OB2372CPA

OB2372 High Performance CCM/QR mode Primary-Side Controller FEATURES OB2372 is an excellent primary side regulation controller with CC/CV operation for medium level power AC/DC charger and adapter applications. The device directly drives a power MOSFET and operates in CCM/QR mode to provide high efficiency along with several functions of built-in protections. It removes the need for secondary feedback circuitry to lower the total bill of material cost. Proprietary Constant Voltage (CV) and Constant Current (CC) control is integrated as shown in the figure below. In CV control, the controller changes the mode of operation according to line voltage and load condition. At full loading, the controller operates in fixed frequency CCM in low line voltage and operates quasi-resonant (QR) mode in high line voltage. The primary side regulation power supplies up to high power without the efficiency limitation of DCM or audible noise. In CC control, OB2372 samples the Vcs peak current and the demagnetization pulse to regulation the output constant current. The current and output power setting can be adjusted externally by the sense resistor Rs at CS pin. OB2372 offers comprehensive protection coverage with auto-recovery feature including Cycle-by-Cycle current limiting, VDD OVP, OLP, SCP, OTP etc. OB2372 consumes less than 75mW input power at no- load condition with high line voltage. OB2372 is offered in SOP8 package.  Primary-side sensing and regulation operates in CCM/QR mode without TL431 and opto-coupler  High precision constant voltage and current regulation at universal AC input  Fixed frequency (65kHz) CCM mode operation with low line voltage at full load  Quasi-resonant operation for high efficiency in high line voltage  Good dynamic response  Programmable CV and CC regulation  Built-in primary winding inductance compensation  Programmable cable drop compensation  Built-in control loop compensation  External over temperature protection with latch shutdown (OTP)  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 (OVP)  VDD under voltage lockout with hysteresis (UVLO)  Cycle-by-cycle current limiting  Feedback open loop protection (OLP)  Output short circuit protection (SCP) on fid en tia lt o 富 华 GENERAL DESCRIPTION APPLICATIONS n- br ig ht c Medium level Power AC/DC offline SMPS for  Cell phone charger  Tablet PC  AC/DC adapter  Set-top box power supplies O Figure.1. Typical CC/CV Curve ©On-Bright Electronics Confidential -1- Preliminary datasheet OB_DOC_DS_237200 OB2372 High Performance CCM/QR mode Primary-Side Controller on fid en tia lt o 富 华 TYPICAL APPLICATION Absolute Maximum Ratings Parameter Value VDD Voltage -0.3 to 30V FB Input Voltage -0.3 to 7V RT Input Voltage -0.3 to 7V CS Input Voltage -0.3 to 7V GATE Input Voltage -0.3 to 24V 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 GENERAL INFORMATION Pin Configuration The pin map is shown as below for SOP8. 1 8 VDD RT 2 7 GND NC 3 6 GATE 5 CS 4 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. br ig COMP ht c FB Ordering Information Part Number Description OB2372CP SOP8, Pb-free in Tube OB2372CPA SOP8, Pb-free in T&R n- Recommended Operating Condition Symbol Parameter Range VDD VDD Supply Voltage 9 to 22V Operating Ambient TA -20 to 85 ℃ Temperature O Package Dissipation Rating Package RθJA (℃/W) SOP8 150 ©On-Bright Electronics Confidential -2- Preliminary datasheet OB_DOC_DS_237200 OB2372 High Performance CCM/QR mode Primary-Side Controller on fid en tia lt o 富 华 Marking Information TERMINAL ASSIGNMENTS Pin Num Pin Name I/O Description 1 FB I 2 RT I 3 NC 4 COMP I/O 5 CS I Current sense input. Connect a sense resistor from this pin to ground. 6 GATE O Gate driver of power MOSFET. 