Preliminary Datasheet 2A, 4MHz High Efficiency Synchronous Buck Converter General Description Features The AP3408 is a current mode, PWM synchronous buck DC/DC converter, capable of driving a 2A load with high efficiency, excellent line and load regulation. It operates in continuous PWM mode. • • • • • • • • • • • • • • • • The AP3408 integrates synchronous P-channel and N-channel power MOSFET switches with low on-resistance. It is ideal for portable applications powered from a single Li-ion battery. 100% duty cycle and low on-resistance P-channel internal power MOSFET can maximize the battery life. The switching frequency of AP3408 can be programmable from 300kHz to 4MHz, which allows small-sized components, such as capacitors and inductors. A standard series of inductors from several different manufacturers are available. This feature greatly simplifies the design of switch-mode power supplies. AP3408 Input Voltage Range: 2.6 to 5.5V Adjustable Output from 0.8 to 5V 0.8V Reference Voltage with ± 2% Precision Output Current: 2A High Efficiency up to 95% Low RDSON Internal Switches Programmable Frequency: 300kHz to 4MHz Current Mode Control Forced Continuous-mode Operation 100% Duty Cycle Synchronizable Switching Frequency Power Good Output Voltage Monitoring Built-in Soft-start Built-in Short Circuit Protection Built-in Thermal Shutdown Protection Built-in Current Limit Function Applications The AP3408 is available in DFN-3×3-10 and PSOP-8 packages. • • • DFN-3×3-10 Portable Media Player Digital Still and Video Cameras Notebook PSOP-8 Figure 1. Package Types of AP3408 Jul. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited 1 Preliminary Datasheet 2A, 4MHz High Efficiency Synchronous Buck Converter AP3408 Pin Configuration DN Package MP Package (DFN-3×3-10) (PSOP-8) P in 1 D ot by M arking SHDN/RT 10 1 SYNC 2 Exposed Pad Connected to PGND COMP 9 FB 8 PGOOD GND 3 SW 4 7 VDD PGND 5 6 PVDD SHDN/RT 1 GND 2 SW 3 PGND 4 Exposed Pad Connected to PGND 8 COMP 7 FB 6 VDD 5 PVDD Figure 2. Pin Configuration of AP3408 (Top View) Pin Description Pin Number DFN-3×3-10 PSOP-8 1 1 2 Pin Name SHDN/RT SYNC 3 2 GND 4 3 SW 5 4 PGND 6 5 PVDD 7 6 VDD 8 PGOOD 9 7 FB 10 8 COMP Jul. 2011 Description Oscillator resistor input. Connect a resistor to GND from this pin to set the switching frequency. Forcing this pin to VDD to shutdown the device External clock synchronization input. The oscillation frequency can be synchronized to an external oscillation applied to this pin. When tied to VDD, the internal oscillator is selected Signal ground. All small-signal ground, such as the compensation components and the exposed pad should be connected to this pin, which in turn connects to PGND at one point Internal power switch output. Connect this pin with one terminal of the inductor Power ground. Connect this pin as close as possible to CIN and COUT Power input supply. Decouple this pin to PGND with a capacitor Signal input supply. Decouple this pin to GND with a capacitor. Normally VDD is equal to VPVDD Power Good Indicator. Open-drain logic output that is pulled to ground when the output voltage is not within ± 12.5% of regulation point Feedback voltage. This pin is the inverting input of internal error amplifier. It senses the converter output voltage through an external resistor divider. The internal reference voltage is 0.8V, which determines the output voltage through the resistor divider Compensation input. This pin is the output of internal error amplifier. Connect external compensation elements to this pin to stabilize the control loop Rev. 1. 