Description The SC46 is a versatile charge pump designed for use in battery operated power supply applications over the wide input range of.6 to. volts. A simple, low quiescent current charge pump doubler can be implemented without costly inductors or capacitors. Internal MOSFETs and control circuitry eliminate the need for costly board space and design time. The small 6 lead SOT- package helps minimize board space. The SC46 charge pump can be used for applications that require up to 80mA of output current with =.V to.v. Typical dropout voltage ( )-V OUT is shown below for several values of. Features SC46 High Output Current Charge Pump Doubler Input supply voltage range of.6v to.v Small size - 6 pin SOT- package Typical effi ciency of : 9% @ =.V, = 4mA 94% @ =.6V, = ma Short circuit and over-temperature protection 40μA typical input current @ no load Shutdown current <μa Designed to work with ceramic or tantalum capacitors Fixed frequency of 60kHz All specifi cations rated over full temperature range (-40 C to 8 C) 0.9 Typical Dropout Voltage vs. @T A = Deg. C. Output Dropout Voltage (V) VIN =.V 0.8 VIN =.V VIN =.6V 0.7 VIN = 4.V VIN =.V 0.6 0. 0.4 0. 0. Typical 0. Application Circuit Applications Cellular phones Handheld devices LCD Display 0.0 000E+0 0E- 40E- 60E- 80E- 00E- (A) Typical Application Circuit Logic Control or GND SC46 4 SHDN VOUT C OUT V OUT C IN VIN GND C+ C- 6 C BUCKET December, 00
SC46 Absolute Maximum Ratings () Exceeding the specifi cations below may result in permanent damage to the device or device malfunction. Operation outside of the parameters specifi ed in the Electrical Characteristics section is not implied. Parameter Symbol Maximum Units Supply Voltage -0. to +6.0 V Output Voltage V OUT -0. to + V V OUT Short Circuit Duration SC Indefi nite Thermal Resistance Junction to Ambient () θ JA 0 C/W Operating Ambient Temperature Range T A -40 to +8 C Junction Temperature Range T J -40 to + C Storage Temperature Range T STG -6 to +0 C Peak IR Flow Temperature, SC46ISKTR T LEAD 40 C Peak IR Flow Temperature, SC46ISKTRT T LEAD 60 C Notes: ) This device is ESD sensitive. Use of standard ESD handlng precautions is required. ) Calculated from package in still air, mounted to x 4., 4 layer FR4 PCB with thermal vias under the exposed pad as per JESD standards. Electrical Characteristics Unless specifi ed: T A = -40 C to 8 C, SHDN = GND,.6V.V, Frequency =60kHz, C IN = C OUT = C BUCKET = (ESR = 0.Ω). Parameter Symbol Conditions Min Typ Max Units Input Supply Voltage.6. V = 0, =.V 40 60 μa Input Supply Current I IN = 0, =.6V 00 400 μa SHDN = 0. μa Ouput Resistance () R OUT =.V 9.. Ω Output Resistance () R OUT =.6V 7. 0. Ω Total Switch Resistance () R SW =.V 4. Ω Total Switch Resistance () R SW =.6V Ω Output Current =.V 80 ma =.6V 80 ma Oscillator Frequency f OSC 00 60 00 khz 00 Semtech Corp.
SC46 Electrical Characteristics (Cont.) Parameter Symbol Conditions Min Typ Max Units Short Circuit Current I SC V OUT = 0V 00 ma Output Ripple (pk-pk) ()(4) V R = 4mA, =.V 7 mv Power Effi ciency () η = 4mA, =.V 86 % Maximum Output Voltage (4) V OUT = 0mA V Time to Regulation at t Turn-On () ON = 0 to 60mA, =.6V 00 μs Input High Threshold SHDN pin,.v.v.6 V Input Low Threshold V IL SHDN pin,.v.v 0.4 V Over-Temperature Protection (4) T OT 40 C Over-Temperature Hystereis (4) Hysteresis 0 C Notes: ) The internal switch resistance, the capacitor ESR and the oscillator s switching frequency all contribute to R OUT. See the CAPACITOR SELECTION section on Page 6 for information on applying the R OUT specifi cation. ) The parameter R SW is equal to the total resistance of all 4 internal switches. See the CAPACITOR SELECTION section for information on applying the R SW specifi cation. The parameter was calculated from actual output resistance and the equation on Page 6 for R OUT. ) All electrical characteristics are for the Typical Application Circuit on Page. 4) Guaranteed by design. ) Soft start functionality is performed along with short circuit protection. If V OUT is less than - 00mV, then all switches are turned off and V OUT is charged with a 00mA current source from. When V OUT reaches - 00mV all switches are enabled. 00 Semtech Corp.
