參數(shù)資料
型號(hào)： MAX1904
廠商： Maxim Integrated Products, Inc.
英文描述： 500kHz Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers
中文描述： 500kHz、多路輸出、低噪聲、電源控制器，用于筆記本電腦
文件頁(yè)數(shù)： 26/33頁(yè)
文件大?。?/td> 649K
代理商： MAX1904
M
500kHz Multi-Output, Low-Noise Power-Supply
Controllers for Notebook Computers
26
______________________________________________________________________________________
Lossless-Inductor Current-Sensing
The DC resistance (DCR) of the inductor can be used
to sense inductor current to improve the efficiency and
to reduce the cost by eliminating the sense resistor.
Figure 7 shows the sense circuit, where L is the induc-
tance, R
L
is the inductor DCR, R
S
, and C
S
form an RC
low-pass sense network. If the time constant of the
inductor is equal to that of the sense network, i.e.:
then the voltage across C
S
becomes
where I
L
is the inductor current.
Determine the required sense-resistor value using the
equation given in the
Current-Sense Resistor Value
section. Choose an inductor with DCR equal or greater
than the sense resistor value. If the DCR is greater than
the sense-resistor value, use a divider to scale down
the voltage. Use the maximum inductance and mini-
mum DCR to get the maximum possible inductor time
constant. Select R
S
and C
S
so that the maximum sense
network time constant is equal or greater than the maxi-
mum inductor time constant.
Reduced Output Capacitance Application
In applications where higher output ripple is accept-
able, lower output capacitance or higher ESR output
capacitors can be used. In such cases, cycle-by-cycle
stability is maintained by adding feedforward compen-
sation to offset for the increased output ESR. Figure 8
shows the addition of the feedforward compensation
circuit. C
FB
provides noise filtering, R
FF
is the feedfor-
ward resistor and C
LX
provides DC blocking. Use
100pF for C
FB
and C
LX
. Select R
FF
according to the
equation below:
Set the value for R
FF
close to the calculation. Do not
make R
FF
too small as that will introduce too much
feedforward, possibly causing an overvoltage to be
seen at the feedback pin, and changing the mode of
operation to a voltage mode.
PC Board Layout Considerations
Good PC board layout is required in order to achieve
specified noise, efficiency, and stability performance.
The PC board layout artist must be given explicit
instructions, preferably a pencil sketch showing the
placement of power-switching components and high-
current routing. A ground plane is essential for optimum
R
R
ESR
L
f
FF
≤
×
×
×
4
3
V
R
I
S
L
L
=
×
L
R
R C
L
=
L
DL_
DH_
LX_
MAX1901
MAX1902
MAX1904
CSH_
CSL_
INDUCTOR
R
L
V
OUT
V
IN
C
IN
C
OUT
C
S
R
S
Figure 7. Lossless Inductor Current Sensing
R3
R4
FB_
L
C
IN
DL_
DH_
LX_
MAX1901
MAX1902
MAX1904
CSH_
CSL_
V
IN
C
LX
R
FF
C
FB
R
SENSE
V
OUT
C
OUT
Figure 8. Adding Feedforward Compensation
相關(guān)PDF資料
PDF描述
MAX1901 SWITCH, 3 POS DIP
MAX1901-MAX1904 3 POSITION RIGHT ANGLE DIP SWITCH
MAX1901EAI 500kHz Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers
MAX1901ETJ 500kHz Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers
MAX1902 500kHz Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX1904BEAI 制造商:Maxim Integrated Products 功能描述:
MAX1904BEAI+ 功能描述:DC/DC 開(kāi)關(guān)控制器 500kHz Multi-Output Power-Supply Ctlr RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開(kāi)關(guān)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(fēng)格: 封裝 / 箱體:CPAK
MAX1904BEAI+T 功能描述:DC/DC 開(kāi)關(guān)控制器 500kHz Multi-Output Power-Supply Ctlr RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開(kāi)關(guān)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(fēng)格: 封裝 / 箱體:CPAK
MAX1904EAI 功能描述:DC/DC 開(kāi)關(guān)控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開(kāi)關(guān)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(fēng)格: 封裝 / 箱體:CPAK
MAX1904EAI+ 功能描述:DC/DC 開(kāi)關(guān)控制器 500kHz Multi-Output Power-Supply Ctlr RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開(kāi)關(guān)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(fēng)格: 封裝 / 箱體:CPAK
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