7 GND P Ground 8 VDD P Power Supply The voltage feedback from auxiliary winding. Connected to resistor divider from auxiliary winding reflecting output voltage. Connected through a NTC resistor to ground for over temperature protection. O n- br ig ht c Connected through Cap to ground for CC loop compensation. ©On-Bright Electronics Confidential -3- Preliminary datasheet OB_DOC_DS_237200 OB2372 High Performance CCM/QR mode Primary-Side Controller O n- br ig ht c on fid en tia lt o 富 华 BLOCK DIAGRAM ©On-Bright Electronics Confidential -4- Preliminary datasheet OB_DOC_DS_237200 OB2372 High Performance CCM/QR mode Primary-Side Controller ELECTRICAL CHARACTERISTICS (TA = 25℃, VDD=18V, if not otherwise noted) Symbol Parameter Supply Voltage (VDD) Section I start-up Start up current Min VDD=UVLO_OFF-1V Static current Unit 5 15 uA 1.2 1.8 mA 1.8 15.6 7.9 25 5.3 42 2.5 16.6 8.6 26.6 6.3 60 mA V V V V uA 华 14.6 7.2 23.5 4.3 30 Max O n- br ig ht c on fid en tia lt o Iop_s Operating current FB=1V, 1nF gate load. UVLO(OFF) VDD under voltage lockout exit UVLO(ON) VDD under voltage lockout enter VDD_OVP VDD over voltage protection Vlatch_off Latch release vdd voltage Ilatch_off Latch release Icc current Current Sense Input Section TLEB LEB time TD_OC OCP propagation delay Vth_ocp_max Maximum over current threshold Vcs_mini Minimum CS threshold FB Input Section Reference voltage for feedback Vref_fb threshold V_OVP Output Over voltage threshold Tpause_min Minimum Toff Maximum cable compensation Icomp_cable current CC Loop Section Vref_cc CC loop reference CC loop integrator Gm transconductance Timer Section Fs_ccm CV CCM switch frequency Duty_max Maximum duty 65K fixed switch frequency Fs_ccm_jitter jittering Fs_max CV QR maximum frequency Fmin Minimum switch frequency Gate Driver Section V_clamp Output clamp voltage level Tr Output rising time CL=1nF Tf Output falling time CL=1nF Output Over Voltage Protection V_OVP Output Over voltage threshold External OTP Section I_otp RT pin source current V_otp Over temperature trigger voltage Typ. 富 I static Test Conditions ©On-Bright Electronics Confidential -5- 300 100 750 150 ns ns mV mV 2.475 2.500 2.525 V 2.95 190 3.05 2.0 3.15 48 200 uA 210 16 60 250 65 68 V us mV us 70 KHz % +/- 4 % 90 300 KHz Hz 350 10 11.5 150 50 13 V ns ns 2.95 3.05 3.15 V 47.5 1.0 50 1.05 52.5 1.1 uA V Preliminary datasheet OB_DOC_DS_237200 OB2372 High Performance CCM/QR mode Primary-Side Controller O n- br ig ht c on fid en tia lt o 富 华 CHARACTERIZATION PLOTS ©On-Bright Electronics Confidential -6- Preliminary datasheet OB_DOC_DS_237200 OB2372 O n- br ig ht c on fid en tia lt o 富 华 High Performance CCM/QR mode Primary-Side Controller ©On-Bright Electronics Confidential -7- Preliminary datasheet OB_DOC_DS_237200 OB2372 High Performance CCM/QR mode Primary-Side Controller 华 富 Principle of Operation With OB2372 proprietary CC/CV control, system can be designed in CCM/DCM mode for flyback system (Refer to the Typical Application Diagram in page1). In the 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 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 on fid en tia lt OB2372 is an excellent integrated multi-mode (see Figure 2) PWM controller optimized for off-line middle power AC/DC applications. It operates in continuous conduction mode (CCM) and quasi-resonant mode (QR) to provide high efficiency with primary side sensing and regulation thus provide cost effective solution for energy efficient power supplies. At full loading, the IC operates in fixed frequency (65KHz) CCM mode in the low line input voltage and it operates in QR mode in high line input voltage. In this way, high efficiency in the universal input range at full loading can be achieved. At normal load condition, it operates in QR mode. To minimize switching loss, the maximum switching frequency in QR mode is internally limited to 90 KHz (typical). When the load goes low, it operates in PFM mode with valley switching for high power conversion efficiency. When the load is very small, the IC switch frequency can be reduced to 300Hz to minimize the standby power loss. As a result, high conversion efficiency can be achieved in the whole loading range. CV mode Operation OB2372 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, OB2372 will regulate the output current constant regardless of the output voltage drop. o OPERATION DESCRIPTION IS  NP  IP NS (1) The auxiliary winding voltage reflects the output voltage as shown in Figure.3 and it is given by V AUX  N AUX  (VO  V ) NS (2) br ig ht c Where V indicates the voltage drop of the output Diode. n- Figure 2 Multi-mode operation diagram Proprietary built-in CV and CC control can achieve high precision CC/CV control meeting most charger application requirements. O Startup Current and Start up Control Startup current of OB2372 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. Figure.3. Auxiliary winding voltage waveform Via a resistor divider connected between the auxiliary winding and FB (pin 1), the auxiliary winding voltage is sampled at the middle of the de-magnetization and it is hold until the next sampling. 