SC615

SC615 SEMTECH | Alldatasheet

Document overview

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Technical content

Features

‹ 500mA Output Current - Flash Mode ‹ 3.0V to 5.25V Input Range ‹ Two Selectable Modes - Flash and Spotlight ‹ External Flash Control Pin for Synchronization to a Camera Module or Graphics Controller ‹ Spotlight Mode Current Setting - 100mA ‹ Short Circuit, Over-Voltage, and Over-Temperature Protection ‹ Soft-Start Functionality ‹ Two Control Inputs for Maximum Versatility ‹ Shutdown Current < 2 µA ‹ Micro Lead-frame Package MLPD-10, 3mm x 3mm ‹ Mobile Camera Phones ‹ Digital Cameras ‹ PDAs with Built-in Cameras ‹ Multi-LED Backlit LCDs The SC615 is a high-current charge pump designed spe- cifically for use with white LEDs used in camera flash applications. Only two small bucket capacitors are re- quired to develop the output drive, providing a low EMI solution compared to inductive boost regulators. The SC615 has two modes of operation: Flash mode and Spotlight mode. The SC615 is capable of delivering 500mA of peak current for a duration of 500ms in Flash mode. In Spotlight mode the SC615 outputs 100mA and can remain enabled continuously. A minimum 0.5 Ω sense resistor is used to set the cur- rent through the LED in both modes. This resistor dissi- pates up to 0.125W, reducing the power dissipation re- quirement of the SC615. The flash input (FLASH) over- rides the control input (CTRL) to make sure the flash func- tion is activated when called for. The thermally efficient MLPD-10 package and ceramic bypass and bucket capacitors help make the SC615 a high output current driver that requires a minimal amount of PCB area.

Description

3.0V to 5.25V SC615 VIN1 C2-2 C2+10 C1-4 C1+8 VOUT 9 FLASH 5 CTRL 7 GND 3 ISET 6 1µF 1µF FLASH CTRL 1µF white LED 0.5Ω 10µF

2 2005 Semtech Corp. www.semtech.com POWER MANAGEMENT SC615 Notes: 1) Calculated from package in still air, mounted to 3”x 4.5”, 4 layer FR4 PCB with thermal vias under the exposed pad per JESD51 standards. 2) Tested according to JEDEC standard JESD22-A114-B retemaraPl obmySm umixaMs tinU egatloVylppuSV NI 5.6ot3.0-V egatloVtuptuOV TUO 5.6ot3.0-V -2C,-1C,TESI,LRTC,HSALF-egatloVniP Vot3.0- NI 3.0+V +2C,+1C-egatloVniP Vot3.0- TUO 3.0+V V TUO noitaruDtiucriCtrohSC Se tinifednI tneibmAotnoitcnuJ,ecnatsiseRlamrehT )dohteMdradnatS15DSEJ( )1( θ AJ 94W /C° egnaRerutarepmeTtneibmAgnitarepOT A 58+ot04-C ° egnaRerutarepmeTnoitcnuJT CJ 051+ot04-C ° egnaRerutarepmeTegarotST GTS 051+ot56-C ° erutarepmeTwolfeRRIT DAEL 062C ° leveLnoitcetorPDSE )2( V DSE 2V k Absolute Maximum Ratings

Electrical Characteristics

Unless otherwise specified: TA = 25°C for TYP, -40°C to +60°C for MIN and MAX; retemaraPl obmySs noitidnoCn iMp yTx aMs tinU tnerruCtuptuOI TUO R,hgihHSALF TESI 5.0= Ω V<V3.3 NI V2.4< V<V8.2 TUO V52.4< 0640 050 45 Am R,wolHSALF TESI 5.0= Ω V<V8.2,hgihLRTC TUO V5.4< V<V0.3 NI V5.4< 570 015 21 egatloVecnerefeRTESIV TESI R,hgihHSALF TESI 5.0= Ω V<V3.3 NI V2.4< V<V8.2 TUO V52.4< 0320 520 72 Vm ,hgihLRTC,wolHSALF V<V8.2 TUO V5.4< V<V0.3 NI V5.4< 5.730 55 .26 Exceeding the specifications below may result in permanent damage to the device or device malfunction. Operation outside of the parameters specified in the Electrical Characteristics section is not implied.

