OB2203CPA

OB2203 Quasi-Resonant Flyback PWM Controller GENERAL DESCRIPTION OB2203 is a highly integrated Quasi-Resonant (QR) controller optimized for high performance offline flyback converter applications. At normal load condition, it operates in QR mode with minimum drain voltage switching. To meet the CISPR-22 EMI starting at 150KHz, the maximum switching frequency is internally limited to 130KHz. It operates in PFM mode for high power conversion efficiency at light load condition. When the loading is very small, the IC operates in ‘Extended Burst Mode’ to minimize the switching loss. As a result, lower standby power consumption and higher conversion efficiency is achieved. A built-in P-channel MOSFET and its control are integrated to automatically turn on or off PFC stage according to the load conditions. When used with OB6563 (On-Bright’s PFC controller), the standby power consumption of less than 400mW can be achieved in typical 150W SMPS. OB2203 offers comprehensive protection coverage including Cycle-by-Cycle Current Limiting(OCP), VCC Under Voltage Lockout(UVLO), Over Voltage Protection(OVP), VCC Clamp, Gate Clamp, Over Load Protection(OLP), On-chip Thermal Shutdown, Programmable Soft Start, and External Latch Triggering, Max On-time Limit, etc. OB2203 is offered in SOP-8 and DIP-8 packages. FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Multi-Mode Operation Quasi-Resonant Operation at Normal Loading Pulse Frequency Modulation (PFM) Operation at Light Load Burst Mode at No Load Direct Control of the Power Supply of PFC Controller for Improved Standby Power at No/Light Load 40KHz Minimum Frequency Limit at QR Mode 130KHz Maximum Frequency Limit Internal Minimum T_off for Ringing Suppression 45us Maximum On Time Limit Adaptive Slope Compensation Internal Leading Edge Blanking Programmable Soft-start External Latch Triggering Internal Temperature Shutdown 1A Peak Current Sink/Source Capability Programmable Over Voltage Protection (OVP) APPLICATIONS Offline AC/DC flyback converter for Power Adaptor and Open-frame SMPS ■ LCD Monitor/TV/PC/Set-Top Box Power Supplies ■ NB/DVD/Portable DVD Power Supplies ■ TYPICAL APPLICATION ©On-Bright Electronics Confidential -1- OB_DOC_DS_0300 OB2203 Quasi-Resonant Flyback PWM Controller GENERAL INFORMATION Pin Configuration The pin map of OB2203 in DIP8 and SOP8 package is shown as below. Ordering Information Part Number Description OB2203AP 8 Pin DIP, Pb free in Tube OB2203CP 8 Pin SOP, Pb free in Tube OB2203CPA 8 Pin SOP, Pb free in T&R Note: All Devices are offered in Pb-free Package if not otherwise Package Dissipation Rating Package DIP8 SOP8 RθJA (°C/W) 90 150 Absolute Maximum Ratings Parameter Value VCC Zener Clamp Voltage 31 V VCC Clamp Continuous 10 mA Current SS Input Voltage -0.3 to 7V FB Input Voltage -0.3 to 7V CS Input Voltage -0.3 to 7V DEM Input Voltage -0.3 to 7V Min/Max Operating Junction -20 to 150 oC Temperature TJ Min/Max Storage Temperature -55 to 150 oC Tstg Lead Temperature (Soldering, 260 oC 10secs) Note: 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. noted. ©On-Bright Electronics Confidential -2- OB_DOC_DS_0300 OB2203 Quasi-Resonant Flyback PWM Controller Marking Information SOP8 DIP8 LT LT YWW YWW OB2203AP OB2203CP s s Y: Year Code (0-9) Y: Year Code (0-9) WW: Week Code (1-52) WW: Week Code (1-52) C: SOP8 A: DIP8 P:lead-free P:lead-free s: internal code s: internal code TERMINAL ASSIGNMENTS Pin Num 1 Pin Name SS I/O I/O 2 FB I/O 3 4 5 6 7 CS GND GATE VCC PFCVCC I O O P P 8 DEM I/O Description Soft-start programming pin. Program the soft-start rate with a capacitor to ground. After soft-start, the pin’s voltage is clamped at 2V. External latch input, latch will be triggered when SS pin voltage higher than 