Datasheet DK1203 (Dongke Semiconductor) - 4

SHENZHEN DONGKE SEMICONDUCTOR CO., LTD SMALL POWER OFF-LINE SWITCH MODE POWER CONTROLLER -DK1203
4 Diode SR2100 D6 1 5 Zener Diode 11V/0.5W ZD1 1 6 Electrolytic capacitor 22uF/400V EC1 1 7 Electrolytic capacitor 22uF/10V EC2 1 8 Electrolytic capacitor 470uF/16V EC3,4 2 9 Ceramic capacitor 103/200V C1 1 10 Ceramic capacitor 103/25V C2 1 11 IC DK1203 IC1 1 12 Y capacitor 222/400V Y1 1 13 I-shape inductance 10uH L1 1 14 LED red LED 1 15 Photo-coupler PC817 IC2 1 16 Transformer EF20 T1 1 17 Resistance 100K/0.25W R1 1 18 Resistance 1K/0.125W R2,3 2
8.2 TRANSFORMER DESIGN (for reference only) 8.2.1 Parameter confirmation: confirm the below parameter before transformer design
(1) Input voltage range: AC85V-265V (2) Output Voltage and current: DC12V 1A (3) Switch frequency: 65Khz (4) MAX. duty cycle: D=0.5
8.2.2 Core selecting
(1) Input power calculation P=Pout/η (η is the efficiency of the power supply, take it 0.8 for example), Pout=Vout*lout=12V*1A=12W, so P =12/0.8=15W. B B B B (2) Choose the core: Checking via supplier or the correlative chart can know that EE25 or EF20 core is suitable for 15W power supply. Now we choose EE25 for below calculation.
8.2.3 Original input voltage
Vs =85*1.3=110V
8.2.4 PMW conducting time
Ton =(1/F)*D=(1/65)*0.5=7.7uS
8.2.5 Number of the original(input) turns (Np) 8.2.6 Number of the output turns (Ns)
Address: Building 18, Hejing industrial zone, Heping village, Fuyong, Baoan Area, Shenzhen, China. 4 Tel: 86-755- 29598396 Email: amy@dkpower.cn Website: www.dkpower.cn