SC46 Pin Confi guration Ordering Information DEVICE () SC46ISKTR SC46ISKTRT () PACKAGE() SOT--6 SOT--6 Notes: ) Available in tape and reel only. A reel contains,000 devices. ) This Pb free device is WEEE and RoHS compliant. Pin Descriptions Pin# Pin Name Pin Function VIN Supply input voltage. GND Ground. C- This pin should be connected to the negative terminal of the external charging capacitor. 4 SHDN Shutdown pin. When this pin is connected to, the device enters sleep mode. VO Voltage output. 6 C+ This pin should be connected to the positive terminal of the external charging capacitor. Block Diagram Marking Information Top Mark 46 yyww Bottom Mark yyww = Datecode (Example : 0) 00 Semtech Corp. 4
SC46 Pin Confi guration Applications Information Theory of Operation The SC46 utilizes a switched capacitor charge pump to generate an output voltage approximately. An internal oscillator generates two out of phase fi xed frequency clock signals which turn on and off internal MOS- FET switches. During phase, the fl ying charge pump capacitor is charged to through switches S and S. During phase, the fl ying charge pump capacitor is connected in series with the input voltage via S and S4, producing an output voltage. ON S,S Charge transfer from C IN to C BUCKET If V OUT is less than - 00mV, then all switches are turned off and V OUT is charged with a 00mA current source from. When V OUT reaches - 00mV, the current source is disconnected from output and the charge pump circuitry is enabled again. Output Current The dropout voltage for a charge pump doubler is defi ned as ( ) - V OUT. The maximum output current is usually specifi ed as that which will not cause the dropout voltage to exceed the requirements of the application. The calculation of the dropout voltage is given in the capacitor selection section on Page 6. Typical dropout voltages versus are graphed on Page 8. Thermal Shutdown OFF ON S,S4 OFF Charge transfer from: C IN and C BUCKET to C OUT (Doubler) S S4 V OUT = x The thermal shutdown circuit provides added protection to the SC46. During a V OUT short circuit condition or if the load is excessive, the over-temperature circuitry will shut down the charge pump if the junction temperature exceeds approximately 40 C. The charge pump is enabled only if the junction temperature drops to approximately 0 C. The SC46 will cycle in and out of thermal shut down until the short circuit or the excessive load condition on V OUT is removed, thereby improving device reliability. The junction temperature can be calculated from the following formula if the ambient temperature (T A ) and the charge pump power dissipation (P DISS ) are known. CBUCKET COUT Cin S S T J = T A + P DISS θ JA ; θ JA = 0 C/W Doubler Short Circuit/Soft-Start An internal current limit and soft-start circuit provides protection against output short circuit and limits large current spikes generated during the initial start-up to charge output capacitor. 00 Semtech Corp.
SC46 Applications Information (Cont.) Capacitor Selection Capacitor selection is based on both the maximum acceptable ripple voltage and the maximum tolerable drop at the output. Ripple The peak-to-peak output ripple voltage is dependent on the following factors: ) Oscillator frequency ) ESR of C OUT ) Capacitance value of C OUT Item is fi xed and depend on the charge pump device used. Item, and can be optimized for best performance and reduction of the output ripple. The following formula could be used for an approximation for V OUT_RIPPLE. V OUT Drop V OUT_RIPPLE = + I ESR_ C OUT f OSC C OUT This equation can be used to calculate C BUCKET for a specifi c V OUT when and are known. The maximum value for the R SW from the Electrical Characteristics section on Page should be used in order to fi nd a worst-case number. Layout Consideration Standard power board layout should be followed to ensure proper operation. Any stray inductance should be minimized, this can be achieved by using large power planes or traces, and reducing the distances between input, output and the load. All components should be placed as close as possible to the SC46. The following table shows typical capacitor characteristics. Component ESR(Ω) ESL(nH) 0.