OB2512RNJPA

OB2512RN High Precision CC/CV Primary-Side Power Switch FEATURES OB2512RN is a high performance offline PSR power switch for low power AC/DC charger and adapter applications. It 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 as well at large load condition and it operates in PWM with frequency reduction at light/medium load. The chip consumes very low operation current, it can achieve less than 75mW standby power. OB2512RN offers comprehensive protection coverage with auto-recovery features including Cycle-by-Cycle current limiting, VDD over voltage protection, short circuit protection, built-in leading edge blanking, VDD under voltage lockout (UVLO), OTP etc. OB2512RN is offered in SOP7 package.  Primary-side sensing and regulation without TL431 and opto-coupler  High precision constant voltage and current regulation at universal AC input  Multi-mode PWM/PFM operation for efficiency improving  Good dynamic response  Programmable CV and CC regulation  Built-in line voltage and primary winding inductance compensation  Programmable cable drop compensation  No need for control loop compensation  Audio noise free operation  Internal BJT switch  Built-in leading edge blanking (LEB)  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  Output short circuit protection  Over temperature protection (OTP) nf id en tia lt o 台 和 GENERAL DESCRIPTION APPLICATIONS Br ig ht co 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 Figure.1. Typical CC/CV Curve O n- TYPICAL APPLICATION ©On-Bright Electronics Confidential -1- Datasheet OB_DOC_DS_2512RNA0 OB2512RN High Precision CC/CV Primary-Side Controller GENERAL INFORMATION Ordering Information Part Number Description OB2512RNJP SOP7, Pb-free, Tube OB2512RNJPA SOP7, Pb-free, T&R Pin Configuration SOP7. 和 Package Dissipation Rating Package RθJA (℃/W) SOP7 95 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. O n- Br ig ht co nf id en tia lt o 台 Absolute Maximum Ratings Parameter Value C-B Voltage 800V VDD Voltage -0.3 to 30V FB Input Voltage -0.3 to 7V CS Input Voltage -0.3 to 7V Min/Max Operating Junction -40 to 150 ℃ Temperature TJ Min/Max Storage -55 to 150 ℃ Temperature Tstg Lead Temperature 260 ℃ (Soldering, 10secs) Note: Stresses beyond those listed under “absolute maximum ©On-Bright Electronics Confidential -2- Datasheet OB_DOC_DS_2512RNA0 OB2512RN High Precision CC/CV Primary-Side Controller en tia lt o 台 和 Marking Information FB 3 NC 4 CS 5、6 C 7 GND I Description Power Supply The voltage feedback from auxiliary winding. Connected to resistor divider from auxiliary winding reflecting output voltage. nf 2 I/O P co Pin Name VDD I Current sense input P HV BJT collector pin. P Ground O n- Br ig ht Pin Num 1 id TERMINAL ASSIGNMENTS: ©On-Bright Electronics Confidential -3- Datasheet OB_DOC_DS_2512RNA0 OB2512RN High Precision CC/CV Primary-Side Controller O n- Br ig ht co nf id en tia lt o 台 和 BLOCK DIAGRAM ©On-Bright Electronics Confidential -4- Datasheet OB_DOC_DS_2512RNA0 OB2512RN High Precision CC/CV Primary-Side Controller ELECTRICAL CHARACTERISTICS (TA = 25℃, VDD=15V, if not otherwise noted) Symbol Parameter Supply Voltage (VDD) Section I start-up Start up current Min Typ. Max VDD=UVLO_OFF-1V 485 tia en id nf co Confidential -5- 0.72 1.0 mA 19.4 7.1 28.0 20.4 7.8 29.5 26 V V V V 0.48 500 555 100 515 us mV mV ns 2.475 2.500 2.525 V 720 2.0 800 us Hz 880 48 2.85 ht Br ig O n- ©On-Bright Electronics uA 台 18.4 6.5 26.5 lt UVLO(OFF) VDD under voltage lockout exit UVLO(ON) VDD under voltage lockout enter VDD_OVP VDD over voltage protection VDD_max Max. Operating Voltage Current Sense Input Section TLEB LEB time Vth_ocp_min Minimum over current threshold Vth_ocp_max Maximum over current threshold Td_oc OCP propagation delay FB Input Section Reference voltage for feedback Vref_fb threshold