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参数资料
| 型号： | TPS23757PW |
| 厂商： | Texas Instruments |
| 文件页数： | 17/39页 |
| 文件大小： | 0K |
| 描述： | IC CTRLR POE PD IEEE 20TSSOP |
| 标准包装： | 70 |
| 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： | 465mA |
| 电源电压： | 0 V ~ 57 V |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 20-TSSOP（0.173"，4.40mm 宽） |
| 供应商设备封装： | 20-TSSOP |
| 包装： | 管件 |
| 产品目录页面： | 1012 (CN2011-ZH PDF) |
| 其它名称： | 296-24949-5 |
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TPS23757
www.ti.com
50 mA/div
I PI
Inrush
Cvtr. Starts
SLVS948D – JULY 2009 – REVISED NOVEMBER 2013
V VDD VSS
Detect
Class
-V
V RTN VSS
10 V/div
(Four Point)
-V
t - Time - 50 ms/div
Figure 20. Startup
Detection
The TPS23757 drives DEN to V SS whenever V VDD -V VSS is in the detection state per Figure 19 . When the input
voltage rises above V CL-ON , the DEN pin goes to an open-drain condition to conserve power. While in detection,
RTN is high impedance, and almost all the internal circuits are disabled. An R DEN of 24.9 k ? (1%), presents the
correct signature. It may be a small, low-power resistor since it only sees a stress of about 5 mW. A valid PD
detection signature is an incremental resistance ( Δ V / Δ I ) between 23.7 k ? and 26.3 k ? at the PI.
The detection resistance seen by the PSE at the PI is the result of the input bridge resistance in series with the
parallel combination of R DEN and internal V DD loading. The input diode bridge’s incremental resistance may be
hundreds of ohms at the very low currents drawn when 2.7 V is applied to the PI. The input bridge resistance is
partially cancelled by the TPS23757's effective resistance during detection.
Detection is the same for type 1 and type 2 PDs.
Hardware Classification
Hardware classification allows a PSE to determine a PD’s power requirements before powering, and helps with
power management once power is applied. The PSE applies a voltage of between 14.5 V and 20.5 V at the PD
PI and the PD responds with a current representing the class per the standard. A type 1 PD presents class 0 - 3
in hardware to indicate it is a low-power device (no change from IEEE 802.3-2008). Type 1 PD hardware class
interoperates properly with type 2 PSEs. A type 1 PD must present the hardware class which covers its
maximum power draw. IEEE 802.3at provides a new option for type 1 PDs to negotiate their power allocation to
a lower level using DLL after startup. DLL communication is implemented by the ethernet communication system
in the PD and is not implemented by the TPS23757.
The maximum power entries in Table 1 determine the class the PD must advertise. The PSE may disconnect a
PD if it draws more than its stated class power, which may be the hardware class or an optional lower DLL-
derived power level. The standard permits the PD to draw limited current peaks that increase the instantaneous
power above the Table 1 limit, however the average power requirement always applies.
The TPS23757 disables classification above V CU_OFF to avoid excessive power dissipation. CLS is turned off
during PD thermal limit or when APD, PPD (level 1), or DEN are active. CLS is enabled when APD and PPD
(level 2) are active. The CLS output is inherently current limited, but should not be shorted to V SS for long periods
of time.
Copyright ? 2009–2013, Texas Instruments Incorporated
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相关代理商/技术参数 |
参数描述 |
|---|---|
| TPS23757PWR | 功能描述:热插拔功率分布 Hi Eff PoE Interface & DC/DC Controller RoHS:否 制造商:Texas Instruments 产品:Controllers & Switches 电流限制: 电源电压-最大:7 V 电源电压-最小:- 0.3 V 工作温度范围: 功率耗散: 安装风格:SMD/SMT 封装 / 箱体:MSOP-8 封装:Tube |
| TPS2375D | 功能描述:热插拔功率分布 IEEE 802.3af PoE Pwr Device Cntrler RoHS:否 制造商:Texas Instruments 产品:Controllers & Switches 电流限制: 电源电压-最大:7 V 电源电压-最小:- 0.3 V 工作温度范围: 功率耗散: 安装风格:SMD/SMT 封装 / 箱体:MSOP-8 封装:Tube |
| TPS2375D | 制造商:Texas Instruments 功能描述:POWER OVER ETHERNET ((NW)) |
| TPS2375DG4 | 功能描述:热插拔功率分布 IEEE 802.3af PoE Pwr Device Cntrler RoHS:否 制造商:Texas Instruments 产品:Controllers & Switches 电流限制: 电源电压-最大:7 V 电源电压-最小:- 0.3 V 工作温度范围: 功率耗散: 安装风格:SMD/SMT 封装 / 箱体:MSOP-8 封装:Tube |
| TPS2375DR | 功能描述:热插拔功率分布 IEEE 802.3af PoE Pwr Device Cntrler RoHS:否 制造商:Texas Instruments 产品:Controllers & Switches 电流限制: 电源电压-最大:7 V 电源电压-最小:- 0.3 V 工作温度范围: 功率耗散: 安装风格:SMD/SMT 封装 / 箱体:MSOP-8 封装:Tube |
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