전자부품 데이터시트 검색엔진 |
|
FAN7530 데이터시트(PDF) 24 Page - Fairchild Semiconductor |
|
FAN7530 데이터시트(HTML) 24 Page - Fairchild Semiconductor |
24 / 37 page © 2008 Fairchild Semiconductor Corporation www.fairchildsemi.com FAN9611 / FAN9612 • Rev. 1.1.3 24 Step 4: Output Capacitance OUT,RIPPLE OUT LINE,MIN OUT ) OUT(RIPPLE V V f 4 P C (7) 2 OUT,MIN 2 OUT,RIPPLE OUT HOLD OUT OUT(HOLD) V 2 V V t P 2 C (8) The output capacitance must be calculated by two different methods. The first equation determines the capacitor value based on the allowable ripple voltage at the minimum line frequency. It is important to remember that the scaled version of this ripple is present at the FB pin. The feedback voltage is continuously monitored by the non-latching over voltage protection circuit. Its threshold is about 8% higher the nominal output voltage. To avoid triggering the OVP protection during normal operation, VOUT,RIPPLE should be limited to less 12% of the nominal output voltage, VOUT. The second expression yields the minimum output capacitance based on the required hold-up time based on the power supply specification. Ultimately, the larger of the two values satisfies both design requirements and has to be selected for COUT. Step 5: Boost Inductance per Channel CH MAX, OUT MIN SW, OFF LINE, OUT 2 OFF LINE, OFF LINE, P V f 2 V 2 V V η L (9) CH MAX, OUT SW,MIN LINE,MAX OUT 2 LINE,MAX LINE,MAX P V f 2 V 2 V V η L (10) The minimum switching frequency can occur either at the lowest or at the highest input line voltage. Accordingly, two boost inductor values are calculated and the lower of the two inductances must be selected. This L value keeps the minimum operating frequency above fSW,MIN under all operating conditions. Step 6: Maximum On-Time per Channel 2 OFF LINE, CH MAX, MAX ON, V η P L 2 t (11) Step 7: Peak Inductor Current per Channel ON,MAX OFF LINE, L,PK t L V 2 I (12) Step 8: Maximum DC Output Current OUT CH MAX, OUT,MAX V P 2 I (13) Step 9: Zero Current Detect Resistors 0.5mA N V 0.5 R R OUT ZCD2 ZCD1 (14) where 0.5·VOUT is the maximum amplitude of the resonant waveform across the boost inductor during zero current detection; N is the turns ratio of the boost inductor and the auxiliary winding utilized for the zero current detection; and 0.5mA is the maximum current of the ZCD pin during the zero current detection period. Step 10: Maximum On-Time Setting Resistor MAX ON, 6 MOT t 10 4340 R (15) where RMOT should be between 40k and 130k. Step 11: Output Voltage Setting Resistors (Feedback) FB FB OUT FB2 I 3V P V 3V R (16) where 3V is the reference voltage of the error amplifier at its non-inverting input and PFB or IFB are selected by the designer. If the power loss associated to the feedback divider is critical to meet stand-by power consumption regulations, it might be beneficial to start the calculation by choosing PFB. Otherwise, the current of feedback divider, IFB should be set to approximately 0.4mA at the desired output voltage set point. This value ensures that parasitic circuit board and pin capacitances do not introduce unwanted filtering effect in the feedback path. If the feedback divider is used to provide startup power for the FAN9611/12 (see AN-6086 for implementation details) , the following equation is used to calculate RFB2: OUT ON LINE, FB2 V 0.12mA 0.7V 3 12.5V V 2 3V R (17) where 3V is the reference voltage of the error amplifier at its non-inverting input; 12.5V is the controller’s UVLO turn-on threshold; 0.12mA is the worst-case startup current required to start operation; and 3·0.7V accounts for the forward voltage drop of three diodes in series of the startup current. Once the value of RFB2 is determined, RFB1 is given by the following formula: FB2 OUT FB1 R 1 3V V R (18) RFB1 can be implemented as a series combination of two or three resistors; depending on safety regulations, maximum voltage, and or power rating of the selected resistor type. |
유사한 부품 번호 - FAN7530 |
|
유사한 설명 - FAN7530 |
|
|
링크 URL |
개인정보취급방침 |
ALLDATASHEET.CO.KR |
ALLDATASHEET 가 귀하에 도움이 되셨나요? [ DONATE ] |
Alldatasheet는? | 광고문의 | 운영자에게 연락하기 | 개인정보취급방침 | 링크교환 | 제조사별 검색 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 |