3 2005 Semtech Corp. www.semtech.com POWER MANAGEMENT SC615 Unless otherwise specified: TA = 25°C for TYP, -40°C to +60°C for MIN and MAX; Notes: (1) Guaranteed by design - not tested in production. Electrical Characteristics (Cont.) retemaraPl obmySs noitidnoCn iMp yTx aMs tinU tnerruCtnecseiuQ IQ hgihHSALF4 .35 A m hgihLRTC,wolHSALF0 .25 .4A m wolLRTC,wolHSALF1 .02A µ noitaruDesluPedoMhsalF )1( t HSALF V<V3.3 NI V2.4< I TUO V,Am005= TUO V8.2> 005s m emiTpU-tratSedoMhsalF )1( t TS-F othgihseogHSALFnehw0=t I TUO eulavlaniffo%09= 1s m emiTpU-tratSedoMthgiltopS )1( t TS-S othgihseogLRTCnehw0=t I TUO eulavlaniffo%09= 1s m ycneuqerFrotallicsOf CSO delbanEeciveD0 52z Hk ycaruccAycneuqerFrotallicsO ∆f CSO 51-5 1% timiLtnerruCtuptuOtiucriC-trohSI CS V TUO V0=5 64A m timiLtnerruCtupnII TIMIL VNI V,V7.3= TUO V0.4=0 .11 .2A noitcetorPerutarepmeT-revO T TO 051C ° siseretsyH0 1C ° dlohserhThgiHtupnIcigoLV HI LRTC,HSALF5 .1V dlohserhTwoLtupnIcigoLV LI LRTC,HSALF4 .0V tnerruChgiHtupnIcigoLI HI LRTC,HSALF1 0 25 3 µA tnerruCwoLtupnIcigoLI LI LRTC,HSALF1 .02 µA egatloVelppiRTESI )1( V PP I-edomthgiltopS TUO Am001=5 2 Vm I-edomHSALF TUO Am005=0 01

4 2005 Semtech Corp. www.semtech.com POWER MANAGEMENT SC615 Ordering InformationPin Configuration niPe maNniPn oitcnuFniP 1N IV. egatlovtupnI 2- 2C. 2roticapactekcubfolanimretevitageN 3D NG. saivelpitlumgnisuenalpdnuorgottcennoc-dnuorG 4- 1C. 1roticapactekcubfolanimretevitageN 5H SALF sedirrevoosladnahgihnehwedomhsalFevitcaniecivedehtstup-nipelbaneedomhsalF .LRTC 6T ESI .rotsisergnittestnerrucehtdnaedohtacDELehtottcennoc-nipecnerefergnittes-tnerruC 7L RTC .hgihnehwedomthgiltopSnitnerructuptuoehttesdnaelbaneotdesu-tibtupnilortnoC 8+ 1C. 1roticapactekcubfolanimretevitisoP 9T UOV. niptuptuO 01+ 2C. 2roticapactekcubfolanimretevitisoP T lamrehT daP elpitlumgnisuenalpdnuorgottcennoC.yllanretnidetcennocton-sesoprupgniknistaehrofdaP .saiv Pin Descriptions ECIVEDE GAKCAP TRTLMI516CS )1( 3x301-DPLM )2( BVE516CSd raoBnoitaulavE Notes: (1) Available in tape and reel only. A reel contains 3000 devices. (2) Available in lead-free package only. This product is fully WEEE and RoHS compliant. TOP VIEW MLP10: 3X3 10 LEAD T VIN C2- GND C1- FLASH C2+ VOUT C1+ CTRL ISET

