IEEE 802.3af/at-Compliant, Powered Device Interface
Controller with Integrated Power MOSFET
10 _____________________________________________________________________________________
turns off the internal power MOSFET and 2EC current
sink. When the junction temperature falls below +112NC,
the devices enter inrush mode and then return to power
mode. Inrush mode ensures the downstream DC-DC
converter is turned off as the internal power MOSFET is
turned on.
Wall Power Adapter Detection
and Operation
For applications where an auxiliary power source such
as a wall power adapter is used to power the PD,
the MAX5972A features wall power adapter detection.
The MAX5972A gives highest priority to the WAD and
smoothly switches the power supply to WAD when it is
detected. Once the input voltage (V
DD
- V
SS
) exceeds
the mark event threshold, the MAX5972A enables wall
adapter detection. The wall power adapter is connected
from WAD to RTN. The MAX5972A detects the wall
power adapter when the voltage from WAD to RTN is
greater than 9V. When a wall power adapter is detected,
the internal n-channel isolation MOSFET turns off, 2EC
current sink turns on, and classification current is dis-
abled if V
IN
is in the classification range.
Applications Information
Operation with 12V Adapter
Layout Procedure
Careful PCB layout is critical to achieve high efficiency
and low EMI. Follow these layout guidelines for optimum
performance:
1) Place the input capacitor, classification resistor, and
transient voltage suppressor as close as possible to
the MAX5972A.
2) Use large SMT component pads for power dissipat-
ing devices such as the MAX5972A and the external
diodes.
3) Use short and wide traces for high-power paths.
4) Use the MAX5972A evaluation kit layout as a refer-
ence.
5) Place enough vias in the pad for the EP of the
MAX5972A so that heat generated inside can be
effectively dissipated by the PCB copper. The rec-
ommended spacing for the vias is 1mm to 1.2mm
pitch. The thermal vias should be plated (1oz cop-
per) and have a small barrel diameter (0.3mm to
0.33mm).
Figure 2. Typical Configuration When Using a 12V Wall Power Adapter
68nF
2-EVENT
CLASSIFICATION
(ASSERTED ON)
ENABLE
DC-DC
CONVERTER
IN+
IN-
RJ-45
AND
BRIDGE
RECTIFIER
GND
GND
-54V
SMAJ58A
MAX5972A
R
DET
24.9kI
R
CLS
V
DD
V
SS
RTN
WAD
PG
DET
CLS
2EC/WAD
2EC
12V
BATTERY
1.5mA
THIS CIRCUIT ACHIEVES
PROPER 2EC LOGIC WHEN
BATTERY IS < 12.5V
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相关代理商/技术参数
MAX5972AEVKIT
制造商:Maxim Integrated Products 功能描述:IEEE 802.3AF/AT-COMPLIANT POWERED DEVICE INTERFACE CONTROLLE - Boxed Product (Development Kits)
MAX5972BETE+
功能描述:热插拔功率分布 IEEE 802.3af/at PDIC 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
MAX5972BETE+T
功能描述:热插拔功率分布 IEEE 802.3af/at PDIC 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
MAX5973BETL+
功能描述:监控电路 Phase Redundancy Power Supervisor RoHS:否 制造商:STMicroelectronics 监测电压数: 监测电压: 欠电压阈值: 过电压阈值: 输出类型:Active Low, Open Drain 人工复位:Resettable 监视器:No Watchdog 电池备用开关:No Backup 上电复位延迟（典型值）:10 s 电源电压-最大:5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:UDFN-6 封装:Reel
MAX5973BETL+T
功能描述:监控电路 Phase Redundancy Power Supervisor RoHS:否 制造商:STMicroelectronics 监测电压数: 监测电压: 欠电压阈值: 过电压阈值: 输出类型:Active Low, Open Drain 人工复位:Resettable 监视器:No Watchdog 电池备用开关:No Backup 上电复位延迟（典型值）:10 s 电源电压-最大:5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:UDFN-6 封装:Reel
MAX5973ETL+
功能描述:监控电路 Phase Redundancy Power Supervisor RoHS:否 制造商:STMicroelectronics 监测电压数: 监测电压: 欠电压阈值: 过电压阈值: 输出类型:Active Low, Open Drain 人工复位:Resettable 监视器:No Watchdog 电池备用开关:No Backup 上电复位延迟（典型值）:10 s 电源电压-最大:5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:UDFN-6 封装:Reel
MAX5973ETL+T
功能描述:监控电路 Phase Redundancy Power Supervisor RoHS:否 制造商:STMicroelectronics 监测电压数: 监测电压: 欠电压阈值: 过电压阈值: 输出类型:Active Low, Open Drain 人工复位:Resettable 监视器:No Watchdog 电池备用开关:No Backup 上电复位延迟（典型值）:10 s 电源电压-最大:5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:UDFN-6 封装:Reel
MAX5974AETE+
功能描述:电流型 PWM 控制器 Current-Mode PWM Controller RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14