ZHCSMS3 December 2020 TPS54622-EP
PRODUCTION DATA
- 1 特性
- 2 应用
- 3 说明
- 4 Revision History
- 5 Pin Configurations 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 Continuous Current Mode Operation (CCM)
- 7.3.3 VIN and Power VIN Pins (VIN and PVIN)
- 7.3.4 Voltage Reference
- 7.3.5 Adjusting the Output Voltage
- 7.3.6 Safe Start-Up Into Prebiased Outputs
- 7.3.7 Error Amplifier
- 7.3.8 Slope Compensation
- 7.3.9 Enable and Adjusting Undervoltage Lockout
- 7.3.10 Adjustable Switching Frequency and Synchronization (RT/CLK)
- 7.3.11 Slow Start (SS/TR)
- 7.3.12 Power Good (PWRGD)
- 7.3.13 Output Overvoltage Protection (OVP)
- 7.3.14 Overcurrent Protection
- 7.3.15 Thermal Shutdown
- 7.3.16 Small Signal Model for Loop Response
- 7.3.17 Simple Small Signal Model for Peak Current Mode Control
- 7.3.18 Small Signal Model for Frequency Compensation
- 7.4 Device Functional Modes
-
8 Application and Implementation
- 8.1 Application Information
- 8.2
Typical Application
- 8.2.1 Design Requirements
- 8.2.2
Detailed Design Procedures
- 8.2.2.1 Custom Design With WEBENCH® Tools
- 8.2.2.2 Operating Frequency
- 8.2.2.3 Output Inductor Selection
- 8.2.2.4 Output Capacitor Selection
- 8.2.2.5 Input Capacitor Selection
- 8.2.2.6 Slow-Start Capacitor Selection
- 8.2.2.7 Bootstrap Capacitor Selection
- 8.2.2.8 Undervoltage Lockout Setpoint
- 8.2.2.9 Output Voltage Feedback Resistor Selection
- 8.2.2.10 Compensation Component Selection
- 8.2.2.11 Fast Transient Considerations
- 8.2.3 Application Curves
- 9 Power Supply Recommendations
- 10Layout
- 11Device and Documentation Support
- 12Mechanical, Packaging, and Orderable Information
7.3.5 Adjusting the Output Voltage
The output voltage is set with a resistor-divider from the output (VOUT) to the VSENSE pin. TI recommends using 1% tolerance or better divider resistors. Referring to the application schematic of Figure 8-1, start with a 10 kΩ for R6 and use Equation 1 to calculate R5. To improve efficiency at light loads, consider using larger value resistors. If the values are too high, the regulator is more susceptible to noise and voltage errors from the VSENSE input current and are noticeable.
where
- Vref = 0.6 V
The minimum output voltage and maximum output voltage can be limited by the minimum on-time of the high-side MOSFET and bootstrap voltage (BOOT-PH voltage) respectively. More discussions are located in Minimum Output Voltage and Bootstrap Voltage (BOOT) and Low Dropout Operation.