SC1462A High Efficiency Charge Pump Doubler POWER MANAGEMENT Description Features K Input supply voltage range of 1.65V to 5.5V KSmall size - 6 pin SOT-23 package KTypical efficiency of : The SC1462A is a versatile charge pump designed for use in battery operated power supply applications over the wide input range of 1.65 to 5.5 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-23 package helps minimize board space. K K K K K K The SC1462A charge pump can be used for applications that require up to 25mA of output current with VIN = 2.5V to 5.5V. Typical dropout voltage (2*Vin)-Vout is shown on page 8 for several values of Vin. 8 0 0 .0 E -3 Out pu t Dropo ut V olta ge (V) 7 0 0 .0 E -3 Applications Typ ic a l D ro p ou t V ol ta ge v s Io u t @ T a = 2 5 De g . C . K Cellular phones K Handheld devices K LCD display Vin = 1.5 V Vin = 2.5 V Vin = 3.6 V 6 0 0 .0 E -3 91% @ Vin = 2.5V, Iout = 15mA Short circuit and over-temperature protection 55µA typical input current @ no load Shutdown current <1µA Designed to work with ceramic or Tantalum capacitors Fixed frequency of 32kHz All specifications rated over full temperature range (-40°C to 85°C) Vin = 4.5 V Vin = 5.5 V 5 0 0 .0 E -3 4 0 0 .0 E -3 3 0 0 .0 E -3 2 0 0 .0 E -3 1 0 0 .0 E -3 0 00 .0 E + 0 0 00 E + 0 5 E -3 1 0 E -3 1 5 E -3 2 0 E -3 2 5 E -3 3 0 E -3 Io u t (A ) Typical Application Schematic SC1462A 1uF 1uF Revision 1/2001 1uF 1 www.semtech.com 5+"$ ) POWER MANAGEMENT Absolute Maximum Rating Parameter Symbol Maximum Units Supply Voltage VIN -0.3 to +6.0 V Output Voltage VO -0.3 to +12 V VOUT Short Circuit Duration SC Indefinite Thermal Resistance Junction to Ambient θJA 230 °C/W Operating Ambient Temperature Range TA -40 to +85 °C Junction Temperature Range TJ -40 to +125 °C Storage Temperature Range TSTG -65 to +150 °C TL 300 °C Lead Temperature (Soldering) 10 seconds Electrical Characteristics Unless specified: TA = -40°C to 85°C, SHDN = GND, 1.65V ≤ VIN ≤ 5.5V, Frequency =32 kHz, CIN = COUT = CBUCKET = 1.0µF (ESR = 0.3Ω). Parameter Symbol Input Supply Voltage VIN Input Supply Current I IN Conditions MIN T YP 1.65 MAX Units 5.5 V IO = 0, VIN = 2.5V 55 75 µA IO = 0, VIN = 5.0V 160 225 µA SHDN = VIN 0.1 1 µA (5) Output Resistance ROUT VIN = 2.5V 50 60 Ω Output Resistance(5) ROUT VIN = 5.0V 38 45 Ω Total Switch Resistance(6) RSW VIN = 2.5V 8.5 Ω Total Switch Resistance (6) RSW VIN = 5.0V 7.4 Ω IO VIN = 2.5V Output Current 42 KHz OSC Short Circuit Current ISC VOUT = 0V 100 mA VR IO = 8mA, VIN = 2.5V 290 mV η IO = 8mA, VIN = 2.5V 90 % IO = 15mA, VIN = 5.0V 90 % (1) (3) Power Efficiency(1) Maximum Output Voltage(3) Vout IO = 0mA Input High Threshold VIH SHDN pin, 2.5V ≤ VIN ≤ 5.5V Input Low Threshold VIL SHDN pin, 2.5V ≤ VIN ≤ 5.5V 2001 Semtech Corp. 2 32 mA Oscillator Frequency Output ripple (pk-pk) 22 25 2*Vin 1.6 V V 0.4 V www.semtech.com 5+"$ ) POWER MANAGEMENT Electrical Characteristics (Cont.) Unless specified: TA = -40°C to 85°C, SHDN = GND, 1.65V ≤ VIN ≤ 5.5V, Frequency =32 kHz, CIN = COUT = CBUCKET = 1.0µF (ESR = 0.3Ω). Parameter Symbol Conditions Time to Regulation at Turn on(2) t ON IO = 0 to 15mA, VIN = 5.0V Over Temperature Protection (3) Over Temperature Hysteresis (3) MIN T YP MAX Units 350 us O.T. 140 °C O.T.H. 20 °C NOTES: (1) All electrical characteristics are for the application circuit on page 1. (2) Soft start functionality is performed along with short circuit protection. If VOUT is less than VIN - 200mV, then all switches are turned off and VOUT is charged with a 100mA current source from VIN. When VOUT reaches VIN - 200mV all switches are enabled. (3) Guaranteed by design. (4) This device is ESD sensitive. Use of standard ESD handling precautions is required. (5) The