APR34309CA SECONDARY SIDE SYNCHRONOUS RECTIFICATION SWITCHER Description Pin Assignments APR34309CA is a secondary side Combo IC, which combines an NChannel MOSFET and a driver circuit designed for synchronous rectification (SR) in DCM operation. It also integrates output voltage detect function for primary side control system. (Top View) DRISR 1 8 GND VDET 2 7 GND AREF 3 6 GND VCC 4 5 DRAIN NEW PRODUCT The N-Channel MOSFET has been optimized for low gate charge, low RDS(ON), fast switching speed and body diode reverse recovery performance. The synchronous rectification can effectively reduce the secondary side rectifier power dissipation and provide high performance solution. By sensing MOSFET drain-to-source voltage, APR34309CA can output ideal drive signal with less external components. It can provide high performance solution for 5V output voltage application. Same as AP4341, APR34309CA detects the output voltage and provides a periodical signal when the output voltage is lower than a certain threshold. By fast response to secondary side voltage, APR34309CA can effectively improve the transient performance of primary side control system. SO-8EP Applications The APR34309CA is available in SO-8EP package. • Features • Synchronous Rectification for DCM Operation Flyback • Eliminate Resonant Ring Interference • Fast Detector of Supply Voltages • Fewest External Components Note: The DRAIN pin of internal MOSFET is exposed PAD, which is at the bottom of IC (the dashed box). The secondary current should flow from GND(pin 6,7,8) to this exposed PAD. • Adapters/Chargers for Cell/Cordless Phones, ADSL Modems, MP3 and Other Portable Apparatus Standby and Auxiliary Power Supplies Totally Lead-free & Fully RoHS Compliant (Notes 1 & 2) Halogen and Antimony Free. “Green” Device (Note 3) Notes: 1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant. 2. See http://www.diodes.com/quality/lead_free.html for more information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green" and Lead-free. 3. Halogen- and Antimony-free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and <1000ppm antimony compounds. Typical Applications Circuit C21 + C23 C22 + R21 APR34309CA R23 CAREF DRAIN DRAIN GND DRISR GND VDET GND AREF VCC R24 C24 RAREF APR34309CA Document number: DS37672 Rev. 5 - 2 1 of 11 www.diodes.com July 2015 © Diodes Incorporated APR34309CA NEW PRODUCT Pin Descriptions Pin Number Pin Name Function 1 DRISR Synchronous rectification MOSFET drive. 2 VDET Synchronous rectification sense input and dynamic function output, connected to DRAIN through a resistor. 3 AREF Program a voltage reference with a resistor from AREF to GND, to enable synchronous rectification MOSFET drive signal. 4 VCC Power supply, connected with system output. 5 DRAIN 6,7,8 GND Exposed PAD DRAIN Drain pin of internal MOSFET. The Drain voltage signal can obtain from this pin. Source pin of internal MOSFET, connected to Ground. Drain pin of internal MOSFET. The secondary current should flow from GND (pin 6.7.8) to this DRAIN pad. Functional Block Diagram VCC 4 VREF VDET Integrator (VDET-VCC)*tONP IOVP Dynamic OVP IAREF tONPDET AREF DRISR Counter 3 OSC 1 SRDRIVER 6,7,8 DRAIN GND 5, EP 2 VDET APR34309CA Document number: DS37672 Rev. 5 - 2 2 of 11 www.diodes.com July 2015 © Diodes Incorporated APR34309CA Absolute Maximum Ratings (Note 4) Symbol NEW PRODUCT VCC Notes: Parameter Supply Voltage Value Unit -0.3 to 7.5 V VDET, VDRAIN Voltage at VDET, DRAIN Pin -2 to 50 V VAREF, VDRISR Voltage at AREF, DRISR Pin -0.3 to 6 V ID Continuous Drain Current 20 A IDM Pulsed Drain Current 80 A PD Power Dissipation at TA=+25ºC 2.2 W θJA Thermal Resistance (Junction to Ambient) (Note 5) 56 ºC/W θJC Thermal Resistance (Junction to Case) (Note 5) 12 ºC/W TJ Operating Junction Temperature +150 ºC -65 to +150 ºC TSTG Storage Temperature TLEAD Lead Temperature (Soldering, 10 sec) +300 ºC ESD Charge Device Model 1000 V 4. 