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參數(shù)資料
| 型號： | MAX5941A-MAX5941B |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | Octal D-Type Transparent Latches with 3-state Outputs 20-LCCC -55 to 125 |
| 中文描述： | 符合IEEE 802.3af標準供電以太網接口/ PWM控制器的功率器件 |
| 文件頁數(shù)： | 19/24頁 |
| 文件大?。?/td> | 453K |
| 代理商： | MAX5941A-MAX5941B |
M
IEEE 802.3af-Compliant Power-Over-Ethernet
Interface/PWM Controller for Power Devices
______________________________________________________________________________________
19
4) The reset winding turns ratio (N
R
/N
P
) needs to be
low enough to guarantee that the entire energy in
the transformer is returned to V+ within the off cycle
at the maximum duty cycle. Use the following equa-
tion to determine the reset winding turns ratio:
where:
N
R
/N
P
= Reset winding turns ratio.
D
MAX
’
= Maximum value of maximum duty cycle:
Round N
R
to the nearest smallest integer.
The turns ratio of the reset winding (N
R
/N
P
) deter-
mines the peak voltage across the N-channel MOS-
FET.
Use the following equation to determine the maxi-
mum drain-source voltage across the N-channel
MOSFET:
V
DSMAX
= Maximum MOSFET drain-source voltage.
V
IN_MAX
= Maximum input voltage:
Choose MOSFETs with appropriate avalanche
power ratings to absorb any leakage energy.
5) Choose the tertiary winding turns ratio (N
T
/N
P
) so that
the minimum input voltage provides the minimum
operating voltage at V
DD
(13V). Use the following
equation to calculate the tertiary winding turns ratio:
where:
V
DDMIN
is the minimum V
DD
supply voltage (13V).
V
DDMAX
is the maximum V
DD
supply voltage (30V).
V
IN_MIN
is the minimum input voltage (30V).
V
IN_MAX
is the maximum input voltage (67V in this
design example).
N
P
is the number of turns of the primary winding.
N
T
is the number of turns of the tertiary winding:
Choose N
T
= 7.
6) Choose R
SENSE
according to the following equation:
where:
V
ILIM
is the current-sense comparator trip threshold
voltage (0.465V).
N
S
/N
P
is the secondary side turns ratio (5/14 in this
example).
I
OUTMAX
is the maximum DC output current (10A in
this example):
0 465
6
14
7) Choose the inductor value so that the peak ripple
current (LIR) in the inductor is between 10% and
20% of the maximum output current:
where V
D
is the output Schottky diode forward volt-
age drop (0.5V) and LIR is the ratio of inductor rip-
ple current to DC output current:
8) The size and ESR of the output filter capacitor deter-
mine the output ripple. Choose a capacitor with a
low ESR to yield the required ripple voltage.
Use the following equations to calculate the peak-to-
peak output ripple:
V
V
V
RIPPLE
RIPPLEESR
RIPPLEC
=
+
,
,
2
2
L
-
≥
(
.
)
×
(
)
×
=
μ
5 5
.
1 0 198
.
kHz
0 4 275
10
4 01
.
A
H
L
V
LIR
-
OUT
≥
+
275
(
)
×
(
kHz I
)
×
×
V
D
D
MIN
OUTMAX
1
2
R
SENSE
≤
×
=
1 2 10
.
90 4
.
.
V
m
R
V
N
N
SENSE
ILIM
×
S
P
≤
×
1 2
I
OUTMAX
13 7
30
4
36 7
67
14
6 39
.
7 67
.
.
.
1
N
N
T
T
×
≤
≤
×
≤
≤
V
V
N
N
V
V
N
DDMIN
IN_MIN
P
T
DDMAX
IN_MAX
P
+
×
≤
≤
+
×
0 7
.
0 7
.
V
1 + 14
14
DSMAX
≥
×
=
67
134
V
V
V
V
1 + N
N
DSMAX
IN_MAX
P
R
≥
×
N
1
1-0.5
0.5
R
≤
×
=
4
14
N
N
1-D
D
R
P
MAX
MAX
≤
×
′
′
相關PDF資料 |
PDF描述 |
|---|---|
| MAX5941AESE | Octal D-Type Transparent Latches with 3-state Outputs 20-CDIP -55 to 125 |
| MAX5941BCSE | Octal D-Type Positive Edge Triggered Flip-Flops with 3-State Outputs 20-CDIP -55 to 125 |
| MAX5941BESE | Octal D-Type Positive Edge Triggered Flip-Flops with 3-State Outputs 20-LCCC -55 to 125 |
| MAX5942A | IEEE 802.3af Power-Over-Ethernet Interface/PWM Controller for Power Devices |
| MAX5942B | IEEE 802.3af Power-Over-Ethernet Interface/PWM Controller for Power Devices |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| MAX5941BCSE | 功能描述:電源開關 IC - POE / LAN RoHS:否 制造商:Fairchild Semiconductor 開關數(shù)量:Single 開關配置:SPST 開啟電阻（最大值）:7.3 Ohms 串話: 帶寬: 開啟時間（最大值）:13 ns 關閉時間（最大值）:20 ns 切換電壓（最大）: 工作電源電壓:8 V to 26 V 最大工作溫度:+ 125 C 安裝風格:Through Hole 封裝 / 箱體:TO-220F-6 |
| MAX5941BCSE+ | 功能描述:輸入/輸出控制器接口集成電路 IEEE 802.3af POE Int/PWM Controller RoHS:否 制造商:Silicon Labs 產品: 輸入/輸出端數(shù)量: 工作電源電壓: 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 安裝風格:SMD/SMT 封裝 / 箱體:QFN-64 封裝:Tray |
| MAX5941BCSE+T | 功能描述:輸入/輸出控制器接口集成電路 IEEE 802.3af POE Int/PWM Controller RoHS:否 制造商:Silicon Labs 產品: 輸入/輸出端數(shù)量: 工作電源電壓: 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 安裝風格:SMD/SMT 封裝 / 箱體:QFN-64 封裝:Tray |
| MAX5941BCSE-T | 功能描述:電源開關 IC - POE / LAN RoHS:否 制造商:Fairchild Semiconductor 開關數(shù)量:Single 開關配置:SPST 開啟電阻（最大值）:7.3 Ohms 串話: 帶寬: 開啟時間（最大值）:13 ns 關閉時間（最大值）:20 ns 切換電壓（最大）: 工作電源電壓:8 V to 26 V 最大工作溫度:+ 125 C 安裝風格:Through Hole 封裝 / 箱體:TO-220F-6 |
| MAX5941BESE | 功能描述:電源開關 IC - POE / LAN RoHS:否 制造商:Fairchild Semiconductor 開關數(shù)量:Single 開關配置:SPST 開啟電阻（最大值）:7.3 Ohms 串話: 帶寬: 開啟時間（最大值）:13 ns 關閉時間（最大值）:20 ns 切換電壓（最大）: 工作電源電壓:8 V to 26 V 最大工作溫度:+ 125 C 安裝風格:Through Hole 封裝 / 箱體:TO-220F-6 |
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