参数资料
| 型号： | LTC4266IGW#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 15/30页 |
| 文件大小： | 0K |
| 描述： | IC CTRLR IEEE 802.3AT 36-SSOP |
| 产品培训模块： | Power over Ethernet |
| 标准包装： | 32 |
| 控制器类型： | 以太网控制器（IEEE 802.3） |
| 接口： | I²C，2 线串口 |
| 电源电压： | 3.3V |
| 工作温度： | -40°C ~ 85°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： | 管件 |
| 产品目录页面： | 1338 (CN2011-ZH PDF) |
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LTC4266
22
4266fd
supply. If a port is turned off via MSD, the corresponding
detection and classification enable bits are cleared, so
the port will remain off until the host explicitly re-enables
detection.
SERIAL DIGITAL INTERFACE
Overview
The LTC4266 communicates with the host using a standard
SMBus/I2C 2-wire interface. The LTC4266 is a slave-only
device, and communicates with the host master using
the standard SMBus protocols. Interrupts are signaled to
the host via the INT pin. The timing diagrams (Figures 5
through 9) show typical communication waveforms and
their timing relationships. More information about the
SMBus data protocols can be found at www.smbus.org.
The LTC4266 requires both the VDD and VEE supply rails
to be present for the serial interface to function.
Bus Addressing
The LTC4266’s primary serial bus address is 010xxxxb, with
the lower four bits set by the AD3-AD0 pins; this allows up
to 16 LTC4266s on a single bus. All LTC4266s also respond
to the address 0110000b, allowing the host to write the
same command (typically configuration commands) to
multiple LTC4266s in a single transaction. If the LTC4266
is asserting the INT pin, it will also respond to the alert
response address (0001100b) per the SMBus spec.
Interrupts and SMBALERT
Most LTC4266 port events can be configured to trigger
an interrupt, asserting the INT pin and alerting the host to
the event. This removes the need for the host to poll the
LTC4266, minimizing serial bus traffic and conserving host
CPU cycles. Multiple LTC4266s can share a common INT
line, with the host using the SMBALERT protocol (ARA)
to determine which LTC4266 caused an interrupt.
Register Description
For information on serial bus usage and device configura-
tion and status, refer to the LTC4266 Software Program-
ming documentation.
EXTERNAL COMPONENT SELECTION
Power Supplies and Bypassing
The LTC4266 requires two supply voltages to operate. VDD
requires 3.3V (nominally) relative to DGND. VEE requires
a negative voltage of between –45V and –57V for Type 1
PSEs, or –51V to –57V for Type 2 PSEs, relative to AGND.
The relationship between the two grounds is not fixed;
AGND can be referenced to any level from VDD to DGND,
although it should typically be tied to either VDD or DGND.
VDD provides power for most of the internal LTC4266 cir-
cuitry, and draws a maximum of 3mA. A ceramic decoupling
cap of at least 0.1μF should be placed from VDD to DGND,
as close as practical to each LTC4266 chip.
Figure 16 shows a three component low dropout regulator
for a negative supply to DGND generated from the negative
VEE supply. VDD is tied to AGND and DGND is negative
referenced to AGND. This regulator drives a single LTC4266
device. In Figure 17, DGND is tied to AGND in this boost
converter circuit for a positive VDD supply of 3.3V above
AGND. This circuit can drive multiple LTC4266 devices
and opto couplers.
VEE is the main supply that provides power to the PDs.
Because it supplies a relatively large amount of power and
is subject to significant current transients, it requires more
design care than a simple logic supply. For minimum IR
loss and best system efficiency, set VEE near maximum
amplitude (57V), leaving enough margin to account for
transient over- or undershoot, temperature drift, and the line
regulation specs of the particular power supply used.
APPLICATIONS INFORMATION
4266 F16
R5
750k
D1
CMHZ4687-4.3V
C1
0.1μF
Q2
CMPTA92
VEE
VDD
LTC4266
AGND
VEE
AGND
DGND
Figure 16. Negative LDO to DGND
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| LTC4266IUHF#PBF | 制造商:Linear Technology 功能描述:POE Controller 25.5W 38-Pin QFN EP 制造商:Linear Technology 功能描述:IC POE 802.3AT QUAD PSE 38-QFN 制造商:Linear Technology 功能描述:POE CNTRL QUAD 25.5W 1MHZ 制造商:Linear Technology 功能描述:IC, POE CONTROLLER, 3.3V, QFN-38; Input Voltage:3.3V; Supply Current:-2.4mA; UVLO:25V; Digital IC Case Style:QFN; No. of Pins:38; Frequency:1MHz; Operating Temperature Min:-40C; Operating Temperature Max:85C; MSL:MSL 1 - Unlimited ;RoHS Compliant: Yes |
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| LTC4267-3 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Power over Ethernet IEEE 802.3af PD Interface with Integrated Switching Regulator |
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