GA1706 Preliminary Datasheet PRIMARY SIDE CONTROL IC FOR OFF-LINE BATTERY CHARGERS AP3706 General Description Features The GA1706 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 GA1706 provides constant voltage, constant current (CV/CC) regulation without requiring an optocoupler and secondary control circuitry. It also eliminates the need of loop compensation circuitry while maintaining stability. · · · · · · · The GA1706 achieves excellent regulation and high · power efficiency, the no-load power consumption is · less than 200mW at 265VAC input. Primary Side Control for Rectangular Constant Current and Constant Voltage Output Eliminates Opto-Coupler and Secondary CV/CC Control Circuitry Eliminates Control Loop Compensation Circuitry Flyback Topology in DCM Operation Random Frequency Modulation to Reduce System EMI Valley Turn on of External Power NPN Transistor Built-in Soft Start Open Circuit Protection Over Voltage Protection Short Circuit Protection Applications · · Adapters/Chargers for Cell/Cordless Phones, PDAs, MP3 and Other Portable Apparatus Standby and Auxiliary Power Supplies · LED Driver SOIC-8 Figure 1. Package Type of GA1706 Jun. 2009 Rev. 1. 0 1 Preliminary Datasheet Pin Configuration M Package (SOIC-8) CS 1 8 COMP VCC 2 7 BIAS OUT 3 6 VDD GND 4 5 FB Figure 2. Pin Configuration of GA1706 (Top View) Pin Description Pin Number Pin Name Function 1 CS 2, VCC The primary current sense Supply voltage 3 OUT This pin drives the base of external power NPN switch 4 GND Ground 5 FB The voltage feedback from the auxiliary winding 6 VDD The 5V output of the internal voltage regulator 7 BIAS This pin sets the bias current inside GA1706 with an external resistor to GND 8 COMP This pin connects a bypass capacitor for CC function Jun. 2009 Rev. 1. 0 2 Preliminary Datasheet Functional Block Diagram VCC UVLO pro OVP & OCkP FB VDD Regulator & Bias 0.1V COMP Tonsec Detector UVLO Tons pfm BIAS EA 4.0V Vea S&H Tons COMP CV_ctrl V+ R pfm_d V+ pfm Driver Q OUT Vea S t CS COMP 0.5V pfm LEB Delay 430ns pfm_d COMP 0.46V VDD I Tons 3.75V COMP COMP R Q CC_ctrl S 0.75*I Figure 3. Functional Block Diagram of GA1706 Jun. 2009 Rev. 1. 0 3 GND Preliminary Datasheet Ordering Information GA1706 - E1: Lead Free Circuit Type TR: Tape and Reel Blank: Tube Package M: SOIC-8 Package Temperature Range SOIC-8 -40 to 85oC Part Number Marking ID Packing Type GA1706M-E1 1706M-E1 Tube GA1706MTR-E1 1706M-E1 Tape & Reel GA Semiconductor's Pb-free products, as designated with "E1" suffix in the part number, are RoHS compliant. Absolute Maximum Ratings (Note 1) Parameter Value Unit Supply Voltage VCC -0.3 to 30 V Voltage at CS, BIAS, OUT, VDD, COMP to GND -0.3 to 7 V FB input (Pin 5) -20 to 10 V Internally limited A Power Dissipation at TA=25oC 0.657 W Operating Junction Temperature 150 oC Output Current at OUT Storage Temperature -65 to 150 o C Lead Temperature (Soldering, 10s) 300 oC Thermal Resistance Junction-to-Ambient 190 oC/W ESD (Machine Model) 200 V 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. Jun. 2009 Rev. 1. 0 4 Preliminary Datasheet Electrical Characteristics (VCC=15V, TA=25oC, unless otherwise specified.) Parameter Symbol Conditions Min Typ Max Unit 17.2 18.2 19.2 V 6.7 7.4 8.1 V 1.170 1.205 1.240 V 4.75 5.0 5.25 V VCC = VTH (ST)-0.5V, RBIAS=200kΩ, Before turn on 70 80 µA ICC(OPR) RBIAS=200kΩ 680 900 µA IOUT RBIAS=200kΩ UVLO SECTION VTH (ST) Start-up Threshold Minimal Operating Voltage VOPR(min) After turn on REFERENCE VOLTAGE SECTION BIAS Pin Voltage VBIAS VDD Pin Voltage VDD RBIAS=200kΩ, Before turn on STANDBY CURRENT SECTION IST Start-up Current Operating Current DRIVE OUTPUT SECTION OUT Maximum Current Sink Source 50 mA 25 30 VCS 480 500 520 mV VCS(PRE) 440 460 480 mV CURRENT SENSE SECTION Current Sense Threshold Pre-Current Sense Leading Edge Blanking 430 ns FEEDBACK INPUT SECTION Feedback Threshold Enable Turn-on Voltage VFB 3.90 4.00 4.10 V VFB(EN) -0.9 -0.7 -0.5 V VCOMP 3.42 3.60 3.78 V VFB(OVP) 7 8 9 V COMP THRESHOLD VOLTAGE SECTION Turn-on Threshold Voltage PROTECTION SECTION Over Voltage Protection Jun. 2009 Rev. 1. 0 5 Preliminary Datasheet Typical Performance Characteristics 19.5 100 90 19.0 Startup Current (µA) Start-up Voltage (V) 80 18.5 18.0 17.5 RBIAS=200kΩ 17.0 16.5 -40 -20 0 20 40 60 80 70 60 50 40 RBIAS=200kΩ 30 100 20 -40 120 -20 0 o 750 5.15 700 5.10 650 5.05 VDD (V) Operating Current (µA) 5.20 600 4.95 500 4.90 RBIAS=200kΩ 0 20 40 60 80 80 100 120 5.00 550 -20 60 Figure 5. Start-up Current vs. Ambient Temperature 800 400 -40 40 Ambient Temperature ( C) Figure 4. Start-up Voltage vs. Ambient Temperature 450 20 o Ambient Temperature ( C) 100 4.85 4.80 -40 120 o -20 0 20 40 60 80 100 o Ambient Temperature ( C) Ambient Temperature ( C) Figure 7. VDD vs. Ambient Temperature Figure 6. Operating Current vs. Ambient Temperature Jun. 2009 Rev. 1. 