Datasheet
Table Of Contents
- FEATURES
- APPLICATIONS
- DESCRIPTION
- ABSOLUTE MAXIMUM RATINGS
- OPERATING RATINGS
- ELECTRICAL CHARACTERISTICS
- TYPICAL PERFORMANCE CHARACTERISTICS
- BLOCK DIAGRAM
- OPERATION DESCRIPTION
- GENERAL
- PRECISION ENABLE
- PEAK CURRENT MODE CONTROL
- CURRENT LIMIT
- SOFT-START AND VOLTAGE TRACKING
- PRE-BIAS START UP CAPABILITY
- POWER GOOD AND OVER VOLTAGE FAULT HANDLING
- UVLO
- THERMAL PROTECTION
- LIGHT LOAD OPERATION
- Design Guide
- INDUCTOR SELECTION (L)
- OUTPUT CAPACITOR SELECTION (COUT)
- INPUT CAPACITOR SELECTION (CIN)
- SETTING THE OUTPUT VOLTAGE (RFB1, RFB2)
- LOOP COMPENSATION (RC1, CC1)
- AVIN FILTERING COMPONENTS (CF and RF)
- SUB-REGULATOR BYPASS CAPACITOR (CVCC)
- SETTING THE START UP TIME (CSS)
- USING PRECISION ENABLE AND POWER GOOD
- TRACKING AN EXTERNAL SUPPLY
- THERMAL CONSIDERATIONS
- PCB LAYOUT CONSIDERATIONS
- Typical Application Circuit
- Bill of Materials (VIN = 5V, VOUT = 3.3V, IOUTMAX = 3A)
- Bill of Materials (VIN = 3.3V to 5V, VOUT = 1.2V, IOUTMAX = 3A)
- Revision History

LM20123
SNVS524E –OCTOBER 2007–REVISED MARCH 2013
www.ti.com
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
Unless otherwise specified: C
IN
= C
OUT
= 100 µF, L = 1.0 µH (Coilcraft MSS1038), V
IN
= 5V, V
OUT
= 1.2V, R
LOAD
= 1.2Ω, T
A
=
25°C for efficiency curves, loop gain plots and waveforms, and T
J
= 25°C for all others.
Feedback Pin Voltage
Load Regulation vs. Temperature
Figure 7. Figure 8.
Switching Frequency Quiescent Current vs.
vs. Temperature V
IN
(Not Switching)
Figure 9. Figure 10.
Shutdown Current Enable Threshold
vs. Temperature vs. Temperature
Figure 11. Figure 12.
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