Offiline Step- down Buck LED Driver IC

Transcription

1 General Description The is a high precision non-isolated buck driver IC, specially designed for universal input offline constant current LED lighting, and reach out low THD. Operating in critical conduction mode, the power MOSFET switching loss is reduced and the inductor is fully utilized. By integrating a 500V power MOSFET, the fewest external components, and cutting- edge circuit design, output ability can be precisely controlled in the most competitive method of all kinds. adopt floating ground structure, inductor current is hence sensed during the whole switching cycle, which generates precise output current, line and load regulation when being applied in system. also features full protection function to enhance Reliability on board, including LED Open/ Short circuit Protection, OVP/ UVP/ OTP( Self- reduce)/ OCP Current Sensing Open protection and so on. Features No Auxiliary Winding Valley Switch, High Efficiency, LOW EMI High- V MOSFET embedded Easy reach of > 90% system power efficiency ±5% Output Current Accuracy Universal AC input Auto Induction Compensate Auto Output Voltage adaption Full Protection Features: ( LED O/S CKT; OTPOCP; OVP/ UVP; Auto Recovery to default Fewest external components required on board Application LED High Brightness Lighting Light Bulb, Light Tube Typical Application Circuit E-CMOS Corp. ( Page 1 of 8 4E16N-Rev. P001

2 Pin definition Pin Description Pin Name Pin # Feature Description GND 1 Ground ROVP 2 Over Voltage Protection Setting Pin. Connect a resistor to GND is recommended N.C. 3 No Connection. Connected to GND is recommended VCC 4 VCC in Drain 5, 6 Drain Nodes of the internal HV MODFET CS 7 Current Sense Pin. Connect a resistor to GND to sense the Inductor Current; CS 8 Source Nodes of the internal HV MOSFET Ordering Information Marking Information Device Package Type Marking Remarks NNM1F SOP-8L LLLLL YYWWF 1. LLLLL:Lot No 2. YYWW: Date Code E-CMOS Corp. ( Page 2 of 8 4E16N-Rev. P001

3 Function Block Absolute Maximum Rating(Note 1) Symbol Parameter Range Unit VDS Internal MOSFET Drain to Source voltage -0.3~500 V Icc Max Maximum sink current on Vcc Pin 2.5 ma VRovp Current sense pin input voltage -0.3~7 V VSource Feedback pin input voltage -0.3~7 V VCS Compensation pin voltage -0.3~7 V PDMAX Power dissipation(note 2) 0.45 W TJ Maximum junction temperature 160 TSTG Storage temperature -55~150 Note 1: Stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. Under recommended operating conditions the device operation is assured, but some particular parameter may not be achieved. The electrical characteristics table defines the operation range of the device, the electrical characteristics is assured on DC and AC voltage by test program. For the parameters without minimum and maximum value in the EC table, the typical value defines the operation range, the accuracy is not guaranteed by spec Note 2: The maximum power dissipation decrease if temperature rise, it is decided by TJ MAX, θ JA, and environment temperature (TA). The maximum power dissipation is the lower one between PD MAX = (TJ MAX - T A )/ θja and the number listed in the maximum table. E-CMOS Corp. ( Page 3 of 8 4E16N-Rev. P001

4 Recommended Operation Conditions Condition Parameter Unit Iout 264Vac (full range) 9 W Vac input (single range) 18 W T A Operating temperature -20~85 Electrical Characteristics (Unless otherwise specified, VCC= TA =25 ) Symbol Parameter Condition Min. Typ. Max. Unit Supply Voltage Section V cc_clamp VCC clamp Voltage V I cc_clamp VCC clamp Current 2.5 ma V CC_ST Start-up Voltage VCC rising V V uvlo_hys UVLO Hysteresis Voltage VCC falling 1.5 V I st Start-up Current VCC<VCC_ST-0.5V ua I op Operating Current 200 ua Current Sensing Section Vcs_th Threshold Voltage for Peak mv Current Limit T LEB Leading Edge Blanking 350 ns Time for Current Sense Td Switch off Delay Time 300 ns Over Voltage Protection Section V ROVP Internal Reference Voltage 0.5 V Internal Driving Section T OFF_MIN Minimum Off Time Rovp= 100K Ω 3 us T ON_MAX Maximum On Time 40 us T OFF_Max Maximum Off Time 240 us Feedback Section V FB FB Over Voltage Protection 1.6 V V ZCD FB Falling Edge Threshold Voltage 0.2 V High V MOSFET Section R DSON D-S on resistance VGS=7.3V/IDS=0.5A 10 Ω V DS D-S breakdown Voltage VGS=0V/IDS=250uA 500 V Over Temp. Protection Section T comp Thermal regulation Temp. 140 T SD OTP Shut Down Temp. 160 T SD_HYS Shut Down Hysteresis 20 Temp. E-CMOS Corp. ( Page 4 of 8 4E16N-Rev. P001

