OB2573YCPA

OB2573Y High Precision CC/CV Primary-Side Power Switch FEATURES OB2573Y is a high performance offline PSR power switch for low power AC/DC charger and adapter applications. The device integrates an internal power MOSFET and operates in primary-side sensing and regulation. Consequently, opto-coupler and TL431 could be eliminated. Proprietary Constant Voltage (CV) and Constant Current (CC) control is integrated as shown in the figure below. In CC control, the current and output power setting can be adjusted externally by the sense resistor Rs at CS pin. In CV control, multi-mode operations are utilized to achieve high performance and high efficiency. In addition, good load regulation is achieved by the built-in cable drop compensation. Device operates in PFM in CC mode at large load condition and it operates in PWM with frequency reduction at light/medium load. The chip consumes very low operation current. It achieves less than 75mW standby power to meet strict standby power standard. OB2573Y offers comprehensive protection coverage with auto-recovery feature including Cycle-by-Cycle current limiting, VDD over voltage protection, feedback loop open protection, built-in leading edge blanking, VDD under voltage lockout (UVLO), OTP etc. OB2573Y is offered in SOP8 packages.  Primary-side sensing and regulation without TL431 and opto-coupler  High precision constant voltage and current regulation at universal AC input  PFM operation for efficiency improving  Integrated Power MOSFET  Good dynamic response  Programmable CV and CC regulation  Built-in primary winding inductance compensation  No need for control loop compensation  Audio noise free operation  Built-in leading edge blanking (LEB)  Ultra low start-up current and low operating current  Comprehensive protection coverage with auto-recovery  VDD over voltage protection  VDD under voltage lockout with hysteresis (UVLO)  Cycle-by-Cycle current limiting  Feedback loop open protection  On-chip OTP fid e nt ia lt o 辰 阳 GENERAL DESCRIPTION APPLICATIONS on Low Power AC/DC offline SMPS for  Cell Phone Charger  Digital Cameras Charger  Small Power Adapter  Auxiliary Power for PC, TV etc.  Linear Regulator/RCC Replacement Vo ht c ±5% Io ig I CC Figure.1. Typical CC/CV Curve O n- Br TYPICAL APPLICATION ©On-Bright Electronics Confidential -1- Preliminary Datasheet OB_DOC_DS_2573Y01 OB2573Y High Precision CC/CV Primary-Side Power Switch Absolute Maximum Ratings Parameter Value Drain Voltage (off state) -0.3V to Vds_maxNote2 VDD Voltage -0.3 to 28V INV Input Voltage -0.3 to 7V CS Input Voltage -0.3 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) GENERAL INFORMATION 1 8 DRAIN GND 2 7 DRAIN INV 3 6 DRAIN CS 4 5 DRAIN 辰 VDD 阳 Pin Configuration The pin map is shown as below for SOP8. Ordering Information Part Number Description OB2573YCP SOP8, Halogen-free, Tube OB2573YCPA SOP8, Halogen-free in T&R o nt ia lt Package Dissipation Rating Package RθJA (℃/W) SOP-8 85 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: Refer to Vds_max’s definition and value in the Electrical Characteristics section on Page5 RθJC (℃/W) 25 Recommended Operating Condition Symbol Parameter Range VDD VDD Supply Voltage 10 to 25V fid e on Marking Information Output Power Table Part Number 90Vac~264Vac OB2573Y 12W ht c OB2573Y X X Package Green Package Packing C:SOP8 P:Halogen -free Blank:Tube A:Tape/Reel YWWZZZ OB2573Y Ps O n- Br ig High Precision CC/CV Primary-Side PWM Power Switch X Y:Year Code WW:Week Code(01-52) ZZZ:Lot Code P:Green Package(Halogen-free) s:Internal Code(Optional) ©On-Bright Electronics Confidential -2- Preliminary Datasheet OB_DOC_DS_2573Y01 OB2573Y High Precision CC/CV Primary-Side Power Switch TERMINAL ASSIGNMENTS Pin Name I/O Description 1 VDD P Power Supply 2 GND P Ground 3 INV I The voltage feedback from auxiliary winding. Connected to resistor divider from auxiliary winding reflecting output voltage. 