internal switch resistance, the capacitor ESR and the oscillators switching frequency all contribute to ROUT. See the CAPACITOR SELECTION section for information on applying the ROUT specification. (6) The parameter RSW is equal to the total resistance of all 4 internal switches. See the CAPACITOR SELECTION section for information on applying the RSW specification. The parameter was calculated from actual output resistance and the equation on page 6 for ROUT. 2001 Semtech Corp. 3 www.semtech.com 5+"$ ) POWER MANAGEMENT Pin Configuration Ordering Information (TOP VIEW) Part Number(1) Package SC1462AISKTR SOT-23-6 Note: (1) Only available in tape and reel packaging. A reel contains 3000 devices. (6 Lead SOT-23) Pin Descriptions Pin # Pin Name Pin Function SOT -23-6 1 VIN Supply voltage input. 2 GND Ground. 3 C- 4 SHDN 5 VO Voltage output. 6 C+ This pin should be connected to the positive terminal of the external charging capacitor. This pin should be connected to the negative terminal of the external charging capacitor. Shutdown pin. When this pin is connected to VIN, the device enters sleep mode. Marking Information Block Diagram Top Mark 462A yyww Bottom Mark yyww = Datecode (Example : 9908) 2001 Semtech Corp. 4 www.semtech.com 5+"$ ) POWER MANAGEMENT Applications Information THEORY OF OPERATION The SC1462A utilizes a switched capacitor charge pump, to generate an output voltage approximately 2xVin. An internal oscillator generates two out of phase fixed frequency clock signals which turn on and off internal MOSFET switches. During phase1 of clock, the flying charge pump capacitor is charged to Vin through switches S1, and S2. During phase2 the flying charge pump capacitor is connected in series with the input voltage via S3, and S4, producing an output voltage. Charge transfer from Cin to Cbucket ON If VOUT is less than VIN - 200mV, then all switches are turned off and VOUT is charged with a 100mA current source from VIN. When VOUT reaches VIN - 200mV , 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 defined as (2*Vin)-Vout. The maximum output current is usually specified 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 Iout are graphed on page 8. THERMAL SHUTDOWN S1,S2 OFF ON S3,S4 OFF Charge transfer from: Cin and Cbucket to Cout (Doubler) S1 1 S4 2 1 2 Cbucket Vin S3 1 Vout = 2 x Vin The thermal shutdown circuit provides added protection to the SC1462A. During a VOUT 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 140°C. The charge pump is enabled only if the junction temperature drops to approximately 120°C. The SC1462A will cycle in and out of thermal shut down until the short circuit or the excessive load condition on Vout is removed, there by improving device reliability. The junction temperature can be calculated from the following formula if the ambient temperature (Ta) and the charge pump power dissipation (Pdiss) are known. TJ = Ta + Pdiss * θJA ; θJA = 230 °C/W Cout S2 2 1 2 Cin 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. 2001 Semtech Corp. 5 www.semtech.com 5+"$ ) POWER MANAGEMENT Applications Information (Cont.) This equation can be used to calculate Cbucket for a specific Vout when Vin and Iout are known. The maximum value for the Rsw from the Electrical Characteristics section on page 2 should be used in order to find a worst case number. CAPACITOR SELECTION Capacitor selection is based on both the maximum acceptable ripple voltage and the maximum tolerable drop at the output. LAYOUT CONSIDERATION Ripple 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 SC1462A. The peak to peak output ripple voltage is dependent on the following factors: 1- Oscillator Frequency 2- ESR of COUT 3- Capacitance value of Cout