Data Sheet 340kHz, 3A Synchronous DC-DC Buck Converter General Description Features The AP3503F is a 340kHz fixed frequency, current mode, PWM synchronous buck (step-down) DC-DC converter, capable of driving a 3A load with high efficiency, excellent line and load regulation. The device integrates N-channel power MOSFET switches with low on-resistance. Current mode control provides fast transient response and cycle-by-cycle current limit. • • • • • • • • • • The AP3503F employs complete protection to ensure system security. Including output Over Voltage Protection, input Under Voltage LockOut, programmable soft-start, Over Temperature Protection to safeguard the circuit. AP3503F Input Voltage Range: 4.5V to 18V Fixed 340kHz Frequency High Efficiency: up to 95% Output Current: 3A Current Mode Control Built-in Over Current Protection Built-in Thermal Shutdown Function Built-in UVLO Function Built-in Over Voltage Protection Programmable Soft-start Applications • • • • This IC is available in PSOP-8 package. LCD TV Set Top Box Portable DVD Digital Photo Frame PSOP-8 Figure 1. Package Type of AP3503F Oct. 2012 Rev. 1. 3 BCD Semiconductor Manufacturing Limited 1 Data Sheet 340kHz, 3A Synchronous DC-DC Buck Converter AP3503F Pin Configuration MP Package (PSOP-8) 1 8 2 7 3 6 4 5 Figure 2. Pin Configuration of AP3503F (Top View) Pin Description Pin Number Pin Name 1 BS 2 IN 3 SW 4 GND 5 FB 6 COMP 7 EN 8 SS EP Oct. 2012 Function Bootstrap pin. A bootstrap capacitor is connected between the BS pin and SW pin. The voltage across the bootstrap capacitor drives the internal high-side power MOSFET Supply power input pin. A capacitor should be connected between the IN pin and GND pin to keep the input voltage constant Power switch output pin. This pin is connected to the inductor and bootstrap capacitor Ground pin Feedback pin. This pin is connected to an external resistor divider to program the system output voltage. When the FB pin voltage exceeds 1.1V, the over voltage protection is triggered. When the FB pin voltage is below 0.3V, the oscillator frequency is lowered to realize short circuit protection Compensation pin. This pin is the output of the transconductance error amplifier and the input to the current comparator. It is used to compensate the control loop. Connect a series RC network from this pin to GND. In some cases, an additional capacitor from this pin to GND pin is required Control input pin. EN is a digital input that turns the regulator on or off. Drive EN high/low to turn on/off the regulator. Pull up with 100kΩ resistor for automatic startup Soft-start control input pin. SS controls the soft-start period. Connect a capacitor from SS to GND to set the soft-start period. A 0.1μF capacitor sets the soft-start period to 15ms. To disable the soft-start feature, leave SS unconnected Exposed pad. It should be connected to GND in PCB layout Rev. 1. 3 BCD Semiconductor Manufacturing Limited 2 Data Sheet 340kHz, 3A Synchronous DC-DC Buck Converter AP3503F Functional Block Diagram IN 2 SHUTDOWN COMPARATOR 1.5V VA INTERNAL REGULATOR 0.3V VB CURRENT SENSE AMPLIFIER SLOP COMP VA + OSCILLATOR SCP 1 90 k/340k CLK EN LOCK COMPARATOR 7 BS M1 S Q R Q 3 PWM COMPARATOR SW M2 2.5V VB 4 1.3V 6 A SS 8 GND EA 5 0. 