전자부품 데이터시트 검색엔진 |
|
FAN7530 데이터시트(PDF) 26 Page - Fairchild Semiconductor |
|
FAN7530 데이터시트(HTML) 26 Page - Fairchild Semiconductor |
26 / 37 page © 2008 Fairchild Semiconductor Corporation www.fairchildsemi.com FAN9611 / FAN9612 • Rev. 1.1.3 26 Step 16: Gate Resistors It is recommended to place at least a 15 resistor between each of the gate drive outputs (DRV1, DRV2) and their corresponding power devices. The gate drive resistors have a beneficial effect to limit the current drawn from the VDD bypass capacitor during the turn-on of the power MOSFETs and to attenuate any potential oscillation in the gate drive circuits. A 1.0 VDD R R MAX G2 G1 (29) where 1.0A is the recommended peak value of the gate drive current. Figure 34. Recommended Gate Drive Schematic A speed-up discharge diode that feeds switching current back into the IC is not recommended. Figure 35. Discharge Diode is Not Recommended In cases where it is desirable to control the MOSFET turn-on and turn-off transition times independently, the circuit of Figure 36 can be used. Figure 36. Gate Drive Schematic with Independent Turn-On and Turn-Off The FAN9611/12 sources high peak current to the MOSFET gate through RG and DON, where RG is used to control the turn-on transition time. When the MOSFET is commanded to turn off, QOFF conducts, shorting the gate to the source, where the turn-off speed can be controlled by the value of ROFF. Where maximum turn- off time is desired, the value of ROFF can be 0Ω. DON serves the dual purpose of protecting the QOFF base- emitter junction and blocking the MOSFET discharge current from sinking back through the FAN9611/12. In addition to the high-speed turn-off, another advantage of this circuit is that the FAN9611/12 does not have to sink the high peak discharge current from the MOSFET, reducing the internal power dissipation in the gate drive circuitry by a factor of two. Instead, the current is discharged locally in a tighter, more controlled loop, minimizing parasitic trace inductance while protecting the FAN9611/12 from injected disturbances associated with ground bounce and ringing due to high-speed turn-off. Step 17: Current-Sense Resistors PK L, CS2 CS1 I 0.18V R R (30) where 0.18V is the worst-case threshold of the current limit comparator. The size and type of current sense resistors depends on their power dissipation and manufacturing considerations. OUT OFF LINE, CS1 2 L,PK RCS1 V π 9 V 2 4 6 1 R I 1.5 P (31) where the 1.5 factor is used for the worst-case effect of the current-limit threshold variation. When the current- sense resistor is determined, the minimum current- sense threshold must be used to avoid activating over- current protection too early as the power supply approaches full-load condition. The worst-case power dissipation of the current sense resistor occurs when the current-sense threshold is at its maximum value defined in the datasheet. The ratio between the minimum and maximum thresholds squared (since the square of the current determines power dissipation) yields exactly the 1.5 factor used in the calculation. |
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 |