參數(shù)資料
型號： MAX783RCBX
廠商： MAXIM INTEGRATED PRODUCTS INC
元件分類： 穩(wěn)壓器
英文描述： Triple-Output Power-Supply Controller for Notebook Computers
中文描述： DUAL SWITCHING CONTROLLER, 330 kHz SWITCHING FREQ-MAX, PDSO36
封裝： PLASTIC, SSOP-36
文件頁數(shù)： 15/28頁
文件大小： 279K
代理商： MAX783RCBX
+5V Induc tor (L1)
Three inductor parameters are required: the inductance
value (L), the peak inductor current (I
LPEAK
), and the
coil resistance (R
L
). The inductance is:
(V
) (V
- V
)
L = ———————————
(V
IN(MAX)
) (f) (I
OUT
) (LIR)
where:
V
OUT
= output voltage, 5V
V
IN(MAX)
= maximum input voltage (V)
f = switching frequency, normally 300kHz
I
OUT
= maximum +5V DC load current (A)
LIR = ratio of inductor peak-to-peak AC
current to average DC load current, typically 0.3.
A higher value of LIR allows smaller inductance, but
results in higher losses and higher ripple.
The highest peak inductor current (I
) equals the
DC load current (I
OUT
) plus half the peak-to-peak AC
inductor current (I
). The peak-to-peak AC inductor
current is typically chosen as 30% of the maximum DC
load current, so the peak inductor current is 1.15 times
I
OUT
.
The peak inductor current at full load is given by:
(V
) (V
- V
)
I
LPEAK
= I
OUT
+ ———————————
(2) (f) (L) (V
IN(MAX)
)
The coil resistance should be as low as possible,
preferably in the low milliohms. The coil is effectively in
series with the load at all times, so the wire losses alone
are approximately:
Power loss = (I
OUT2
)(R
L
)
In general, select a standard inductor that meets the L,
I
, and R
requirements (see Tables 3 and 4). If a
standard inductor is unavailable, choose a core with an
LI
2
parameter greater than (L)(I
LPEAK2
), and use the
largest wire that will fit the core.
+3.3V T ransformer (L2)
Table 3 lists two commercially available transformers
and parts for a custom transformer. The following
instructions show how to determine the transformer
parameters required for a custom design:
L
P
, the primary inductance value
I
L2
, the peak primary current
LI
, the core’s energy rating
R
and R
, the primary and secondary resistances
N, the primary-to-secondary turns ratio.
The transformer primary is specified just as the +5V
inductor, using V
= +3.3V; but the secondary output
(VDD) power must be added in as if it were part of the
primary. VDD current (I
) usually includes the VPPA
and VPPB output currents. The total +3.3V power,
P
TOTAL
, is the sum of these powers:
P
= P3 + P
DD
where:
P3 = (V
) (I
OUT
);
P
DD
= (VDD) (I
);
and:
V
OUT
= output voltage, 3.3V;
I
= maximum +3.3V load current (A);
VDD = VDD output voltage, 15V;
I
DD
= maximum VDD load current (A);
so:
P
= (3.3V x I
) + (15V x I
DD
)
and the equivalent +3.3V output current, I
TOTAL
, is:
I
TOTAL
= P
/ 3.3V
= [(3.3V x I
OUT
) + (15V x I
DD
)] / 3.3V.
The primary inductance, L
P
, is given by:
(V
) (V
- V
)
L
P
= —————————————
(V
IN(MAX)
) (f) (I
TOTAL
) (LIR)
where:
V
= maximum input voltage
f = switching frequency, normally 300kHz
I
= maximum equivalent load current (A)
LIR = ratio of primary peak-to-peak AC
current to average DC load current, typically 0.3.
The highest peak primary current (I
) equals the
total DC load current (I
TOTAL
) plus half the peak-to-peak
AC primary current (I
current is typically chosen as 30% of the maximum DC
load current, so the peak primary current is 1.15 times
I
. A higher value of LIR allows smaller inductance,
but results in higher losses and higher ripple.
The peak current in the primary at full load is given by:
(V
) (V
) - V
)
I
LPEAK
= I
TOTAL
+ —————————————.
(2) (f) (L
P)
(V
IN(MAX)
)
Choose a core with an LI
2
parameter greater than
(L
P
) (I
LPEAK2
).
The winding resistances, R
and R
, should be as low
as possible, preferably in the low milliohms. Use the
largest gauge wire that will fit on the core. The coil is
effectively in series with the load at all times, so the
resistive losses in the primary winding alone are
approximately (I
TOTAL
)
2
(R
P
).
The minimum turns ratio, N
, is 3.3V:(15V-3.3V). Use
1:4 to accommodate the tolerance of the +3.3V supply. A
greater ratio will reduce efficiency of the VPP regulators.
Minimize the diode capacitance and the interwinding
capacitance, since they create losses through the
VDD shunt regulator. These are most significant when
the input voltage is high, the +3.3V load is heavy, and
there is no load on VDD.
M
Triple-Output Power-S upply Controller
for Notebook Computers
______________________________________________________________________________________
15
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX783SCBX 功能描述:DC/DC 開關(guān)控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(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
MAX783SCBX-T 功能描述:DC/DC 開關(guān)控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(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
MAX783SEBX 功能描述:DC/DC 開關(guān)控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(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
MAX783SEBX-T 功能描述:DC/DC 開關(guān)控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(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
MAX785CAI 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述:
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