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. 5. FR-4 substrate PC board, 2oz copper, with 1 inch2 pad layout. Recommended Operating Conditions Symbol Parameter Min Max Unit VCC Supply Voltage 3.3 6 V TA Ambient Temperature -40 +85 ºC APR34309CA Document number: DS37672 Rev. 5 - 2 3 of 11 www.diodes.com July 2015 © Diodes Incorporated APR34309CA Electrical Characteristics Symbol (@TA = +25°C, VCC=5V, unless otherwise specified.) Parameter Conditions Min Typ Max Unit Supply Voltage ( VCC Pin ) ISTARTUP IOP VSTARTUP NEW PRODUCT – Startup Current VCC=VSTARTUP-0.1V – 100 150 μA Operating Current VDET pin floating VCC=VTRIGGER+20mV 40 100 150 μA Startup Voltage – 2.6 3.1 3.4 V UVLO – 2.3 2.8 3.1 V Internal Trigger Voltage – 5.1 5.15 5.2 V Duty Cycle – 4 15 18 % Oscillation Period VCC=5V 18 30 37.5 μs Internal Trigger Current VCC=VTRIGGER, VCC/VDET pin is separately connected to a 20Ω resistor 30 60 80 mA Dynamic Output Section/Oscillator Section VTRIGGER – tOSC ITRIGGER tDIS Minimum Period – 18 30 37.5 ms VDIS Discharge Voltage – 5.13 5.3 5.38 V IDIS Discharge Current VCC=VDIS+0.1V 1.5 3 4.5 mA Trigger Discharger Gap – 30 110 – mV Overshoot Voltage for Discharge – 5.64 5.74 5.84 V Overshoot Current for Discharge VCC=VOVP+0.1V, VCC pin is connected to a 20Ω resistor 40 – 100 mA 1 V VDIS-VTRIGGER VOVP IOVP Synchronous Voltage Detect VTHON Gate Turn-on Threshold – 0 – VTHOFF Gate Turn-off Threshold – -17 -10 -3 mV tDON Turn-on Delay Time From VTHON to VDRISR=1V – 70 130 ns tDOFF Turn-off Propagation Delay Time From VTHOFF to VDRISR=3V – 100 150 ns tRG Gate Turn-on Rising Time From 1V to 3V, CL=4.7nF – 50 100 ns tFG Gate Turn-off Falling Time From 3V to 1V, CL=4.7nF – 50 100 ns (VDET-VCC)*tONP = 25Vµs 0.9 1.8 2.7 (VDET-VCC)*tONP = 50Vµs – – 6.5 3.7 – – V tLEB_S Minimum On Time tLEB_L VDRISR_HIGH VS_MIN tOVP_LAST Kqs Notes: μs Drive Output Voltage VCC=5V SR Minimum Operating Voltage (Note 6) – – – 4.5 V Added OVP Discharge Time – – 2.0 – ms (Note 7) (VDET-VCC)*tONP = 25Vµs 0.325 – 0.515 mA*μs 6. This item specifies the minimum SR operating voltage of VIN_DC, VIN_DC≥NPS*VS_MIN. 7. This item is used to specify the value of RAREF. APR34309CA Document number: DS37672 Rev. 5 - 2 4 of 11 www.diodes.com July 2015 © Diodes Incorporated APR34309CA Electrical Characteristics (@TA =+25°C, unless otherwise specified. Cont.) MOSFET Static Characteristics NEW PRODUCT Parameters Symbol Conditions Min Typ Max Unit Drain to Source Breakdown Voltage VDSS(BR) VGS=0V, ID=0.25mA 50 – 100 V Gate Threshold Voltage VGS(TH) VDS=VGS, ID=0.25mA 0.7 1.3 2 V Zero Gate Voltage Drain Current IDSS VDS=50V, VGS=0V – – 1 µA Gate to Source Leakage Current IGSS VGS=10V, VDS=0V – – ±100 nA Drain to Source On-state Resistance RDS(ON) VGS=4.5V, ID=3A – 8 – mΩ Min Typ Max Unit – 4149 – – 206 – – 159 – – 10.3 – – 8.4 – MOSFET Dynamic Characteristics Parameters Symbol Conditions Input Capacitance Ciss Output Capacitance Coss Reverse Transfer Capacitance Crss Gate to Source Charge Qgs Gate to Drain Charge (Miller Charger) Qgd Total Gate Charge Qg VGS=4.5V – 39 – Gate Resistance Rg – – 1.8 – APR34309CA Document number: DS37672 Rev. 5 - 2 VGS=0V, VDS=25V, f=1MHz VGS=0V to 10V, VDD=25V, ID=15A 5 of 11 www.diodes.com pF nC Ω July 2015 © Diodes Incorporated APR34309CA Output Voltage Detect Function Description tOSC tDIS tDIS tDIS tDIS tDIS tDIS tOSC VDET VOVP VDIS VDIS NEW PRODUCT VTRIGGER VCC VTRIGGER VON UVLO IOVP IVCC VOFF tOVP_LAST IDIS Figure 1. Typical Waveforms of APR34309CA When VCC is beyond power-on voltage (VON), the APR34309CA starts up. The VDET pin asserts a periodical pulse and the oscillation period is tOSC. When VCC is beyond the trigger voltage (VTRIGGER), the periodical pulse at