ZHCSMU1G October 2020 – May 2024 LMR43610-Q1 , LMR43620-Q1
PRODUCTION DATA
- 1
- 1 特性
- 2 應(yīng)用
- 3 說明
- 4 Device Comparison Table
- 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 Enable, Start-Up, and Shutdown
- 7.3.2 External CLK SYNC (with MODE/SYNC)
- 7.3.3 Adjustable Switching Frequency (with RT)
- 7.3.4 Power-Good Output Operation
- 7.3.5 Internal LDO, VCC, and VOUT/FB Input
- 7.3.6 Bootstrap Voltage and VBOOT-UVLO (BOOT Terminal)
- 7.3.7 Output Voltage Selection
- 7.3.8 Spread Spectrum
- 7.3.9 Soft Start and Recovery from Dropout
- 7.3.10 Current Limit and Short Circuit
- 7.3.11 Thermal Shutdown
- 7.3.12 Input Supply Current
- 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 Procedure
- 8.2.3 Application Curves
- 8.3 Best Design Practices
- 8.4 Power Supply Recommendations
- 8.5 Layout
- 9 Device and Documentation Support
- 10Revision History
- 11Mechanical, Packaging, and Orderable Information
封裝選項
機械數(shù)據(jù) (封裝 | 引腳)
- RPE|9
散熱焊盤機械數(shù)據(jù) (封裝 | 引腳)
- RPE|9
訂購信息
7.4.3.4 Minimum On-Time (High Input Voltage) Operation
The LMR436x0-Q1 continues to regulate output voltage even if the input-to-output voltage ratio requires an on time less than the minimum on time of the chip with a given clock setting. This is accomplished using valley current control. At all times, the compensation circuit dictates both a maximum peak inductor current and a maximum valley inductor current. If for any reason, valley current is exceeded, the clock cycle is extended until valley current falls below that determined by the compensation circuit. If the converter is not operating in current limit, the maximum valley current is set above the peak inductor current, preventing valley control from being used unless there is a failure to regulate using peak current only. If the input-to-output voltage ratio is too high, such that the inductor current peak value exceeds the peak command dictated by compensation, the high-side device cannot be turned off quickly enough to regulate output voltage. As a result, the compensation circuit reduces both peak and valley current. After a low enough current is selected by the compensation circuit, valley current matches that being commanded by the compensation circuit. Under these conditions, the low-side device is kept on and the next clock cycle is prevented from starting until inductor current drops below the desired valley current. Because on time is fixed at the minimum value, this type of operation resembles that of a device using a Constant On-Time (COT) control scheme; see Figure 7-19.
