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參數(shù)資料
| 型號： | LTC4259A |
| 廠商： | Linear Technology Corporation |
| 英文描述： | Quad IEEE 802.3af Power over Ethernet Controller with AC Disconnect |
| 中文描述： | 四IEEE 802.3af標(biāo)準(zhǔn)與AC電源斷開以太網(wǎng)控制器 |
| 文件頁數(shù)： | 27/32頁 |
| 文件大?。?/td> | 326K |
| 代理商： | LTC4259A |
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LTC4259A
27
4259Af
The LTC4259A can also be used to power older powered
Ethernet devices that are not 802.3af compliant and may
be detected with other methods. Although the LTC4259A
does not implement these older detection methods auto-
matically, if software or external circuitry can detect the
noncompliant devices, the host controller may command
the LTC4259A to power the port, bypassing IEEE compli-
ant detection and classification and sending power to the
noncompliant device.
LOGIC LEVEL SUPPLY
In additon to the 48V used to source power to each port,
a logic level supply is required to power the digital portion
of the LTC4259A. To simplify design and meet voltage
isolation requirements, the logic level supply can be
generated from the isolated –48V supply. Figure 19
shows an example method using an LT
1619 to control
a –48V to 3.3V current mode supply. This boost con-
verter topology uses the LT1619 current mode controller
and a current mirror which reflects the 3.3V output
voltage to the –48V rail, improving the regulation toler-
ance over the more traditional large resistor voltage
divider. This approach achieves high accuracy with a
transformerless design.
IEEE 802.3af COMPLIANCE AND EXTERNAL
COMPONENT SELECTION
The LTC4259A is designed to control power delivery in
IEEE 802.3af compliant Power Sourcing Equipment (PSE).
Because proper operation of the LTC4259A may depend
on external signals and power sources, like the –48V
supply (V
EE
) or the OSCIN oscillator source, external
components such as the sense resistors (R
S
), and possi-
bly software running on an external microprocessor,
using the LTC4259A in a PSE does not guarantee 802.3af
compliance. Using an LTC4259A does get you most of the
way there. This section discusses the rest of the elements
that go along with the LTC4259A to make an 802.3af
complaint PSE. Each paragraph below addresses a com-
ponent which is critical for PSE compliance as well as
APPLICATIOU
W
U
U
DRV
100
100
μ
H
4.7
μ
H
B1100
10
μ
F
16V
4700pF
100pF
CMPZ4702B
ISOLATED
GND
ISOLATED
–48V
Si2328DS
FMMT593
FMMT593
8
7
6
5
2
3
4
1
GATE
SENSE
V
IN
V
C
S/S
LT1619
FB
GND
Si2328DS
510
47k
3.32k
1%
0.100
1%
1W
1.24k
1%
100k
4259A F19
910k
1
μ
F
100V
+
V
EE
10
47
μ
F
10V
V
3.3V
300mA
+
47
μ
F
10V
ISOLATED
GND
+
Figure 19. –48V to 3.3V Boost Converter
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC4259A-1 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Synchronous No-Opto Flyback Controller |
| LTC4259ACGW | 功能描述:IC CTRLR POE QUAD AC DISC 36SSOP RoHS:否 類別:集成電路 (IC) >> 接口 - 控制器 系列:- 標(biāo)準(zhǔn)包裝:2,450 系列:- 控制器類型:SPI 總線至 I²C 總線橋接 接口:I²C，串行，SPI 電源電壓:2.4 V ~ 3.6 V 電流 - 電源:11mA 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:24-VFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:24-HVQFN（4x4） 包裝:托盤 配用:568-3511-ND - DEMO BOARD SPI TO I2C 其它名稱:935286452157SC18IS600IBSSC18IS600IBS-ND |
| LTC4259ACGW#PBF | 功能描述:IC CTRLR POE QUAD AC DISC 36SSOP RoHS:是 類別:集成電路 (IC) >> 接口 - 控制器 系列:- 標(biāo)準(zhǔn)包裝:2,450 系列:- 控制器類型:SPI 總線至 I²C 總線橋接 接口:I²C，串行，SPI 電源電壓:2.4 V ~ 3.6 V 電流 - 電源:11mA 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:24-VFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:24-HVQFN（4x4） 包裝:托盤 配用:568-3511-ND - DEMO BOARD SPI TO I2C 其它名稱:935286452157SC18IS600IBSSC18IS600IBS-ND |
| LTC4259ACGW#TR | 功能描述:IC CTRLR POE QUAD AC DISC 36SSOP RoHS:否 類別:集成電路 (IC) >> 接口 - 控制器 系列:- 標(biāo)準(zhǔn)包裝:2,450 系列:- 控制器類型:SPI 總線至 I²C 總線橋接 接口:I²C，串行，SPI 電源電壓:2.4 V ~ 3.6 V 電流 - 電源:11mA 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:24-VFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:24-HVQFN（4x4） 包裝:托盤 配用:568-3511-ND - DEMO BOARD SPI TO I2C 其它名稱:935286452157SC18IS600IBSSC18IS600IBS-ND |
| LTC4259ACGW#TRPBF | 功能描述:IC CTRLR POE QUAD AC DISC 36SSOP RoHS:是 類別:集成電路 (IC) >> 接口 - 控制器 系列:- 標(biāo)準(zhǔn)包裝:2,450 系列:- 控制器類型:SPI 總線至 I²C 總線橋接 接口:I²C，串行，SPI 電源電壓:2.4 V ~ 3.6 V 電流 - 電源:11mA 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:24-VFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:24-HVQFN（4x4） 包裝:托盤 配用:568-3511-ND - DEMO BOARD SPI TO I2C 其它名稱:935286452157SC18IS600IBSSC18IS600IBS-ND |
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