OB2283MP

OB2283 High Performance Current Mode PWM Controller GENERAL DESCRIPTION FEATURES OB2283 is a highly integrated current mode PWM control IC optimized for high performance, low standby power and cost effective offline flyback converter applications. PWM switching frequency at normal operation is internally fixed and is trimmed to tight range. At no load or light load condition, the IC operates in extended ‘burst mode’ to minimize switching loss. Lower standby power and higher conversion efficiency is thus achieved. VCC low startup current and low operating current contribute to a reliable power on startup and low standby design with OB2283. OB2283 offers comprehensive protection coverage with auto-recovery including Cycle-byCycle current limiting (OCP), over load protection (OLP), and VCC under voltage lockout (UVLO). It also provides the protections with latched shut down including over temperature protection (OTP), and over voltage protection (OVP). Excellent EMI performance is achieved with On-Bright proprietary frequency shuffling technique. The tone energy at below 25KHz is minimized in the design and audio noise is eliminated during operation. OB2283 is offered in SOT23-6 package. ■ ■ ■ on fid en tia lt o 天 晖 ■ ■ ■ Power on soft start reducing MOSFET Vds stress Frequency shuffling for EMI Extended burst mode control for improved efficiency and low standby power design Audio noise free operation Peak load operation with increased frequency Comprehensive protection coverage o VCC Under Voltage Lockout with hysteresis (UVLO) o VCC Over Voltage Protection (VCC OVP) o Cycle-by-cycle over current threshold setting for constant output power limiting over universal input voltage range o Over Load Protection (OLP) with autorecovery o External (if NTC resistor is connected at PRT pin)or internal Over Temperature Protection (OTP) with latched shut down o Output Over Voltage Protection(Output OVP) with latched shut down, and the OVP triggered voltage can be adjusted by the resistor connected between auxiliary winding and PRT pin o Output diode short protection with autorecovery o GND open protection with auto-recovery APPLICATIONS ht c Offline AC/DC flyback converter for ■ Printer, Storage power supply ■ Power Adapter EMI Filter DC Out O n- br AC IN ig TYPICAL APPLICATION Vaux OB2283 6 FB ©On-Bright Electronics VCC 1 5 PRT CS 2 4 GND GATE 3 Confidential -1- Preliminary Datasheet OB_DOC_DS_228300 OB2283 High Performance Current Mode PWM Controller Absolute Maximum Ratings Parameter Value VCC 1 6 FB CS 2 5 PRT Gate 3 GND 4 VCC DC Supply Voltage VOVP-1V FB Input Voltage -0.3 to 7V CS Input Voltage -0.3 to 7V PRT Input Voltage -0.3 to 7V Min/Max Operating Junction Temperature TJ -40 to 150 ℃ Min/Max Storage Temperature Tstg 晖 Pin Configuration -55 to 150 ℃ 天 GENERAL INFORMATION Lead Temperature 260 ℃ (Soldering, 10secs) Note: Stresses beyond those listed under Ordering Information Part Number Description OB2283MP SOT23-6, Pb-free in T&R on fid en tia lt o “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. Package Dissipation Rating Package RJA(℃/W) SOT23-6 200 Recommended operating condition Symbol Parameter Range VCC VCC Supply Voltage 12 to 28V Operating Ambient TA -20 to 85 ℃ Temperature ht c OB2283 ig High Performance Current Mode PWM Controller X Package M:SOT23-6 X Package Pb-free P:Pb-free O n- br Marking Information 83YWW S . ZZZ Y:Year Code WW:Week Code(01-52) s: Internal code ZZZ: Lot code ©On-Bright Electronics Confidential -2- Preliminary Datasheet OB_DOC_DS_228300 OB2283 High Performance Current Mode PWM Controller TERMINAL ASSIGNMENTS I/O Description VCC P Power Supply CS I Current sense input Gate O Totem-pole gate driver output for power MOSFET GND P Ground PRT I Dual functions pin. Connecting a NTC resistor to ground for OTP detection. Connecting a resistor from Vaux can adjust OVP trigger voltage. If both OTP and OVP are needed, a diode should be connected between PRT pin and the NTC resistor. FB I Feedback input pin. The PWM duty cycle is determined by voltage level into this pin and the current-sense signal at Pin CS. O n- br ig ht c on fid en tia lt o 天 晖 Pin Name ©On-Bright Electronics Confidential -3- Preliminary Datasheet OB_DOC_DS_228300 OB2283 High Performance