參數(shù)資料
型號(hào)： MAX5942B
廠商： Maxim Integrated Products, Inc.
英文描述： IEEE 802.3af Power-Over-Ethernet Interface/PWM Controller for Power Devices
中文描述： IEEE 802.3af以太網(wǎng)供電接口/PWM控制器，適用于用電設(shè)備
文件頁(yè)數(shù)： 16/24頁(yè)
文件大小： 465K
代理商： MAX5942B
M
IEEE 802.3af Power-Over-Ethernet
Interface/PWM Controller for Power Devices
16
______________________________________________________________________________________
Current-Sense Comparator
The current-sense (CS) comparator and its associated
logic limit the peak current through the MOSFET.
Current is sensed at CS as a voltage across a sense
resistor between the source of the MOSFET and GND.
To reduce switching noise, connect CS to the external
MOSFET source through a 100
resistor or an RC low-
pass filter (Figures 5, 6). Select the current-sense resis-
tor, R
SENSE
according to the following equation:
where I
LIMPrimary
is the maximum peak primary-side
current.
When V
CS
> 465mV, the power MOSFET switches off.
The propagation delay from the time the switch current
reaches the trip level to the driver turn-off time is 180ns.
Internal Error Amplifier
The MAX5942A/MAX5942B include an internal error
amplifier that can be used to regulate the output volt-
age in the case of a nonisolated power supply (see
Figure 5). Calculate the output voltage using the follow-
ing equation:
where V
REF
= 2.4V.
Choose R1//R2 << R
IN
, where R
IN
50k
is the input
resistance of FB. The gain of the error amplifier is inter-
nally configured for -20 (see Figure 4).
The error amplifier may also be used to regulate the out-
put of the tertiary winding for implementing a primary-
side regulated isolated power supply (see Figure 7).
Calculate the output voltage using the following equation:
where N
S
is the number of secondary turns and N
T
is
the number of tertiary winding turns.
V
N
N
R
R
V
OUT
S
T
1
2
REF
=
+
×
1
V
R
R
V
OUT
1
2
REF
=
+
×
1
R
I
SENSE
LIMPrimary
=
0 465
.
/
V
NDRV
V
OUT
5V/10A
C
OUT
3
560
μ
F
C
DD
4.7
μ
F
C
CC
10
μ
F
C
SS
0.1
μ
F
0.1
μ
F
V
DD
RCL
UVLO
R
SENSE
100m
R
1
2k
R
2
2k
100
20
M1
IRF640N
V
IN
(36V TO 72V)
N
T
N
R
N
P
14
N
S
5
C
IN
3
0.47
μ
F
V
CC
CS
V-
L1
4.7
μ
H
FB
GATE
OUT
PGOOD
MAX5942
V+
GND
GATE
1nF
6
CMHD2003
1N4148
14
SBL204OCT
(OPTIONAL)
C
FB
SS_SHDN
V
EE
25.5k
R
CL
Figure 5. Forward Converter
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX5942BCSE 功能描述:電源開關(guān) IC - POE / LAN RoHS:否 制造商:Fairchild Semiconductor 開關(guān)數(shù)量:Single 開關(guān)配置:SPST 開啟電阻（最大值）:7.3 Ohms 串話: 帶寬: 開啟時(shí)間（最大值）:13 ns 關(guān)閉時(shí)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(fēng)格:Through Hole 封裝 / 箱體:TO-220F-6
MAX5942BCSE+ 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(chǎn)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(fēng)格:SMD/SMT 封裝 / 箱體:QFN-64 封裝:Tray
MAX5942BCSE+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(chǎn)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(fēng)格:SMD/SMT 封裝 / 箱體:QFN-64 封裝:Tray
MAX5942BCSE-T 功能描述:電源開關(guān) IC - POE / LAN RoHS:否 制造商:Fairchild Semiconductor 開關(guān)數(shù)量:Single 開關(guān)配置:SPST 開啟電阻（最大值）:7.3 Ohms 串話: 帶寬: 開啟時(shí)間（最大值）:13 ns 關(guān)閉時(shí)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(fēng)格:Through Hole 封裝 / 箱體:TO-220F-6
MAX5942BESE 功能描述:電源開關(guān) IC - POE / LAN RoHS:否 制造商:Fairchild Semiconductor 開關(guān)數(shù)量:Single 開關(guān)配置:SPST 開啟電阻（最大值）:7.3 Ohms 串話: 帶寬: 開啟時(shí)間（最大值）:13 ns 關(guān)閉時(shí)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(fēng)格:Through Hole 封裝 / 箱體:TO-220F-6
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