OB2005ZKCPA

OB2005xK High Performance synchronous rectifier GENERAL DESCRIPTION FEATURES OB2005xK is a high performance and tightly integrated secondary side synchronous rectifier for switch mode power supply system. It combines a much lower voltage drop N-channel MOSFET to emulate the traditional diode rectifier at the secondary side of Flyback converter, which can reduce heat dissipation, increases output current capability and efficiency and simplify thermal design. OB2005xK can support low system output voltage down to 2V at constant current mode. It is suitable for multiple mode applications including discontinuous conduction mode and quasi-resonant mode. With its versatility and optimization, OB2005xK can be used in various switch mode power supply topologies including secondary-side control topology and primary-side control topology. From the information on the secondary side of the isolation transformer, OB2005xK generates a driving signal with dead time with respect to the primary side PWM signal to turn the integrated Nchannel SR switch on and off in proximity of the zero current transition. It is optimized for 5V output voltage. The property minimum off time control scheme effectively avoid the ring impact induced by parasitic elements so that a reliable and noise free operation of the SR system is insured. OB2005xK is offered in SOP8 package. ■ Secondary-side synchronous rectifier optimized for 5V output system ■ Suitable for DCM, QR operation ■ Property minimum off time control ■ Accurate secondary side MOSFET Vds sensing ■ Low cost small size CC/CV mode support ■ Up to 200kHz operation frequency ■ VDD UVLO protection APPLICATIONS ■ AC/DC 5V adaptors ■ Cell phone charger ■ 5V Bias supply ■ Low voltage rectification circuits TYPICAL APPLICATION ©On-Bright Electronics Confidential 1 Preliminary Datasheet OB_DOC_DS_2005xK00 OB2005xK W High Performance Synchronous Rectifier GENERAL INFORMATION Pin Configuration The OB2005xK is offered in SOP8 package, shown as below. Absolute Maximum Ratings Parameter Value Vin pin -0.6V to 7V VDD pin -0.6V to 7V Drain pin -0.6V to BVdss Note1 Min/Max Operating -40 to 150 ℃ Junction Temperature TJ Operating Ambient -20 to 85 ℃ Temperature TA Min/Max Storage -55 to 150 ℃ Temperature Tstg Lead Temperature 260 ℃ (Soldering, 10secs) Note1: -0.6V is self-clamped Ordering Information Part Number Description OB2005WKCP SOP8, Halogen-free in Tube OB2005WKCPA SOP8, Halogen-free in T&R OB2005VKCP SOP8, Halogen-free in Tube OB2005VKCPA SOP8, Halogen-free in T&R Recommended Operating Range Symbol Parameter Min/Max VDD VDD Supply Voltage 4V to 5.5V Package Dissipation Rating Package RJA(℃/W) SOP8 90 OB2005xK High Performance Synchronous Rectifier ©On-Bright Electronics X X X Package Green Package Packing C:SOP8 P:Halogen-free Blank:Tube A: Tape/Reel Confidential 2 Preliminary Datasheet OB_DOC_DS_2005xK00 OB2005xK W High Performance Synchronous Rectifier Marking Information YWWZZZ OB2005WCP K YWWZZZ OB2005VCP K S Y:Year Code WW:Week Code(01-52) ZZZ:Lot Code C:SOP8 Package P:Halogen-free Package K:Character Code S:Internal Code(Optional) S Y:Year Code WW:Week Code(01-52) ZZZ:Lot Code C:SOP8 Package P:Halogen-free Package K:Character Code S:Internal Code(Optional) TERMINAL ASSIGNMENTS Pin Name GND Drain VDD I/O P I/O P Vin I Description Ground SR Mosfet drain pin. This pin is connected to secondary-side winding of transformer Power Supply System output voltage detection, 30ohm resistor connected to Vin pin is recommended ©On-Bright Electronics Confidential -3- Preliminary Datasheet OB_DOC_DS_2005xK00 OB2005xK W High Performance Synchronous Rectifier BLOCK DIAGRAM ©On-Bright Electronics Confidential 4 Preliminary Datasheet OB_DOC_DS_2005xK00 OB2005xK W High Performance Synchronous Rectifier ELECTRICAL CHARACTERISTICS (TA = 25℃, VDD=5V, unless otherwise noted) Symbol Parameter Supply Voltage (VDD) Test Conditions I_VDD_operation Frequency@VD=65KHz,VDD=5V Frequency@VD=2KHz,VDD=5V Operation current VDD_regulation_mini UVLO(ON) UVLO(OFF) Minimum VDD regulation voltage VDD Under Voltage Lockout Entry VDD Under Voltage Lockout Exit (Recovery) Min Typ. Max Unit 1.5 2.0 mA 0.5 0.7 mA 4.2 V 2.8 3.0 3.2 V 2.9 3.1 3.3 V Drain Section Vth_SR_act Vth_SR_deact Tdelay_on Tdelay_off T_minimum_on SR MOSFET turn on threshold voltage detection at Drain SR MOSFET turn off threshold voltage detection at Drain SR MOSFET turn-on propagation delay SR MOSFET turn-off propagation delay SR MOSFET minimum on time SR Mosfet Section Parameter Product OB2005WK OB2005VK ©On-Bright Electronics -350 mV -5 mV 100 ns 75 2.1 BVdss(V) MOSFET Drain-Source Breakdown Voltage Min Typ. Max 40 40 Confidential 5 Rds,on(mΩ) On resistance Min Typ. 13 25 ns us Max Preliminary Datasheet OB_DOC_DS_2005xK00 OB2005xK W High Performance Synchronous Rectifier CHARACTERIZATION PLOTS UVLO(OFF)(V) vs Tem perature UVLO(ON)(V) vs Tem perature 3.5 UVLO(ON)(V) UVLO(OFF)(V) 3.50 3.30 3.10 2.90 2.70 2.50 3.3 3.1 2.9 2.7 2.5 -40 -10 20 50 80 110 140 -40 Temperature(℃) ©On-Bright Electronics -10 20 50 80 110 140 Temperature(℃) Confidential 6 Preliminary Datasheet OB_DOC_DS_2005xK00 OB2005xK W High Performance Synchronous Rectifier Operation Description OB2005xK