Electronic Components Datasheet Search |
|
NCP1308DR2G Datasheet(PDF) 10 Page - ON Semiconductor |
|
NCP1308DR2G Datasheet(HTML) 10 Page - ON Semiconductor |
10 / 16 page NCP1308 http://onsemi.com 10 Demagnetization Detection The core reset detection is done by monitoring the voltage activity on the auxiliary winding. This voltage features a FLYBACK polarity. The typical detection level is fixed at 50 mV as exemplified by Figure 17. Figure 17. Core Reset Detection is Done through a Dedicated Auxiliary Winding Monitoring POSSIBLE RESTARTS 50 mV 7.0 5.0 3.0 1.0 −1.0 0 V An internal timer prevents any restart within 10 μs further to the driver going−low transition. This prevents the switching frequency to exceed (1/(TON + 10 ms)) but also avoid false leakage inductance tripping at turn−off. In some cases, the leakage inductance kick is so energetic, that a slight filtering is necessary. The NCP1308 demagnetization detection pad features a specific component arrangement as detailed by Figure 18. In this picture, the Zener diodes network protect the IC against any potential ESD discharge that could appear on the pins. The first ESD diode connected to the pad, exhibits a parasitic capacitance. When this parasitic capacitance (10 pF typically) is combined with Rdem, a restart delay is created and the possibility to switch right in the drain−source wave exists. This guarantees QR operation with all the associated benefits (low EMI, no turn−on losses etc.). Rdem should be calculated to limit the maximum current flowing through Pin 1 to less than +3 mA / −2 mA: if during turn−on, the auxiliary winding delivers −30 V (at the highest line level), then the minimum Rdem value is defined by: (−30 + 0.7. This value will be further increased to introduce a restart delay and also a slight filtering in case of high leakage energy. Figure 18. Internal Pad Implementation TO INTERNAL COMPARATOR Aux Resd Rdem ESD ESD 4 1 Figure 19 portrays a typical Vds shot at nominal output power. Figure 19. The NCP1308 Operates in Borderline/Critical Operation 400 300 200 100 0 Overvoltage Protection The overvoltage works by monitoring the VCC pin via a comparator and a reference voltage. Figure 20 portrays the internal arrangement: Figure 20. OVP Section Circuitry + − 50 us FILTER + VCC 16 V OVP COMPARATOR TO LATCH A 50 ms time−constant filter prevents any parasitic spikes superimposed on the VCC to adversely trigger the OVP comparator. When the OVP comparator output goes high, the NCP1308 fully latches off and stays latched, being self−supplied by the DSS. The user must unplug the power supply and wait that the VCC comes down below a reset voltage of typically 4 V. |
Similar Part No. - NCP1308DR2G |
|
Similar Description - NCP1308DR2G |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |