ZHCSF95C December 2015 – February 2018 LMR23610
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 Peak Current Mode Control
- 7.3.2 Adjustable Output Voltage
- 7.3.3 EN/SYNC
- 7.3.4 VCC, UVLO
- 7.3.5 Minimum ON-Time, Minimum OFF-Time and Frequency Foldback at Dropout Conditions
- 7.3.6 Internal Compensation and CFF
- 7.3.7 Bootstrap Voltage (BOOT)
- 7.3.8 Overcurrent and Short-Circuit Protection
- 7.3.9 Thermal Shutdown
- 7.4 Device Functional Modes
-
8 Application and Implementation
- 8.1 Application Information
- 8.2
Typical Applications
- 8.2.1 Design Requirements
- 8.2.2
Detailed Design Procedure
- 8.2.2.1 Custom Design With WEBENCH® Tools
- 8.2.2.2 Output Voltage Setpoint
- 8.2.2.3 Switching Frequency
- 8.2.2.4 Inductor Selection
- 8.2.2.5 Output Capacitor Selection
- 8.2.2.6 Feed-Forward Capacitor
- 8.2.2.7 Input Capacitor Selection
- 8.2.2.8 Bootstrap Capacitor Selection
- 8.2.2.9 VCC Capacitor Selection
- 8.2.2.10 Undervoltage Lockout Setpoint
- 8.2.3 Application Curves
- 9 Power Supply Recommendations
- 10Layout
- 11器件和文檔支持
- 12機械、封裝和可訂購信息
7.3.2 Adjustable Output Voltage
A precision 1-V reference voltage is used to maintain a tightly regulated output voltage over the entire operating temperature range. The output voltage is set by a resistor divider from output voltage to the FB pin. It is recommended to use 1% tolerance resistors with a low temperature coefficient for the FB divider. Select the low-side resistor RFBB for the desired divider current and use Equation 1 to calculate high-side RFBT. RFBT in the range from 10 kΩ to 100 kΩ is recommended for most applications. A lower RFBT value can be used if static loading is desired to reduce VOUT offset in PFM operation. Lower RFBT will reduce efficiency at very light load. Less static current goes through a larger RFBT and might be more desirable when light load efficiency is critical. But RFBT larger than 1 MΩ is not recommended because it makes the feedback path more susceptible to noise. Larger RFBT value requires more carefully designed feedback path on the PCB. The tolerance and temperature variation of the resistor dividers affect the output voltage regulation.
Figure 14. Output Voltage Setting
