OB2001MP

OB2001 High Performance synchronous rectification controller GENERAL DESCRIPTION FEATURES OB2001 is a high performance and tightly integrated secondary side synchronous rectification controller and driver used for secondary side rectification in switch mode power supply system. It drivers 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. OB2001 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, OB2001 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, OB2001 generates a driving signal with dead time with respect to the primary side PWM signal to turn the integrated N-channel SR switch on and off in proximity of the zero current transition with the help of smart driver voltage control. It is optimized for 5V output voltage. The externally adjustable minimum on time and property 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. OB2001 is offered in SOT23-6 package. ■ ■ ■ 一 ■ ■ ■ 派 ■ ■ Secondary-side synchronous rectification controller optimized for 5V output system Suitable for DCM, QR operation Accurate secondary side MOSFET Vds sensing Low cost small size CC/CV mode support Up to 200kHz operation frequency 3A/2A peak current sink/source driver capability Output voltage overshoot control VDD UVLO protection AC/DC 5V adaptors Cell phone charger 5V Bias supply Low voltage rectification circuits Br ig ht co nf id en tia ■ ■ ■ ■ lt o APPLICATIONS O n- TYPICAL APPLICATION ©On-Bright Electronics Confidential 1 Datasheet OB_DOC_DS_2001A0 OB2001 W O n- Br ig ht co nf id en tia lt o 派 一 High Performance synchronous rectification controller ©On-Bright Electronics Confidential -2- Datasheet OB_DOC_DS_2001A0 OB2001 W High Performance synchronous rectification controller GENERAL INFORMATION Absolute Maximum Ratings Parameter Value Vin pin -0.6V to 7V VDD pin -0.6V to 7V VD pin -2.5V to 50V Note2 Gate pin -0.6V to 7V RT pin -0.6V to 7V 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) lt o 派 一 Pin Configuration The OB2001 is offered in SOT23-6 package, shown as below. SOT23-6 en tia 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. co nf Package Dissipation Rating Package RJA(℃/W) SOT23-6 200 id Ordering Information Part Number Description OB2001MP SOT23-6, Pb-free in T&R X X Br ig ht OB2001 Recommended Operating Range Symbol Parameter Min/Max VDD VDD Supply Voltage 4V to 5.5V High Performance Synchronous Rectifier Controller Package P:Pb-free O n- M:SOT23-6 Package Pb-free ©On-Bright Electronics Confidential 3 Datasheet OB_DOC_DS_2001A0 OB2001 W High Performance synchronous rectification controller Marking Information en tia lt o Y:Year Code WW:Week Code(01-52) ZZZ: Lot Code s: Internal Code(Optional) 派 一 001YWW . ZZZ s TERMINAL ASSIGNMENTS I/O Description VD I This pin is connected to external n-channel MOSFET drain Gate O Driver output for external N-channel MOSFET GND P Ground. VDD P Power Supply Vin I System output voltage detection RT O Minimum on time control pin. A resistor is connected from this pin to GND O n- Br ig ht co nf id Pin Name ©On-Bright Electronics Confidential -4- Datasheet OB_DOC_DS_2001A0 OB2001 W High Performance synchronous rectification controller O n- Br ig ht co nf id en tia lt o 派 一 BLOCK DIAGRAM ©On-Bright Electronics Confidential 5 Datasheet OB_DOC_DS_2001A0 OB2001 W High Performance synchronous rectification controller ELECTRICAL CHARACTERISTICS (TA = 25℃, VDD=5V, unless otherwise noted) Symbol Parameter Test Conditions Min Typ Max Unit Supply Voltage (VDD) 1.5 Minimum Vdd regulation voltage VDD Under Voltage Lockout UVLO(ON) Entry VDD Under Voltage Lockout UVLO(OFF) Exit (Recovery) VD Detection Section SR MOSFET turn on threshold Vth_SR_act voltage detection at VD SR MOSFET turn off threshold Vth_SR_deact voltage detection at Vd SR MOSFET turn-on Tdelay_on propagation delay SR MOSFET turn-off Tdelay_off propagation delay 0.5 V 2.8 3.0 3.2 V 2.9 3.1 3.3 V -200 mV -5 mV id 100 ns nf 75 SR MOSFET minimum on time RT=25KΩ 1.9 co RT Section Vrt 0.7 mA 4.2 en tia lt o Vdd_regulation_mini T_minimum_on 2.0 mA 一 Operation current 派 I_Vdd_operation Frequency@Vd=65KHz,VD D=5V,1nF Cap load at GATE. Frequency@Vd=2KHz,VDD =5V,No load at GATE. Voltage reference at RT pin 0.95 1 n- Br ig ht Overshoot Control Section System output 1st overshoot clamp control trigger voltage at st Vo_High_clamp_1 Vin with SR frequency lower than 7.5KHz System output 2nd overshoot nd Vo_High_clamp_2 clamp control trigger voltage at Vin System output overshoot clamp IVo_High_clamp current GATE driver Section VOH Output high level @ VDD=5V VOL Output low level @ VDD=5V Pull-up driver Rds_on Pull-down driver Isource Source current Isink Sink current Us 1.05 V 5.65 V 6.15 V 100 mA 2.5 1.5 2 3 V V Ω Ω A A 4.5 O ns 1 Tf Falling time Gate voltage falling from 4V to 1V @ C L =1nF 30 ns Tr Rising time Gate voltage rising from 1V to 4V @ C L =1nF 30 ns ©On-Bright Electronics Confidential 6 Datasheet OB_DOC_DS_2001A0 OB2001 W High Performance synchronous rectification controller CHARACTERIZATION PLOTS UVLO(OFF)(V) vs Tem perature UVLO(ON)(V) vs Tem perature 3.5 3.30 3.10 2.90 2.70 3.1 2.9 2.7 2.5 -40 -10 20 50 80 110 140 -40 -10 VRT(V) 1.03 1.01 0.99 0.97 0.95 50 80 110 140 O n- Br ig ht co nf Temperature(℃) 140 id 20 110 en tia 1.05 -10 80 Temperature(℃) VRT(V) vs Tem perature -40 50 lt o Temperature(℃) 20 派 2.50 3.3 一 UVLO(ON)(V) UVLO(OFF)(V) 3.50 ©On-Bright Electronics Confidential 7 Datasheet OB_DOC_DS_2001A0 OB2001 W High Performance synchronous rectification controller Operation Description OB2001 is a high performance and tightly integrated secondary side synchronous rectification controller operating in DCM and QR mode and driver in switch mode power supply system. It drivers a much lower voltage drop Nchannel MOSFET to emulate the traditional diode rectifier, which can reduce heat dissipation, increases output current capability and efficiency, and simplify thermal design. 一 Adjustable minimum on time OB2001 offers adjustable minimum on time control. This timer can avoid effectively false turnoff due to high frequency interference caused by parasitic element at the start of secondary-side demagnetization. Tonmin=8*RT*10E(-11) 派 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 OB2001, which can guarantee reliable synchronous rectification operation in DCM, QR. en tia lt o Startup and under voltage lockout(UVLO) OB2001 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. Br ig ht co nf id Synchronization rectifier OB2001 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 OB2001 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 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. OB2001 can offer typical source capability 2A and typical sink capability 3A. This guarantees fast turn-on and turn-off of SR MOSFET. n- Isec O Output overshoot clamp For poor system design, there is usually output overshoot during startup and load transient. To facilitate system design, OB2001 can detect output overshoot condition and prevent overshoot happen. When output voltage rises to meet the inner threshold, OB2001 will open a discharge path from Vin to ground to clamp the system output voltage, so the system output overshoot can be prevented. Vth_SR_deact Vth_SR_act Ton_delay Toff_delay Fig.1 SR MOSFET turn-on and turn-off timing ©On-Bright Electronics Confidential 8 Datasheet OB_DOC_DS_2001A0 OB2001 W High Performance synchronous rectification controller Symbol ht co nf id en tia lt o 派 一 PACKAGE MECHANICAL DATA Dimensions In Millimeters Max Min Max A 1.000 1.450 0.039 0.057 A1 0.000 0.150 0.000 0.006 A2 0.900 1.300 0.035 0.051 b 0.300 0.500 0.012 0.020 c 0.080 0.220 0.003 0.009 D 2.800 3.020 0.110 0.119 E 1.500 1.726 0.059 0.068 E1 2.600 3.000 0.102 0.118 Br ig Min nO Dimensions In Inches e 0.950 (BSC) 0.037 (BSC) e1 1.800 2.000 0.071 0.079 L 0.300 0.600 0.012 0.024 θ 0º 8º 0º 8º ©On-Bright Electronics Confidential 9 Datasheet OB_DOC_DS_2001A0 OB2001 W High Performance synchronous rectification controller IMPORTANT NOTICE 一 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. lt o 派 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 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 n- Br ig ht co nf id 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 10 Datasheet OB_DOC_DS_2001A0