Tpause_min Minimum Toff F_min Minimum frequency Maximum cable compensation Icomp_cable current Output Over Voltage Protection V_OVP Output Over voltage threshold On chip Over temperature Section Over temperature protection T_otp trigger point Over temperature protection T_otp_rec recovery point Power BJT Section Collector-emitter Vceo Ic=10mA, Ib=0 breakdown voltage Collector-base breakdown Vcbo Ic=10mA voltage Ic Collect Peak Current 15 和 Static current Unit 5 o I static Test Conditions 3.00 uA 3.15 V 155 ℃ 145 ℃ 450 V 800 V 0.8 A Datasheet OB_DOC_DS_2512RNA0 R OB2512RN High Precision CC/CV Primary-Side Power Switch CHARACTERIZATION PLOTS Ivdd_startup vs Temperature VDD vs Istatic 5.5 480 320 160 0 4 8 12 16 20 24 5.1 4.9 4.7 4.5 -40 28 20 50 80 110 140 Temperature(℃) lt VDD(V) UVLO(OFF) vs Temperature tia Vref(V)vs Tem perature 19.8 en 2.56 UVLO(OFF)(V) 20 2.6 2.52 2.48 id Vref(V) -10 o 0 5.3 和 Istatic(uA) 640 台 Ivdd_startup(uA) 800 2.4 -40 -10 20 50 nf 2.44 80 110 140 Temperature( ℃) 19.6 19.4 19.2 19 -40 -10 20 50 80 110 140 co Temperature(℃) UVLO(ON) vs Temperature ht 7.08 Br ig UVLO(ON)(V) 7.1 7.06 7.04 7.02 O n- 7 -40 -10 20 50 80 110 140 Temperature(℃) ©On-Bright Electronics Confidential -6- Datasheet OB_DOC_DS_2512RNA0 R OB2512RN High Precision CC/CV Primary-Side Power Switch OPERATION DESCRIPTION 和 OB2512RN 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. o lt nf id en  CC/CV Operation OB2512RN 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, OB2512RN will regulate the output current constant regardless of the output voltage drop. Figure 2 Auxiliary voltage waveform Via a resistor divider connected between the auxiliary winding and FB (pin 1), the auxiliary voltage is sampled at the middle of the de-magnetization and it is hold until the next sampling. The sampled voltage is compared with Vref (typical 2.5V) and the error 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. When the sampled voltage is below Vref and the error amplifier output reaches its minimum, the switching frequency is controlled by the sampled voltage to regulate the output current, thus the constant output current can be achieved. tia  Operating Current The operating current of OB2512RN is as low as 720uA (typical). Good efficiency and low standby power is achieved with the low operating current. 台  Startup Current and Startup Control Startup current of OB2512RN is designed to be very low so that VDD can be charged up quickly. A large value startup resistor can therefore be used to minimize the power loss in application. co  Adjustable CC Point and Output Power In OB2512RN, the CC point and maximum output power can be externally adjusted by external current sense resistor Rs at CS pin as illustrated in 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. O n- Br ig ht  Principle of Operation To support OB2512RN proprietary CC/CV control, system needs to be designed in DCM mode for flyback system (Refer to Typical Application Diagram on page1). In the DCM flyback converter, the output voltage can be sensed via the auxiliary winding. During BJT turn-on time, the load current is supplied from the output filter capacitor, Co. The current in the primary winding ramps up. When BJT turns off, the energy stored in the primary winding is transferred to the secondary side such that the current in the secondary winding is IS  NP  IP NS Figure 3. Adjustable output power by changing Rs (1)  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 OB2512RN, a proprietary OCP compensation block is integrated and no external components are needed. The OCP threshold in OB2512RN is a function of the switching ON time. For the ON time 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 drop voltage of the output Diode. ©On-Bright Electronics Confidential -7- Datasheet OB_DOC_DS_2512RNA0 R OB2512RN High Precision CC/CV Primary-Side Power Switch less than 3.7us (typical), the OCP threshold changes linearly from 500mV (typical) to 555mV (typical). For the ON time larger than 3.7us (typical), the OCP threshold is clamped to 555mV (typical), as shown in Figure 4. 