0 BCD Semiconductor Manufacturing Limited 2 Preliminary Datasheet 2A, 4MHz High Efficiency Synchronous Buck Converter AP3408 Functional Block Diagram SHDN/RT 1(1) SYNC 0.8V 9(7) FB EA Clamp PWM OCP 4(3) SS 0.7V 5(4) PGND 0.9V 8 SW Control Logic 0.4V PGOOD PVDD SUM Oscillator 10(8) COMP 6(5) CS SD Driver 2 DC VREF 3(2) UVLO OTP GND 7(6) A (B) A for DFN-3X3-10 B for PSOP-8 VDD Figure 3. Functional Block Diagram of AP3408 Jul. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited 3 Preliminary Datasheet 2A, 4MHz High Efficiency Synchronous Buck Converter AP3408 Ordering Information AP3408 G1: Green Circuit Type TR: Tape & Reel Blank: Tube Package DN: DFN-3×3-10 MP: PSOP-8 Package Temperature Range DFN-3×3-10 PSOP-8 -40 to 125°C Part Number Marking ID Green Green Packing Type AP3408DNTR-G1 BFA AP3408MP-G1 3408MP-G1 Tape & Reel Tube AP3408MPTR-G1 3408MP-G1 Tape & Reel BCD Semiconductor's Pb-free products, as designated with "G1" suffix in the part number, are RoHS compliant and green. Absolute Maximum Ratings (Note 1) Parameter Symbol Value Unit VDD Pin Voltage VDD -0.3 to 6 V PVDD Pin Voltage VPVDD -0.3 to 6 V VFB -0.3 to 6 V VCOMP -0.3 to 6 V VSW -0.3 to VIN+0.3 V VSHDN/RT V ºC/W FB Pin Voltage COMP Pin Voltage SW Pin Voltage SHDN/RT Pin Voltage DFN-3×3-10 PSOP-8 Operating Junction Temperature θJA TJ -0.3 to 6 110 75 150 Storage Temperature TSTG -65 to 150 ºC Lead Temperature (Soldering, 10 sec) TLEAD 260 ºC ESD (Machine Model) 200 V ESD (Human Body Model) 2000 V Thermal Resistance ºC Note 1: Stresses greater than those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under “Recommended Operating Conditions” is not implied. Exposure to “Absolute Maximum Ratings” for extended periods may affect device reliability. Jul. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited 4 Preliminary Datasheet 2A, 4MHz High Efficiency Synchronous Buck Converter AP3408 Recommended Operating Conditions Parameter Symbol Min Max Unit Input Voltage VIN 2.6 5.5 V IOUT (MAX) 2 TJ -40 Maximum Output Current Operating Junction Temperature A 125 ºC Electrical Characteristics VIN=VDD =VPVDD=3.3V, TA=25℃, unless otherwise specified. Parameters Symbol Conditions Min Typ Max Unit 5.5 V INPUT SECTION Input Voltage Range Supply Current Shutdown Supply Current Under Voltage Threshold Lockout Under Voltage Hysteresis Lockout VDD IQ ISHDN VUVLO 2.6 VFB=0.75V, No Switching Shutdown, VIN=5.5V μA 460 1 VDD Rising VHUVLO μA 2.2 V 300 mV FEEDBACK SECTION Feedback Voltage VFB FB Pin Bias Current Current Sense Transresistance 0.784 0.8 0.816 V IFB 0.1 0.4 μA RT 0.2 VSHDN/RT=VIN =5.5V Switching Leakage Current 1 Error Gain Amplifier Voltage GV 800 Error1Amplifier1Trans-conductance GS 800 Jul. 2011 Rev. 1. 0 Ω μA μA /V BCD Semiconductor Manufacturing Limited 5 Preliminary Datasheet 2A, 4MHz High Efficiency Synchronous Buck Converter AP3408 Electrical Characteristics (Continued) VIN=VDD =VPVDD=3.3V, TA=25℃, unless otherwise specified. Parameters Symbol Conditions Min Typ Max Unit OSCILLATOR SECTION RT Pin Voltage VRT Switching Frequency fOSC Maximum Duty Cycle DMAX 0.8 1 V ROSC=330kΩ 0.8 1.2 MHz ADJ Frequency 0.3 4 MHz VFB=0.75V 100 ILIMIT VFB=0.75V 2.2 RPDSON ISW=500mA 0.11 0.16 Ω RNDSON ISW=-500mA 0.11 0.17 Ω VDD-0.7 VDD-0.4 V ±15 % 120 Ω % POWER SWITCH SECTION Switch Current Limit Internal P-FET Resistance Internal N-FET Resistance On On 3.8 A SHDN/RT SECTION Shutdown Threshold PGOOD SECTION ±12.5 PGOOD Voltage Range PGOOD Pull Down Resistance TOTAL DEVICE Output Current Output Voltage Regulation Output Voltage Regulation IOUT Line Load Soft-start Time Thermal Shutdown Temperature Thermal Shutdown Temperature Hysteresis Jul. 2011 VDD=2.6 to 5.5V VOUT=2.5V VDD=2.7 to 5.5V IOUT=100mA 2 A 0.4 %/V IOUT=0.01 to 2A ±0.2 % IOUT＝10mA 1.5 ms TOTSD 160 ºC THYS 20 ºC LNR LOD tSS Rev. 1. 