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| 型号： | TPS23756PWP |
| 厂商： | TEXAS INSTRUMENTS INC |
| 元件分类： | 稳压器 |
| 英文描述： | 1.1 A SWITCHING CONTROLLER, 278 kHz SWITCHING FREQ-MAX, PDSO20 |
| 封装： | GREEN, PLASTIC, HTSSOP-20 |
| 文件页数： | 11/41页 |
| 文件大小： | 1405K |
| 代理商： | TPS23756PWP |
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Idle
Detect
Class
Mark
Class
Mark
Class
Between
Ranges
Between
Ranges
Operating
T2P
open-drain
Operating
T2P low
Mark
Reset
Between
Ranges
UVLO
Rising
UVLO
Falling
UVLO
Rising
UVLO
Falling
TYPE2PSE
HardwareClass
Class
Mark
Reset
TYPE1PSE
HardwareClass
TPS23754
TPS23754-1
TPS23756
www.ti.com
SLVS885D – OCTOBER 2008 – REVISED DECEMBER 2009
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 a 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 TPS23754 implements two-event classification. Selecting an RCLS of 63.4 provides a valid type 2
signature. TPS23754 may be used as a compatible type 1 device simply by programming class 0–3 per Table 1.
DLL communication is implemented by the ethernet communication system in the PD and is not implemented by
the TPS23754.
The TPS23754 disables classification above VCU_OFF to avoid excessive power dissipation. CLS voltage is turned
off during PD thermal limit or when APD or DEN are active. The CLS output is inherently current limited, but
should not be shorted to VSS for long periods of time.
Figure 24 shows how classification works for the TPS23754. Transition from state-to-state occurs when
comparator thresholds are crossed (see Figure 21 and Figure 22). These comparators have hysteresis, which
adds inherent memory to the machine. Operation begins at idle (unpowered by PSE) and proceeds with
increasing voltage from left to right. A 2-event classification follows the (heavy lined) path towards the bottom,
ending up with a latched type 2 decode along the lower branch that is highlighted. This state results in a low T2P
during normal operation. Once the valid path to type 2 PSE detection is broken, the input voltage must transition
below the mark reset threshold to start anew.
Figure 24. Two-Event Class Internal States
Inrush and Startup
802.3at has a startup current and time limitation, providing type 2 PSE compatibility for type 1 PDs. A type 2 PSE
limits output current to between 400 mA and 450 mA for up to 75 ms after power-up (applying “48 V” to the PI) in
order to mirror type 1 PSE functionality. The type 2 PSE will support higher output current after 75 ms. The
TPS23754 implements a 140 mA inrush current, which is compatible with all PSE types. A high-power PD must
control its converter startup peak and operational currents drawn to below 400 mA for 80 ms. The TPS23754’s
internal softstart permits control of the converter startup, however the application circuits must assure that their
power draw does not cause the PD to exceed the current/time limitation. This requirement implicitly requires
some form of powering down sections of the application circuits. T2P becomes valid within tT2P after switching
starts, or if an adapter is plugged in while the PD is operating from a PSE.
Copyright 2008–2009, Texas Instruments Incorporated
19
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相关代理商/技术参数 |
参数描述 |
|---|---|
| TPS23756PWPR | 功能描述:热插拔功率分布 Hi Pwr Eff PoE Inter face & DC/DC Cntrlr 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 |
| TPS23757EVM | 功能描述:电源管理IC开发工具 TPS23757 Eval Mod 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 |
| TPS23757PW | 功能描述:热插拔功率分布 Hi Eff PoE Inter & 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 |
| 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 |
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