VDET pin is discontinued. When VCC is beyond the discharge voltage (VDIS), the discharge circuit will be enabled, and a 3mA current (IDIS) will flow into VCC pin. When VCC is higher than the overshoot voltage (VOVP), the APR34309CA will enable a discharge circuit, the discharge current (IOVP) will last tOVP_LAST time. After the tOVP_LAST time, APR34309CA will stop the discharge current and detect VCC voltage again. If VCC is still higher than VOVP, the tOVP_LAST time discharge current will be enabled again. Once the OVP discharge current is asserted, the periodical pulse at VDET pin will be disabled. When the VCC falls below the power-off voltage (VOFF), the APR34309CA will shut down. Operation Description MOSFET Driver The operation of the SR is described with timing diagram shown in Figure 2. APR34309CA monitors the MOSFET drain-source voltage. When the drain voltage is lower than the turn-on threshold voltage VTHON, the IC outputs a positive drive voltage after a turn-on delay time (tDON). The MOSFET will turn on and the current will transfer from the body diode into the MOSFET’s channel. In the process of drain current decreasing linearly toward zero, the drain-source voltage rises synchronically. When it rises over the turn off threshold voltage VTHOFF, APR34309CA pulls the drive signal down after a turn-off delay (tDOFF). I,V VDET IS VTHON 0 t VTHOFF VDRISR 0.9VDRISR 0.9VDRISR 0.1VDRISR 0 tDON tRG tDOFF 0.1VDRISR t t FG Figure 2. Typical Waveforms of APR34309CA APR34309CA Document number: DS37672 Rev. 5 - 2 6 of 11 www.diodes.com July 2015 © Diodes Incorporated APR34309CA Operation Description (Cont.) Minimum On Time When the controlled MOSFET gate is turned on, some ringing noise is generated. The minimum on-time timer blanks the VTHOFF comparator, keeping the controlled MOSFET on for at least the minimum on time. If V THOFF falls below the threshold before minimum on time expires, the MOSFET will keep on until the end of the minimum on time. The minimum on time is in direct proportion to the (VDET-VCC)*tONP. When (VDET-VCC)*tONP=5V*5μs, the minimum on time is about 1.8μs. NEW PRODUCT The Value and Meaning of AREF Resistor As to DCM operation Flyback converter, after secondary rectifier stops conduction the primary MOSFET Drain-to-source ringing waveform is resulted from the resonant of primary inductance and equivalent switch device output capacitance. This ringing waveform probably leads to Synchronous Rectifier error conduction. To avoid this fault happening, APR34309CA has a special function design by means of volt-second product detecting. From the sensed voltage of VDET pin to see, the volt-second product of voltage above VCC at primary switch on time is much higher than the volt-second product of each cycle ringing voltage above V CC. Therefore, before every time Synchronous Rectifier turning on, APR34309CA judges if the detected volt-second product of VDET voltage above VCC is higher than a threshold and then turn on synchronous Rectifier. The purpose of AREF resistor is to determine the volt-second product threshold. APR34309CA has a parameter, Kqs, which converts RAREF value to volt-second product, Area2 R AREF * Kqs In general, Area1 and Area3, the value of which should be test on system, depend on system design and are always fixed after system design frozen. As to BCD PSR design, the Area1 value changes with primary peak current value and Area3 value generally keeps constant at all of conditions. So the AREF resistor design should consider the worst case, the minimum primary peak current condition. Since of system design parameter distribution, Area1 and Area3 have moderate tolerance. So Area2 should be designed between the middle of Area1 and Area3 to keep enough design margin. Area3 R AREF * Kqs Area1 Area1=(VDET-VCC)*tONP Area3 VDET