OB2362IMP

OB2362I Adaptive Multi-Mode PWM Controller GENERAL DESCRIPTION FEATURES OB2362I is a highly integrated current mode PWM control IC optimized for high performance, low standby power and cost effective offline flyback converter applications. At full loading, the IC operates in fixed frequency (100KHz) mode. When the loading goes low, it operates in Green mode with valley switching for high power conversion efficiency. When the load is very small, the IC operates in ‘Extended Burst Mode’ to minimize the standby power loss. As a result, high conversion efficiency can be achieved in the whole loading range. VCC low startup current and low operating current contribute to a reliable power on startup and low standby design with OB2362I. OB2362I offers comprehensive protection coverage with auto-recovery including Cycle-byCycle current limiting (OCP), over load protection (OLP), VCC under voltage lockout (UVLO), 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 21KHz is minimized in the design and audio noise is eliminated during operation. OB2362I is offered in SOT23-6 package. ■ ■ ■ ■ ■ ■ APPLICATIONS Offline AC/DC flyback converter for ■ General power supply ■ Power Adapter Power on soft start reducing MOSFET Vds stress Multi-Mode Operation 100KHz fix frequency mode @ Full Load Valley switching operation @ Green mode Burst Mode @ Light Load & No Load Frequency shuffling for EMI Extended burst mode control for improved efficiency and low standby power design Audio noise free operation 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 auto-recovery o Output Over Voltage Protection(Output OVP) with auto-recovery, 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 TYPICAL APPLICATION AC IN EMI Filter DC Out Vaux OB2362I GND GATE FB PRT ©On-Bright Electronics VCC CS Confidential -1- Preliminary Datasheet OB_DOC_DS_2362I00 OB2362I Adaptive Multi-Mode PWM Controller Absolute Maximum Ratings Parameter Value GENERAL INFORMATION Pin Configuration GND 1 6 Gate FB 2 5 VCC PRT 3 4 CS Ordering Information Part Number Description OB2362IMP SOT23-6, Pb-free in T&R 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 ℃ Operating Ambient Temperature TA -40 to 85 ℃ Min/Max Storage Temperature Tstg -55 to 150 ℃ “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. Recommended operating condition Symbol Parameter Range VCC VCC Supply Voltage 12 to 26V High Performance Current Mode PWM Controller VOVP-1V Lead Temperature 260 ℃ (Soldering, 10secs) Note: Stresses beyond those listed under Package Dissipation Rating Package RJA(℃/W) SOT23-6 200 OB2362I VCC DC Supply Voltage X Package M:SOT23-6 X Package Pb-free P:Pb-free Marking Information 362YWW . ZZZI S Y:Year Code WW:Week Code(01-52) ZZZ: Lot code I:Character Code S: Internal code ©On-Bright Electronics Confidential -2- Preliminary Datasheet OB_DOC_DS_2362I00 OB2362I Adaptive Multi-Mode PWM Controller TERMINAL ASSIGNMENTS Pin Name 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 Multiple functions pin. Connecting a NTC resistor to ground for OTP detection. Connecting a resistor from Vaux can adjust OVP trigger voltage and detect transformer core demagnetization. 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. ©On-Bright Electronics Confidential -3- Preliminary Datasheet OB_DOC_DS_2362I00 OB2362I Adaptive Multi-Mode PWM Controller FUNCTIONAL BLOCK DIAGRAM S S Valley OVP UVLO VCC Vref& Iref Logic Control Soft Driver GATE R OVP AVDD Diode short Internal blocks OSC Diode short GND OCP Comparator Vocp Diode short Slope compensation LEB CS OLP AVDD PWM Comparator Multi Mode Control Temp sense EX OTP Q Timer OLP FB OTP OVP PRT EX OVP Valley Detector ©On-Bright Electronics Valley Confidential -4- Preliminary Datasheet OB_DOC_DS_2362I00 OB2362I Adaptive Multi-Mode PWM Controller ELECTRICAL CHARACTERISTICS (TA = 25℃, VCC=18V, unless otherwise noted) Symbol Parameter Supply Voltage (VDD) Istartup VCC Start up Current I_VCC_Operation Operation Current I_VCC_Burst Burst Current UVLO(ON) UVLO(OFF) Vpull-up Test Conditions Min Typ. Max Unit 2 5 uA 2.5 3 mA 0.6 0.7 mA 6.8 7.3 7.8 V 16 17 18 V 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) VCC Under Voltage Lockout Enter VCC Under Voltage Lockout Exit (Recovery) Pull-up PMOS active 10 FB=3V,CS=0V. Slowly VCC Over Voltage Protection OVP ramp VCC, until no 26.5 28 threshold voltage gate switching. Feedback Input Section(FB Pin) VFB_Open VFB Open Loop Voltage 5.1 Avcs PWM input gain ∆VFB/∆VCS 3.5 Maximum duty Max duty cycle @ 77 80 cycle VCC=18V,VFB=3V,VCS=0V Vref_green The threshold enter green mode 2.0 Vref_burst_H The threshold exits burst mode 1.33 The threshold enters burst 1.23 Vref_burst_L mode Short FB pin to GND 0.21 IFB_Short FB pin short circuit current and measure current Open loop protection, FB 4.4 VTH_OLP Threshold Voltage Open loop protection, Td_OLP 60 Debounce Time ZFB_IN Input Impedance 30 Current Sense Input(CS Pin) SST_CS Soft start time for CS peak 2 T_blanking Leading edge blanking time 300 From Over Current Over Current Detection and Occurs till the Gate Td_OC 90 Control Delay driver output start to turn off Internal Current Limiting VTH_OC Threshold Voltage with zero 0.33 0.35 duty cycle VTH_OC_Clamp OCP CS voltage clamper 0.83 PRT pin Output current for external OTP IRT 94 100 detection VOTP Threshold voltage for external 0.95 1 ©On-Bright Electronics Confidential -5- V 29.5 V V V/V 83 % V V V mA V ms KΩ ms ns ns 0.38 V V 106 uA 