5 Application Info. is a high precision driver IC, integrating 500V power MOSFET, specifically designed for non-isolated buck offline constant current LED lighting. Even when switching in critical conduction condition, EC achieves high power factor, high efficiency and ultra- low cost. Chip Power supply and consumption Start Up After system powered up, the VCC pin capacitor is charged up by the start up resistor. When the VCC pin voltage reaches the turn on threshold, the internal circuits start operating with clamp voltage at 7.3V. Output Constant Current control: In addition with the fewest external devices required on board, also facilitates Cycle by Cycle current sense function in order to generate precise output current. CS pin is connected to Current Sense Comparator, and the voltage on CS pin is compared with the internal 400mV reference voltage. Embedded High-V MOS will be turned off when voltage on the CS pin reaches Threshold. Another feature that the CS Comparator can also bring up a 350ns leadingedge-blanking time that eliminates start- up flicker. The Peak Inductor current is given by equation: 400 I PK ( ma ) R CS In which, RCS is the value of current sense resistor. The current on LEDs can be calculated by equation: I I LED 2 PK Inductor Selection The can work under critical conduction mode. When the power MOFET is turned on, the current in the inductor rises up from zero, the turn- on time of the MOSFET can be calculated by equation: L I PK ton V V IN LED In which, L is the inductance value; Vin is the DC voltage after Bridge Rectifier; VLED is voltage on LED strip. After the power MOSFET is turned off, the current on the inductor decreases. When the inductor current reaches zero, the power MOSFET is turned on again by internal Logic. The off time of the MOSFET is given by: L I PK toff V LED The inductance can be calculated by the equation: VLED ( VIN VLED ) L f I V PK IN The f is the system switching frequency, which is proportional to the input voltage. The minimum switching frequency is set at lowest input voltage, and the maximum switching frequency is set at the highest input voltage. The minimum and maximum off time of is therefore set at 4.5us and 240us. Referring to the equation of toff calculation, if the inductance is too small, the toff may be smaller than the minimum off time, system will operate in adiscontinuous E-CMOS Corp. ( Page 5 of 8 4E16N-Rev. P001

6 conduction mode, and output current will be smaller than the designed value. If inductance is too large set, the toff may be larger than the maximum off time, the system will operate in a continuous conduction mode, and the output current will be higher than the designed value. This is very crucial to choose a correct inductance. Over Voltage Protection The over voltage protection can be programmed by the ROVP pin resistor. The ROVP pin voltage is 0.5V. When the LED is open circuit, the output Voltage increases gradually, and the demagnetization time becomes shorter. The demagnetization time at OVP function is therefore suggested installed. Tovp can be calculated by Open circuit protection voltage: Tovp L V R V CS CS OVP In which, Vcs is the CS pin turn off threshold (0.4V) Vovp is the Open circuit Protection voltage, and then the Rovp resistor value is calculated by the equation: Rovp 15 * Tovp *10 6 (K ohm) Protection Function The offers series protection function to improve reliability of whole system, including LED Open/ Short protection, Current Sense resistor short protection, VCC under voltage protection, and Thermal regulation(over- Temp. Protection). When the LED is open circuit, the system will trigger the Over Voltage Protection and turn off switching. When the LED Short Circuit is detected, the system works at low frequency (5kHz), and the CS pin turns Only off threshold is reduced to 200mV. So the system consumes very low power. At spectacular hazardous condition, such as CS resistor- short or inductor saturated, the internal detection circuit will be triggered, and the system will be turned off switching immediately. After the system enters into fault condition, the VCC voltage will decrease until it reaches the UVLO threshold, then the system will re-start again. If the fault condition is removed, the system will recover to normal condition and re-start to operate. Thermal Regulation The integrates thermal regulation function. When the system operates in over temperature state,output current will be gradually reduced along with the output power and thermal dissipation shall also bereduced. System temperature is stringently monitored and controlled, reliability is hence significantly assure and improved. The temperature of Thermal Regulation is set at 160 internally. E-CMOS Corp. ( Page 6 of 8 4E16N-Rev. P001

7 PCB Layout : Bypass Capacitor The Bypass Capacitor on VCC pin should be as close as possible to the Pins of VCC and GND. ROVP Pin The ROVP resistor should be as close as possible to the ROVP Pin. Ground Path The Power Ground path for Current Sense should be shortened, and the Power Ground path should be separated from Small Signal Ground path before being connected to the Negative Node of the Bulk capacitor. The Area of Power Loop Area of main Current loop should be as small as Possible in order to reduce radiation of EMI, such as Inductor, Power MOSFET, the Output diode and the bus capacitor loop. N.C. Pin The N.C. pin should be connected to GND (pin1). Drain Pin For better power dissipation consideration, it is highly Recommended to increase the copper pad of Drain. However, relatively much larger copper pad might effect performance on EMI. Please leverage. E-CMOS Corp. ( Page 7 of 8 4E16N-Rev. P001

8 Package Dimension OUTLINE DRAWING SOP-8L Symbol Dimensions In Milimeters Dimensions In Inches Min Typ. Max Min Typ. Max A A b c D E e F 0.381* *45 H L θ E-CMOS Corp. ( Page 8 of 8 4E16N-Rev. P001