 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
FAN7930C Datasheet(PDF) 16 Page - ON Semiconductor |
|
|
|||||||||||||||||||||||||||||
FAN7930C Datasheet(HTML) 16 Page - ON Semiconductor |
|
|
16 / 22 page  www.onsemi.com 16 RZCD VAUX ZCD Zero-Current Detect 5 Vcc N 1 VREF IMOT reset Sawtooth Generator CMOT THD Optimizer Figure 40. Circuit of THD Optim izer VZCD tON t VZCD at FET on tON get shorter tON not shorter tON is typically constant over 1 AC line frequency, but tON is changed by ZCD voltage. Figure 41. Effect of THD Optim izer By THD optimizer, turn-on time over one A C line per iod is proportionally changed, depending on input voltage. Near zero cross, lengthened turn-on time improves THD performance. 10. VIN-Absent Detection: To save pow er loss caused by input voltage sensing resistors and to optimize THD, the FA N7930C omits AC input voltage detection. Therefore, no information about AC input is available from the internal controller. In many cases, the V CC of PFC controller is supplied by an independent pow er source, like standby pow er. In this scheme, some mis match may ex ist. For example, w hen the electric pow er is suddenly interrupted during tw o or three AC line per iods; VCC is still live dur ing that time, but output voltage drops because there is no input pow er source. Consequently, the control loop tries to compensate for the output voltage drop and V COMP reaches its maximum. This lasts until A C input voltage is live again. When AC input voltage is live again, high V COMP allows high sw itching current and more stress is put on the MOSFET and diode. To protect against this, FA N7930C checks if the input A C voltage ex ists. If input does not exist, soft-start is reset and w aits until AC input is live again. Soft-start manages the turn-on time for smooth operation w hen it detects AC input is applied again and applies less voltage and current stress on startup. VIN t VOUT VAUX MOSFET gate IDS fMIN DMAX High drain current! VCOMP Though VIN is eliminated, operation of controller is normal due to the large bypass capacitor. Figure 42. Without VIN-Absent Circuit VIN t VOUT VAUX MOSFET gate IDS fMIN DMAX VIN Absence Detected NewVCOMP Though VIN is eliminated, operation of controller is normal due to the large bypass capacitor. fMIN DMIN Smooth Soft-Start Figure 43. With VIN-Absent Circuit 11. Current Sense : The MOSFET current is sensed using an external sensing resistor for over-current protection. If the CS pin voltage is higher than 0.8 V, the over-current protection comparator generates a protection signal. An internal RC filter of 40 kΩ and 8 pF is included to filter sw itching noise. 12. Gate Driver Output: FAN7930C contains a single totem-pole output stage designed for a direct dr ive of the pow er MOSFET. The drive output is capable of up to +500 / -800 mA peak current w ith a typical rise and fall time of 50 ns w ith 1 nF load. The output voltage is clamped to 13 V to protect the MOSFET gate even if the VCC voltage is higher than 13 V. |
Similar Part No. - FAN7930C |
|
Similar Description - FAN7930C |
|
|
|
Link URL |
| Privacy Policy |
| ALLDATASHEET.COM |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | 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 |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
