OB2007MP

OB2007 High Performance synchronous rectification controller GENERAL DESCRIPTION FEATURES OB2007 is a high performance and highly integrated secondary side synchronous rectification controller used for secondary side rectification in switch mode power supply system. It drives 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, increase output current capability and efficiency, and simplify thermal design. It can support wide range of system output voltage 3V~21V. It is suitable for multiple mode applications including discontinuous conduction mode (DCM), quasi-resonant mode (QR) and continuous conduction mode (CCM). The drain-to-source voltage of SR MOSFET is sensed to control the turn on and off of the SR MOSFET. In addition, to reduce SR falling time further, soft gate is implemented in OB2007, which would pull down the gate voltage level before being turned off thoroughly. OB2007 is offered in SOT23-6 package. ■ rig AC/DC 3V~21V adaptors Low voltage rectification circuits o ■ ■ DC Out VDD VIN Vaux GND NC GATE VD OB2007 VCC CS O nB PRT 立 讯 APPLICATIONS GND GATE FB 湾 ■ 台 ■ en tia lt EMI Filter ■ ht c AC IN ■ ■ ■ on fid TYPICAL APPLICATION ■ ■ Secondary-side synchronous rectification controller for 3V~21V output system Up to 180V VD pin high voltage tolerance Self-supplying for operation without the use of an auxiliary winding Suitable for DCM, QR and CCM operation Soft gate drive for fast turn-off Accurate secondary side MOSFET Vds sensing Adaptive off time control effectively avoid the ring impact induced by parasitic elements 3A/2A peak current sink/source driver capability VDD UVLO protection ©On-Bright Electronics Confidential 1 Preliminary Datasheet OB_DOC_DS_200700 OB2007 W High Performance synchronous rectification controller GENERAL INFORMATION 1 6 VIN GND 2 5 NC GATE 3 4 VD 湾 VDD Absolute Maximum Ratings Parameter Value VIN pin -0.6V to 24V VDD pin -0.6V to 10.5V VD pin -2.5V to 180V Note2 Gate pin -0.6V to 10.5V Min/Max Operating -40 to 150 ℃ Junction Temperature TJ Min/Max Storage -55 to 150 ℃ Temperature Tstg Lead Temperature 260 ℃ (Soldering, 10secs) 立 讯 Pin Configuration The OB2007 is offered in SOT23-6 package, shown as below. Note1: Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, 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-rated conditions for extended periods may affect device reliability. Note2: -2.5V applies to minimum duty cycle during normal operation only. o RθJC(℃/W) 60 en tia lt Package Dissipation Rating Package RθJA(℃/W) SOT23-6 200 台 Ordering Information Part Number Description OB2007MP SOT23-6, Halogen-free in T&R Recommended Operating Range Symbol Parameter Min/Max VDD VDD Supply Voltage 4.5V to 9.5V Marking Information on fid OB2007 O nB rig ht c High Performance synchronous rectification controller ©On-Bright Electronics X X Package M:SOT23-6 Package Halogen-free P: Green (Halogen-free) 007YWW . ZZZ s Y:Year Code WW:Week Code(01-52) ZZZ: Lot code s: Internal code Confidential 2 Preliminary Datasheet OB_DOC_DS_200700 OB2007 W High Performance synchronous rectification controller TERMINAL ASSIGNMENTS VD I NC VIN I Description Power Supply Ground Driver output for external N-channel MOSFET This pin is connected to external n-channel MOSFET drain, more than 50ohm resistor is recommended to connect between VD and MOS drain. Not connected System output voltage detection 立 讯 I/O P P O BLOCK DIAGRAM VDD Regulator1 UVLO AVDD 200mV VD on fid Min on time 180V HV Switch PG GND System Output Detection AVDD en tia lt Regulator2 o Bias 台 VIN 湾 Pin Name VDD GND Gate R SR Logic Control Driver Gate S ht c 20mV Ring Detection 40mV gm GND O nB rig GND ©On-Bright Electronics Confidential 3 Preliminary Datasheet OB_DOC_DS_200700 OB2007 W High Performance synchronous rectification controller ELECTRICAL CHARACTERISTICS (TA = 25℃, VDD=9.5V, unless otherwise noted) Symbol Parameter Test Conditions Min Typ. Max Unit Supply Voltage (VDD) I_Vdd_operation Operation current 0.6 湾 Frequency@Vd=65KHz, Duty=25%,High level @VD=30V Vin=20V 1.2 1.6 台 Vdd_regulation Vdd regulation voltage mA 立 讯 Frequency@VD=65KHz,VDH=3 0V,VDL= -0.5V,VDD=6.5V, Vin=5V, 1nF Cap load at GATE. Frequency@VD=2KHz,VDH=30 V,VDL= - 0.5V,VDD=6.5V, Vin=5V, No load at GATE. 9.5 V 6.5 V 4.0 4.2 3.7 3.9 V V en tia lt o Frequency@Vd=65KHz, Duty=25%,High level @VD=30V Vin=5V 0.8 mA UVLO_OFF VDD Under Voltage Lockout Exit UVLO_ON VDD Under Voltage Lockout Enter VD Detection Section SR MOSFET turn on threshold Vth_SR_act voltage detection at VD Adjustable SR MOSFET turn off threshold voltage detection at Vd, Vth_SR_deact Which is 0.2*Rd mV, and Rd is the (Note1) resistor connected to Vd. SR MOSFET fast path turn-on propagation delay Tdelay_on SR MOSFET slow path turn-on propagation delay SR MOSFET turn-off propagation Tdelay_off delay 3.8 3.5 -150 -200 -250 mV ht c on fid Rd=0ohm T_minimum_on SR MOSFET minimum on time rig GATE driver Section VOH Output high level @ VDD=9.5V VOL Output low level @ VDD=9.5V Vsoft_reg VDS regulation voltage mV 70 ns 150 ns 30 ns 1.5 us 9.5 -40 V V mV 15 ns 15 ns 1 Tf Falling time Gate voltage falling from 9.5V to 1V @ C L =1nF Tr Rising time Gate voltage rising from 1V to 9.5V @ C L =1nF nB O -20 Note1： Rd can be chosen between 50~100 Ω ©On-Bright Electronics Confidential 4 Preliminary Datasheet OB_DOC_DS_200700 OB2007 W High Performance synchronous rectification controller O nB rig ht c on fid en tia lt o 台 湾 立 讯 CHARACTERIZATION PLOTS ©On-Bright Electronics Confidential 5 Preliminary Datasheet OB_DOC_DS_200700 OB2007 W High Performance synchronous rectification controller Operation Description OB2007 is a high performance and highly integrated secondary side synchronous rectification controller in switch mode power supply system. It drives a much lower voltage drop N-channel MOSFET to emulate the traditional diode rectifier, which can reduce heat dissipation, increase output current capability and efficiency, and simplify the thermal design. 立 讯 starts, the secondary-side current will flow through the body diode of SR MOSFET and the voltage at the drain will drop to below -200mV (typical). As soon as OB2007 detects this negative voltage, the driver voltage is pulled high to turn on the SR MOSFET after variable delay time depending on input line voltage and loading condition, refer to Fig.3. This variable delay time can improve system immunity to noise． 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 goes on. For reliable operation,OB2007 generates an adjustable SR turn-off threshold voltage based on resistor Rd on VD pin， which is determined by 0.2*Rd mV. When the drain voltage rises above SR turn off threshold, the gate of SR MOSFET will be pulled down to ground very quickly after turnoff delay, refer to Fig.3. o 台 湾 Startup and under voltage lockout (UVLO) Whether OB2007 can operate normally or not depends on UVLO function implemented on chip. When power system is plugged in, VDD cap is charged from transformer secondary winding. When VDD rises above UVLO(off), the IC wakes up from under voltage lock out state, refer to Fig.1. en tia lt 4.0V UVLO(off) VDD VDS SR GATE Startup Isec Fig.1 System start up timing diagram With enough high Vin, OB2007 would be powered from VDD and system output (Vin), which can lead to better system efficiency. When VDD drops below UVLO(on),SR would be disable. Refer to the following timing diagram. on fid Vth_SR_act Tonmin 3.7V UVLO(on) Ton_delay Conduction Phase Once the SR MOSFET is turned on, the gate drive voltage will remain at the high level during minimum on time. With the decrease of the switching current, the VDS will rise above Vth_softgate(typ. -40mV), then the soft gate control is implemented. The gate voltage is pulled lower to enlarge the Rds(on) of the synchronous MOSFET, therefore VDS is adjusted to remain at -40mV during the rest of demagnetization time. The low level gate voltage saves the pull-down time, resulting in higher turn-off speed, which is very important in CCM mode. nB Shutdown O Fig.2 System shut down timing diagram Additionally, there is a pull down on-chip 15Kohm resistor to avoid the misconducting by VD pulse coupling. Besides, a hysteresis window between UVLO(off) and UVLO(on) makes system work reliably. Turn-on and Turn-off Phase OB2007 controls the turn-on and turn-off of synchronization rectifier MOSFET (SR MOSFET) by detection of drain-source voltage of SR MOSFET. When demagnetization of transformer ©On-Bright Electronics Toff_delay Fig.3 Synchronous Rectification Operation rig SR GATE Vth_SR_deact GATE ht c VDD Vth_softgate Minimum on time To avoid effectively false turn-off due to high frequency interference caused by parasitic element at the start of secondary-side Confidential 6 Preliminary Datasheet OB_DOC_DS_200700 OB2007 W High Performance synchronous rectification controller demagnetization, OB2007 offers a blanking achieve reliable SR operation, an adaptive minimum off time control is implemented in OB2007, which can guarantee reliable synchronous rectification operation. time(minimum turn-on time) of 1.5μs. Adaptive minimum off time At the end of demagnetization, SR MOSFET will be turn off. The remaining current may 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 unexpectedly. To avoid above mis-turnon of SR MOSFET, constant minimum off time can be used to screen it. But it may disturb SR MOSFET operation. For reliable SR operation O nB rig ht c on fid en tia lt o 台 湾 立 讯 Gate driver For good and efficient synchronous rectification operation, the SR MOSFET should be turned on/off in very short time. Therefore strong driver capability is needed. OB2007 can offer typical source capability 2A and typical sink capability 3A. This guarantees fast turn-on and turn-off of SR MOSFET. In addition, in order to further speed up gate turn off, soft gate control is implemented. Refer to Conduction Phase section for soft gate control. ©On-Bright Electronics Confidential 7 Preliminary Datasheet OB_DOC_DS_200700 OB2007 W High Performance synchronous rectification controller on fid en tia lt o 台 湾 立 讯 PACKAGE MECHANICAL DATA O nB rig A A1 A2 b c D E E1 e e1 L θ Dimensions In Millimeters Min Max 1.000 1.450 0.000 0.150 0.900 1.300 0.300 0.500 0.080 0.220 2.800 3.020 1.500 1.726 2.600 3.000 0.950 (BSC) 1.800 2.000 0.300 0.600 0º 8º ht c Symbol ©On-Bright Electronics Confidential 8 Dimensions In Inches Min Max 0.039 0.057 0.000 0.006 0.035 0.051 0.012 0.020 0.003 0.009 0.110 0.119 0.059 0.068 0.102 0.118 0.037 (BSC) 0.071 0.079 0.012 0.024 0º 8º Preliminary Datasheet OB_DOC_DS_200700 OB2007 W High Performance synchronous rectification controller IMPORTANT NOTICE 立 讯 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. 台 湾 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. en tia lt o 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. O nB rig ht c on fid 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_200700