Preliminary Datasheet LOW-POWER OFF-LINE PRIMARY SIDE REGULATION CONTROLLER General Description Features The AP3703 is a high performance AC/DC power supply controller for battery charger and adapter applications. The device uses Pulse Frequency Modulation (PFM) method to build discontinuous conduction mode (DCM) flyback power supplies. · · · The AP3703 provides accurate constant voltage, constant current (CV/CC) regulation while removing the opto-coupler and secondary control circuitry. It also eliminates the need of loop compensation circuitry while maintaining stability. The AP3703 achieves excellent regulation and high average efficiency, yet meets the requirement for no-load consumption less than 100mW. · · · · · · · The AP3703 is available in SOT-23-5 package. AP3703 Primary Side Control for Rectangular Constant Current and Constant Voltage Output Secondary CV/CC Control Circuitry Eliminating Opto-Coupler No Need for Control Loop Compensation Circuitry Flyback Topology in DCM Operation Random Frequency Modulation to Reduce System EMI Built-in Soft Start Open Feedback Protection Over Voltage Protection Short Circuit Protection Small SOT-23-5 package to achieve compact size and less component Applications · · · Adapters/Chargers for Cell/Cordless Phones, PDAs, MP3 and Other Portable Apparatus Standby and Auxiliary Power Supplies LED Driver SOT-23-5 Figure 1. Package Type of AP3703 Feb. 2009 Rev. 1.0 BCD Semiconductor Manufacturing Limited 1 Preliminary Datasheet LOW-POWER OFF-LINE PRIMARY SIDE REGULATION CONTROLLER AP3703 Pin Configuration K Package (SOT-23-5) OUT 1 GND 2 VCC 3 5 FB 4 CS Figure 2. Pin Configuration of AP3703 (Top View) Pin Description Pin Number Pin Name Function 1 OUT This pin drives the base of external power NPN switch 2 GND Ground 3 VCC Supply voltage 4 CS The primary current sense 5 FB The voltage feedback from the auxiliary winding Feb. 2009 Rev. 1.0 BCD Semiconductor Manufacturing Limited 2 Preliminary Datasheet LOW-POWER OFF-LINE PRIMARY SIDE REGULATION CONTROLLER AP3703 Functional Block Diagram VCC 3 UVLO FB pro OVP & OCkP 5 Regulator & Bias 0.1V COMP Tonsec Detector UVLO Tons pfm EA 4.0V S&H Tons Vea V+ COMP R pfm_d V+ Vea 4 Q CV_ctrl pfm 1 Driver OUT S t CS COMP 0.5V pfm LEB Delay 430ns pfm_d COMP 0.46V VDD I Tons 3.75V COMP R Q CC_ctrl 2 GND S 0.75*I Figure 3. Functional Block Diagram of AP3703 Feb. 2009 Rev. 1.0 BCD Semiconductor Manufacturing Limited 3 Preliminary Datasheet LOW-POWER OFF-LINE PRIMARY SIDE REGULATION CONTROLLER AP3703 Ordering Information AP3703 - Circuit Type G1: Green Package K: SOT-23-5 TR: Tape and Reel Package Temperature Range SOT-23-5 -40 to 85oC Part Number AP3703KTR-G1 Marking ID GAT Packing Type Tape & Reel BCD Semiconductor's products, as designated with "G1" suffix in the part number, are RoHS compliant and Green. Absolute Maximum Ratings (Note 1) Parameter Value Unit Supply Voltage VCC -0.3 to 30 V Voltage at CS, OUT to GND -0.3 to 7 V FB input (Pin 5) -40 to 10 V Internally limited A Output Current at OUT Operating Junction Temperature Storage Temperature 150 oC -65 to 150 oC Lead Temperature (Soldering, 10s) 300 Thermal Resistance Junction-to-Ambient 250 ESD (Machine Model) 200 V ESD (Human Body Model) 2000 V o o C C/W 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. Feb. 2009 Rev. 1.0 BCD Semiconductor Manufacturing Limited 4 Preliminary Datasheet LOW-POWER OFF-LINE