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LM3478Q-Q1
SNVSAX8 – APRIL 2018
LM3478Q-Q1 High-Efficiency Low-Side N-Channel Controller for Switching Regulator
1 Features
•1 LM3478Q-Q1 is AEC-Q100 Qualified and
Manufactured on an Automotive Grade Flow
• 8-lead VSSOP-8
• 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 Soft Start
• Current Mode Operation
• Undervoltage Lockout With Hysteresis
• Create a Custom Design Using the LM3478 with
the WEBENCH Power Designer
2 Applications
• Distributed Power Systems
• Battery Chargers
• Offline Power Supplies
• Telecom Power Supplies
• Automotive Power Systems
• Wide Supply Voltage Range of 2.97 V to 40 V
• 100-kHz to 1-MHz Adjustable Clock Frequency
• ±2.5% (Over Temperature) Internal Reference
• 10-µA Shutdown Current (Over Temperature)
3 Description
The LM3478Q-Q1 is a versatile Low-Side N-Channel
MOSFET controller for switching regulators. It is
suitable for use in topologies requiring a low side
MOSFET, such as boost, flyback, SEPIC, etc.
Moreover, the LM3478Q-Q1 can be operated at
extremely high switching frequency in order to reduce
the overall solution size. The switching frequency of
the LM3478Q-Q1 can be adjusted to any value
between 100 kHz and 1 MHz by using a single
external resistor. Current mode control provides
superior bandwidth and transient response, besides
cycle-by-cycle current limiting. Output current can be
programmed with a single external resistor.
The LM3478Q-Q1 has built in features such as
thermal shutdown, short-circuit protection, over
voltage protection, etc. 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.
Device Information(1)
PART NUMBER
PACKAGE
BODY SIZE (NOM)
LM3478Q-Q1
VSSOP (8)
3.00 mm x 3.00 mm
(1) For all available packages, see the orderable addendum at
the end of the datasheet.
RC
4.7 k
CC 22 nF
20 k
RF2
Typical High Efficiency Step-Up (Boost) Converter
VIN = 3.3 V (±10%)
LM3478
ISEN
-Q1
VIN
COMP
FA/SD
FB DR
RFA
40 k
AGND
PGND
CSN
0.01 µF
L
10 µH
+
CIN
100 µF, 6.3 V
D MBRD340
Q1
IRF7807
60 k
RF1
RSN
0.025 Ÿ
VOUT= 5 V, 2 A
+ COUT
100µF, 10 V
x2
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.
