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参数资料
| 型号： | NCP1080DEG |
| 厂商： | ON Semiconductor |
| 文件页数： | 10/15页 |
| 文件大小： | 221K |
| 描述： | IC CONV CTLR POE-PD 13W 20-TSSOP |
| 标准包装： | 74 |
| 类型： | 以太网供电开关（PoE） |
| 应用： | 远程外设（工业控制，相机，数据访问） |
| 内部开关： | 是 |
| 电流限制： | 500mA |
| 电源电压： | 0 V ~ 57 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 20-TSSOP（0.173"，4.40mm 宽）裸露焊盘 |
| 供应商设备封装： | 20-TSSOP-EP |
| 包装： | 管件 |
NCP1080
http://onsemi.com
10
DESCRIPTION OF OPERATION
Powered Device Interface
The PD interface portion of the NCP1080 supports the
IEEE802.3af defined operating modes: detection signature,
current source classification, inrush and operating current
limits. In order to give more flexibility to the user and also
to keep control of the power dissipation in the NCP1080,
both current limits are configurable. The device enters
operation once its programmable Vuvlo_on threshold is
reached, and operation ceases when the supplied voltage
falls below the Vuvlo_off threshold. Sufficient hysteresis
and Uvlo filter time are provided to avoid false power on/off
cycles due to transient voltage drops on the cable.
Detection
During the detection phase, the incremental equivalent
resistance seen by the PSE through the cable must be in the
IEEE802.3af standard specification range (23.75 kW to
26.25 kW) for a PSE voltage from 2.7 V to 10.1 V. In order
to compensate for the nonlinear effect of the diode bridge
and satisfy the specification at low PSE voltage, the
NCP1080 presents a suitable impedance in parallel with the
25.5 kW R
det
external resistor connected between VPORTP
and VPORTN. For some types of diodes (especially
Schottky diodes), it may be necessary to adjust this external
resistor.
When the Detection_Off level is detected (typically
11.5 V) on VPORTP, the NCP1080 turns on its internal
3.3 V regulator and biasing circuitry in anticipation of the
classification phase as the next step.
Classification
Once the PSE device has detected the PD device, the
classification process begins. In classification, the PD
regulates a constant current source that is set by the external
resistor RCLASS value on the CLASS pin. Figure 6 shows
the schematic overview of the classification block. The
current source is defined as:
I
class
+
V
bg
R
class
, (where V
bg
is 1.2 V)
CLASS
VDDA1
1.2 V
VPORTP
VPORTN1,2
NCP1080
Rclass
Figure 6. Classification Block Diagram
Power Mode
When the classification handshake is completed, the
PSE and PD devices move into the operating mode.
Under Voltage Lock Out (UVLO)
The NCP1080 incorporates an under voltage lock out
(UVLO) circuit which monitors the input voltage and
determines when to apply power to the DCDC controller.
To use the default settings for UVLO (see Table 3), the pin
UVLO must be connected to VPORTN
1,2
. In this case the
signature resistor has to be placed directly between
VPORTP and VPORTN
1,2
, as shown in Figure 7.
Figure 7. Default UVLO Settings
UVLO
VPORTP
VPORTN1,2
NCP1080
VPORT
Rdet
To define the UVLO threshold externally, the UVLO pin
must be connected to the center of an external resistor
divider between VPORTP and VPORTN
1,2
as shown in
Figure 8. The series resistance value of the external resistors
must add to 25.5 kW and replaces the internal signature
resistor.
Figure 8. External UVLO Configuration
UVLO
VPORTN1,2
NCP1080
VPORT
R2
R1
VPORTP
For a Vuvlo_on desired turnon voltage threshold, R1 and
R2 can be calculated using the following equations:
R1 ) R2 + R
det
R2 +
1.2
V
ulvo_on
R
det
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相关代理商/技术参数 |
参数描述 |
|---|---|
| NCP1080DER2G | 功能描述:直流/直流开关转换器 POE-PD 13W DC-DC RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| NCP1081 | 制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:Integrated High Power PoE-PD Interface & DC-DC Converter Controller |
| NCP1081DEG | 功能描述:DC/DC 开关控制器 POE-PD 40W DC-DC RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| NCP1081DER2G | 功能描述:DC/DC 开关控制器 POE-PD 40W DC-DC RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| NCP1081SPCGEVB | 功能描述:电源管理IC开发工具 HPOWER POE-PD SPLITTER RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
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