PFM Step-Up DC-DC Converters with Internal Schottky Diode General Description The compact, high-efficiency, PFM step-up DC- DC converters are available in SOT-89-3,SOT-23-3 and SOT-23-5 packages. They feature an extremely low quiescent supply current to ensure the highest possible light-load efficiency. Optimized for operation from one to two alkaline or nickel-metal-hydride (NiMH) cells, or a single Li+ cell, these devices are ideal for applications where extremely low quiescent current and ultra-small size are critical. The includes an internal Schottky diode that reduces PCB board area and total BOM cost. The family offers different combinations of fixed or adjustable outputs, and shutdown control. Ordering Information - Taping Package R: Tape and Reel A22:SOT-89-3 F Type A30:SOT-23-3 A31:SOT-23-3 A50:SOT-23-5 Output Voltage Voltage Code 1.8 V 18 1.9 V 19 2.1 V 21 2.5 V 25 2.7 V 27 2.8 V 28 3.0 V 30 3.3 V 33 4.0 V 40 Applications Remote Wireless Transmitters Personal Medical Devices Digital Still Cameras Single-Cell Battery-Powered Devices Low-Power Hand-Held Instruments MP3 Players Personal Digital Assistants (PDA) Features Internal Schottky Diode Up to 80% Efficiency (External Schottky Diode) Ultra Low Input Current (9µA at Switch Off) ±2.0% Output Voltage Accuracy Fixed Output Voltage Up to 200mA Output Current 0.8V to 5.5V Input Voltage Range Low Start-up Voltage, 0.9V at 1mA SOT-23-3,SOT-23-5 and SOT-89-3 Package Marking Information For marking information, please contact our sales representative directly or through distributor around your location. Feb.2013 1 V1.0
Typical Application Circuit Absolute Maximum Ratings Recommended Operating Conditions Supply Voltage V IN 7V Input Voltage V IN 0.8V to 5.5V Power Dissipation, P D @ T A =25 C Junction Temperature -40 C to 125 C SOT-89-3 571mW Ambient Operating Temperature -40 C to 85 C SOT-23-3 / SOT-23-5 Thermal Resistance, ja SOT-89-3 SOT-23-3 / SOT-23-5 400mW 175 C/W 250 C/W Lead Temperature 260 C Storage Temperature -65 C to 150 C ESD Susceptibility HBM (Human Body Mode) 4kV MM (Machine Mode) 300V Feb.2013 2 V1.0
Pin Configurations LX 3 VOUT 3 (TOP VIEW) LX GND 5 4 1 2 1 2 1 2 3 1 2 3 GND VOUT GND LX EN VOUT NC GND VOUT LX SOT-23-3 (A30) Pin Description SOT-23-3 (A31) SOT-23-5 SOT-89-3 SOT-23-3 SOT-23-5 SOT-89-3 Name Description 3 5 3 LX Pin for Switching 1 4 1 GND Ground -- 1 -- EN Chip Enable (Active High). Note that this pin is high impedance. There should be a pull low 100k resistor connected to GND when the control signal is floating. -- 3 -- NC No Connecting 2 2 2 VOUT Output Voltage Feb.2013 3 V1.0
Electrical Characteristics All of the below electrical characteristics are tested at room temperature (25 ) Notes: Parameter Symbol Test Conditions Min Typ Max Units Output Voltage Accuracy ΔV OUT -2 -- +2 % Input Voltage V IN -- -- 5.5 V Start-up Voltage V ST I OUT = 1mA, V IN : 0 2.0V -- 0.9 1 V Hold-on Voltage V HO I OUT = 1mA, V IN : 0 2.0V 0.7 -- -- V Input Current 1 Input Current 2 (1)(2) Input Current 3 LX Switching Current (1) V IN = 1.8V, V SS = 0V, I OUT = 1mA, T A = 25 C. (2) V IN = 3.0V, V SS = 0V, I OUT = 1mA, T A = 25 C. V OUT 3.5V (1) To be measured at V -- 35 -- I IN DD1 3.5V<VOUT 5.0V (2) continuous switching -- 40 -- To be measured at V I OUT in DD2 -- 9 -- µa switch off condition V OUT 3.5V (1) To be measured at