9014 查看數據表（PDF） - Fairchild Semiconductor

零件编号

产品描述 (功能)

生产厂家

9014

Fairchild QFET for Synchronous Rectification DC to DC Converters

Fairchild Semiconductor 

Vcc

ENABLE/SS

10K

PWRGD

0.1uF

0.1uF

VID[0..4]

+3.3V

Q3

Vt2t

+3.3V

+

1000uF

Q4

Vclock3

Vagp4

+3.3V

+

1000uF

Q5

+

1000uF

+5V +12V

10

+

4.7uF

33 1200uF×5 +

+

C1 1uF

+

1uF

+5V

L1

1.3uH

21

16 E/SS

17 PWRGD

24

VTTP 19

DROOP 18

ILIM

8

1

7

6

VID0

VID1

5 VID2

HDRV

SW 2

4 VID3

9

10

VID4

VTTG

RC5058

VTTFB

11 VCKG

12 VCKFB

14 AGPG

13 AGPFB

23

LODRV

20

VFB

22

GNDP

15 AGPTYP

3.92K

8.2K

4.7

4.7

FQP60N03L

Q1

2.5uH

1VccCORE

L2

+ C2

Q2 Schottky diode

1500uF×10

5.1

3

SW

1K

Figure 4-1. Synchronous Rectification DC-DC Converter using the PWM Control IC RC5058

1) L1/L2 design

(1) Output Inductor, L2

The output inductor must be designed so that it operates in a continuous mode having no dis-

continuous interval in the output inductor current to stabilize frequency and optimize load reg-

ulation.

When Q1 is on, the voltage at both terminals of L2 is VL=Vin - VDS(on) - Vout. L2 can be calcu-

lated with the following equation (4-1).

L2 ≥ V-----i--n-----–-----V-----D-∆---S--i-(-L-o----n---)--–---V-----o---u----t Ton

≥ -(--5----[---V-----]---–-----0---.-2-3---[-7--A--[--V-]----]----–----2-----[--V-----]--)- × 1.58[µ sec ] ≥ 2.08[µH]

L2 = 2.50[µH]……………………(4 – 1)

(2) Input Inductor, L1

Used after the 5V terminal to eliminate the switching noise caused by the input ripple current,

a L1 of 1.3µH is generally sufficient. Care must be taken not to make L1 too large because an

excessively large input inductor can restrict the current change rate at the converter input,

which in turn, can weaken the converter transient response characteristics.

10

Rev. B, July 2000

Share Link: