Electronic Components Datasheet Search |
|
NCP1379 Datasheet(PDF) 11 Page - ON Semiconductor |
|
NCP1379 Datasheet(HTML) 11 Page - ON Semiconductor |
11 / 22 page NCP1379 http://onsemi.com 11 NCP1379 OPERATING MODES NCP1379 has two operating mode: quasi−resonant operation and VCO operation for the frequency foldback. The operating mode is fixed by the FB voltage as portrayed by Figure 22: • Quasi−resonant operation occurs for FB voltage higher than 0.8 V (FB decreasing) or higher than 1.4 V (FB increasing) which correspond to high output power and medium output power. The peak current is variable and is set by the FB voltage divided by 4. • Frequency foldback or VCO mode occurs for FB voltage lower than 0.8 V (FB decreasing) or lower than 1.4 V (FB increasing). This corresponds to low output power. • During VCO mode, the peak current decreases down to 17.5% of its maximum value and is then frozen. The switching frequency is variable and decreases as the output load decreases. • The switching frequency is set by the end of charge of the capacitor connected to the CT pin. This capacitor is charged with a constant current source and the capacitor voltage is compared to an internal threshold fixed by FB voltage. When this capacitor voltage reaches the threshold the capacitor is rapidly discharged down to 0 V and a new period start. Figure 22. Operating Valley According to FB Voltage VALLEY DETECTION AND SELECTION The valley detection is done by monitoring the voltage of the auxiliary winding of the transformer. A valley is detected when the voltage on pin 1 crosses down the 55 mV internal threshold. When a valley is detected, an internal counter is incremented. The operating valley (1st, 2nd, 3rd or 4th) is determined by the FB voltage as shown by Figure 22. |
Similar Part No. - NCP1379_11 |
|
Similar Description - NCP1379_11 |
|
|
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 |