V IN in -- 23 -- I IN no load (guaranteed by I 1 µa 3.5V<VOUT 5.0V (2) and I 2 ) -- 28 -- V OUT 3.5V (1) I SWITCHING V LX = 0.4V 120 -- -- 3.5V<VOUT 5.0V (2) 160 -- -- LX Leakage Current I LEAKAGE V LX = 6.0V -- -- 1.0 µa Maximum Oscillator Frequency F MAX µa ma V OUT = 2.5V to 5.0V 140 190 240 khz V OUT = 1.8V to 2.4V 140 190 320 khz Oscillator Duty Cycle D OSC On (V LX L ) side 65 75 85 % Efficiency -- 80 -- % V LX Voltage Limit LX Switch on 0.65 0.8 1.0 V EN High Voltage EN Low Voltage EN Input Bias Current Shut-down Current V ENH V ENL I BIAS-EN I SHDN Same as I DD1, LX Pin Oscillation Start Same as I DD1, LX Pin Oscillation Stop Same as I DD1, V EN = 0 2.0V Same as I DD1, V EN = 0V 0.9 -- -- V -- -- 0.4 V -- -- 0.5 µa -- -- 2 µa Feb.2013 4 V1.0
Function Block Diagram EN/NC *SOT-89-3 Chip Enable V LX Limiter LX V OUT Buffer + _ PFM Control OSC 190kHz GND V REF Feb.2013 5 V1.0
Typical Operating Characteristics (VOUT = 1.9V, CIN = 10μ F (Ceramic), COUT = 47μ F (Tantalum), L = 47μ H (0.62A), without External Schottky Diode, TA = 25 ) Start-up Voltage vs. Output Current Hold-on Voltage vs. Output Current 1.60 1.40 V OUT = 1.9V, C OUT = 47μF, L = 47μH (without External Schottky Diode) 1.05 0.90 V OUT = 1.9V, C OUT = 47μF, L = 47μH (without External Schottky Diode) Start-up Voltage (V) 1.20 1.00 0.80 Start-up (-40 ) 0.60 Start-up (-25 ) Start-up (0 ) 0.40 Start-up (25 ) Start-up (50 ) 0.20 Start-up (85 ) Start-up (100 ) (Resistive Load) Start-up (125 ) 0.00 0.01 0.1 1 10 100 Output Current (ma) Hold-on Voltage (V) 0.75 0.60 0.45 Hold-on (2%) (-40 ) Hold-on (2%) (-25 ) 0.30 Hold-on (2%) (0 ) Hold-on (2%) (25 ) Hold-on (2%) (50 ) 0.15 Hold-on (2%) (85 ) Hold-on (2%) (100 ) (Resistive Load) Hold-on (2%) (125 ) 0.00 0.01 0.1 1 10 100 Output Current (ma) Efficiency vs. Output Current Output Voltage vs. Output Current 90 V OUT = 1.9V, C OUT = 47μF, L = 47μH (without External Schottky Diode) 2 V OUT = 1.9V, C OUT = 47μF, L = 47μH (without External Schottky Diode) 80 1.9 Efficiency (%) 70 60 50 VIN=0.9V VIN=1.0V VIN=1.2V Output Voltage (V) 1.8 1.7 1.6 VIN=0.9V VIN=1.0V VIN=1.2V VIN=1.5V 40 0 10 20 30 40 50 60 70 80 Output Current (ma) VIN=1.5V 1.5 0 10 20 30 40 50 60 70 80 Output Current (ma) Output Ripple vs. Output Current Shutdown Current vs. Temperature Output Ripple (mv) 50 40 30 V OUT = 1.9V, C OUT = 47μF, L = 47μH (without External Schottky Diode) 20 VIN=0.9V VIN=1.0V 10 VIN=1.2V VIN=1.5V 0 0 10 20 30 40 50 60 70 80 Output Current (ma) Shutdown Current (μa) 1.8 1.5 1.2 0.9 0.6 0.3 V OUT = 1.9V, EN=GND, C OUT = 47μF, L = 47μH (without External Schottky Diode) VIN =0.9V VIN =1V VIN =1.2V VIN =1.5V 0-50 -25 0 25 50 75 100 125 Temperature ( o C) Feb.2013 6 V1.0
Low Start-up Voltage at 1mA Low Start-up Voltage at 10mA V IN (DC) V IN (DC) V OUT (DC) (2.00V/Div) V OUT (DC) (2.00V/Div) I IN (DC) (200mA/Div) V IN =1.0V, V OUT =1.9V, I OUT =1mA (Resistive Load) (without External Schottky Diode) Time (2.00s/Div) I IN (DC) (500mA/Div) V IN =1.2V, V OUT =1.9V, I OUT =10mA (Resistive Load) (without External Schottky Diode) Time (20.0ms/Div) Steady State Operation Steady State Operation V OUT (AC) (10.0mV/Div) V OUT (AC) (10.0mV/Div) V IN =0.9V, V OUT =1.9V, I OUT =10mA Time (4.00μs/Div) V IN =0.9V, V OUT =1.9V, I OUT =30mA Time (4.00μs/Div) Steady State Operation Steady State Operation V OUT (AC) (10.0mV/Div) V OUT (AC) (10.0mV/Div) V IN =1.0V, V OUT =1.9V, I OUT =10mA Time (4.00μs/Div) V IN =1.0V, V OUT =1.9V, I OUT =40mA Time (4.00μs /Div) Feb.2013 7 V1.0