1.05 V Preliminary Datasheet OB_DOC_DS_2362I00 OB2362I Adaptive Multi-Mode PWM Controller Ioutput_ovp Td_output_ovp In-chip OTP OTP enter OTP Current threshold for adjustable output OVP Output OVP debounce time 170 OTP exit Oscillator VDD=18V,FB=3V, CS=0V 180 190 uA 5 Cycles 150 ℃ 120 ℃ 100 105 KHz FOSC Normal Oscillation Frequency ᇞf_OSC Frequency jittering +/-6 % F_shuffling Shuffling frequency 32 Hz ᇞf_Temp Frequency Stability 1 % ᇞf_VCC Frequency Voltage Stability 1 % F_Burst Gate driver Burst Mode Switch Frequency 21 KHz VOL VOH V_clamping T_r T_f Temperature 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 ©On-Bright Electronics 95 Confidential 6 1 6 V V 11 V 100 ns 30 ns Preliminary Datasheet OB_DOC_DS_2362I00 OB2362I Adaptive Multi-Mode PWM Controller CHARACTERIZATION PLOTS VDD = 18V, TA = 25℃ condition applies if not otherwise noted. UVLO(ON)(V) vs Tem perature UVLO(OFF)(V) vs Tem perature UVLO(OFF)(V) UVLO(ON)(V) 8.00 7.80 7.60 7.40 7.20 7.00 -40 -10 20 50 80 19.00 18.20 17.40 16.60 15.80 15.00 -40 110 140 -10 20 50 80 110 140 Temperature(℃) Temperature(℃) Ton_cmp(uS) Ton_cm p(uS) vs Tem perature 8.00 7.60 7.20 6.80 6.40 6.00 -40 -10 20 50 80 110 140 Temperature(℃) Vref_OTP(V) Vref_OTP(V) vs Tem perature 1.100 1.060 1.020 0.980 0.940 0.900 -40 -10 20 50 80 110 140 Temperature(℃) IRT(uA) vs Tem perature 29.30 28.94 28.58 102.0 IRT(uA) OVP(V) OVP(V) vs Tem perature 28.22 27.86 27.50 101.5 101.0 100.6 100.1 99.6 -40 -10 20 50 80 -40 110 140 20 50 80 110 140 Temperature(℃) Temperature(℃) ©On-Bright Electronics -10 Confidential 7 Preliminary Datasheet OB_DOC_DS_2362I00 OB2362I Adaptive Multi-Mode PWM Controller ©On-Bright Electronics Confidential 8 Preliminary Datasheet OB_DOC_DS_2362I00 OB2362I Adaptive Multi-Mode PWM Controller OPERATION DESCRIPTION OB2362I 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. Startup Current and Start up Control Startup current of OB2362I 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. Operating Current The Operating current of OB2362I is low at 2.5mA (typical). Good efficiency is achieved with OB2362I low operation current together with the ‘extended burst mode’ control features. Demagnetization Detection The transformer core demagnetization is detected by monitoring the voltage activity on the auxiliary windings through PRT pin. This voltage features a flyback polarity. After the on time (determined by the CS voltage and FB voltage), the switch is off and the flyback stroke starts. After the flyback stroke, the drain voltage shows an oscillation with Soft Start OB2362I features an internal 2ms (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. a frequency of approximately 1 / 2 where L p is the primary self inductance of Frequency shuffling for EMI improvement The frequency shuffling (switching frequency modulation) is implemented in OB2362I. 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. primary winding of the transformer and Cd is the capacitance on the drain node. The typical detection level is fixed at -50mV at the PRT pin. Demagnetization is recognized by detection of a possible “valley” when the voltage at PRT is below -50mV in falling edge. Multi Mode Operation for High Efficiency OB2362I is a multi mode controller. The controller changes the mode of operation according to the FB pin voltage. At the normal operating condition, the IC operates in traditional fix frequency （100KHz）PWM mode. As the output load current is decreased , the IC enter into green mode smoothly from the PWM mode. In this mode , the switching frequency will start to linearly decrease from 100KHz to 23KHz, meanwhile the valley turn on can be realized by monitoring the voltage activity on auxiliary windings through the PRT pin. So the switching loss is minimized and the high conversion efficiency can be achieved. 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 L pCd , Current Sensing and Leading Edge Blanking Cycle-by-Cycle current limiting is offered in OB2362I 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 Confidential 9 Preliminary Datasheet OB_DOC_DS_2362I00 OB2362I Adaptive Multi-Mode PWM Controller 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 duty cycle is determined by the current sense input voltage and the FB input voltage. Internal Synchronized Slope Compensation Built-in slope compensation circuit adds voltage ramp into the current sense input voltage for PWM generation. This greatly improves the close loop stability at CCM and prevents the sub-harmonic oscillation and thus reduces the output ripple voltage. Driver The power MOSFET is driven by a dedicated gate driver for power switch control. Too weak the gate driver strength results in higher conduction and switch loss of MOSFET while too strong gate driver strength results the compromise of EMI. A good tradeoff is achieved through the built-in totem pole gate design with right output strength and dead time control. The low idle loss and good EMI system design is easier to achieve with this dedicated control scheme. Dual Function of External OTP and Output OVP On-Bright proprietary dual function of external OTP and output OVP provides feasible and accurate detection of external OTP through NTC resistor and output OVP. The dual function is realized through time-division technology as shown in the figure. For external OTP detection, 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  ROVP VOTP  100uA . ROVP  RT When △Votp