SLVS974F
September 2009 – May 2020
PRODUCTION DATA.
1
Features
2
Applications
3
Description
Device Images
Simplified Schematic
Efficiency versus Output Current
4
Revision History
5
Pin Configuration and Functions
Pin Functions
6
Specifications
6.1
Absolute Maximum Ratings
6.2
ESD Ratings
6.3
Recommended Operating Conditions
6.4
Thermal Information
6.5
Electrical Characteristics
6.6
Typical Characteristics
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
Slope Compensation and Output Current
7.3.3
Bootstrap Voltage (Boot) and Low Dropout Operation
7.3.4
Error Amplifier
7.3.5
Voltage Reference
7.3.6
Adjusting the Output Voltage
7.3.7
Enable and Adjusting Undervoltage Lockout
7.3.8
Soft-Start Pin
7.3.9
Sequencing
7.3.10
Constant Switching Frequency and Timing Resistor (RT/CLK Pin)
7.3.11
Overcurrent Protection
7.3.12
Frequency Shift
7.3.13
Reverse Overcurrent Protection
7.3.14
Synchronize Using the RT/CLK Pin
7.3.15
Power Good (PWRGD Pin)
7.3.16
Overvoltage Transient Protection
7.3.17
Thermal Shutdown
7.4
Device Functional Modes
7.4.1
Small Signal Model for Loop Response
7.4.2
Simple Small Signal Model for Peak Current Mode Control
7.4.3
Small Signal Model for Frequency Compensation
8
Application and Implementation
8.1
Application Information
8.2
Typical Application
8.2.1
Design Requirements
8.2.2
Detailed Design Procedure
8.2.2.1
Step One: Select the Switching Frequency
8.2.2.2
Step Two: Select the Output Inductor
8.2.2.3
Step Three: Choose the Output Capacitor
8.2.2.4
Step Four: Select the Input Capacitor
8.2.2.5
Step Five: Minimum Load DC COMP Voltage
8.2.2.6
Step Six: Choose the Soft-Start Capacitor
8.2.2.7
Step Seven: Select the Bootstrap Capacitor
8.2.2.8
Step Eight: Undervoltage Lockout Threshold
8.2.2.9
Step Nine: Select Output Voltage and Feedback Resistors
8.2.2.9.1
Output Voltage Limitations
8.2.2.10
Step 10: Select Loop Compensation Components
8.2.2.11
Power Dissipation Estimate
8.2.3
Application Curves
9
Power Supply Recommendations
10
Layout
10.1
Layout Guidelines
10.2
Layout Example
11
Device and Documentation Support
11.1
Device Support
11.1.1
Development Support
11.1.1.1
Custom Design With WEBENCH® Tools
11.2
Receiving Notification of Documentation Updates
11.3
Support Resources
11.4
Trademarks
11.5
Electrostatic Discharge Caution
11.6
Glossary
12
Mechanical, Packaging, and Orderable Information
6.6
Typical Characteristics
Figure 1.
High-Side and Low-Side On-Resistance versus Junction Temperature
Figure 3.
High-Side Current Limit versus Junction Temperature
Figure 5.
Switching Frequency versus RT Resistance Low Frequency Range
Figure 7.
Switching Frequency versus Vsense
Figure 9.
Transconductance (Soft Start) versus Junction Temperature
Figure 11.
Pin Current versus Junction Temperature
Figure 13.
Junction Temperature versus SS Charge Current
Figure 15.
Input Voltage versus Junction Temperature
Figure 17.
Shutdown Supply Current versus Input Voltage
Figure 19.
Supply Current versus Input Voltage
Figure 21.
PWRGD On Resistance versus Junction Temperature
Figure 2.
Switching Frequency versus Junction Temperature
Figure 4.
Voltage Reference versus Junction Temperature
Figure 6.
Switching Frequency versus RT Resistance High Frequency Range
Figure 8.
Transconductance versus Junction Temperature
Figure 10.
Enable Pin Voltage versus Junction Temperature
Figure 12.
Pin Current versus Junction Temperature
Figure 14.
Discharge Current versus Junction Temperature
Figure 16.
Shutdown Supply Current versus Junction Temperature
Figure 18.
Supply Current versus Junction Temperature
Figure 20.
PWRGD Threshold versus Junction Temperature
Figure 22.
Minimum Comp Voltage Clamp versus Junction Temperature