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參數(shù)資料
| 型號： | FAN5071 |
| 廠商： | Fairchild Semiconductor Corporation |
| 英文描述： | High Performance Programmable Synchronous DC-DC Controller for Multi-Voltage Platforms |
| 中文描述： | 高性能可編程同步DC - DC控制器的多電壓平臺 |
| 文件頁數(shù)： | 12/15頁 |
| 文件大小： | 424K |
| 代理商： | FAN5071 |
FAN5071
PRODUCT SPECIFICATION
12
REV. 1.0.4 1/29/02
Adjusting the Linear Regulators
’
Output
Voltages
Any or all of the linear regulators’ outputs may be adjusted
high to compensate for voltage drop along traces, as shown
in Figure 5.
Figure 5. Adjusting the Output Voltage of the
Linear Regulator
The resistor value should be chosen as
For example, to get the V
ADJ
voltage to be 1.50V instead of
1.20V, use R = 2K
* [(1.50/1.20) – 1] = 500
.
Using the FAN5071 for Vnorthbridge = 1.8V
Similarly, the FAN5071 can also be used to generate Vnorth-
bridge = 1.8V by utilizing the AGP regulator as shown in
Figure 5: tie the TYPEDET pin to ground, and use R = 399
.
Coppermine/Tualatin VTT
The adjustable regulator may be used for powering VTT
in systems in which either a Coppermine or a Tualatin
processor may be used, as shown in Figure 6.
Figure 6. Using VADJ to Generate VTT
PCB Layout Guidelines
Placement of the MOSFETs relative to the FAN5071 is
critical. Place the MOSFETs such that the trace length of
the HIDRV and LODRV pins of the FAN5071 to the FET
gates is minimized. A long lead length on these pins will
cause high amounts of ringing due to the inductance of the
trace and the gate capacitance of the FET. This noise
radiates throughout the board, and, because it is switching
at such a high voltage and frequency, it is very difficult to
suppress.
In general, all of the noisy switching lines should be kept
away from the quiet analog section of the FAN5071. That
is, traces that connect to pins 1, 2, 23, and 24 (HIDRV,
SW, LODRV and V
CCP
) should be kept far away from the
traces that connect to pins 3, 20 and 21.
Place the 0.1μF decoupling capacitors as close to the
FAN5071 pins as possible. Extra lead length on these
reduces their ability to suppress noise.
Each V
CC
and GND pin should have its own via to the
appropriate plane. This helps provide isolation between
pins.
Place the MOSFETs, inductor, and Schottky as close
together as possible for the same reasons as in the first
bullet above. Place the input bulk capacitors as close to
the drains of the high side MOSFETs as possible. In
addition, placement of a 0.1μF decoupling cap right on the
drain of each high side MOSFET helps to suppress some
of the high frequency switching noise on the input of the
DC-DC converter.
Place the output bulk capacitors as close to the CPU as
possible to optimize their ability to supply instantaneous
current to the load in the event of a current transient.
Additional space between the output capacitors and the
CPU will allow the parasitic resistance of the board traces
to degrade the DC-DC converter’s performance under
severe load transient conditions, causing higher voltage
deviation. For more detailed information regarding
capacitor placement, refer to Application Bulletin AB-5.
A PC Board Layout Checklist is available from Fairchild
Applications. Ask for Application Bulletin AB-11.
Additional Information
For additional information contact your local Fairchild
Semiconductor representative, or visit us at our web site
www.fairchildsemi.com.
VFB
VGATE
VOUT
10K
R
R
2K
*
V
out
V
nom
=
VFB
VGATE
VTT
3.16K
2N7002
2N7002
487
100
10K
10K
AF36
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|---|---|
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| FAN5071AB WAF | 制造商:Fairchild Semiconductor Corporation 功能描述: |
| FAN5071M | 功能描述:DC/DC 開關控制器 DC/DC RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風格: 封裝 / 箱體:CPAK |
| FAN5071MX | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| FAN5077MPX | 制造商:Fairchild Semiconductor Corporation 功能描述: |
| FAN5078 | 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:DDR/ACPI Regulator Combo |
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