NCP1251GEVB:25W POWER SUPPLY DEMO BD
This evaluation board is a very simple, low cost, yet high performance off-line flyback power supply using ON Semiconductor's NCP1251B controller (TSOP6 package), NDD04N60 D-Pak Mosfet, and the NCP431 programmable zener (SOT23 package). The flyback design operates in discontinuous conduction mode and uses the conventional optocoupler (U2) feedback scheme for the voltage loop and an auxiliary Vcc winding on the flyback transformer to power the NCP1251. The Design Note provides the complete circuit and transformer design details for 5 volt, 4 amp, and 12 volt, 1.8 amp output models. Other output voltages from 3.3 up to 28 Vdc are easy to implement by modifying the values (or ratings) of R11, R12, D9, C9 and T1's secondary turns. Over-current limiting is provided by sensing the peak current in the MOSFET Q1 via R8. Once the 800 mV threshold level on U1's pin 4 is exceeded the circuit will go into "hiccup" mode until the over-current condition is removed. An optional OVP circuit is implemented via Z1
评估板信息
| 评估板 |
状况 |
无铅(Pb-free) |
简短说明 |
所用产品 |
| NCP1251GEVB |
Active |
 |
25W POWER SUPPLY DEMO BD |
NCP1251BSN100T1G |
技术文档
This evaluation board is a very simple, low cost, yet high performance off-line flyback power supply using ON Semiconductor's NCP1251B controller (TSOP6 package), NDD04N60 D-Pak Mosfet, and the NCP431 programmable zener (SOT23 package). The flyback design operates in discontinuous conduction mode and uses the conventional optocoupler (U2) feedback scheme for the voltage loop and an auxiliary Vcc winding on the flyback transformer to power the NCP1251. The Design Note provides the complete circuit and transformer design details for 5 volt, 4 amp, and 12 volt, 1.8 amp output models. Other output voltages from 3.3 up to 28 Vdc are easy to implement by modifying the values (or ratings) of R11, R12, D9, C9 and T1's secondary turns. Over-current limiting is provided by sensing the peak current in the MOSFET Q1 via R8. Once the 800 mV threshold level on U1's pin 4 is exceeded the circuit will go into "hiccup" mode until the over-current condition is removed. An optional OVP circuit is implemented via Z1