μF Ceramic 060 Package 0.00.60.0μF Ceramic 06 Package 0.040 0.47 0μF Ceramic 060 Package 0.07 0.0 47μF Ceramic, 6V Tantalum D case 0.00 0.60 0μF, 6.V OSCON 0.0.0 0μF, 6V AL. Electrolytic 0.4.7 80μF, 4V OSCON 0.0.0 000μF, 0V Al. Electrolytic 0.0.00 The voltage drop at the output is specifi ed with the following equation: V OUT_DROP = R OUT R OUT is dependent on the following factors: ) Oscillator frequency ) ESR of C OUT & C BUCKET ) Capacitance value of C OUT and C BUCKET 4) Internal switch resistance (R SW = Total of all 4 switch resistances). A good approximation for calculating the output resistance is shown below. R OUT = f OSC C BUCKET + R SW + 4 ESR_ C BUCKET + ESR_ C OUT 00 Semtech Corp. 6
SC46 Applications Information (Cont.) = V to.v U SC46 VIN Vo VIN U SC98 VOUT V OUT = V C IN 4 SHDN C+ 6 C BUCKET C OUT GND EN BYPASS 4 GND C- C 0nF C μf EN Volts Fixed Ouput Voltage = V to V U SC46 VIN Vo IN U SC4 OUT V OUT =.V C IN 4 SHDN C+ 6 C BUCKET C OUT EN 4 GND BYP GND C- EN C C 0nF μf. Volts Fixed Ouput Voltage VIN =.V 0 BSTH DRV H 6 SC46 4 OCSET PHASE VIN Vo 9 BSTL DRV L 8 4 SHDNC+ 6 GND C- 4 VCC GND PGND VREF 7 SS/SHDN Sense Power Good PWRGD OVP SC0 (.V Input Supply) Battery Operated Synchronous Buck Converter 00 Semtech Corp. 7
SC46 Typical Characteristics Typical I IN vs., = 0mA Typical Dropout vs. Typical I IN vs. @T A = Deg. C. 0.9 Typical Dropout Voltage vs. @T A = Deg. C. 700E-6 0.8 VIN =.V VIN =.V IIN (A) 600E-6 00E-6 400E-6 00E-6 00E-6 Output Dropout Voltage (V) 0.7 0.6 0. 0.4 0. 0. VIN =.6V VIN = 4.V VIN =.V 00E-6 IOUT = 0mA 0. 000E+0.0.0.0 4.0.0 6.0 (V) 0.0 000E+0 0E- 40E- 60E- 80E- 00E- (A) Typical I IN vs. T A, = 0mA Typical Dropout vs. T A Typical I IN vs. T A @ = 0mA Typical Dropout Voltage vs. T A 900E-6 800E-6 VIN =.V VIN = 4.V 0E- VIN =.V, IOUT = 0mA IIN (A) 700E-6 600E-6 00E-6 400E-6 00E-6 00E-6 VIN =.6V VIN =.V VIN =.V Output Dropout Voltage (V) 00E- 40E- 400E- 0E- VIN =.6V, IOUT = 60mA 00E-6 000E+0-40 -0 0 0 40 60 80 TA (Deg. C.) 00E- -40-0 0 0 40 60 80 T A (Deg. C.) Typical Efficiency vs. Typical Output Ripple Typical Efficiency vs. @T A = Deg. C. 00% 96% V OUT Ripple 0mV/Div. Efficiency (%) 9% 88% VIN =.V VIN = 4.V 84% VIN =.6V VIN =.V VIN =.V 80% 000E+0 0E- 40E- 60E- 80E- 00E- (A) =.6V = 60mA C IN = C OUT = C BUCKET =.µf 00 Semtech Corp. 8
SC46 Outline Drawing - SOT--6L X E/ ccc C X N/ TIPS aaa C SEATING PLANE C A N B D e D EI E e A A A bxn bbb C A-B D DIMENSIONS INCHES MILLIMETERS DIM MIN NOM MAX MIN NOM MAX A.0 -.07 0.90 -.4 A.000 -.006 0.00-0. A.0.04.0.90..0 b.00 -.00 0. - 0.0 c.00 -.009 0.08-0. D.0.4..80.90.0 E.060.06.069.0.60.7 E e.0 BSC.07 BSC.80 BSC 0.9 BSC e.07 BSC.90 BSC L.0.08.04 0.0 0.4 0.60 L (.04) (0.60) N 6 6 0 0-0 0-0 aaa.004 0.0 bbb.008 0.0 ccc.008 0.0 GAGE PLANE H c SIDE VIEW SEE DETAIL A 0. DETAIL L (L) A 0 NOTES:. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES).. DATUMS -A- AND -B- TO BE DETERMINED AT DATUM PLANE -H-. DIMENSIONS "E" AND "D" DO NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. 00 Semtech Corp. 9
SC46 Land Pattern - SOT--6L X (C) P G Y Z DIM C G P X Y Z DIMENSIONS INCHES MILLIMETERS (.098).0.07.04.04.4 (.0).40 0.9 0.60.0.60 NOTES:. THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY. CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES ARE MET. Contact Information Semtech Corporation Power Management Products Division 00 Flynn Road, Camarillo, CA 90 Phone: (80) 498- FAX (80) 498-804 00 Semtech Corp. 0