Datasheet LM25149-Q1 (Texas Instruments) - 3

link to page 4
LM25149-Q1 www.ti.com
SNVSBV6 – DECEMBER 2020
6 Pin Configuration and Functions TION MA R NCE INFO A V
Connect the exposed pad to AGND and PGND on the PCB.
AD Figure 6-1. 24-Pin VQFN RGY Package with Wettable Flanks (Top View) Table 6-1. Pin Functions PIN I/O(1) DESCRIPTION NO. NAME
1 AVSS G Active EMI bias ground connection 2 INJ O Active EMI injection output Connect a resistor to ground to set primary/secondary, spread spectrum enable/disable, or interleaved 3 CNFG 1 operation. After start-up, CNFG is used to enable AEF. Frequency programming pin. A resistor from RT to AGND sets the oscillator frequency between 100 kHz 4 RT I and 2.2 MHz. The output of the transconduction amplifier. If used, connect the compensation network from EXTCOMP to 5 EXTCOMP O AGND. Connect FB to VDDA to set the output voltage to 3.3 V. Connect FB through 24.9 kΩ to set the output 6 FB I voltage to 5 V, or a resistor divider from VOUT to FB to set the output voltage level between 0.8 V to 55 V. The regulation threshold is 0.8 V. 7 AGND G Analog ground connection. Ground return for the internal voltage reference and analog circuits 8 VDDA O Internal analog bias regulator. Connect a ceramic decoupling capacitor from VDDA to AGND. 9 VCC P VCC bias supply pin. Connect ceramic capacitors between VCC and PGND. 10 PGND G Power ground connection pin for low-side NMOS gate driver 11 LO O Low-side gate driver signal 12 VIN P Supply voltage input source for the VCC regulators Copyright © 2020 Texas Instruments Incorporated Submit Document Feedback 3 Product Folder Links: LM25149-Q1 Document Outline 1 Features 2 Applications 3 Description Table of Contents 4 Revision History 5 Description (continued) 6 Pin Configuration and Functions 6.1 Wettable Flanks 7 Specifications 7.1 Absolute Maximum Ratings 7.2 ESD Ratings  7.3 Recommended Operating Conditions 7.4 Thermal Information 7.5 Electrical Characteristics 7.6 Active EMI Filter 8 Detailed Description 8.1 Overview 8.2 Functional Block Diagram 8.3 Feature Description 8.3.1 Input Voltage Range (VIN) 8.3.2 High-Voltage Bias Supply Regulator (VCC, VCCX, VDDA) 8.3.3 Enable (EN) 8.3.4 Power Good Monitor (PG) 8.3.5 Switching Frequency (RT) 8.3.6 Active EMI Filter 8.3.7 Dual Random Spread Spectrum (DRSS) 8.3.8 Soft-Start 8.3.9 Output Voltage Setpoint (FB) 8.3.10 Minimum Controllable On-Time 8.3.11 Error Amplifier and PWM Comparator (FB, EXTCOMP) 8.3.12 Slope Compensation 8.3.13 Inductor Current Sense (ISNS+, VOUT) 8.3.13.1 Shunt Current Sensing 8.3.13.2 Inductor DCR Current Sensing 8.3.14 Hiccup Mode Current Limiting 8.3.15 High-Side and Low-Side Gate Drivers (HO, LO) 8.3.16 Output Configurations (CNFG) 8.3.17 Single-Output Two-phase Operation 8.4 Device Functional Modes 8.4.1 Standby Modes 8.4.2 Pulse Frequency Modulation and Synchronization (PFM/SYNC) 8.4.3 Thermal Shutdown 9 Application and Implementation 9.1 Application Information 9.1.1 Power Train Components 9.1.1.1 Buck Inductor 9.1.1.2 Output Capacitors 9.1.1.3 Input Capacitors 9.1.1.4 Power MOSFETs 9.1.1.5 EMI Filter 9.1.2 Error Amplifier and Compensation 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 Custom Design With Excel Quickstart Tool 9.2.2.3 Buck Inductor 9.2.2.4 Current-Sense Resistance 9.2.2.5 Output Capacitors 9.2.2.6 Input Capacitors 9.2.2.7 Frequency Set Resistor 9.2.2.8 Feedback Resistors 9.2.2.9 Compensation Components 9.2.2.10 Active EMI Components 9.2.3 Application Curves 10 Power Supply Recommendations 11 Layout 11.1 Layout Guidelines 11.1.1 Power Stage Layout 11.1.2 Gate-Drive Layout 11.1.3 PWM Controller Layout 11.1.4 Active EMI Layout 11.1.5 Thermal Design and Layout 11.1.6 Ground Plane Design 11.2 Layout Example 12 Device and Documentation Support 12.1 Device Support 12.1.1 Development Support 12.1.2 Custom Design With WEBENCH® Tools 12.2 Documentation Support 12.2.1 Related Documentation 12.2.1.1 PCB Layout Resources 12.2.1.2 Thermal Design Resources 12.3 Receiving Notification of Documentation Updates 12.4 Support Resources 12.5 Trademarks 12.6 Electrostatic Discharge Caution 12.7 Glossary 13 Mechanical, Packaging, and Orderable Information