Datasheet
Table Of Contents
- FEATURES
- APPLICATIONS
- CONTENTS
- DESCRIPTION
- DEVICE RATINGS
- ABSOLUTE MAXIMUM RATINGS
- RECOMMENDED OPERATING CONDITIONS
- ELECTROSTATIC DISCHARGE (ESD) PROTECTION
- PACKAGE DISSIPATION RATINGS
- ELECTRICAL CHARACTERISTICS
- TYPICAL CHARACTERISTICS
- DEVICE INFORMATION
- BLOCK DIAGRAM
- APPLICATION INFORMATION
- FUNCTIONAL DESCRIPTION
- Voltage Reference
- Oscillator
- Input Undervoltage Lockout (UVLO) and Startup
- Enable and Timed Turn On of the Outputs
- Output Voltage Sequencing
- Soft Start
- Output Voltage Regulation
- Feedback Loop and Inductor-Capacitor (L-C) Filter Selection
- Inductor-Capacitor (L-C) Selection
- Maximum Output Capacitance
- Minimum Output Capacitance
- Modifying The Feedback Loop
- Example: TPS54386 Buck Converter Operating at 12-V Input, 3.3-V Output and 400-mA(P-P) Ripple Current
- Bootstrap for the N-Channel MOSFET
- Light Load Operation
- SW Node Ringing
- Output Overload Protection
- Operating Near Maximum Duty Cycle
- Dual Supply Operation
- Cascading Supply Operation
- Multiphase Operation
- Bypass and FIltering
- Over-Temperature Protection and Junction Temperature Rise
- Power Derating
- PowerPAD Package
- PCB Layout Guidelines
- FUNCTIONAL DESCRIPTION
- DESIGN EXAMPLES
- ADDITIONAL REFERENCES

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Example 3: 5-V to 3.3V and 5-V to 1.2 V
1 k 10 k 100 k 300 k
-180
-90
-45
45
90
-135
0
180
135
f - Frequency -Hz
Phase - °
-80
-20
0
60
80
-60
20
Gain - dB
-40
40
V
OUT
= 1.2 V
Gain Phase
WIth Lead
Without Lead
10
40
70
0
90
100
50
h - Efficiency - %
30
20
60
80
0 0.5 1.0 1.5 2.0 2.5 3.0
I
OUT
- Load Current - A
V
OUT
= 1.2 V
V
OUT
= 3.3 V
V
IN
= 5 V
V
OUT
(V)
1.2
3.3
TPS54383 , , TPS54386
SLUS774B – AUGUST 2007 – REVISED OCTOBER 2007
For a low input voltage application, the TPS54386 is selected for reduced size and all ceramic output capacitors
are used. 22- µ F input capacitors are selected to reduce input ripple and lead capacitors are placed in the
feedback to boost phase margin.
Figure 50. 5-V to 3.3V and 5-V to 1.2 V
Figure 51. Efficiency vs. Load Current Figure 52. Example 3 Loop Response
44 Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated
Product Folder Link(s): TPS54383 TPS54386