Following tables show typical capacitor characteristics, and capacitor manufactures. Item 1 is fixed and depend on the charge pump device used. Item 2, and 3 can be optimized for best performance and reduction of the output ripple. Vou t_ripp le= ESR(Ω) Ω) ESL(nH) 0.1uF Ceramic 0603 Package 0.050 1.60 1.0uF Ceramic 1206 Package 0.040 0.47 Component The following formula could be used for an approximation for Vout_ripple. Iou t + 2 x Iou t x ESR_ C ou t 2 x Fosc x C ou t 10uF Ceramic 1206 Package 0.075 0.50 47uF,16V Tantalum D case 0.100 0.60 330uF,6.3V "OSCON" 0.025 2.50 Vout Drop 330uF,16V Al. Electrolytic 0.143 2.37 820uF,4V "OSCON" 0.012 2.50 The voltage drop at the output is specified with the following equation: 1000uF,10V Al. Electrolytic 0.053 5.00 Vout_drop = Iout * Rout Capacitor Manufacturers Phone Rout is dependent on the following factors: AVX Corp. (803) 448-9411 1- Oscillator Frequency 2- ESR of COUT & Cbucket 3- Capacitance value of COUT & Cbucket 4- Internal switch resistance (Rsw = Total of all 4 switch resistances). VISHAY (207) 324-4140 Nichicon Corp. (708) 843-7500 muRata (800) 831-9172 TOKIN (408) 432-8020 Taiyo Yuden (800) 348-2496 Sanyo (619) 661-6835 A good approximation for calculating the output resistance is shown below. R out ≅ 1 + 2 × R SW + 4 × ESR_ C bucket + ESR_ C out Fosc x C bucket 2001 Semtech Corp. 6 www.semtech.com 5+"$ ) POWER MANAGEMENT Applications Information (Cont.) VIN = 3V to 5.5V 1 4 Cin 1.0uF U1 SC1462A VIN 5 Vo 6 SHDN C+ 3 GND C- 1 2 Cbucket Cout 1.0uF 1.0uF 3 U2 SC2982 VIN GND EN 4 BYPASS C2 10nF 2 Cin 1.0uF 1 4 U1 SC1462A VIN C3 1uF EN 5 Volts Fixed output Voltage VIN = 2V to 3V VOUT = 5V 5 VOUT Vo SHDN C+ GND C- 5 6 3 1 Cbucket Cout 1.0uF 1.0uF 3 EN U2 SC1453 IN OUT EN GND BYP 2 VOUT = 3.3V 5 4 C2 10nF 2 C3 1uF 3.3 Volts Fixed output Voltage 2001 Semtech Corp. 7 www.semtech.com 5+"$ ) POWER MANAGEMENT Typical Characteristics T ypi cal Iin v s V in @ T a = 25 D eg . C . 8 0 0 .0 E -3 1 8 0 E -6 Vin = 1.5 V 7 0 0 .0 E -3 1 4 0 E -6 1 2 0 E -6 1 0 0 E -6 8 0 E -6 6 0 E -6 4 0 E -6 2 0 E -6 Vin = 2.5 V Vin = 3.6 V Out pu t Dropo ut V olta ge (V) 1 6 0 E -6 Ii n (A ) Typ ic a l D ro p ou t V ol ta ge v s Io u t @ T a = 2 5 De g . C . 6 0 0 .0 E -3 Vin = 4.5 V Vin = 5.5 V 5 0 0 .0 E -3 4 0 0 .0 E -3 3 0 0 .0 E -3 2 0 0 .0 E -3 1 0 0 .0 E -3 Io = 0mA 0 00 .0 E + 0 0 00 E + 0 1 .0 2 .0 3 .0 4 .0 5 .0 0 00 E + 0 6 .0 5 E -3 1 0 E -3 V i n (V ) 1 5 E -3 2 0 E -3 2 5 E -3 3 0 E -3 60 80 Io u t (A ) Typical Dropout vs Iout Typical Iin vs Vin Io = 0mA T yp ic a l D r opo u t V o lta ge v s T a T ypi c a l Iin v s T a @ Io = 0 mA 6 0 0 E -3 2 5 0E -6 Vin = 5. 5V Vin = 4. 5V O u tpu t Drop ou t V o lt ag e (V) Vin = 3. 6V 2 00E -6 Vin = 2. 5V Vin = 1. 5V Ii n (A) 1 5 0E -6 1 00E -6 5 0E -6 5 5 0 E -3 V in = 2 .5 V , Iou t = 1 0mA 5 0 0 E -3 V in = 5 .5 V , Iou t = 1 5mA 4 5 0 E -3 4 0 0 E -3 3 5 0 E -3 3 0 0 E -3 2 5 0 E -3 2 0 0 E -3 0 00 E + 0 -4 0 -2 0 0 20 40 60 -4 0 80 -2 0 0 20 40 T a (D e g. C .) T a ( D e g . C .) Typical Dropout vs Ta Typical Iin vs Ta Io = 0mA T yp ic a l E ff ic i e nc y v s Io u t @ T a = 2 5 D eg . C . 1 00 % Vout Ripple 100mV/Div. Eff ic ie ncy (%) 96 % 92 % 88 % Vin = 5. 5V Vin = 4. 5V Vin = 3. 6V 84 % Vin = 2. 5V Vin = 1. 5V Vin = 2.5V Iout = 8mA Cin = Cout = Cbucket = 1.0uF 80 % 3 E -3 8 E -3 1 3E -3 1 8E -3 2 3E -3 2 8E -3 Io ut (A ) Typical Output Ripple Typical Efficiency vs Iout 2001 Semtech Corp. 8 www.semtech.com 5+"$ ) POWER MANAGEMENT Outline Drawing - SOT-23-6L Land Pattern - SOT-23-6L Contact Information Semtech Corporation Power Management Products Division 652 Mitchell Rd., Newbury Park, CA 91320 Phone: (805)498-2111 FAX (805)498-3804 2001 Semtech Corp. 9 www.semtech.com