Steady State Operation Steady State Operation V OUT (AC) (10.0mV/Div) V OUT (AC) (10.0mV/Div) V IN =1.2V, V OUT =1.9V, I OUT =10mA Time (10.0μs /Div) V IN =1.2V, V OUT =1.9V, I OUT =60mA Time (4.00μs /Div) Steady State Operation Steady State Operation V OUT (AC) (10.0mV/Div) V OUT (AC) (10.0mV/Div) V IN =1.5V, V OUT =1.9V, I OUT =10mA Time (20.0μs /Div) V IN =1.5V, V OUT =1.9V, I OUT =40mA Time (4.00μs /Div) Feb.2013 8 V1.0
Application Information Capacitor Selection A 47μF tantalum (SMT) output filter capacitor typically provides 50mV to 100mV output ripple when stepping up from 3.0V to 5.0V at 1mA to 200mA. Smaller capacitors (down to 10μF with higher ESR) are acceptable for light loads or in applications that can tolerate higher output ripple. Values in the 10μF to 47μF range are recommended for the. The equivalent series resistance (ESR) of both bypass and filter capacitors affects efficiency and output ripple. The output voltage ripple is the product of the peak inductor current and the output capacitor s ESR. Use low-esr capacitors for best performance, or connect two or more filter capacitors in parallel. Figure 1: Typical Application Circuit for SOT-23-3 Figure 2: Typical Application Circuit for SOT-23-5 Figure 3: Typical Application Circuit for SOT-89-3 V IN + L1 47µH (Shield Inductor) C1 22µF Inductor Selection 1 3 GND 2 VOUT LX + V OUT C2 47µF (Tantalum) An inductor value of 47μH performs well in applications. However, the inductance value is not critical, and the will work with inductors in the 10μH to 100μH range. Smaller inductance values typically offer a smaller physical size for a given series resistance, allowing the smallest overall circuit dimensions. However, due to higher peak inductor currents, the output voltage ripple also tends to be higher. Circuits using larger inductance values exhibit higher output current capability and larger physical dimensions for a given series resistance. The inductor s incremental saturation current rating should be greater than the peak switch-current limit, which is 240mA for the. However, it is generally acceptable to bias the inductor into saturation by as much as 20%, although this will slightly reduce efficiency. The inductor s DC resistance significantly affects efficiency. Thermal Considerations V OUT 1 2 EN VOUT LX 5 L1 47µH (Shield Inductor) + V IN C1 22µF For continuous operation, do not exceed the maximum operation junction temperature 125. The maximum power dissipation depends on the thermal resistance of IC package, PCB layout, the rate of surroundings C2 47µF (Tantalum) + 3 NC GND 4 airflow and temperature difference between junctions to ambient. The maximum power dissipation can be calculated by following formula: P D MAX T J MAX JA T A Feb.2013 9 V1.0
