ZHCSMU0D July 2009 – December 2020 TPS23753A
PRODUCTION DATA
- 1 特性
- 2 应用
- 3 说明
- 4 Revision History
- 5 Product Information
- 6 Pin Configuration and Functions
- 7 Specifications
-
8 Detailed Description
- 8.1 Overview
- 8.2 Functional Block Diagram
- 8.3 Feature Description
- 8.4
Device Functional Modes
- 8.4.1 Threshold Voltages
- 8.4.2 PoE Start-Up Sequence
- 8.4.3 Detection
- 8.4.4 Hardware Classification
- 8.4.5 Maintain Power Signature (MPS)
- 8.4.6 TPS23753A Operation
- 8.4.7 Special Switching MOSFET Considerations
- 8.4.8 Thermal Considerations
- 8.4.9 FRS and Synchronization
- 8.4.10 Blanking – RBLNK
- 8.4.11 Current Slope Compensation
- 8.4.12 Adapter ORing
- 8.4.13 Protection
- 8.4.14 Frequency Dithering for Conducted Emissions Control
- 9 Application and Implementation
- 10Power Supply Recommendations
- 11Layout
- 12Device and Documentation Support
- 13Mechanical, Packaging, and Orderable Information
8.3.1.1 APD
APD forces power to come from an external adapter connected from VDD1 to RTN by opening the hotswap switch. TI recommends using a resistor divider. The divider provides ESD protection, leakage discharge for the adapter ORing diode, and input voltage qualification. Voltage qualification assures the adapter can support the PD before the PoE current is cut off.
Select the APD divider resistors per Equation 1 and Equation 2, where VADPTR-ON is the desired adapter voltage that enables the APD function as adapter voltage rises.
The CLS output is disabled when a voltage above VAPDEN is applied to the APD pin.
Place the APD pulldown resistor adjacent to the APD pin.
APD must be tied to RTN when not used.