5 2005 Semtech Corp. www.semtech.com POWER MANAGEMENT SC615 Applications Information General Operation The SC615 is a powerful 2X charge pump designed to drive a high-intensity white LED with a constant current (Spotlight mode) or with a pulsed current of higher inten- sity (Flash mode) used for camera flash. In Flash mode the SC615 output can drive 500mA at 4.25V into an LED for a minimum duration of 500ms. The FLASH pin is used to trigger this mode (active high). In spotlight mode the SC615 regulates the output cur- rent to 100mA when the CTRL pin is pulled high and the FLASH pin is low. Note that Flash mode has priority over Spotlight mode, i.e., the FLASH pin triggers Flash mode regardless of the state of the CTRL pin. Output current is regulated by attaching the ISET pin to the cathode(s) of the LED package and a low resistance sense resistor (typically 0.5 Ω ). The ISET pin monitors the voltage at the cathode and signals the charge pump to increase or decrease the output current until the ISET voltage reaches the programmed setting. The resistor value is chosen to set the current through the LED based on this reference voltage. The resistor can be chosen to set either the flash mode current or spotlight mode cur- rent, but it should not be less than 0.5 Ω due to output current limitations of the device. Flash Mode Flash mode is enabled whenever the FLASH pin is pulled high and remains active until the FLASH pin is released. This mode has higher priority than Spotlight mode, so the state of the CTRL pin is overridden whenever the FLASH pin is activated. While in flash mode the refer- ence voltage on the ISET pin is set to 250mV. The dura- tion of the pulse is limited by the amount of power that can be dissipated in the SC615 before it exceeds the maximum operating temperature. Note that if an output current less than the rated 500mA is desired, the dura- tion of the pulse can increase proportionally. However, great care should be taken to insure the FLASH pin is not held high for an extended amount of time so that overheating does not occur. Extending flash mode be- yond the 500ms pulse limit could adversely affect the long term reliability of the SC615. Spotlight Mode Spotlight mode is enabled by setting the CTRL pin high and keeping the FLASH pin low. When in Spotlight mode, the SC615 can maintain a constant current indefinitely to drive an LED or bank of LEDs. The ISET reference voltage is set to 50mV so that the output current is main- tained at 100mA when a 0.5 Ω resistor is used. Protection Circuitry The SC615 also provides protection circuitry that pre- vents the device from operating in an unspecified state. These funtions include Input Over-Voltage Protection (IOVP), Output Over-Voltage Protection (OVP), Over-Tem- perature (OT) Protection, Over-Current Protection (OCP), and Short-Circuit Current Protection (SCCP). Input Over-Voltage Protection Input over-voltage protection is included to prevent op- eration at high input voltages that could damage the device. The IOVP circuit senses the input voltage and determines when the supply exceeds 6V. Hysteresis is included in this circuit to avoid chattering between states. When the voltage rises above this threshold, the device is disabled until the input voltage drops to a level within the specified range. Output Over-Voltage Protection Output over-voltage protection is included to prevent the SC615 from generating an output voltage that could dam- age other devices connected to it such as load LEDs and bypass capacitors. When the output voltage exceeds 5.5V, the OVP circuit disables the charge pump until the voltage decreases to a level within the acceptable range. This circuit allows the device to drive LEDs with high for- ward voltages at a reduced level without exceeding the output voltage limits specified for the device. Note, how- ever, that this effect is a consequence of the OVP circuit and is not its intended purpose. Over-Temperature Protection The over-temperature circuit helps prevent the device from overheating and experiencing a catastrophic fail- ure. When the junction temperature exceeds 150°C the device is disabled. It remains disabled until the junction temperature drops below this threshold. As with the UVLO and OVP circuits, hysteresis is included to prevent tog- gling between modes.

6 2005 Semtech Corp. www.semtech.com POWER MANAGEMENT SC615 Over-Current Protection When the SC615 is in 2X charge pump mode, the input current will be approximately doubled the required out- put. When the steady-state load requires the maximum current available in 2X mode, the OCP circuit prevents the device from overheating due to excessive power dis- sipation. 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. Resistor Selection The ISET resistor selection is critical in generating the correct current. The value can be chosen to set the Spot- light mode current or the Flash mode current, but it must be noted that the two current settings are dependent on the same resistor. It is recommended that the resistor be selected to match the desired LED current for Flash mode. This allows the designer to set the SC615’s maxi- mum current and select the package size necessary for the power dissipation required in Flash mode. The typi- cal application shown on page 1, uses a 0.5 Ω resistor to set a flash mode current of 500mA and spotlight mode current of 100mA. A high precision resistor should be used to ensure the specified accuracy for LED current. To avoid malfunction of the charge pump, it is recom- mended that the resistance seen at the ISET pin remain constant while the device is active (Flash or Spotlight mode). Changing the resistance value or the load cur- rent while the device is active could cause instability that would result in non-compliant behavior. The load current return path is from the ISET sense point through the resistor and back to the ground pins. Resis- tance in this path adds to the total resistance and has the effect of reducing the LED current by about 4% per 10mV of DC drop across the return copper trace in flash mode. For this reason, it is crucial to have a low resis- tance return path. Place and ground the resistor as close as possible to the ground pin of the SC615. The trace from the ISET pin has virtually no current. The ISET trace should make contact at the pad of the power sense re- sistor to minimize the effect of voltage drop between the LED cathode and the resistor. Capacitor Selection The SC615 is designed to use low-ESR ceramic capaci- tors for the input and output bypass capacitors as well as the charge pump bucket capacitors. Ideal perfor- mance is achieved when C1 is exactly equal to C2. It is recommended that X5R or X7R ceramic capacitors be used for best performance. Thermal Resistance The SC615 package is thermally efficient when the cir- cuit board layout connects the thermal pad though mul- tiple vias to the ground plane. The thermal resistance is rated at 49°C/W and this rating is dependent on the connection between the thermal pad and the ground plane. A layout that is done correctly should keep the junction temperature below the OT limit while operating the SC615 within the specified electrical conditions for I OUT and VISET. A poor layout may allow the junction tem- perature to reach the OT limit while in Flash or Spotlight mode. So, it is important to maintain adequate ground plane around the device to maximize heat transfer to the PCB. Applications Information (Cont.)