0 6 120 Preliminary Datasheet 120 80 110 70 100 60 Out Source Current (µA) Start-up Current (µA)) Typical Performance Characteristics (Continued) 90 80 70 60 50 40 100 50 40 30 20 o TA=25 C 150 10 200 250 300 350 0 100 400 Bias Resistor (kΩ) o TA=25 C 150 200 250 300 350 400 Bias Resistor (kΩ) Figure 9. OUT Source Current vs. Bias Resistor Figure 8. Start-up Current vs. Bias Resistor Jun. 2009 Rev. 1. 0 7 Preliminary Datasheet Operation Description Bridge Vg VIN + VS LM NP C1 NS VO D1 IS + CO IO VAUX Q1 NAUX OUT GA1706 IP FB GND CS RCS Figure 10. Simplified Flyback Converter Controlled by GA1706 The energy stored in the magnetizing inductance LM each cycle is therefore: Figure 10 illustrates a simplified flyback converter controlled by GA1706. Constant Primary Peak Current The primary current ip(t) is sensed by a current sense resistor RCS as shown in Figure 10. Eg = P= ................(1) 1 ⋅ LM ⋅ Ipk 2 ⋅ f SW 2 ................(4) Where the fsw is the switching frequency. When the peak current Ipk is constant, the output power depends on the switching frequency fsw. See equation 2 Constant Voltage Operation The GA1706 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. The auxiliary voltage is given by: Ip 0A Figure 11. Primary Current Waveform As illustrated in Figure 11, when the current ip(t) rises up to Ipk, the switch Q1 turns off. The constant peak current is given by: Vcs Ipk = Rcs ................(3) 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 1 ⋅ LM ⋅ Ipk 2 2 VAUX = ................(2) Jun. 2009 Rev. 1. 0 8 N AUX ⋅ (Vo + Vd ) NS ................(5) Preliminary Datasheet 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 Iout = Tons 1 ................(7) ⋅ Ipks ⋅ Tons + Toffs 2 At the instant of D1 turn-on, the primary current transfers to the secondary at an amplitude of: 0V 2/3 Tons Ipks = Tons NP ⋅ Ipk NS ................(8) Figure 12. Auxiliary Voltage Waveform Thus the output constant-current is given by: The output voltage is different from the secondary voltage in a diode forward drop voltage. The diode drop voltage depends on the current. If the secondary voltage is always detected at a constant secondary current, the difference between the output voltage and the secondary voltage will be a fixed Vd. The voltage detection point is at two-thirds of the D1 on-time. The CV loop control function of GA1706 then generates a D1 off-time to regulate the output voltage. Iout = ................(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 The GA1706 is designed to work in constant-current (CC) mode. Figure 13 shows the secondary current waveforms. See equation 8 Is CCM Protection The GA1706 is designed to operate in discontinuous conduction mode (DCM) in both CV and CC modes. To avoid operating in continuous conduction mode (CCM), the GA1706 detects the falling edge of the FB input voltage on each cycle. If a 0.1V falling edge of FB is not detected, the GA1706 will stop switching. Iout 0A Tons Toffs Figure 13. Secondary Current Waveform OVP & OCkP The GA1706 includes output over-voltage protection (OVP) and open circuit protection (OCkP) circuitry as shown in Figure 14. If the voltage at FB pin exceeds 8V, 100% above the normal detection voltage, or the -0.7V falling edge of the FB input can not be monitored, the GA1706 will immediately shut off and enters hiccup mode. The GA1706 sends out a fault detection pulse every 8ms in hiccup mode until the fault has been removed. In CC operation, the CC loop control function of GA1706 will keep a fixed proportion between D1 ontime Tons and D1 off-time Toffs by discharging or charging the capacitance connected in COMP pin. The fixed proportion is Tons 4 = Toffs 3 2 N 1 NP Tons ⋅ ⋅ Ipk ⋅ = ⋅ P ⋅ Ipk 2 NS Tons + Toffs 7 N S ................(6) Jun. 2009 Rev. 1. 0 9 Preliminary Datasheet Operation Description (Continued) FB COMP pro 8V R Q S COMP -0.7V Timer_8ms UVLO Figure 14. OVP and OCkP Function Block Typical Application Figure 10. 5V/0.3A Output for LED power Jun. 2009 Rev. 1. 0 10 Preliminary Datasheet Mechanical Dimensions SOIC-8 4.700(0.185) 5.100(0.201) 7° Unit: mm(inch) 0.320(0.013) 1.350(0.053) 1.750(0.069) 8° 8° 7° 0.675(0.027) 0.725(0.029) D 5.800(0.228) 1.270(0.050) 6.200(0.244) TYP D 20:1 φ 0.800(0.031) 0.300(0.012) R0.150(0.006) 0.100(0.004) 0.200(0.008) 0° 8° 1.000(0.039) 3.800(0.150) 4.000(0.157) 0.330(0.013) 0.190(0.007) 0.250(0.010) 1° 5° 0.510(0.020) 0.900(0.035) R0.150(0.006) 0.450(0.017) 0.800(0.031) Jun. 2009 Rev. 1. 0 11