BP9116A/B Application Notes

Transcription

1 BP9116A/B Application Notes

2 Contents BP9116A/B Characteristic BP9116A/B Typical Application BP9116A 280mA/10V under universal input BP9116B 280mA/16V under universal input BP9116A/B Working Principle BP9116A/B Design Details Working frequency Transformer Design When circuit is open, how to choose output capacitor How to get reliability How to get good Line Regulation PCB layout

3 BP9116A/B Characteristic BP9116A/B The BP9116A/B is a high precision primary-side feedback and regulation controller for LED lighting, it operates in constant current control mode and is designed to work in inductor current discontinuous conduction mode and especially suitable for flyback convertor under universal input. The output power of BP9116A system is recommended to less than 3W. The output power of BP9116B system is recommended to less than 5W. Features Available in SOP-8 Package Internal 650V Power MOSFET Constant current control without secondary sense and feedback circuit. Integrated HV JFET for VCC Power Supply No Auxiliary winding for sensing and supplying Universal input voltage ±6% LED current accuracy LED short and open circuit protection VCC under-voltage protection Thermal regulation

4 BP9116A/B Typical Application NP N S VCC 1 8 CS AC BP9116A/B CS DRAIN 4 CS NC 3 CS NC 2 CS VCC 1 NC NC DRAIN 2 3 BP9116A XXXXXY XYY CS CS CS BV Rdson Recommended Output Power 1. BP9116A<3W 2. BP9116B<5W BP9116A 650V 30Ω BP9116B 650V 18Ω 3. If the output power is too high, the chip will lead to higher temperature

5 BP9116A Typical Application BP9116A 280mA/10V under universal input BP9116A SOP8 3W Nps5.58 Cin=3.3uF Temperature Rise Ta30 IC( ) ( ) IO(mA) VO(V) PIN(W) 90V V V V Vds(V) 587

6 BP9116B Typical Application BP9116B 280mA/16V under universal input BP9116B SOP8 5W Nps3.89 Cin=4.7uF Temperature Rise Ta28 IC( ) ( ) IO(mA) VO(V) PIN(W) 90V V V V Vds(V) 568

7 BP9116A/B Constant Principle I ILs_pk ILs_pk=ILp _p k*n Iout Iout=ILS_p k/4 ILp _pk ILp _pk=vcs/rcs Toff T Toff=0.5T Io 1 NP 0.6 ( A ) 4 N R Iout concerned with Nps and Rcs S 系统工作于 DCM Dmax < 0.42 CS t

8 BP9116A/B System Design System Frequency F s NP RCS ( VO VF ) ( Hz ) 2* N L * V S P CS Vo:Output voltage ; VF:Output diode forward voltage drop; Lp:Primary inductance Np:Primary turns; Ns:Secondary turns; Rcs: Primary-side current sensing resistor ; Vcs:CS Off point threshold (600mV) System maximum operating frequency BP9116A/B <=100KHz If the set value exceeds the maximum operating frequency, it will enter the OVP protection System minimum operating frequency BP9116A/B >=20KHz

9 BP9116A/B system design Transformer design and the winding process 1.BP9116A MOS current less than 180mA 2.BP9116B MOS current less than 310mA 3.Clip around to get less Leakage inductance 4.Each layer covered to make a good coupling 5. Enameled wire can be used for Secondary winding to reduce costs and increase efficiency

10 BP9116A/B system design When circuit is open, how to choose output capacitor? When the LED is open circuit, the output voltage increases gradually, and the demagnetization time gets shorter. When the demagnetization time is less 5us set by chip, chip will trigger the OVP. T=2*T demagnetization=10us Fovp=100KHz Vovp~=(Fovp/Fs)*Vo Fs:working frequency The voltage of capacitance should be higher than Vovp How to reduce the open voltage? 1. try to reduce the output resistance 2. increase the frequency 3. Good capacitance voltage coefficient

11 BP9116A/B system design How to ensure the reliability of sampling When Mos is close, the ZCD-MASK time will prevent the incorrect Demagnetization detection BP9116A/B ZCD-MASK time=3.5us Make sure the shock time is less than ZCD-MASK time. Adding the RCD circuit to reduce the shock time for preventing the incorrect Demagnetization detection

12 BP9116A/B system design How to get good Line Regulation? Make sure the ON TIME is longer than 1.5uS,When input voltage is 220Vac. Then the line regulation will be good

13 BP9116A/B system design PCB Layout 1.The bypass capacitor on VCC pin should be as close as possible to the VCC Pin 2.The CS resistor should be as close as possible to the CS pin, and makes the connection to the VCC bypass capacitor as short as possible. 3.The area of main current loop should be as small as possible to reduce EMI radiation, such as the inductor, the power MOSFET, the output diode and the bus capacitor loop. 4.increasing the copper area of CS pin for better thermal dissipation.

14 Q&A Thanks!