Current Mode PWM Controller FUNCTIONAL BLOCK DIAGRAM S Vref& Iref AVDD Diode short Internal blocks OSC Diode short EX OTP Vocp Diode short Slope compensation OLP on fid en tia lt Temp sense OCP Comparator 晖 R OVP GND open Soft Driver 天 UVLO Logic Control o OVP Q LEB AVDD PWM Comparator PK/Green/ Burst Timer OLP OTP OVP Latch O n- br ig ht c EX OVP ©On-Bright Electronics Confidential -4- Preliminary Datasheet OB_DOC_DS_228300 OB2283 High Performance Current Mode PWM Controller ELECTRICAL CHARACTERISTICS (TA = 25℃, VCC=18V, unless otherwise noted) Symbol Parameter Supply Voltage (VDD) Operation Current I_VCC_Burst Burst Current VCC Under Voltage Lockout Enter VCC Under Voltage Lockout Exit (Recovery) Pull-up PMOS active UVLO(ON) UVLO(OFF) ht c ig br n- 10 uA 2.5 3 mA mA 7 8 9 V 19 21 23 V FB=3V,CS=0V. Slowly VCC Over Voltage Protection OVP ramp VCC, until no 29 threshold voltage gate switching. Vlatch_release Latch release voltage Feedback Input Section(FB Pin) VFB_Open VFB Open Loop Voltage Avcs PWM input gain ∆VFB/∆VCS Maximum duty Max duty cycle @ 75 cycle VCC=18V,VFB=3V,VCS=0V Vref_green The threshold enter green mode Vref_burst_H The threshold exits burst mode The threshold enters burst Vref_burst_L mode Short FB pin to GND IFB_Short FB pin short circuit current and measure current Open loop protection, FB VTH_OLP Threshold Voltage Open loop protection, Td_OLP Debounce Time ZFB_IN Input Impedance Current Sense Input(CS Pin) SST_CS Soft start time for CS peak T_blanking Leading edge blanking time From Over Current Over Current Detection and Occurs till the Gate Td_OC Control Delay driver output start to turn off Internal Current Limiting VTH_OC 0.43 Threshold Voltage with zero duty cycle VTH_OC_Clamp OCP CS voltage clamper O 3 0.55 0.65 on fid en tia lt Vpull-up Unit 晖 I_VCC_Operation VCC=UVLO(OFF)-1V, measure leakage current into VCC VDD=18V,CS=4V, FB=3.5V,measure I(VCC) CS=0V,FB=0.5V, measure I(VCC) Typ Max 天 VCC Start up Current Min o Istartup Test Conditions 10 30 V 31 V 5 V 5.1 3.5 V V/V 78 81 % 1.85 1.33 V V 1.23 V 0.3 mA 4.4 V 15 ms 16 Kohm 4 250 ms ns 90 ns 0.45 0.47 V 0.69 V Vdiode_scp Diode short protection voltage 1.4 V Td_dio Diode short debounce time 8 Cycles ©On-Bright Electronics Confidential -5- Preliminary Datasheet OB_DOC_DS_228300 OB2283 High Performance Current Mode PWM Controller Vgnd_open Td_gnd_open Td_OCP GND open protection voltage difference between GND and CS GND open protection debounce time Over Current protection debounce Time 0.3 V 20 us 60 ms 100 105 uA PRT pin Ioutput_ovp Td_output_ovp In-chip OTP OTP enter OTP exit Oscillator FOSC Normal Oscillation Frequency Fosc_PK Peak frequency SST_freq △f_OSC F_shuffling Soft start time of frequency Frequency jittering Shuffling frequency Frequency Temperature Stability Frequency Voltage Stability Burst Mode Switch Frequency △f_Temp Output low level @ VDD=18V, Io=5mA Output high level @ VCC=18V, Io=20mA Output clamp voltage Output rising time 1.2V ~ 10.8V @ CL=1000pF Output falling time 10.8V ~ 1.2V @ CL=1000pF ig VOL br VOH V_clamping n- T_r VDD=18V,FB=3V, CS=0V VDD=18V,FB=4.5V, CS=0V O T_f 60 ht c △f_VCC F_Burst Gate driver 晖 0.95 1 ©On-Bright Electronics 1.05 天 Td_OTP 95 o VOTP Output current for external OTP detection Threshold voltage for external OTP External OTP debounce time Current threshold for adjustable output OVP Output OVP debounce time on fid en tia lt IRT Confidential -6- V 5 Cycles 70 uA 5 Cycles 150 120 ℃ ℃ 65 70 KHz 142 KHz 30 +/-6 32 ms % Hz 1 % 1 25 % KHz 1 6 V V 12 V 160 ns 50 ns Preliminary Datasheet OB_DOC_DS_228300 OB2283 High Performance Current Mode PWM Controller CHARACTERIZATION PLOTS VDD = 18V, TA = 25℃ condition applies if not otherwise noted. UVLO_OFF vs Temperature 8 21 7.8 20.8 7.6 7.4 7.2 20.6 20.4 晖 UVLO_OFF(V) 20.2 20 7 -40 -10 20 50 80 110 -40 140 -10 110 140 o on fid en tia lt Ton_comp (us) Fosc(KHz) 68 66 64 62 60 -40 -10 20 50 80 110 7.8 7.6 7.4 7.2 7 -40 140 -10 20 50 80 110 140 110 140 110 140 Temperature( ℃) Temperature( ℃) V TH_OC vs Tem perature VOTP vs Tem perature 0.6 ht c 1.05 1.01 ig 0.99 -10 20 br 0.95 -40 50 80 110 0.54 VTH _OC(V) 1.03 VOTP(V) 80 8 70 0.48 0.42 0.36 0.3 -40 140 -10 50 80 n- IRT vs Tem perature OVP vs Tem perature 120 29.6 110 IRT (V) 30 29.2 