925V FB 6 COMP Figure 3. Functional Block Diagram of AP3503F Ordering Information AP3503F - Circuit Type G1: Green Package MP: PSOP-8 Package Temperature Range PSOP-8 -40 to 85°C TR: Tape & Reel Blank: Tube Part Number Marking ID Packing Type AP3503FMP-G1 3503FMP-G1 Tube AP3503FMPTR-G1 3503FMP-G1 Tape & Reel BCD Semiconductor's Pb-free products, as designated with "G1" suffix in the part number, are RoHS compliant and green. Oct. 2012 Rev. 1. 3 BCD Semiconductor Manufacturing Limited 3 Data Sheet 340kHz, 3A Synchronous DC-DC Buck Converter AP3503F Absolute Maximum Ratings (Note 1) Parameter Symbol Value Unit IN Pin Voltage VIN -0.3 to 20 V EN Pin Voltage VEN -0.3 to VIN V SW Pin Voltage VSW 21 V BS Pin Voltage VBS -0.3 to VSW+6 V FB Pin Voltage VFB -0.3 to 6 V VCOMP -0.3 to 6 V SS Pin Voltage VSS -0.3 to 6 V Thermal Resistance θJA 60 ºC/W Operating Junction Temperature TJ 150 ºC Storage Temperature TSTG -65 to 150 ºC Lead Temperature (Soldering, 10sec) TLEAD 260 ºC ESD (Human Body Model) VHBM 2000 V ESD (Machine Model) VMM 200 V COMP Pin Voltage 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. Recommended Operating Conditions Parameter Symbol Min Max Unit Input Voltage VIN 4.5 18 V Operating Ambient Temperature TA -40 85 ºC Oct. 2012 Rev. 1. 3 BCD Semiconductor Manufacturing Limited 4 Data Sheet 340kHz, 3A Synchronous DC-DC Buck Converter AP3503F Electrical Characteristics TA=25ºC, VIN=VEN=12V, VOUT=3.3V, unless otherwise specified. Parameter Symbol Conditions Min Typ Max Unit 1.2 0.1 18 1.4 10 V mA μA SUPPLY VOLTAGE (IN PIN) Input Voltage Quiescent Current Shutdown Supply Current VIN IQ ISHDN 4.5 VFB=1V,VEN=3V VEN=0V UNDER VOLTAGE LOCKOUT Input UVLO Threshold Input UVLO Hysteresis VUVLO VHYS VIN Rising 3.65 4.00 200 4.25 V mV 1.1 1.5 2 V ENABLE (EN PIN) EN Shutdown Threshold Voltage EN Shutdown Threshold Voltage Hysteresis (Note 2) EN Lockout Threshold Voltage EN Lockout Hysteresis 350 mV 2.2 2.5 210 2.7 V mV 0.907 0.925 1.1 0.943 V V μA VOLTAGE REFERENCE (FB PIN) Feedback Voltage Feedback Over Voltage Threshold Feedback Bias Current VFB VFBOV IFB VFB=1V RDSONH RDSONL ISW=0.2A/0.7A ISW=-0.2A/-0.7A ILEAKH ILIMH ILIML VIN=18V,VEN=VSW=0V -0.1 0.1 MOSFET High-side Switch On-resistance(Note 3) Low-side Switch On-resistance(Note 3) 100 100 mΩ mΩ CURRENT LIMIT High-side Switch Leakage Current High-side Switch Current Limit Low-side Switch Current Limit 4.3 From drain to Source 0.1 5.6 1.4 10 μA A A 340 90 90 400 kHz kHz % % SWITCHING REGULATOR Oscillator Frequency Short Circuit Oscillator Frequency Max. Duty Cycle Min. Duty Cycle fOSC1 fOSC2 DMAX DMIN 280 VFB=0.85V VFB=1V 0 ERROR AMPLIFIER Error Amplifier Voltage Gain (Note 2) Error Amplifier Transconductance COMP to Current Sense Transconductance AEA GEA GCS 400 800 5.2 V/V μA/V A/V TOTSD THYS 160 20 ºC ºC CSS=0.1μF 15 ms VSS=0V 6 μA THERMAL SHUTDOWN Thermal Shutdown (Note 2) Thermal Shutdown Hysteresis (Note 2) SOFT START (SS PIN) Soft-start Time (Note 2) Soft-start Current tSS Note 2: Not tested, guaranteed by design. Note 3: RDSON= Oct. 2012 VSW1 - VSW2 . ISW1 - ISW2 Rev. 1. 