ZHCSJY4B July 2008 – June 2019 TPS5450-Q1
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 Oscillator Frequency
- 7.3.2 Voltage Reference
- 7.3.3 Enable (ENA) and Internal Slow Start
- 7.3.4 Undervoltage Lockout (UVLO)
- 7.3.5 Output Feedback (VSENSE) and Internal Compensation
- 7.3.6 Voltage Feedforward
- 7.3.7 Pulse-Width-Modulation (PWM) Control
- 7.3.8 Overcurrent Limiting
- 7.3.9 Overvoltage Protection
- 7.3.10 Thermal Shutdown
-
8 Application Information
- 8.1 Application Information
- 8.2
Typical Application
- 8.2.1 Design Requirements
- 8.2.2
Detailed Design Procedure
- 8.2.2.1 Custom Design With WEBENCH® Tools
- 8.2.2.2 Boost Capacitor (BOOT)
- 8.2.2.3 Switching Frequency
- 8.2.2.4 Input Capacitors
- 8.2.2.5 Output Filter Components
- 8.2.2.6 Output Voltage Setpoint
- 8.2.2.7 Boot Capacitor
- 8.2.2.8 Catch Diode
- 8.2.2.9 Output Voltage Limitations
- 8.2.2.10 Internal Compensation Network
- 8.2.3 Application Curves
- 9 Layout
- 10器件和文檔支持
- 11機械、封裝和可訂購信息
封裝選項
機械數(shù)據(jù) (封裝 | 引腳)
- DDA|8
散熱焊盤機械數(shù)據(jù) (封裝 | 引腳)
- DDA|8
訂購信息
8.2.2.5.1 Inductor Selection
To calculate the minimum value of the output inductor, use Equation 4:
KIND is a coefficient that represents the amount of inductor ripple current relative to the maximum output current. Three things need to be considered when determining the amount of ripple current in the inductor: the peak-to-peak ripple current affects the output ripple voltage amplitude, the ripple current affects the peak switch current, and the amount of ripple current determines at what point the circuit becomes discontinuous. For designs using the TPS5450-Q1, KIND of 0.2 to 0.3 yields good results. Low output ripple voltages can be obtained when paired with the proper output capacitor, the peak switch current will be well below the current limit set point, and relatively low load currents can be sourced before discontinuous operation.
For this design example use KIND = 0.2 and the minimum inductor value is calculated to be 10.4 μH. A higher standard value is 15 μH, which is used in this design.
For the output filter inductor it is important that the RMS current and saturation current ratings not be exceeded. The RMS inductor current can be found from Equation 5:
and the peak inductor current can be determined with Equation 6:
For this design, the RMS inductor current is 5.004 A, and the peak inductor current is 5.34 A. The chosen inductor is a Sumida CDRH1127/LD-150 15 μH. It has a minimum rated current of 5.65 A for both saturation and RMS current. In general, inductor values for use with the TPS5450-Q1 are in the range of 10 μH to 100 μH.