LM3481MM Datasheet, PDF (1/30 Pages) Texas Instruments – LM3481/LM3481Q High Efficiency Low-Side N-Channel Controller for Switching

LM3481
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SNVS346E – NOVEMBER 2007 – REVISED APRIL 2012
LM3481/LM3481Q High Efficiency Low-Side N-Channel Controller for Switching
Regulators
Check for Samples: LM3481
FEATURES
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•2 LM3481QMM in the VSSOP-10 Package are
Automotive Grade Products that are AEC-Q100
Grade 1 Qualified (-40°C to +125°C Operating
Junction Temperature)
• 10-Lead VSSOP Package
• Internal Push-Pull Driver with 1A Peak Current
Capability
• Current Limit and Thermal Shutdown
• Frequency Compensation Optimized with a
Capacitor and a Resistor
• Internal Softstart
• Current Mode Operation
• Adjustable Undervoltage Lockout with
Hysteresis
• Pulse Skipping at Light Loads
APPLICATIONS
• Distributed Power Systems
• Notebook, PDA, Digital Camera, and other
Portable Applications
• Offline Power Supplies
• Set-Top Boxes
KEY SPECIFICATIONS
• Wide Supply Voltage Range of 2.97V to 48V
• 100 kHz to 1 MHz Adjustable and
Synchronizable Clock Frequency
• ±1.5% (Over Temperature) Internal Reference
• 10 µA Shutdown Current (Over Temperature)
DESCRIPTION
The LM3481 is a versatile Low-Side N-FET high
performance controller for switching regulators. It is
suitable for use in topologies requiring a low-side
FET, such as boost, flyback, SEPIC, etc. The
LM3481 can be operated at extremely high switching
frequencies in order to reduce the overall solution
size. The switching frequency of the LM3481 can be
adjusted to any value between 100 kHz and 1 MHz
by using a single external resistor or by synchronizing
it to an external clock. Current mode control provides
superior bandwidth and transient response in addition
to cycle-by-cycle current limiting. Current limit can be
programmed with a single external resistor.
The LM3481 has built in protection features such as
thermal shutdown, short-circuit protection and over
voltage protection. Power saving shutdown mode
reduces the total supply current to 5µA and allows
power supply sequencing. Internal soft-start limits the
inrush current at start-up.
TYPICAL APPLICATION CIRCUIT
R7
R8
R_C
C_C
R_F2
R_F1
I_SEN
V_IN
UVLO
V_CC
COMP LM3481 DR
FB
PGND
C_BYP
AGND
FA/SYNC/SD
R_FA
C_SEN
L1
C_S
Q1
R_SEN
V_IN = 3.0V to 48V
+
C_IN
D1
L2
V_OUT = 5V, 1A
+
C_OUT
Figure 1. Typical SEPIC Converter
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2
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2007–2012, Texas Instruments Incorporated