LM3481_15 Datasheet, PDF (1/38 Pages) Texas Instruments – LM3481 / -Q1 High-Efficiency Controller for Boost, SEPIC and Flyback DC-DC Converters

Product
Folder
Sample &
Buy
Technical
Documents
Tools &
Software
Support &
Community
LM3481, LM3481-Q1
SNVS346F – NOVEMBER 2007 – REVISED NOVEMBER 2014
LM3481 / -Q1 High-Efficiency Controller for Boost, SEPIC and Flyback DC-DC Converters
1 Features
•1 LM3481QMM 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 1-A 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
• Key Specifications
– Wide Supply Voltage Range of 2.97 V to 48 V
– 100-kHz to 1-MHz Adjustable and
Synchronizable Clock Frequency
– ±1.5% (Over Temperature) Internal Reference
– 10-µA Shutdown Current (Over Temperature)
3 Description
The LM3481 device is a versatile Low-Side N-FET
high-performance controller for switching regulators.
The device is designed for use in Boost, SEPIC and
Flyback converters and topologies requiring a low-
side FET as the primary switch. The LM3481 device
can be operated at very high switching frequencies to
reduce the overall solution size. The switching
frequency of the LM3481 device can be adjusted to
any value between 100kHz and 1MHz 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 device has built-in protection features
such as thermal shutdown, short-circuit protection
and overvoltage protection. Power-saving shutdown
mode reduces the total supply current to 5 µA and
allows power supply sequencing. Internal soft-start
limits the inrush current at start-up. Integrated current
slope compensation simplifies the design and, if
needed for specific applications, can be increased
using a single resistor.
2 Applications
• Automotive Start-Stop Applications
• Automotive ADAS Driver Information
• One Cell/Two Cell Li-ion Battery Powered
Portable Bluetooth Audio Systems
• Notebooks, PDAs, Digital Cameras, and Other
Portable Applications
• Offline Power Supplies
• Set-Top Boxes
• Boost for Audio Amplifiers
Device Information⁽¹⁾
PART NUMBER
PACKAGE
BODY SIZE (NOM)
LM3481
LM3481-Q1
VSSOP (10)
3.00 mm × 3.00 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
R7
121 k:
V_IN = 5V
C8
390 pF
R8
121 k:
RC
CC
22.6 k: 82 nF
RF2
20 k:
RF1
169 k:
I_SEN
V_IN
1 PF
UVLO
VCC
C9
COMP LM3481 DR
FB
PGND
AGND
FA/SYNC/SD
RFA
90.9 k:
CSEN
1 nF
L1
6.8 PH
Q1 ^D1
RSEN
20 m:
+ _{CIN1, CIN2}
150 PF
VOUT = 12V
IOUT = 1.8A
+ COUT1, COUT2
150 PF
Figure 1. LM3481 Typical 5Vin to 12Vout Boost Converter Application
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.