3 BCD Semiconductor Manufacturing Limited 5 Data Sheet 340kHz, 3A Synchronous DC-DC Buck Converter AP3503F Typical Performance Characteristics TA=25ºC, VIN=12V, VOUT=3.3V, unless otherwise noted. 1.4 100 90 1.3 Quiescent Current (mA) 80 Efficiency (%) 70 60 50 o VOUT=3.3V, TA=25 C, L=10μH VIN=5V VIN=12V 40 30 1.2 1.1 1.0 20 10 0.0 0.4 0.8 1.2 1.6 2.0 2.4 2.8 0.9 -50 3.2 -25 0 Output Current (A) 3.6 1.1 3.5 1.0 3.4 Output Voltage (V) Feedback Voltage (V) 75 100 125 150 Figure 5. Quiescent Current vs. Case Temperature 1.2 0.9 0.8 3.3 3.2 3.1 0.7 -25 0 25 50 75 100 125 3.0 0.0 150 0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.2 Output Current (A) o Case Temperature ( C) Figure 6. Feedback Voltage vs. Case Temperature Oct. 2012 50 o Figure 4. Efficiency vs. Output Current 0.6 -50 25 Case Temperature ( C) Figure 7. Output Voltage vs. Output Current Rev. 1. 3 BCD Semiconductor Manufacturing Limited 6 Data Sheet 340kHz, 3A Synchronous DC-DC Buck Converter AP3503F Typical Performance Characteristics (Continued) TA=25ºC, VIN=12V, VOUT=3.3V, unless otherwise noted. 160 180 Low-side Switch On-resistance (mΩ) High-side Switch On-resistance (mΩ) 200 160 140 120 100 80 60 40 -60 -40 -20 0 20 40 60 80 100 120 140 120 100 80 60 40 -60 140 -40 -20 0 20 40 60 80 100 120 140 o o Case Temperature ( C) Case Temperature ( C) Figure 8. High-side Switch On-resistance vs. Case Temperature Figure 9. Low-side Switch On-resistance vs. Case Temperature VIN_AC 200mV/div VOUT_AC 200mV/div VOUT_AC 20mV/div IL 2A/div IOUT 1A/div VSW 10V/div Time Time 4μs/div Figure 10. Output Ripple (IOUT=3A) Oct. 2012 200μs/div Figure 11. Load Transient (IOUT =1.5A to 3A) Rev. 1. 3 BCD Semiconductor Manufacturing Limited 7 Data Sheet 340kHz, 3A Synchronous DC-DC Buck Converter AP3503F Typical Performance Characteristics (Continued) TA=25ºC, VIN=12V, VOUT=3.3V, unless otherwise noted. VEN 2V/div VEN 2V/div VSS 2V/div VSS 2V/div VOUT 2V/div VOUT 2V/div IL 2A/div IL 2A/div Time 10ms/div Time Figure 12. Enable Turn on Characteristic (VIN=12V, VEN=3.3V, VOUT=3.3V, IL=3A) Figure 13. Enable Turn off Characteristic (VIN=12V, VEN=3.3V, VOUT=3.3V, IL=3A) VOUT 2V/div VOUT 2V/div IL 2A/div IL 2A/div Time Time 40μs/div Figure 14. Short Circuit Protection (IOUT=0A) Oct. 2012 200μs/div 40μs/div Figure 15. Short Circuit Recovery (IOUT=0A) Rev. 1. 3 BCD Semiconductor Manufacturing Limited 8 Data Sheet 340kHz, 3A Synchronous DC-DC Buck Converter AP3503F Typical Application Input Voltage=12V 1 Output Voltage=3.3V L 10μH C4 10nF 2 3 4 C22 C21 22μF/25V 22μF/25V BS IN SW GND AP3503F R4 100k SS EN COMP FB C12 10μF/25V 8 C5 0.1μF 7 C6 Optional 6 C3 3.3nF 5 R2 D1 Optional C11 10μF/25V R3 13k 10k R1 26.1k Figure 16. Typical Application of AP3503F Oct. 2012 Rev. 1. 3 BCD Semiconductor Manufacturing Limited 9 Data Sheet 340kHz, 3A Synchronous DC-DC Buck Converter AP3503F Mechanical Dimensions Unit: mm(inch) 3.202(0.126) 3.402(0.134) PSOP-8 Oct. 2012 Rev. 1. 3 BCD Semiconductor Manufacturing Limited 10 BCD Semiconductor Manufacturing Limited http://www.bcdsemi.com IMPORTANT NOTICE BCD Semiconductor Manufacturing Limited reserves the right to make changes without further notice to any products or specifications herein. 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