Where TJ (MAX) is the maximum operation junction temperature 125, TA is the ambient temperature and the JA is the junction to ambient thermal resistance. For recommended operating conditions specification of where TJ (MAX) is the maximum junction temperature of the die (125 ) and TA is the maximum ambient temperature. The junction to ambient thermal resistance JA is layout dependent. For SOT-89-3 packages, the thermal resistance JA is 175 /W on the standard JEDEC 51-7 four-layers thermal test board. The maximum power dissipation at TA = 25 can be calculated by following formula: PD(MAX) = (125-25 ) / (175 /W) = 0.571W for SOT-89-3 packages. The maximum power dissipation depends on operating ambient temperature for fixed TJ (MAX) and thermal resistance JA. For packages, the Figure 4 of de-rating curves allows the designer to see the effect of rising ambient temperature on the maximum power allowed. Maximum Power Dissipation (W) Figure 4: Maximum Power Dissipation 0.8 0.7 0.6 0.5 0.4 0.3 0.2 SOT-89-3 0.1 SOT-23-3 / SOT-23-5 0-50 -25 0 25 50 75 100 125 Ambient Temperature ( ) Feb.2013 10 V1.0
Layout Considerations Careful PC board layout is important for minimizing ground bounce and noise. Keep the IC s GND pin and the ground leads of the input and output capacitors less than 0.2in (5mm) apart using a ground plane. In addition, keep all connections to VOUT and LX as short as possible. Figure5. PCB Layout Guide (SOT-23-3) V IN C1 C1 must be near LX should be connected to Inductor by wide and short trace, keep sensitive compontents away from this trace. L1 LX GND 5 4 SOT-23-5 1 2 3 EN VOUT NC C2 The output capacitor C2 should be connected directly from the VOUT Pin to ground. Figure6. PCB Layout Guide (SOT-23-5) Feb.2013 11 V1.0
C2 The output capacitor C2 should be connected directly from the VOUT Pin to ground. SOT-89-3 L1 C1 C1 must be near 1 2 3 V IN GND VOUT LX LX should be connected to Inductor by wide and short trace, keep sensitive compontents away from this trace. Figure7. PCB Layout Guide (SOT-89-3) Feb.2013 12 V1.0
Packaging SOT-23-3 SYMBOLS DIMENSIONS IN MILLIMETERS DIMENSIONS IN INCH MIN NOM MAX MIN NOM MAX A 1.00 1.10 1.30 0.039 0.043 0.051 A1 0.00 --- 0.10 0.000 --- 0.004 A2 0.70 0.80 0.90 0.027 0.031 0.035 b 0.35 0.40 0.50 0.013 0.016 0.020 C 0.10 0.15 0.25 0.004 0.006 0.001 D 2.70 2.90 3.10 0.106 0.114 0.122 E 1.40 1.60 1.80 0.055 0.063 0.071 e --- 1.90(TYP) --- --- 0.075 --- H 2.60 2.80 3.00 0.102 0.110 0.118 L 0.370 --- --- 0.015 --- --- Θ1 1 5 9 1 5 9 Feb.2013 13 V1.0
SOT-23-5 SYMBOLS DIMENSIONS IN MILLIMETERS DIMENSIONS IN INCH MIN NOM MAX MIN NOM MAX A 1.00 1.10 1.30 0.039 0.043 0.051 A1 0.00 --- 0.10 0.000 --- 0.004 A2 0.70 0.80 0.90 0.027 0.031 0.035 b 0.35 0.40 0.50 0.013 0.016 0.020 C 0.10 0.15 0.25 0.004 0.006 0.001 D 2.70 2.90 3.10 0.106 0.114 0.122 E 1.50 1.60 1.80 0.059 0.063 0.071 e --- 1.90(TYP) --- --- 0.075 --- H 2.60 2.80 3.00 0.102 0.110 0.118 L 0.370 --- --- 0.015 --- --- Θ1 1 5 9 1 5 9 e1 --- 0.95(TYP) --- --- 0.037 --- Feb.2013 14 V1.0
SOT-89-3 SYMBOLS DIMENSIONS IN MILLIMETERS DIMENSIONS IN INCH MIN NOM MAX MIN NOM MAX A 1.40 1.50 1.60 0.055 0.059 0.063 A1 0.80 1.04- --- 0.031 0.041 --- b 0.36 0.42 0.48 0.014 0.016 0.018 b1 0.41 0.47 0.53 0.016 0.185 0.020 C 0.38 0.40 0.43 0.014 0.016 0.017 D 4.40 4.50 4.600 0.173 0.177 0.181 D1 1.40 1.60 1.75 0.055 0.062 0.069 HE --- --- 4.25 --- --- 0.167 E 2.40 2.50 2.60 0.094 0.098 0.102 e 2.90 3.00 3.10 0.114 0.118 0.122 H 0.35 0.40 0.45 0.014 0.016 0.018 S 0.65 0.75 0.85 0.026 0.030 0.034 e1 1.40 1.50 1.60 0.054 0.059 0.063 Feb.2013 15 V1.0
Footprint SOT-23-3 Package Number of Footprint Dimension (mm) PIN P1 P2 A B C D M Tolerance SOT-23-3 3 0.95 1.90 3.60 1.60 1.00 0.80 2.70 ±0.10 SOT-23-5 Feb.2013 16 V1.0
SOT-89-3 Feb.2013 17 V1.0