ZHCS360F July 2012 – November 2020 TPS54020
PRODUCTION DATA
- 1 特性
- 2 應用
- 3 說明
- 4 Revision History
- 5 Description (Continued)
- 6 Pin Configuration and Functions
- 7 Specifications
-
8 Detailed Description
- 8.1 Overview
- 8.2 Functional Block Diagram
- 8.3
Feature Description
- 8.3.1 Fixed Frequency PWM Control
- 8.3.2 Input Voltage and Power Input Voltage Pins (VIN and PVIN)
- 8.3.3 Voltage Reference (VREF)
- 8.3.4 Adjusting the Output Voltage
- 8.3.5 Safe Start-up into Prebiased Outputs
- 8.3.6 Error Amplifier
- 8.3.7 Slope Compensation
- 8.3.8 Enable and Adjusting Undervoltage Lockout
- 8.3.9 Adjustable Switching Frequency and Synchronization (RT/CLK)
- 8.3.10 Soft-Start (SS) Sequence
- 8.3.11 Power Good (PWRGD)
- 8.3.12 Bootstrap Voltage (BOOT) and Low Dropout Operation
- 8.3.13 Sequencing (SS)
- 8.3.14 Output Overvoltage Protection (OVP)
- 8.3.15 Overcurrent Protection
- 8.3.16 Thermal Shutdown
- 8.4 Device Functional Modes
-
9 Application and Implementation
- 9.1 Application Information
- 9.2
Typical Application
- 9.2.1 Design Requirements
- 9.2.2
Detailed Design Procedure
- 9.2.2.1 Custom Design With WEBENCH? Tools
- 9.2.2.2 Operating Frequency
- 9.2.2.3 Output Inductor Selection
- 9.2.2.4 Output Capacitor Selection
- 9.2.2.5 Input Capacitor Selection
- 9.2.2.6 Soft-Start Capacitor Selection
- 9.2.2.7 Bootstrap Capacitor Selection
- 9.2.2.8 Undervoltage Lockout Set Point
- 9.2.2.9 Output Voltage Feedback Resistor Selection
- 9.2.2.10 Compensation Component Selection
- 9.2.3 Application Curves
- 10Power Supply Recommendations
- 11Layout
- 12Device and Documentation Support
- 13Mechanical, Packaging, and Orderable Information
8.3.4 Adjusting the Output Voltage
The output voltage is set by the resistor divider network of RUPPER and RLOWER. It is recommended that the lower divider resistor, RLOWER, maintain a range between 1 kΩ and 3 kΩ. During light-load conditions, this resistor range provides enough load current to exceed the bias leakage current that can be sourced by the PH pin. To change the output voltage of a design, it is necessary to change the value of the resistor RUPPER. Changing the value of RUPPER can change the output voltage between 0.6 V and 5 V. The value of RUPPER for a specific output voltage can be calculated using Equation 1.
The minimum output setpoint voltage cannot be less than the reference voltage of 0.6 V, but it can also be limited by the minimum ON time of the high-side MOSFET. The maximum output voltage can be limited by bootstrap voltage (BOOT-PH voltage). See more details located in Section 9.2.2.9.1 and Section 8.3.12.