SNVS853E
August 2012 – August 2018
LMZ21701
PRODUCTION DATA.
1
Features
2
Applications
3
Description
Device Images
Simplified Schematic
Efficiency for VIN = 12 V
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
Package Construction
7.4
Feature Description
7.4.1
Input Undervoltage Lockout
7.4.2
Enable Input (EN)
7.4.3
Soft Start and Tracking Function (SS)
7.4.4
Power Good Function (PG)
7.4.5
Output Voltage Setting
7.4.6
Output Current Limit and Output Short Circuit Protection
7.4.7
Thermal Protection
7.5
Device Functional Modes
7.5.1
PWM Mode Operation
7.5.2
PSM Operation
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
Custom Design With WEBENCH® Tools
8.2.2.2
Input Capacitor (CIN)
8.2.2.3
Output Capacitor (COUT)
8.2.2.4
Soft-start Capacitor (CSS)
8.2.2.5
Power Good Resistor (RPG)
8.2.2.6
Feedback Resistors (RFBB and RFBT)
8.2.3
Application Curves
8.2.3.1
VOUT = 1.2 V
8.2.3.2
VOUT = 1.8 V
8.2.3.3
VOUT = 2.5 V
8.2.3.4
VOUT = 3.3 V
8.2.3.5
VOUT = 5.0 V
8.3
Do's and Don'ts
9
Power Supply Recommendations
9.1
Voltage Range
9.2
Current Capability
9.3
Input Connection
9.3.1
Voltage Drops
9.3.2
Stability
10
Layout
10.1
Layout Guidelines
10.1.1
Minimize the High di/dt Loop Area
10.1.2
Protect the Sensitive Nodes in the Circuit
10.1.3
Provide Thermal Path and Shielding
10.2
Layout Example
10.2.1
High Density Layout Example for Space Constrained Applications
10.2.1.1
35 mm² Solution Size (Single Sided)
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
Trademarks
11.3
Electrostatic Discharge Caution
11.4
Glossary
12
Mechanical, Packaging, and Orderable Information
12.1
Tape and Reel Information
8.2.3.5
V
OUT
= 5.0 V
Figure 68.
Typical Applications Circuit
Figure 70.
Efficiency V
OUT
= 5.0 V
Figure 72.
Load Transient V
OUT
= 5.0 V
Figure 74.
20MHz Oscilloscope Bandwidth
Output Voltage Ripple V
OUT
= 5.0 V
Figure 76.
Typical Switching Frequency at 1000 mA Load V
OUT
= 5 V
Figure 78.
Line and Load Regulation V
OUT
= 5 V
Figure 69.
External Component Values
(V
OUT
= 5.0 V)
Figure 71.
Power Dissipation V
OUT
= 5.0 V
Figure 73.
Startup V
OUT
= 5.0 V
Figure 75.
500 MHz Oscilloscope Bandwidth, 3x1000 pF additional output capacitance
Output Voltage Ripple and HF Noise V
OUT
= 5.0 V
Figure 77.
Typical Current Limit V
OUT
= 5 V, T
A
= 85°C
Figure 79.
Thermal Derating for θ
JA
= 47 ºC/W, V
OUT
= 5 V