PRIMARY SIDE REGULATION CONTROLLER AP3703 Electrical Characteristics (VCC=15V, TA=25oC, unless otherwise specified.) Parameter Symbol Conditions Min Typ Max Unit VTH (ST) 16.5 19.5 22.5 V VOPR(min) 6.5 8 9.5 V VCC = VTH (ST)-0.5V, Before start-up 45 60 µA Static 240 300 µA 24 30 36 VCS 450 485 530 mV VCS(PRE) 350 395 440 mV UVLO SECTION Start-up Threshold Minimal Operating Voltage STANDBY CURRENT SECTION IST Start-up Current Operating Current ICC(OPR) DRIVE OUTPUT SECTION OUT Maximum Current Sink Source 50 IOUT mA CURRENT SENSE SECTION Current Sense Threshold Pre-Current Sense Leading Edge Blanking 430 ns FEEDBACK INPUT SECTION Feedback Current Pin Input Leakage 2.3 2.7 3.1 µA VFB 3.65 3.95 4.25 V Enable Turn-on Voltage VFB(EN) -2.0 -1.5 -1.0 V Over Voltage Protection VFB(OVP) 6.4 8 9.6 V Feedback Threshold IFB VFB=4V Feb. 2009 Rev. 1.0 BCD Semiconductor Manufacturing Limited 5 Preliminary Datasheet LOW-POWER OFF-LINE PRIMARY SIDE REGULATION CONTROLLER AP3703 Typical Performance Characteristics 100 21 80 Start-up Current (µA) Start-up Voltage (V) 20 19 18 17 60 40 20 16 15 -40 -20 0 20 40 60 80 100 0 -40 120 -20 0 20 40 60 80 100 120 o Ambient Temperature ( C) o Ambient Temperature ( C) Figure 4. Start-up Voltage vs. Ambient Temperature Figure 5. Start-up Current vs. Ambient Temperature 400 Operating Current (µA) 350 300 250 200 150 100 -40 -20 0 20 40 60 80 100 120 o Ambient Temperature ( C) Figure 6. Operating Current vs. Ambient Temperature Feb. 2009 Rev. 1.0 BCD Semiconductor Manufacturing Limited 6 Preliminary Datasheet LOW-POWER OFF-LINE PRIMARY SIDE REGULATION CONTROLLER AP3703 Operation Description Bridge VIN Vg + VS C1 LM NP IS + CO IO VAUX Q1 OUT AP3703 NS VO D1 NAUX IP FB CS GND RCS Figure 7. Simplified Flyback Converter Controlled by AP3703 The energy stored in the magnetizing inductance LM each cycle is therefore: Figure 7 illustrates a simplified flyback converter controlled by AP3703. 1 Eg = × LM ⋅ Ipk 2 2 Constant Primary Peak Current The primary current ip(t) is sensed by a current sense resistor RCS as shown in Figure 7. So the power transferring from the input to the output is given by: The current rises up linearly at a rate of: dip (t ) vg (t ) = dt LM ......(3) 1 P = × LM × Ipk2 × f SW 2 ......(1) ......(4) See equation 2 Where the fsw is the switching frequency. When the peak current Ipk is constant, the output power depends on the switching frequency fsw. Figure 8. Primary Current Waveform Constant Voltage Operation The AP3703 captures the auxiliary winding feedback voltage at FB pin and operates in constant-voltage (CV) mode to regulate the output voltage. Assuming the secondary winding is master, the auxiliary winding is slave during the D1 on-time and the auxiliary voltage is given by: Ip 0A As illustrated in Figure 8, when the current ip(t) rises up to Ipk, the switch Q1 turns off. The constant peak current is given by: Vcs Ipk = Rcs V AUX = ......(2) Feb. 2009 Rev. 1.0 N AUX × (Vo + Vd ) NS ......(5) BCD Semiconductor Manufacturing Limited 7 Preliminary Datasheet LOW-POWER OFF-LINE PRIMARY SIDE REGULATION CONTROLLER AP3703 Operation Description (Continued) The relationship between the output constant-current and secondary peak current Ipks is given by: where the Vd is the diode forward drop voltage. See equation 5 1 Tons Iout = × Ipks× 2 Tons + Toffs ......