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 Operating Current The Operating current of OB2372 is as low as 1.8mA (typical). Good efficiency and less than 100mW standby power is achieved with the low operating current. ©On-Bright Electronics Confidential -8- Preliminary datasheet OB_DOC_DS_237200 OB2372 High Performance CCM/QR mode Primary-Side Controller switching off time to regulate the output voltage, thus constant output voltage can be achieved. CC mode operation OB2372 sample the CS peak and the transformer core demagnetization period to regulate to output current. The primary CS peak is adaptively controlled according to the voltage of COMP pin. I o  N  I pk  Tdemag maximum compensation is V 48  6200  10 6   100%  11.9% Vo 2.5 (3) Ts 华 Where Ipk indicates the peak current of primary winding, Tdemag is the transformer core demagnetization period, and Ts the switch period. Refer to the equation 3, regulating the Ipk can achieve the constant output current. The constant output current is not related to the primary winding inductance and switch frequency. 富 Figure 5 Diagram for cable drop compensation o Current Sensing and Leading Edge Blanking Cycle-by-Cycle current limiting is offered in OB2372. 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 MOSFET on state so that the external RC filtering on sense input is no longer needed. on fid en tia lt Adjustable CC point and Output Power In OB2372, 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.4. Gate Driver The GATE pin is connected to the gate of an external power switch. An internal 11.5V (typical) clamp is added for MOSFET gate protection at high VDD voltage. When VDD voltage drops below UVLO(ON), the GATE pin is internally pull low to maintain the off state. ht c Over Temperature Protection with latch shutdown A NTC resistor in series with a regular resistor should be connected between RT and GND for temperature sensing and protection. NTC resistor value becomes lower when the ambient temperature rises. With the fixed internal 50uA current source flowing through the resistors, the voltage at RT pin becomes lower at high temperature. The internal OTP circuit is triggered and shuts down the MOSFET when the sensed input voltage is lower than 1.05V. OTP is a latched shutdown. Figure.4. Adjustable output power by changing Rs n- br ig Programmable Cable Drop Compensation In OB2372, cable drop compensation is implemented to achieve good load regulation (see Figure 5). 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, and 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 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% Vo 2.5 V is load compensation voltage and Vo is output voltage; For example: R1//R2=6.2Kohm, the percentage of O Protection Control Good power supply system reliability is achieved with its rich protection features including Cycle-by-Cycle current limiting, Output over voltage protection, VDD over voltage protection, short circuit protection, Under Voltage Lockout on VDD. VDD is supplied by transformer auxiliary winding output after startup. The output of OB2372 is shut down when VDD drops below UVLO (ON) and the power converter enters power on start-up sequence thereafter. ©On-Bright Electronics Confidential -9- Preliminary datasheet OB_DOC_DS_237200 OB2372 High Performance CCM/QR mode Primary-Side Controller Symbol 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 O n- br ig A A1 A2 b c D E E1 e L θ ht c on fid en tia lt o 富 华 PACKAGE MECHANICAL DATA ©On-Bright Electronics Confidential - 10 - 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 Preliminary datasheet OB_DOC_DS_237200 OB2372 High Performance CCM/QR mode Primary-Side Controller 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. o 富 华 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. on fid en tia lt 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 c 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 - 11 - Preliminary datasheet OB_DOC_DS_237200