is a high performance and versatile synchronous rectifier. It can emulate the behavior of Schottky diode rectifier which directly reduces power dissipation of the traditional rectifiers and indirectly reduces primary-side loss due to compounding of efficiency gains. Adaptive minimum off time At the end of demagnetization, SR MOSFET will be turn off. The remaining current will flow through body diode again, which may result in negative voltage (about -700mV) appears at drain and SR MOSFET will turn on again. In addition, the resonance oscillation between the magnetization inductance and parasitic capacitance after demagnetization may cause negative drain voltage. These may turn on SR MOSFET by mistake. To avoid above mis-turn-on of SR MOSFET, constant minimum off time can be used to screen it. But it may disturb SR MOSFET operation. For reliable SR operation, proprietary adaptive minimum off time control is implemented in OB2005xK, which can guarantee reliable synchronous rectification operation in DCM, QR. Startup and under voltage lockout (UVLO) OB2005xK implements UVLO function during startup. When VDD rises above UVLO(off), the IC wakes up from under voltage lock out state and enter normal operation. When VDD drops below UVLO(on), the IC enter under voltage lock out state again and the SR gate is pulled low by 10K resistor on chip. In addition, there is a hysteresis window between UVLO(off) and UVLO(on) to make system work reliably. Synchronization rectifier OB2005xK controls the turn-on and turn-off of synchronization rectifier MOSFET (SR MOSFET) by detection of drain-source voltage. When demagnetization of transformer starts, the secondary-side current will flow through the body diode of SR MOSFET and the voltage at the drain will drop to about -700mV. As soon as OB2005xK detects this negative voltage, the driver voltage is pulled high to turn on the SR MOSFET after very short delay time about 100nS, refer to Fig.1. After the SR MOSFET is turned on, the drain voltage of SR MOSFET begins to rise based on its Rdson and secondary-side current. The drain voltage becomes higher with demagnetization going on. When the drain voltage rises above 5mV, the driver voltage will be pulled down to ground very quickly, refer to Fig.1 PCB Layout Consideration The following rules should be followed in OB2005Cx PCB Layout: The Area of Power Loop: The area of the secondary current loop including the OB2005xK and the output capacitor should be as small as possible to reduce EMI radiation. And the PCB trace must be wide and short for thermal consideration. Bypass Capacitor: The bypass capacitor on VDD should be placed as close as possible to the VDD pin. And the negative node of VDD capacitor should be connected directly to the GND pin (White region as shows in Fig.3). Isec Vth_SR_deact Vth_SR_act Fig.2 Proper Loop at the Secondary Side of the Flyback with OB2005xK Ton_delay Toff_delay Fig.1 SR MOSFET turn-on and turn-off timing Fig.3 Recommend PCB Layout of OB2005xK ©On-Bright Electronics Confidential 7 Preliminary Datasheet OB_DOC_DS_2005xK00 OB2005xK W High Performance Synchronous Rectifier PACKAGE MECHANICAL DATA SOP8 PACKAGE OUTLINE DIMENSIONS Dimensions In Millimeters Dimensions In Inches Min Max Min Max A 1.350 1.750 0.053 0.069 A1 0.050 0.250 0.002 0.010 A2 1.250 1.650 0.049 0.065 b 0.310 0.510 0.012 0.020 c 0.100 0.250 0.004 0.010 D 4.700 5.150 0.185 0.203 E 3.800 4.000 0.150 0.157 E1 5.800 6.200 0.228 0.244 e 1.270 (BSC) L 0.400 1.270 0.016 0.050 θ 0º 8º 0º 8º Symbol ©On-Bright Electronics 0.050 (BSC) Confidential 8 Preliminary Datasheet OB_DOC_DS_2005xK00 OB2005xK W High Performance Synchronous Rectifier IMPORTANT NOTICE RIGHT TO MAKE CHANGES On-Bright Electronics Corp. reserves the right to make corrections, modifications, enhancements, improvements and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. WARRANTY INFORMATION On-Bright Electronics Corp. warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with its standard warranty. Testing and other quality control techniques are used to the extent it deems necessary to support this warranty. Except where mandated by government requirements, testing of all parameters of each product is not necessarily performed. On-Bright Electronics Corp. assumes no liability for application assistance or customer product design. Customers are responsible for their products and applications using On-Bright’s components, data sheet and application notes. To minimize the risks associated with customer products and applications, customers should provide adequate design and operating safeguards. LIFE SUPPORT On-Bright Electronics Corp.’s products are not designed to be used as components in devices intended to support or sustain human life. On-bright Electronics Corp. will not be held liable for any damages or claims resulting from the use of its products in medical applications. MILITARY On-Bright Electronics Corp.’s products are not designed for use in military applications. On-Bright Electronics Corp. will not be held liable for any damages or claims resulting from the use of its products in military applications. ©On-Bright Electronics Confidential 9 Preliminary Datasheet OB_DOC_DS_2005xK00