ZHCSA47E July 2012 – January 2018 TPS23751 , TPS23752
PRODUCTION DATA.
- 1 特性
- 2 應用
- 3 說明
- 4 修訂歷史記錄
- 5 Pin Configuration and Functions
-
6 Specifications
- 6.1 Absolute Maximum Ratings
- 6.2 ESD Ratings
- 6.3 ESD Ratings: Surge
- 6.4 Recommended Operating Conditions
- 6.5 Thermal Information
- 6.6 Electric Characteristics - Controller Section
- 6.7 Electrical Characteristics - Sleep Mode (TPS23752 Only)
- 6.8 Electrical Characteristics - PoE Interface Section
- 6.9 Typical Characteristics
-
7 Detailed Description
- 7.1 Overview
- 7.2 Functional Block Diagrams
- 7.3 Feature Description
- 7.4
Device Functional Modes
- 7.4.1 PoE Overview
- 7.4.2
Sleep Mode Operation (TPS23752 only)
- 7.4.2.1 Converter Controller Features
- 7.4.2.2 PWM and VFO Operation; CTL, SRT, and SRD Pin Relationships to Output Load Current
- 7.4.2.3 Bootstrap Topology
- 7.4.2.4 Current Slope Compensation and Current Limit
- 7.4.2.5 RT
- 7.4.2.6 T2P, Startup and Power Management
- 7.4.2.7 Thermal Shutdown
- 7.4.2.8 Adapter ORing
- 7.4.2.9 Using DEN to Disable PoE
- 7.4.2.10 ORing Challenges
-
8 Application and Implementation
- 8.1 Application Information
- 8.2
Typical Application
- 8.2.1 Design Requirements
- 8.2.2
Detailed Design Procedure
- 8.2.2.1 Input Bridges and Schottky Diodes
- 8.2.2.2 Protection, D1
- 8.2.2.3 Capacitor, C1
- 8.2.2.4 Detection Resistor, RDEN
- 8.2.2.5 Classification Resistor, RCLS
- 8.2.2.6 APD Pin Divider Network, RAPD1, RAPD2
- 8.2.2.7 Setting the PWM-VFO Threshold using the SRT pin
- 8.2.2.8 Setting Frequency (RT)
- 8.2.2.9 Current Slope Compensation
- 8.2.2.10 Voltage Feed-Forward Compensation
- 8.2.2.11 Estimating Bias Supply Requirements and Cvc
- 8.2.2.12 Switching Transformer Considerations and RVC
- 8.2.2.13 T2P Pin Interface
- 8.2.2.14 Softstart
- 8.2.2.15 Special Switching MOSFET Considerations
- 8.2.2.16 ESD
- 8.2.2.17 Thermal Considerations and OTSD
- 8.2.3 Application Curves
- 9 Power Supply Recommendations
- 10Layout
- 11器件和文檔支持
- 12機械、封裝和可訂購信息
8.2.2.8 Setting Frequency (RT)
The converter switching frequency in PWM mode is set by connecting resistor, RT from the RT pin to ARTN (see Figure 31). The frequency may be set as high as 1 MHz with some loss in programming accuracy as well as converter efficiency. As an example:
- Assume a desired switching frequency (fSW) of 250 kHz.
- Compute RT:
- Select 34 kΩ for RT.
Equation 4. 