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
4.8A
+
-
COMP
CONTROL
LOGIC
CURRENT
LIMIT
OVERVOLTAGE
UNDERVOLTAGE
ERROR AMP
PWM COMPARATOR
SS/TRK
PGOOD
+
-
+2.7V
REGULATOR
PVIN
PVIN
THERMAL
PROTECTION
PGND
SW
AVIN
CURRENT SENSE
VCC
1.18V
UVLO
2.7V
AGND
OSCILLATOR
+
752 mV
864 mV
PG-L
PG-L
2.7V
5 PA
g
m
= 510 Pmho
800 mV
+
-
+
DISCHARGE
DISCHARGE
SLOPE COMP
DIODE
EMULATION
+
-
VREF
+
-
FB
EN
+
-
+
-
(50 Ps)
+
-
+
-
PVIN
LM20123
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SNVS524E –OCTOBER 2007–REVISED MARCH 2013
BLOCK DIAGRAM
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