0 BCD Semiconductor Manufacturing Limited 6 Preliminary Datasheet 2A, 4MHz High Efficiency Synchronous Buck Converter AP3408 Typical Performance Characteristics VIN=VDD =VPVDD=3.3V, TA=25℃, unless otherwise specified. 700 600 600 Supply Current (μA) Supply Current (μA) 500 400 300 500 400 300 VIN=3.3V 200 200 VFB=0.75V VFB=0.75V 100 2.5 3.0 3.5 4.0 4.5 5.0 5.5 100 -60 -30 0 30 60 90 120 150 o Ambient Temperature ( C) 6.0 Input Voltage (V) Figure 5. Supply Current vs. Ambient Temperature Figure 4. Supply Current vs. Input Voltage 100 140 PMOS ON Resistance (mΩ) 90 Efficiency (%) 80 70 60 50 VOUT=2.5V VIN=3.3V 40 120 100 80 VIN=3.3V VFB=0.75V 60 VIN=5.0V -60 30 0 500 1000 1500 2000 2500 -30 0 30 60 90 120 150 o Ambient Temperature ( C) Output Current (mA) Figure 6. Efficiency vs. Output Current Jul. 2011 Figure 7. PMOS ON Resistance vs. Ambient Temperature Rev. 1. 0 BCD Semiconductor Manufacturing Limited 7 Preliminary Datasheet 2A, 4MHz High Efficiency Synchronous Buck Converter AP3408 Typical Performance Characteristics (Continued) VIN=VDD =VPVDD=3.3V, TA=25℃, unless otherwise specified. 1.2 140 Frequency (MHz) NMOS ON Resistance (mΩ) 1.1 120 100 80 1.0 0.9 60 ROSC=330k 0.8 VIN=3.3V VIN=3.3V VFB=0.85V -60 -30 0 30 60 90 120 VOUT=2.5V 0.7 -60 150 -30 0 30 60 90 120 150 O o Ambient Temperature ( C) Ambient Temperature ( C) Figure 8. NMOS ON Resistance vs. Ambient Temperature Figure 9. Frequency vs. Ambient Temperature 0.9 5.0 4.5 Current Limit (A) VFB (V) 0.8 0.7 4.0 3.5 0.6 VIN=3.3V VIN=3.3V 3.0 VOUT=2.5V 0.5 -60 -30 0 30 60 90 120 2.5 150 -40 O 40 80 120 160 Temperature ( C) Figure 10. VFB vs. Ambient Temperature Jul. 2011 0 O Ambient Temperature ( C) Figure 11. Current Limit vs. Ambient Temperature Rev. 1. 0 BCD Semiconductor Manufacturing Limited 8 Preliminary Datasheet 2A, 4MHz High Efficiency Synchronous Buck Converter AP3408 Typical Application Figure 12. Typical Application of AP3408 Jul. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited 9 Preliminary Datasheet 2A, 4MHz High Efficiency Synchronous Buck Converter AP3408 Mechanical Dimensions DFN-3×3-10 Unit: mm(inch) 1.600(0.063) 0.300(0.012) 1.800(0.071) 0.500(0.020) 0.500(0.020) 2.900(0.114) TYP 3.100(0.122) N6 N10 ` 2.300(0.090) 2.500(0.098) 2.900(0.114) 3.100(0.122) PIN #1 IDENTIFICATION Pin 1 Dot by Marking N5 N1 0.200(0.008) 0.700(0.028) 0.800(0.031) 0.000(0.000) 0.300(0.012) 0.050(0.002) 0.153(0.006) 0.253(0.010) Jul. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited 10 Preliminary Datasheet 2A, 4MHz High Efficiency Synchronous Buck Converter AP3408 Mechanical Dimensions (Continued) Unit: mm(inch) 3.202(0.126) 3.402(0.134) PSOP-8 Jul. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited 11 BCD Semiconductor Manufacturing Limited http://www.bcdsemi.com IMPORTANT NOTICE IMPORTANT NOTICE BCD Semiconductor BCD Semiconductor Manufacturing Manufacturing Limited Limited reserves reserves the the right right to to make make changes changes without without further further notice notice to to any any products products or or specifispecifications herein. cations herein. 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