ZHCSF14D March 2010 – October 2018 TPS54260
PRODUCTION DATA.
- 1 特性
- 2 應(yīng)用
- 3 說明
- 4 修訂歷史記錄
- 5 Pin Configuration and Functions
- 6 Specifications
-
7 Detailed Description
- 7.1 Overview
- 7.2 Functional Block Diagram
- 7.3
Feature Description
- 7.3.1 Fixed Frequency PWM Control
- 7.3.2 Slope Compensation Output Current
- 7.3.3 Pulse-Skip Eco-Mode
- 7.3.4 Low-Dropout Operation and Bootstrap Voltage (BOOT)
- 7.3.5 Error Amplifier
- 7.3.6 Voltage Reference
- 7.3.7 Adjusting the Output Voltage
- 7.3.8 Enable and Adjusting Undervoltage Lockout
- 7.3.9 Slow-Start / Tracking Pin (SS/TR)
- 7.3.10 Overload Recovery Circuit
- 7.3.11 Sequencing
- 7.3.12 Constant Switching Frequency and Timing Resistor (RT/CLK Pin)
- 7.3.13 Overcurrent Protection and Frequency Shift
- 7.3.14 Selecting the Switching Frequency
- 7.3.15 How to Interface to RT/CLK Pin
- 7.3.16 Powergood (PWRGD Pin)
- 7.3.17 Overvoltage Transient Protection
- 7.3.18 Thermal Shutdown
- 7.3.19 Small Signal Model for Loop Response
- 7.3.20 Simple Small Signal Model for Peak Current Mode Control
- 7.3.21 Small Signal Model for Frequency Compensation
- 7.4 Device Functional Modes
-
8 Application and Implementation
- 8.1 Application Information
- 8.2
Typical Applications
- 8.2.1
3.3-V Output Application
- 8.2.1.1 Design Requirements
- 8.2.1.2
Detailed Design Procedure
- 8.2.1.2.1 Custom Design With WEBENCH® Tools
- 8.2.1.2.2 Selecting the Switching Frequency
- 8.2.1.2.3 Output Inductor Selection (LO)
- 8.2.1.2.4 Output Capacitor
- 8.2.1.2.5 Catch Diode
- 8.2.1.2.6 Input Capacitor
- 8.2.1.2.7 Slow-Start Capacitor
- 8.2.1.2.8 Bootstrap Capacitor Selection
- 8.2.1.2.9 Undervoltage Lock Out Set Point
- 8.2.1.2.10 Output Voltage and Feedback Resistors Selection
- 8.2.1.2.11 Compensation
- 8.2.1.2.12 Discontinuous Mode and Eco-Mode Boundary
- 8.2.1.2.13 Power Dissipation Estimate
- 8.2.1.3 Application Curves
- 8.2.2 Inverting Power Supply
- 8.2.3 Split-Rail Power Supply
- 8.2.4 12-V to 3.8-V GSM Power Supply
- 8.2.5 24-V to 4.2-V GSM Power Supply
- 8.2.1
3.3-V Output Application
- 9 Power Supply Recommendations
- 10Layout
- 11器件和文檔支持
- 12機械、封裝和可訂購信息
封裝選項
機械數(shù)據(jù) (封裝 | 引腳)
散熱焊盤機械數(shù)據(jù) (封裝 | 引腳)
訂購信息
7.3.12 Constant Switching Frequency and Timing Resistor (RT/CLK Pin)
The switching frequency of the TPS54260 is adjustable over a wide range from approximately 100 kHz to 2500 kHz by placing a resistor on the RT/CLK pin. The RT/CLK pin voltage is typically 0.5 V and must have a resistor-to-ground to set the switching frequency. To determine the timing resistance for a given switching frequency, use Equation 11 or the curves in Figure 39 or Figure 40. To reduce the solution size one would typically set the switching frequency as high as possible, but tradeoffs of the supply efficiency, maximum input voltage and minimum controllable on time should be considered.
The minimum controllable on time is typically 135 ns and limits the maximum operating input voltage.
The maximum switching frequency is also limited by the frequency shift circuit. More discussion on the details of the maximum switching frequency is located below.
Figure 39. Switching Frequency vs RT/CLK Resistance High-Frequency Range 
Figure 40. Switching Frequency vs RT/CLK Resistance Low-Frequency Range