3.8V. Feedback input pin. PWM duty cycle is determined by voltage level into this pin and current-sense signal level at Pin 3. The voltage level at this pin also controls the mode of operation in one of the three modes: quasi-resonant (QR), pulse frequency modulation mode (PFM) and burst mode (BM). Current sense input. Ground for internal circuitry. Totem-pole gate drive output for power MOSFET. Chip DC power supply pin. This pin is a direct connection to the VCC pin via a low impedance switch. In standby and during the startup sequence, the switch is open and the PFCVCC is shut down. As soon as the auxiliary winding is stabilized, PFCVCC connects to the VCC pin and provides power supply to PFC controller. It goes down in any fault or at No/Light conditions. Input from auxiliary winding for demagnetization timing. Also this pin is used for load over voltage protection (OVP). ©On-Bright Electronics Confidential -3- OB_DOC_DS_0300 OB2203 Quasi-Resonant Flyback PWM Controller BLOCK DIAGRAM RECOMMENDED OPERATING CONDITION Symbol VCC TA Parameter VCC Supply Voltage Operating Ambient Temperature Min 12 -20 ©On-Bright Electronics Max 23 85 Unit V o C Confidential -4- OB_DOC_DS_0300 OB2203 Quasi-Resonant Flyback PWM Controller ELECTRICAL CHARACTERISTICS (TA = 25OC, VCC=16V, if not otherwise noted) Symbol Parameter Supply Voltage (VCC) Section I_VCC_Startup VCC Start up Current I_VCC_quiet Operation Current without switching I_VCC_operation Operation current with switching UVLO(ON) VCC Under Voltage Lockout Enter UVLO(OFF) VCC Under Voltage Lockout Exit (Startup) OVP(ON) VCC Over Voltage Protection Enter VCC_Clamp VCC Zener Clamp Voltage Feedback Input Section(FB Pin) AVCS PWM Input Gain VFB_Open FB Open Voltage IFB_Short FB pin short circuit current VTH_0D Zero Duty Cycle FB Threshold Voltage VTH_PFM_H PFM mode up threshold VTH_PFM_L PFM mode down threshold VTH_BM_on Burst Mode on threshold VTH_BM_off Burst Mode off threshold VTH_PFC_GTS Threshold for PFC to go to standby VTH_PFC_on Threshold for PFC to leave standby mode VTH_PL Power Limiting FB Threshold Voltage TD_PL Power limiting Debounce Time ZFB_IN Input Impedance Current Sense Input(CS Pin) Section T_blanking CS Input Leading Edge Blanking Time VTH_OC_0 Internal current limiting threshold VTH_OC_60% Internal current limiting threshold TD_OC Over Current Test Conditions Min Typ Max Unit VCC =13.5V, Measure current into VCC FB=3V, CS is floating, - 5 15 uA - 2.0 3.0 mA FB=3V, Fsw=40KHz, 1nF load at GATE - 3.0 4.0 mA 7.5 8.5 9.5 V 14 15 16 V 29 31 33 V I(VCC ) = 5 mA 30 32 34 V ΔVFB /ΔVcs 4.8 3.5 5.3 6.0 V/V V Short FB pin to GND, measure current 1.0 1.5 - mA 0.95 V 60 Zero duty cycle 0.43 1.45 V 1.0 V 1.0 V 0.9 V 1.35 V 1.45 V 4.4 V 80 mSec 4 Kohm 350 nSec 0.45 60% duty cycle 0.80 CL=1nf at GATE, 100 ©On-Bright Electronics 120 0.47 V V 160 nSec Confidential -5- OB_DOC_DS_0300 OB2203 Quasi-Resonant Flyback PWM Controller Detection and Control Delay Demagnetization Detection Section VTH_DEM Demagnetization comparator threshold voltage VTH_DEM_hyst Hysteresis for DEM comparator Negative clamp VDEM_clamp(neg) voltage VDEM_clamp(pos) Positive clamp voltage Tsupp Suppression of the transformer ringing at start of secondary stroke TOUT Timeout after last demag transistion TDEM_delay Demag propagation delay VTH_OVP OVP trigger point T_ovp_plateau OVP plateau sampling after switching off N_true_OVP Number of subsequent cycles to be true OVP Soft Start Section Iss Soft start charge current VTH_ss_over Soft start over threshold voltage ISS_clamp_sink Maximum sink current capability when SS is clamped VSS_clamp SS pin high clamp voltage Timer Section F_burst Burst mode switching frequency F_QR_clamp_h Frequency high clamp in QR mode F_QR_clamp_l Frequency