(7) At the instant of D1 turn-on, the primary current transfers to the secondary at an amplitude of: 0V 2/3 Tons Ipks = Tons Figure 9. Auxiliary Voltage Waveform 1 N Tons 2 N Iout = × P × Ipk × = × P × Ipk 2 NS Tons + Toffs 7 N S CCM Protection The AP3703 is designed to operate in discontinuous conduction mode (DCM) in both CV and CC modes. To avoid operating in continuous conduction mode (CCM), the AP3703 detects the falling edge of the FB input voltage on each cycle. If a 0.1V falling edge of FB is not detected, the AP3703 will stop switching. See equation 8 Iout 0A OVP & OCkP The AP3703 includes output over-voltage protection (OVP) and open circuit protection (OCkP) circuitry as shown in Figure 11. If the voltage at FB pin exceeds 8V, 100% above the normal detection voltage, or the -1.5V falling edge of the FB input can not be monitored, the AP3703 will immediately shut off and enters hiccup mode. The AP3703 sends out a fault detection pulse every 24ms in hiccup mode until the fault has been removed. Toffs Figure 10. Secondary Current Waveform In CC operation, the CC loop control function of AP3703 will keep a fixed proportion between D1 ontime Tons and D1 off-time Toffs by discharging or charging a capacitor embedded in the IC. The fixed proportion is: Tons 4 = Toffs 3 ......(9) Leading Edge Blanking When the power switch is turned on, a turn-on spike will occur on the sense-resistor. To avoid falsetermination of the switching pulse, a 430ns leadingedge blanking is built in. During this blanking period, the current sense comparator is disabled and the gate driver can not be switched off. Constant Current Operation Figure 10 shows the secondary current waveforms. Tons ......(8) Thus the output constant-current is given by: The output voltage is different from the secondary voltage in a diode forward drop voltage that depends on the current. If the secondary voltage is always detected at a fixed secondary current, the difference between the output voltage and the secondary voltage will be a fixed Vd. For AP3703, the voltage detection point is at two-thirds of the D1 on-time, which means the the secondary voltage is detected at a fixed secondary current of one-third of Ipks. The CV loop control function of AP3703 then generates a D1 offtime to regulate the output voltage. Is NP × Ipk NS ......(6) Feb. 2009 Rev. 1.0 BCD Semiconductor Manufacturing Limited 8 Preliminary Datasheet LOW-POWER OFF-LINE PRIMARY SIDE REGULATION CONTROLLER AP3703 Operation Description (Continued) FB COMP pro 8V R Q S COMP -1.5V Timer_24ms UVLO Figure 11. OVP and OCkP Function Block Typical Application T1 + C1 R1 + R5 C2 D1 VO+ C4 VCC OUT Q1 AP3703 CS + Ns D3 R3 R4 C3 Np R2 D2 VO- Nfb R6 FB GND R7 Rs Figure 12. 5V/500mA Output for Battery Charger of Mobile Phone Feb. 2009 Rev. 1.0 BCD Semiconductor Manufacturing Limited 9 Preliminary Datasheet LOW-POWER OFF-LINE PRIMARY SIDE REGULATION CONTROLLER AP3703 Mechanical Dimensions SOT-23-5 Unit: mm(inch) 0.300(0.012) 0.600(0.024) 1.500(0.059) 1.700(0.067) 0.100(0.004) 0.200(0.008) 2.950(0.116) 2.650(0.104) 2.820(0.111) 3.020(0.119) 0.200(0.008) φ 0.700(0.028) REF 0.300(0.012) 0.400(0.016) 0° 8° 1.800(0.071) 2.000(0.079) 1.250(0.049) 1.050(0.041) 0.950(0.037) TYP 0.000(0.000) 0.100(0.004) 1.050(0.041) 1.150(0.045) Feb. 2009 Rev. 1.0 BCD Semiconductor Manufacturing Limited 10 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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