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參數(shù)資料
| 型號： | MAX5940DESA+ |
| 廠商： | Maxim Integrated Products |
| 文件頁數(shù)： | 13/15頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC IEEE 802.3AF PD INTFC 8-SOIC |
| 產(chǎn)品培訓(xùn)模塊： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 標(biāo)準(zhǔn)包裝： | 100 |
| 控制器類型： | 供電設(shè)備接口控制器（PD） |
| 接口： | IEEE 802.3af |
| 電源電壓： | 48V |
| 電流 - 電源： | 1mA |
| 工作溫度： | -40°C ~ 85°C |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 8-SOIC（0.154"，3.90mm 寬） |
| 供應(yīng)商設(shè)備封裝： | 8-SOIC |
| 包裝： | 管件 |
Classification Mode (12.6V
≤ VIN ≤ 20V)
In the classification mode, the PSE classifies the PD
based on the power consumption required by the PD.
This allows the PSE to efficiently manage power distri-
bution. The IEEE 802.3af standard defines five different
classes as shown in Table 1. An external resistor (RCL)
connected from RCLASS to VEE sets the classification
current.
The PSE determines the class of a PD by applying a volt-
age at the PD input and measures the current sourced
out of the PSE. When the PSE applies a voltage between
12.6V and 20V, the MAX5940_ exhibit a current charac-
teristic with values indicated in Table 2. The PSE uses the
classification current information to classify the power
requirement of the PD. The classification current includes
the current drawn by the 25.5k
Ω detection signature
resistor and the supply current of the MAX5940_ so the
total current drawn by the PD is within the IEEE 802.3af
standard figures. The classification current is turned off
whenever the device is in power mode.
Power Mode
During power mode, when VIN rises above the under-
voltage lockout threshold (VUVLO,ON), the MAX5940_
gradually turn on the internal N-channel MOSFET Q1
(see Figure 2). The MAX5940_ charge the gate of Q1
with a constant current source (10A, typ). The drain-
to-gate capacitance of Q1 limits the voltage rise rate at
the drain of the MOSFET, thereby limiting the inrush
current. To reduce the inrush current, add external
drain-to-gate capacitance (see the Inrush Current Limit
section). When the drain of Q1 is within 1.2V of its
source voltage and its gate-to-source voltage is above
5V, the MAX5940_ asserts the PGOOD/PGOOD out-
puts. The MAX5940_ have a wide UVLO hysteresis and
turn-off deglitch time to compensate for the high
impedance of the twisted-pair cable.
Undervoltage Lockout
The MAX5940_ operate up to a 67V supply voltage with a
default UVLO turn-on (VUVLO,ON) set at 35V
(MAX5940A/MAX5940C) or 39V (MAX5940B/MAX5940D)
and a UVLO turn-off (VUVLO,OFF) set at 30V. The
MAX5940B/MAX5940D have an adjustable UVLO thresh-
old using a resistor-divider connected to UVLO (see
Figure 3). When the input voltage is above the UVLO
threshold, the IC is in power mode and the MOSFET is
on. When the input voltage goes below the UVLO thresh-
old for more than tOFF_DLY, the MOSFET turns off.
MAX5940A/MAX5940B/MAX5940C/MAX5940D
IEEE 802.3af PD Interface Controller
For Power-Over-Ethernet
_______________________________________________________________________________________
7
CLASS
USAGE
RCL (
Ω)
MAXIMUM POWER USED BY PD (W)
0
Default
10k
0.44 to 12.95
1
Optional
732
0.44 to 3.84
2
Optional
392
3.84 to 6.49
3
Optional
255
6.49 to 12.95
4
Not Allowed
178
Reserved*
*Class 4 reserved for future use.
Table 1. PD Power Classification/RCL Selection
CLASS CURRENT SEEN AT VIN (mA)
IEEE 802.3af PD CLASSIFICATION
CURRENT SPECIFICATION (mA)
CLASS
RCL (
Ω)VIN* (V)
MIN
MAX
MIN
MAX
0
10k
12.6 to 20
02
04
1
732
12.6 to 20
9.17
11.83
9
12
2
392
12.6 to 20
17.29
19.71
17
20
3
255
12.6 to 20
26.45
29.55
26
30
4
178
12.6 to 20
36.6
41.4
36
44
*VIN is measured across the MAX5940 input pins, which does not include the diode bridge voltage drop.
Table 2. Setting Classification Current
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX5940DESA+ | 功能描述:輸入/輸出控制器接口集成電路 IEEE 802.3af PD Int 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 |
| MAX5940DESA+T | 功能描述:輸入/輸出控制器接口集成電路 IEEE 802.3af PD Int 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 |
| MAX5940DESA-T | 功能描述:輸入/輸出控制器接口集成電路 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 |
| MAX5941ACSE | 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: 開啟時間（最大值）:13 ns 關(guān)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(fēng)格:Through Hole 封裝 / 箱體:TO-220F-6 |
| MAX5941ACSE+ | 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 |
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