ZHCSF14D March 2010 – October 2018 TPS54260
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
-
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
機械數據 (封裝 | 引腳)
散熱焊盤機械數據 (封裝 | 引腳)
訂購信息
8.2.1.2.6 Input Capacitor
The TPS54260 requires a high-quality ceramic, type X5R or X7R, input decoupling capacitor of at least 3 μF of effective capacitance and in some applications a bulk capacitance. The effective capacitance includes any dc bias effects. The voltage rating of the input capacitor must be greater than the maximum input voltage. The capacitor must also have a ripple current rating greater than the maximum input current ripple of the TPS54260. The input ripple current can be calculated using Equation 38.
The value of a ceramic capacitor varies significantly over temperature and the amount of dc bias applied to the capacitor. The capacitance variations due to temperature can be minimized by selecting a dielectric material that is stable over temperature. X5R and X7R ceramic dielectrics are usually selected for power regulator capacitors because they have a high capacitance to volume ratio and are fairly stable over temperature. The output capacitor must also be selected with the dc bias taken into account. The capacitance value of a capacitor decreases as the dc bias across a capacitor increases.
For this example design, a ceramic capacitor with at least a 60-V voltage rating is required to support the maximum input voltage. Common standard ceramic capacitor voltage ratings include 4 V, 6.3 V, 10 V, 16 V, 25 V, 50 V or 100 V so a 100-V capacitor should be selected. For this example, two 2.2-μF, 100-V capacitors in parallel have been selected. Table 2 shows a selection of high-voltage capacitors. The input capacitance value determines the input ripple voltage of the regulator. The input voltage ripple can be calculated using Equation 39. Using the design example values, Ioutmax = 2.5 A, Cin = 4.4 μF, ƒsw = 300 kHz, yields an input voltage ripple of 473 mV and a RMS input ripple current of 1.15 A.
Table 2. Capacitor Types
| VENDOR | VALUE (μF) | EIA Size | VOLTAGE | DIALECTRIC | COMMENTS |
|---|---|---|---|---|---|
| Murata | 1.0 to 2.2 | 1210 | 100 V | X7R | GRM32 series |
| 1.0 to 4.7 | 50 V | ||||
| 1.0 | 1206 | 100 V | GRM31 series | ||
| 1.0 to 2.2 | 50 V | ||||
| Vishay | 1.0 10 1.8 | 2220 | 50 V | VJ X7R series | |
| 1.0 to 1.2 | 100 V | ||||
| 1.0 to 3.9 | 2225 | 50 V | |||
| 1.0 to 1.8 | 100 V | ||||
| TDK | 1.0 to 2.2 | 1812 | 100 V | C series C4532 | |
| 1.5 to 6.8 | 50 V | ||||
| 1.0. to 2.2 | 1210 | 100 V | C series C3225 | ||
| 1.0 to 3.3 | 50 V | ||||
| AVX | 1.0 to 4.7 | 1210 | 50 V | X7R dielectric series | |
| 1.0 | 100 V | ||||
| 1.0 to 4.7 | 1812 | 50 V | |||
| 1.0 to 2.2 | 100 V |