4 CS I Power MOSFET source 5/6/7/8 Drain O Drain of internal power MOSFET 5V POR Internal Supply Drain Gate Driver fid e OVP on Output OVP Logic core ht c CC Controller ig Br Vref EA OCP CS Drop Comp INV 辰 o VDD nt ia lt BLOCK DIAGRAM UVLO 阳 Pin Num. LEB CV Controller GND O n- sampler ©On-Bright Electronics Confidential -3- Preliminary Datasheet OB_DOC_DS_2573Y01 OB2573Y High Precision CC/CV Primary-Side Power Switch ELECTRICAL CHARACTERISTICS Min Typ. VDD=UVLO_OFF-1V Static current 0.65 1 16.5 8.3 28.0 17.5 9.3 29.5 o 25 500 485 Unit uA 辰 15.5 7.3 26.5 mA V V V 500 V ns 515 mV 2.475 2.500 2.525 V on fid e UVLO(OFF) VDD under voltage lockout exit UVLO(ON) VDD under voltage lockout enter VDD_OVP VDD over voltage protection Max. Operating Voltage Current Sense Input Section LEB time+OCP Propagation TLEB+TD_oc delay Vth_ocp_min Minimum over current threshold INV Input Section Reference voltage for feedback Vref_INV threshold F_min Minimum frequency F_max Maximum frequency Maximum cable compensation Icomp_cable current Iline_det High line/low line judge current Output Over Voltage Protection V_OVP Output Over voltage threshold MOSFET Section Mosfet drain-source spike Vds_maxNote3 voltage capability Static drain to source on Rdson resistance Max 5 nt ia lt I static Test Conditions 阳 (TA = 25℃, VDD=15V, if not otherwise noted) Symbol Parameter Supply Voltage (VDD) Section I start-up Start up current 270 72 ht c 2.85 300 330 Hz KHz 30 uA 1.1 mA 3.0 650 3.15 V V 5.5 Ώ O n- Br ig Note3: MOSFET minimum drain to source breakdown voltage is 600V,Voltage spike at not higher than 650V is allowed under the condition that A) Voltage spike duty cycle does NOT exceed 3% B) Voltage spike pulse width does NOT exceed 200ns. ©On-Bright Electronics Confidential -4- Preliminary Datasheet OB_DOC_DS_2573Y01 OB2573Y High Precision CC/CV Primary-Side Power Switch CHARACTERIZATION PLOTS Ivdd_startup(uA) 1000 Ivdd(uA) 800 600 400 200 0 9 11 13 15 17 -40 19 -10 50 80 110 140 Temperature(℃) on 20 50 80 110 140 o -10 20 50 80 110 140 Temperature(℃) Vocp(V) vs Tem perature 0.600 0.560 0.520 0.480 0.440 0.400 -40 110 140 Br -40 -10 Vocp(V) 2.420 2.360 2.300 -40 ht c 2.600 2.540 2.480 ig Vref(V) Vref(V) vs Tem perature 19.00 18.20 17.40 16.60 15.80 15.00 nt ia lt UVLO(OFF)(V) 9.00 8.80 8.60 8.40 8.20 8.00 20 80 UVLO(OFF)(V) vs Tem perature fid e UVLO(ON)(V) UVLO(ON)(V) vs Tem perature -10 50 Temperature(℃) VDD(V) -40 20 辰 7 10.00 8.00 6.00 4.00 2.00 0.00 阳 Ivdd_startup(uA) vs Tem perature Vdd(V) vs Ivdd(uA) -10 20 50 80 110 140 Temperature(℃) O n- Temperature(℃) ©On-Bright Electronics Confidential -5- Preliminary Datasheet OB_DOC_DS_2573Y01 OB2573Y High Precision CC/CV Primary-Side Power Switch output Diode. OPERATION DESCRIPTION Sampling Instance OB2573Y is a cost effective PSR power switch optimized for off-line low power AC/DC applications including battery chargers. It operates in primary side sensing and regulation, thus opto-coupler and TL431 are not required. Proprietary built-in CV and CC control can achieve high precision CC/CV control meeting most charger application requirements. V AUX PWM Off 辰 PWM On Figure.2. Auxiliary voltage waveform o Via a resistor divider connected between the auxiliary winding and INV (pin 3), the auxiliary voltage is sampled and hold during the demagnetization cycle. The sampling instance is variable according to the demagnetization width. The output voltage can be monitored when the secondary current is small. Thus ∆V can be ignored. The sampled voltage is compared with reference voltage Vref (typical 2.5V) and the difference is amplified. The error amplifier output reflects the load condition and controls the switching off time to regulate the output voltage, thus constant output voltage can be achieved. on fid e CC/CV Operation OB2573Y is designed to produce good CC/CV control characteristic as shown in the Figure. 1. In charger applications, a discharged battery charging starts in the CC portion of the curve until it is nearly full charged and smoothly switches to operate in CV portion of the curve. The CC portion provides output current limiting. In CV operation, the output voltage is regulated through the primary side control. In CC operation mode, OB2573Y will regulate the output current constant regardless of the output voltage drop. TON nt ia lt Operating Current The operating current of OB2573Y is as low as 650uA (typical). Good efficiency and les than 75mW standby power is achieved with the low operating current. 阳 TDemag Startup Current and Start up Control Startup current of OB2573Y is designed to be very low so that VDD could be charged up above UVLO threshold level and device starts up quickly. A large value startup resistor can therefore be used to minimize the power loss yet achieve a reliable startup in application. ht c Adjustable CC Point and Output Power In OB2573Y series, the CC point and maximum output power can be externally adjusted by external current sense resistor Rs at CS pin as illustrated in the typical application diagram. The larger Rs, the smaller CC point is, and the smaller output power becomes, and vice versa as shown in Figure.3. ig Principle of Operation To support OB2573Y series proprietary CC/CV control, system needs to be designed in DCM mode for flyback system (Refer to Typical Application Diagram in page1). In the DCM flyback converter, the output voltage can be sensed via the auxiliary winding. During MOSFET turn-on time, the load current is supplied from the output filter capacitor, Co, and the current in the primary winding ramps up. When MOSFET turns off, the energy stored in the primary winding is transferred to the secondary side and the current in the secondary winding is Vo Br Large Rs O n- Small Rs IS  NP  IP NS Io Figure.3. Adjustable output power by changing Rs (1) Operation Switching Frequency The switching frequency of OB2573Y is adaptively controlled according to the load conditions and the operation modes. For flyback operating in DCM, the maximum output power is given by The auxiliary voltage reflects the output voltage as shown in Figure.2 and it is given by V AUX  N AUX  (VO  V ) NS (2) Where V indicates the voltage drop of the ©On-Bright Electronics Confidential -6- Preliminary Datasheet OB_DOC_DS_2573Y01 OB2573Y High Precision CC/CV Primary-Side Power Switch PoMAX  1 LP FSW I p2 2 INV PIN up side resistor, Vin is the input AC voltage. (3) Where Lp indicate the inductance of primary winding and Ip is the peak current of primary winding. Refer to the equation 3, the change of the primary winding inductance results in the change of the maximum output power and the constant output current in CC mode. To compensate the change from variations of primary winding inductance, the switching frequency is locked by an internal loop and the switching frequency is 阳 o Since TDemag is inversely proportional to the inductance, as a result, the product Lp and fsw is constant, thus the maximum output power and constant current in CC mode will not change as primary winding inductance changes. Up to ±7% variation of the primary winding inductance can be compensated. . . On Time OCP Compensation The variation of max output current in CC mode can be rather large if no compensation is provided. The OCP threshold value is self adjusted higher at higher AC voltage. This OCP threshold slope adjustment helps to compensate the increased output current limit at higher AC voltage. In OB2573Y, a proprietary OCP compensation block is integrated and no external components are needed. The OCP threshold in OB2573Y series is a function of the switching ON time. For the ON time between 1.6us to 6.4us (typical), the OCP threshold changes linearly from 500mV to 590mV. For the ON time larger than 6.4us, the OCP threshold is clamped to 590mV, as shown in Figure 5. (4) 2TDemag 165 辰 1 √2 nt ia lt FSW  Recommended application set Naux, NP, R2 as Vth_OCP 590 mV fid e The switching frequency of OB2573Y is adaptively controlled according to the IINV to provide high efficiency. If IINV