/or functional performance of the device. shall be connected to a system ground plane. thermal vias in the land pattern of the exposed pad 3. h .067 1.70 k .031 0.80 r .006 0.15 y r g z p x (c) 1. controlling dimensions are in millimeters (angles in degrees). h k .030 .106 (.077) .047 0.75 2.70 (1.95) 1.20 0.30 0.50 .020 .012 this land pattern is for reference purposes only. consult your manufacturing group to ensure your company's manufacturing guidelines are met. notes: 2.

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