low clamp in QR mode Ton_max Maximum on time Toff_max Maximum off time G_PFM PFM mode frequency modulation slope versus control voltage Thermal Protection T_shutdown Thermal shutdown temperature Latch Protection V_latch_trigger Latch trigger threshod 10 75 30 20 mV -0.7 V 5.8 V 1.5 2 2.5 usec 4 5 6 usec 1.5 150 nsec 3.75 V 2 2.5 4 8.0 10 80 ©On-Bright Electronics 120 usec Cycle 12 2.2 SS pin pull up current mV uA V 200 uA 5.8 V 22 KHz 117 130 143 KHz 35 40 45 KHz 30 30 45 45 240 55 55 usec usec KHz/V 130 140 150 ◦C 3.8 V Confidential -6- OB_DOC_DS_0300 OB2203 Quasi-Resonant Flyback PWM Controller voltage at SS pin V_latch_release Ivdd(latch) VCC latch release voltage VCC current when latch off PFCVCC section Rdson On-resistance of PMOS switch T_PFC_GTS PFC go to standby debounce time T_PFC_ON PFC ON debounce time Gate Drive Output VOL Output Low Level VOH Output High Level VG_Clamp Output Clamp Voltage Level T_r Output Rising Time T_f Output Falling Time should be larger than 200uA 5.5 VCC=V_latch_release+1 V Io = 100 mA (sink) Io = 100 mA (source) VCC=20V CL = 1nf CL = 1nf 6 V 40 uA 10 20 30 Ω 100 125 140 ms 4 8 12 mS 1 V V V 7.5 15.5 16.5 50 20 ©On-Bright Electronics 6.5 17.5 nSec nSec Confidential -7- OB_DOC_DS_0300 OB2203 Quasi-Resonant Flyback PWM Controller CHARACTERIZATION PLOTS ©On-Bright Electronics Confidential -8- OB_DOC_DS_0300 OB2203 Quasi-Resonant Flyback PWM Controller OPERATION DESCRIPTION Quasi-Resonant (QR) converter typically features lower EMI and higher power conversion efficiency compared to conventional hard-switched converter with a fixed switching frequency. OB2203 is a highly integrated QR controller optimized for offline flyback converter applications. The built-in advanced energy saving with high level protection features provide cost effective solutions for energy efficient power supplies. z Startup Current and Start up Control Startup current of OB2203 is designed to be very low so that VCC could be charged up above UVLO(exit) threshold level and device starts up quickly. A large value startup resistor can therefore be used to minimize the power loss yet reliable startup in application. For a typical AC/DC adaptor with universal input range design, a 2 MΩ, 1/8 W startup resistor could be used together with a VCC capacitor to provide a fast startup and yet low power dissipation design solution. z Operating Current The operating current of OB2203 is as low as 2.3mA. Good efficiency is achieved by the low operating current together with extended burst mode control schemes at No/light conditions. the frequency according to the load conditions. Generally, in flyback converter, the decreasing of loading results in voltage level decreasing at FB pin. The controller monitors the voltage level at FB and control the switching frequency. However, the valley switching characteristic is still preserved in PFM mode. That is, when loading decreases, the system automatically skip more and more valleys and the switching frequency is thus reduced. In such way, a smooth frequency foldback is realized and high power conversion efficiency is achieved. ■ At zero load or very light load conditions (VFBVth2, Figure 1), the system operates in QR mode. The frequency variation in QR mode is limited to the range of 40KHz ~ 130KHz due to the fact that frequency varies depending on the line voltage and the load conditions. Therefore, the system may actually work in DCM when 130KHz frequency clamping is reached. In contrast, the system may actually work in CCM when 40KHz frequency clamping is reached. System design should be optimized such that the operation frequency is within the range specified at full loading conditions and in universal AC line input range. ■ At light load condition (Vth1