參數(shù)資料
型號： MAX15004
廠商： Maxim Integrated Products, Inc.
英文描述： 4.5V to 40V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers
中文描述： 4.5V至40V輸入、用于汽車電子的反激/boost/SEPIC電源控制器
文件頁數(shù)： 18/29頁
文件大?。?/td> 547K
代理商： MAX15004
M
4.5V to 40V Input Automotive
Flyback/Boost/SEPIC Power-Supply Controllers
18
______________________________________________________________________________________
Selecting V
CC
Resistor (R
VCC
)
The V
CC
external supply series resistor should be sized
to provide enough average current from V
OUT
to drive
the external MOSFET (I
DRIVE
) and I
SUPPLY
. The V
CC
is
clamped internally to 10.4V and capable of sinking
30mA current. The V
CC
resistor must be high enough to
limit the V
CC
sink current below 30mA at the highest
output voltage. Maintain the V
CC
voltage to 8V while
feeding the power from V
OUT
to V
CC
. For a regulated
output voltage of V
OUT
, calculate the R
VCC
using the
following equation:
See Figure 5 and the Power Dissipation section for the
values of I
SUPPLY
and I
DRIVE
.
Flyback Converter
The choice of the conversion topology is the first stage
in power-supply design. The topology selection criteria
include input voltage range, output voltage, peak cur-
rents in the primary and secondary circuits, efficiency,
form factor, and cost.
For an output power of less than 50W and a 1:2 input
voltage range with small form factor requirements, the
flyback topology is the best choice. It uses a minimum
of components, thereby reducing cost and form factor.
The flyback converter can be designed to operate
either in continuous or discontinuous mode of opera-
tion. In discontinuous mode of operation, the trans-
former core completes its energy transfer during the
off-cycle, while in continuous mode of operation, the
next cycle begins before the energy transfer is com-
plete. The discontinuous mode of operation is chosen
for the present example for the following reasons:
It maximizes the energy storage in the magnetic
component, thereby reducing size.
Simplifies the dynamic stability compensation design
(no right-half plane zero).
Higher unity-gain bandwidth.
A major disadvantage of discontinuous mode operation
is the higher peak-to-average current ratio in the primary
and secondary circuits. Higher peak-to-average current
means higher RMS current, and therefore, higher loss
and lower efficiency. For low-power converters, the
advantages of using discontinuous mode easily surpass
the possible disadvantages. Moreover, the drive capabil-
ity of the MAX15004/MAX15005 is good enough to drive
a large switching MOSFET. With the presently available
MOSFETs, power output of up to 50W is easily achiev-
able with a discontinuous mode flyback topology using
the MAX15004/MAX15005 in automotive applications.
Transformer Design
Step-by-step transformer specification design for a dis-
continuous flyback example is explained below.
Follow the steps below for the discontinuous mode
transformer:
Step 1) Calculate the secondary winding inductance
for guaranteed core discharge within a mini-
mum off-time.
Step 2) Calculate primary winding inductance for suffi-
cient energy to support the maximum load.
Step 3) Calculate the secondary and bias winding
turns ratios.
Step 4) Calculate the RMS current in the primary and
estimate the secondary RMS current.
Step 5) Consider proper sequencing of windings and
transformer construction for low leakage.
Step 1)
As discussed earlier, the core must be dis-
charged during the off-cycle for discontinuous mode
operation. The secondary inductance determines the
time required to discharge the core. Use the following
equations to calculate the secondary inductance:
where:
D
OFFMIN
= minimum D
OFF
.
V
D
= secondary diode forward voltage drop.
I
OUT
= maximum output rated current.
Step 2)
The rising current in the primary builds the
energy stored in the core during on-time, which is then
released to deliver the output power during the off-time.
Primary inductance is then calculated to store enough
energy during the on-time to support the maximum out-
put power.
D
MAX
= Maximum D.
L
V
2
D
f
P
D
t
t
t
P
INMIN
×
MAX
OUT MAX
(
OUT
ON
+
ON
OFF
=
×
×
×
=
2
2
η
)
L
V
V
D
I
t
f
D
t
t
S
OUT
2
D
OFFMIN
OUT
OUT MAX
(
OFF
OFF
+
ON
OFF
≤
+
(
)
×
(
×
)
×
=
2
)
R
V
I
I
VCC
OUT
SUPPLY
DRIVE
=
+
(
)
(
)
8
相關PDF資料
PDF描述
MAX15004AAUE 4.5V to 40V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers
MAX15004BAUE 4.5V to 40V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers
MAX15005 4.5V to 40V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers
MAX15005AAUE 4.5V to 40V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers
MAX15005BAUE 4.5V to 40V Input Automotive Flyback/Boost/SEPIC Power-Supply Controllers
相關代理商/技術參數(shù)
參數(shù)描述
MAX15004AAUE/V+ 功能描述:電流型 PWM 控制器 Flyback/Boost/SEPIC Power-Supply Ctlr RoHS:否 制造商:Texas Instruments 開關頻率:27 KHz 上升時間: 下降時間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風格:SMD/SMT 封裝 / 箱體:TSSOP-14
MAX15004AAUE/V+T 功能描述:電流型 PWM 控制器 Flyback/Boost/SEPIC Power-Supply Ctlr RoHS:否 制造商:Texas Instruments 開關頻率:27 KHz 上升時間: 下降時間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風格:SMD/SMT 封裝 / 箱體:TSSOP-14
MAX15004AAUE+ 功能描述:電流型 PWM 控制器 Flyback/Boost/SEPIC Power-Supply Ctlr RoHS:否 制造商:Texas Instruments 開關頻率:27 KHz 上升時間: 下降時間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風格:SMD/SMT 封裝 / 箱體:TSSOP-14
MAX15004AAUE+T 功能描述:電流型 PWM 控制器 Flyback/Boost/SEPIC Power-Supply Ctlr RoHS:否 制造商:Texas Instruments 開關頻率:27 KHz 上升時間: 下降時間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風格:SMD/SMT 封裝 / 箱體:TSSOP-14
MAX15004BAUE/V+ 功能描述:電流型 PWM 控制器 Flyback/Boost/SEPIC Power-Supply Ctlr RoHS:否 制造商:Texas Instruments 開關頻率:27 KHz 上升時間: 下降時間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風格:SMD/SMT 封裝 / 箱體:TSSOP-14
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