28.8 100 90 28.4 28 -40 20 Temperature( ℃) Temperature( ℃) O 50 Ton_com p vs Tem perature Fosc vs Tem perature OVP (V) 20 Tem perature(℃) Tem perature(℃) 0.97 天 UVLO_ON(V) UVLO_ON vs Temperature -10 20 50 80 110 80 -40 140 Temperature( ℃) ©On-Bright Electronics -10 20 50 80 Temperature( ℃) Confidential 7 Preliminary Datasheet OB_DOC_DS_228300 OB2283 High Performance Current Mode PWM Controller OPERATION DESCRIPTION OB2283 is a highly integrated current mode PWM control IC optimized for high performance, low standby power and cost effective offline flyback converter applications. The ‘extended burst mode’ control greatly reduces the standby power consumption and helps the design easier to meet the international power conservation requirements. snubber circuit. The magnitude of power loss is in proportion to the switching frequency. Lower switching frequency leads to the reduction on the power loss and thus conserves the energy. The switching frequency is internally adjusted at no load or light load condition. The switch frequency reduces at light/no load condition to improve the conversion efficiency. At light load or no load condition, the FB input drops below Vref_burst_L (the threshold enter burst mode) and device enters Burst Mode control. The Gate drive output switches when FB input rises back to Vref_burst_H (the threshold exit burst mode). Otherwise the gate drive remains at off state to minimize the switching loss and reduces the standby power consumption to the greatest extend. o 天 晖  Startup Current and Start up Control Startup current of OB2283 is designed to be very low so that VCC 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. on fid en tia lt  Operating Current The Operating current of OB2283 is low at 2.5mA (typical). Good efficiency is achieved with OB2283 low operation current together with the ‘extended burst mode’ control features.  Oscillator Operation During the full load power operation, OB2283 operates at a 65KHz (typical) fixed frequency. The efficiency and system cost is controlled at an optimal level. A peak power mode is implemented to supply a peak current output requirement. In peak power mode, frequency is increased from 65KHz (typical) to 142KHz (typical). At light load levels, OB2283 enters the light load mode, where the output current is reduced. The switching losses are reduced by lowering the switching frequency.  Soft Start OB2283 features an internal 4ms (typical) soft start to soften the electrical stress occurring in the power supply during startup. It is activated during the power on sequence. As soon as VCC reaches UVLO(OFF), the CS peak voltage is gradually increased from 0.05V to the maximum level. Every restart up is followed by a soft start. n- br ig ht c  Frequency shuffling for EMI improvement The frequency shuffling (switching frequency modulation) is implemented in OB2283. The oscillation frequency is modulated so that the tone energy is spread out. The spread spectrum minimizes the conduction band EMI and therefore eases the system design.  O Current Sensing and Leading Edge Blanking Cycle-by-Cycle current limiting is offered in OB2283 current mode PWM control. 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 internal power MOSFET on state due to snubber diode reverse recovery and surge gate current of power MOSFET. The current limiting comparator is disabled and cannot turn off the internal power MOSFET during the blanking period. The PWM  Extended Burst Mode Operation At light load or no load condition, most of the power dissipation in a switching mode power supply is from switching loss of the MOSFET, the core loss of the transformer and the loss of the ©On-Bright Electronics Confidential 8 Preliminary Datasheet OB_DOC_DS_228300 OB2283 High Performance Current Mode PWM Controller duty cycle is determined by the current sense input voltage and the FB input voltage. realized through time-division technology as shown in the figure. For external OTP detecttion, when switch control signal S1= “1”, about 20uA (typical) current flows out from PRT pin. When switch control signal S0= “1”,about 120uA (typical) current flows out from PRT pin. The PRT pin voltage difference △Votp at phase S0 and S1 phase is equal to RT*Iotp. When △Votp