和 the resistance of the divider to compensate the drop for various cable lines used. The percentage of maximum compensation is 6 V I comp _ cable  R1 // R2 10  100% 2.5 Vout V is load compensation voltage and Vout is output voltage; For example: R1//R2=6.2Kohm, the percentage of maximum compensation is o 台 V 48  6200  10 6   100%  11.9% Vout 2.5 1 LP FSW I p2 2 tia (3) id Po MAX   co nf 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 such that the switching frequency is 1 2TDemag (4) O n- 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.  Programmable Cable Drop Compensation In OB2512RN, cable drop compensation is implemented to achieve good load regulation. An offset voltage is generated at FB pin by an internal current flowing into the resister divider. The current is proportional to the switching off time, as a result, it is inversely proportional to the output load current, thus the drop due to the cable loss can be compensated. As the load current decreases from full-load to no-load, the offset voltage at FB will increase. It can also be programmed by adjusting ©On-Bright Electronics Cycle-by-Cycle current limiting is offered in OB2512RN. The switch current is detected by a sense resistor into the CS pin. An internal leading edge blanking circuit chops off the sensed voltage spike at initial power BJT on state so that the external RC filtering on sense input is no longer needed.  Protection Control Good power supply system reliability is achieved with its rich protection features including Cycle-by-Cycle current limiting (OCP), Output over voltage protection, VDD over voltage protection, short circuit protection, Under Voltage Lockout on VDD (UVLO) and over temperature protection (OTP). VDD is supplied by transformer auxiliary winding output. The output of OB2512RN is shut down when VDD drops below UVLO (ON) and the power converter enters power on start-up sequence thereafter. To prevent the circuit being damaged under abnormal conditions, OB2512RN provides over thermal protection function. When the die temperature rises above over temperature threshold T_otp, the OB2512RN will shut down the base output and then latch the power supply off. The controller will remains latched until the die temperature drops below the recovery threshold T_otp_rec and the OB2512RN will reset at the same time. ht Br ig FSW  Current Sensing and Leading Edge Blanking en  Operation Switching Frequency The switching frequency of OB2512RN is adaptively controlled according to the load conditions and the operation modes. For flyback operating in DCM, The maximum output power is given by lt Figure.4 On time OCP compensation Confidential -8- Datasheet OB_DOC_DS_2512RNA0 R OB2512RN High Precision CC/CV Primary-Side Power Switch PACKAGE MECHANICAL DATA Br ig Symbol ht co nf id en tia lt o 台 和 SOP7 PACKAGE OUTLINE DIMENSIONS O n- A A1 A2 b c D E E1 e L θ ©On-Bright Electronics Dimensions In Millimeters Min Max 1.350 1.750 0.050 0.250 1.250 1.650 0.310 0.510 0.100 0.250 4.700 5.150 3.800 4.000 5.800 6.200 1.270 (BSC) 0.400 1.270 0º 8º Confidential -9- Dimensions In Inches Min Max 0.053 0.069 0.002 0.010 0.049 0.065 0.012 0.020 0.004 0.010 0.185 0.203 0.150 0.157 0.228 0.244 0.050 (BSC) 0.016 0.050 0º 8º Datasheet OB_DOC_DS_2512RNA0 R OB2512RN High Precision CC/CV Primary-Side Power Switch IMPORTANT NOTICE 和 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. tia lt o 台 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 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_2512RNA0