Schematic for the NCP1251GEVB Evaluation Board L1A F1 2A 250Vac AC Input T1 C4 C1 C2 0.1uF "X2" 0.1uF L1B "X2" R1 4.7 ohms 3W 820uH 10 D1-D4 MRA4007 X4 820uH R2 43K 1W 4.7nF 1 1kV R3 47uF 400V R4 470K 470K Q1 D6 D5 2 10 5 R8A/B 2 ohms 1/2W 10nF R9 1K C5 1nF 1K 5 1 4 MMSD 4148 0 ohms 10uF 50V Vout 0.1uF 50V _ 1000uF, 16V (12Vout) 3300uF, 6.3V (5Vout) 1nF "Y1" R12 39K C11 (12V) 3 R5 C10 C13 0.1 6 D7 6 U1 R16 3K C12 R10 2 + D9 R7 10K MMSZ5254B NCP1251B (27V) J2 C9A C9B R6 D8 3 MBRS360 (12V) MBRS540 (5V) 1N4937 MRA 4007 Z1 C8 EE20/10/6 9 NDD03N60Z C3 MMSD4148 J1 R11 1K (12V) 240 (5V) 8 C6 U3 C7 220pF R15 U2 4 1 1K R14 10K 0.1 10K (5V) NCP431 R13 10K NOTES: 3 2 1. Crossed lines on schematic are NOT connected. 2. U2 is NEC PS2561L-1 or equivalent optocoupler (CTR > 50%). 3. R1 is for inrush limiting - use carbon comp or wire wound. 4. L1A/L1B are Wurth 7447728215 components (820 uH, 500mA). 5. Output caps (C9A/B) are radial lead, low impedance types (UCC LXV series or similar). 6. Z1 sets OVP trip level. 7. R5 is for Vcc trimming (< 28Vmax), typically zero ohms. 8. R8A/B sets max output current. 9. See drawing for T1 details. 20 Watt NCP1251 Power Supply with Universal AC Input (Rev 5A) 5/30/2012 -1- www.onsemi.com