VCC Area2=Kqs*RAREF Figure 3. AREF Function SR Minimum Operating Voltage APR34309CA sets a minimum SR operating voltage by comparing the difference between V DET and output voltage (VCC). The value of VDET–VCC must be higher than its internal reference, then APR34309CA will begin to integrate the area of (VDET–VCC)*tONP. If not, the area integrating will not begin and the SR driver will be disabled. SR Turning Off Timing Impact on PSR CV Sampling As to synchronous rectification on Flyback power system, SR MOSFET need to turn off in advance of secondary side current decreasing to zero to avoid current flowing reversely. When SR turns off in advance, the secondary current will flow through the body diode. The SR turning off time is determined by the VTHOFF at a fixed system. When VTHOFF is more close to zero, the SR turning on time gets longer and body diode conduction time gets shorter. Since of the different voltage drop between SR MOSFET and body diode, the PSR feedback signal VFB appears a voltage jump at the time of SR MOSFET turning off. If the PSR CV sampling time tSAMPLE is close to even behind this voltage jump time, there will be system unstable operation issue or the lower output voltage issue. APR34309CA Document number: DS37672 Rev. 5 - 2 7 of 11 www.diodes.com July 2015 © Diodes Incorporated APR34309CA Operation Description (Cont.) To ensure stable operating of system, it must be met: tBODYDIODE<tONS*(1- tSAMPLE) tSAMPLE SR Turnoff, Bodydiode operating SR Operating NEW PRODUCT tBODYDIODE VFB tONS Figure 4. SR Turning Off Timing Impact on PSR CV Sampling Recommended Application Circuit Parameters The two resistors R23 and R24 are used to pass ESD test. The value of R23 and R24 should be over 20Ω and below 47Ω respectively because of the undershoot performance. The package of R23 and R24 should be at least 0805 and there isn’t any trace under these two resistors. CAREF is suggested to parallel with AREF resistor to keep the volt-second product threshold stable. And the recommended value of CAREF is 100nF. The recommended value of C24 is 100nF. Ordering Information APR34309CA XX XX - XX Product Name Package Temperature Range SO-8EP -40 to +85C APR34309CA Document number: DS37672 Rev. 5 - 2 Package Packing RoHS/Green MP: SO-8EP TR : Tape & Reel G1 : Green Part Number APR34309CAMPTR-G1 8 of 11 www.diodes.com Marking ID 34309CAMP-G1 Packing 4000/Tape & Reel July 2015 © Diodes Incorporated APR34309CA Marking Information First and Second Lines: Logo and Marking ID Third Line: Date Code Y: Year WW: Work Week of Molding A: Assembly House Code th th XX: 7 and 8 Digits of Batch No. 34309C AMP-G1 YWWAXX - Package Outline Dimensions (All dimensions in mm(inch).) (1) Package Type: SO-8EP 3.800(0.150) 4.000(0.157) 2.110(0.083) 2.710(0.107) 2.750(0.108) 3.402(0.134) NEW PRODUCT (Top View) 1.270(0.050) TYP 4.700(0.185) 5.100(0.201) 0.300(0.012) 0.510(0.020) 5.800(0.228) 6.200(0.244) 0.050(0.002) 0.150(0.006) 1.350(0.053) 1.550(0.061) 0° 8° 0.400(0.016) 1.270(0.050) 0.150(0.006) 0.250(0.010) Note: Eject hole, oriented hole and mold mark is optional. APR34309CA Document number: DS37672 Rev. 5 - 2 9 of 11 www.diodes.com July 2015 © Diodes Incorporated APR34309CA Suggested Pad Layout Package Type: SO-8EP NEW PRODUCT (1) Y1 G Z X1 Y E X Dimensions Z (mm)/(inch) G (mm)/(inch) X (mm)/(inch) Y (mm)/(inch) X1 (mm)/(inch) Y1 (mm)/(inch) E (mm)/(inch) Value 6.900/0.272 3.900/0.154 0.650/0.026 1.500/0.059 3.600/0.142 2.700/0.106 1.270/0.050 APR34309CA Document number: DS37672 Rev. 5 - 2 10 of 11 www.diodes.com July 2015 © Diodes Incorporated APR34309CA IMPORTANT NOTICE DIODES INCORPORATED MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARDS TO THIS DOCUMENT, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION). 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