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参数资料
| 型号： | LTC4259ACGW#TR |
| 厂商： | Linear Technology |
| 文件页数： | 7/32页 |
| 文件大小： | 0K |
| 描述： | IC CTRLR POE QUAD AC DISC 36SSOP |
| 标准包装： | 1,000 |
| 控制器类型： | 以太网供电控制器（POE） |
| 接口： | I²C |
| 电源电压： | 3 V ~ 4 V |
| 电流 - 电源： | 2.5mA |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 36-BSOP（0.295"，7.50mm 宽） |
| 供应商设备封装： | 36-SSOP |
| 包装： | 带卷 (TR) |
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LTC4259A
15
4259afb
APPLICATIO S I FOR ATIO
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The LTC4259A provides a complete solution for detection
and powering of PD devices in an IEEE 802.3af compliant
system. The LTC4259A consists of four independent
ports, each with the ability to detect, classify, and provide
isolated –48V power to a PD device connected to it. The
LTC4259A senses removal of a PD with IEEE 802.3af
compliant AC or DC methods and turns off –48V power
when the PD is removed. An internal control circuit takes
care of system configuration and timing, and uses an I2C
interface to communicate with the host system.
OPERATING MODES
Each LTC4259A port can operate in one of four modes:
Manual, Semiauto, Auto or Shutdown. The operating
mode for a port is set by the appropriate bits in the
Operating Mode register. The LTC4259A will power up
with all ports in Shutdown mode if the external AUTO pin
is tied low; if AUTO is high, all ports will wake up in Auto
mode. The operating mode can be changed at any time via
the I2C interface, regardless of the state of the AUTO pin.
In Manual mode, a port will wait for instructions from
the host system before taking any action. It will run
single detection or classification cycles when com-
manded, and will report results in the Port Status
registers. When the host system decides it is time to
turn on or off power to a port, it can do so by setting
the appropriate Power On/Off bits in the Power Enable
PB register regardless of the current status of detec-
tion or classification.
In Semiauto mode, the port will repeatedly attempt to
detect and classify a PD device attached to the link. It
will report this information in its Port Status register,
and wait for the host system to set the appropriate
Power On bit in the Power Enable PB register before
applying power to the port.
In Auto mode, the port will detect and classify a PD
device connected to it, then immediately turn on the
power if detection was successful regardless of the
result of classification.
In Shutdown mode, the port is disabled and will not detect
or power a PD. Also, the detect and fault event bits, status
bits and enable bits for the port are reset to zero.
Regardless of which mode it is in, the LTC4259A will
remove power automatically from any port that generates
a tSTART or tICUT overcurrent fault event (see tICUT Timing
and tSTART Timing sections). It will also automatically
remove power from any port that generates a disconnect
event if the appropriate Disconnect Enable bit is set in the
Disconnect Enable register. The host controller may also
remove power at any time by setting the appropriate
Power Off bit in the Power Enable PB register.
Power-On RESET
At turn-on or any time the LTC4259A is reset (either by
pulling the RESET pin low or writing to the global Reset All
bit), all the ports turn off and all internal registers go to a
predefined state, shown in Table 1.
Several of the registers assume different states based on
the state of the AUTO pin at reset. The default states with
AUTO high allow the LTC4259A to detect and power up a
PD in Automatic mode, even if nothing is connected to the
I2C interface.
SIGNATURE DETECTION
The IEEE defines a specific pair-to-pair PD signature
resistance that identifies a device that can accept Power
over Ethernet in accordance with the 802.3af specifica-
tion. When the port voltage is below 10V, an 802.3af
compliant PD will have a 25k signature resistance. Figure
12 illustrates the relationship between the PD signature
resistance (white box from 23.75k to 26.25k) and required
resistance ranges the PSE must accept (white box) and
reject (gray boxes). According to the 802.3af specifica-
tion, the PSE may or may not accept resistances in the two
ranges of 15k to 19k and 26.5k to 33k. Note that the black
box in Figure 12 represents the 150
pair-to-pairtermina-
tion used in legacy 802.3 devices like a computer’s net-
work interface card (NIC) that cannot accept power.
Figure 12. IEEE 802.3af Signature Resistance Ranges
RESISTANCE
PD
PSE
0
10k
15k
4259A F12
19k
26.5k
26.25k
23.75k
150
(NIC)
20k
30k
33k
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相关代理商/技术参数 |
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|---|---|
| LTC4259AIGW-1 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Quad IEEE 802.3af Power over Ethernet Controller with AC Disconnect |
| LTC4259AIGW-1#PBF | 功能描述:IC CTRLR POE QUAD AC DISC 36SSOP RoHS:是 类别:集成电路 (IC) >> 接口 - 控制器 系列:- 标准包装:2,450 系列:- 控制器类型:SPI 总线至 I²C 总线桥接 接口:I²C，串行，SPI 电源电压:2.4 V ~ 3.6 V 电流 - 电源:11mA 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:24-VFQFN 裸露焊盘 供应商设备封装:24-HVQFN（4x4） 包装:托盘 配用:568-3511-ND - DEMO BOARD SPI TO I2C 其它名称:935286452157SC18IS600IBSSC18IS600IBS-ND |
| LTC4259AIGW-1#TRPBF | 功能描述:IC CTRLR POE QUAD AC DISC 36SSOP RoHS:是 类别:集成电路 (IC) >> 接口 - 控制器 系列:- 标准包装:2,450 系列:- 控制器类型:SPI 总线至 I²C 总线桥接 接口:I²C，串行，SPI 电源电压:2.4 V ~ 3.6 V 电流 - 电源:11mA 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:24-VFQFN 裸露焊盘 供应商设备封装:24-HVQFN（4x4） 包装:托盘 配用:568-3511-ND - DEMO BOARD SPI TO I2C 其它名称:935286452157SC18IS600IBSSC18IS600IBS-ND |
| LTC4259CGW-ES | 制造商:LINEAR_TECH 功能描述: |
| LTC4260 | 制造商:LINER 制造商全称:Linear Technology 功能描述:UV, OV and Reverse Supply Protection Controller Low Operating Current: 125μA |
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