7 2005 Semtech Corp. www.semtech.com POWER MANAGEMENT SC615 Block Diagram 0.5Ω 1µF 1µF 1µF10µF CHARGE PUMP VBAT 250kHz Logic Control Reference Voltage Generator LDO C1+ C1- C2+ C2- VOUT ISET VIN CTRL FLASH GND white LEDCTRL FLASH

8 2005 Semtech Corp. www.semtech.com POWER MANAGEMENT SC615 Typical Characteristics Flash Duration Flash Current at 500ms Flash Current at 100ms Flash Current at 10ms VOUT = 3.53V(start) to 3.40V(LED heated 500ms) VOUT = 3.4V VOUT = 3.46V VOUT = 3.53V 100mA Spotlight Current VOUT = 2.93V 460 480 500 520 540 0 100 200 300 400 500 Pulse Duration [ms] LED Current [mA] VIN=4.2V VIN=3.75V VIN=3.3V 460 480 500 520 540 VIN [V] Current [mA] 460 480 500 520 540 VIN [V] Current [mA] 460 480 500 520 540 VIN [V] Current [mA] 70.0 85.0 100.0 115.0 130.0 VIN [V] Current [mA]

9 2005 Semtech Corp. www.semtech.com POWER MANAGEMENT SC615 Ch1 100mV/div Ch2 2V/div Ch3 2V/div 40us/div Startup Flash Mode 500mA Ch1 100mV/div Ch2 2V/div Ch3 2V/div 4us/div Flash Mode VISET Ripple Typical Characteristics (Cont.)

10 2005 Semtech Corp. www.semtech.com POWER MANAGEMENT SC615 Layout Guidelines The following layout is suggested for a two-layer design. The capacitors C1 and C2 are the bucket capacitors and each conducts the full load current of up to 500mA pulsed for one half clock cycle. C3 is the output decoupling capacitor placed near the SC615 VOUT pin. C4 is the input decoupling capacitor placed near the SC615 VIN pin. Multiple vias should be used whenever it is necessary to change layers on nets connecting to pins VIN, VOUT, GND, C1-, C1+, C2- and C2+. Resistor R1 is routed with a very low resistance connection be- tween R1 and GND pin 3. The sense trace between Pin 6 and R1 is routed around the ground vias, allowing the Bottom Copper Top Copper shortest ground return path possible. The sense trace is connected to R1 at the positive terminal pad for the most accurate output possible. The bottom copper layer is mostly a ground plane with no obstructions between the ground vias. The smaller rectangle to the left connects the input power to VIN pin 1 and input capacitor C4. The two traces at the lower left are for logic inputs FLASH and CTRL. The trace to the right is the ISET pin "sense" trace. The sense trace is routed out of the path of the returning ground current.

11 2005 Semtech Corp. www.semtech.com POWER MANAGEMENT SC615 Outline Drawing -MLPD-10 3x3 Marking Diagram MIN aaa bbb b e L N D C E A DIM MILLIMETERS NOM DIMENSIONS MAXNOM INCHES MIN MAX (LASER MARK) INDICATOR PIN 1 N NOTES: CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS TERMINALS.2. .003 .007 .042 .009 .048 .000 .031 (.008) 0.08 0.23 .011 .052 0.18 1.06 .039 .002 0.00 0.80 1.31 0.30 1.21 0.05 1.00 (0.20) .004 0.10 0.50 BSC.020 BSC A aaa C SEATING PLANE A bxN bbb C A B B e C C D LxN E E 615 yyww Top Mark xxxx yyww = Datecode (Example = 0552) xxxx = Semtech Lot Number

12 2005 Semtech Corp. www.semtech.com POWER MANAGEMENT SC615 Land Pattern - MLPD-10 pin .087 .055 2.20 1.40 .150 .020 .012 .037 3.80 0.30 0.95 0.50 (.112) .075 1.90 (2.85) K H X THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY. CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES ARE MET. NOTES: INCHES DIMENSIONS G K H X Y P Z C DIM MILLIMETERS Y ZG(C) P Semtech Corporation Power Management Products Division

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