LM3488_05 Datasheet, PDF (1/24 Pages) National Semiconductor (TI) – High Efficiency Low-Side N-Channel Controller for Switching Regulators

May 2005
LM3488
High Efficiency Low-Side N-Channel Controller for
Switching Regulators
General Description
The LM3488 is a versatile Low-Side N-FET high perfor-
mance controller for switching regulators. It is suitable for
use in topologies requiring low side FET, such as boost,
flyback, SEPIC, etc. Moreover, the LM3488 can be operated
at extremely high switching frequency in order to reduce the
overall solution size. The switching frequency of LM3488 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 band-
width and transient response, besides cycle-by-cycle current
limiting. Output current can be programmed with a single
external resistor.
The LM3488 has built in 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.
Key Specifications
n Wide supply voltage range of 2.97V to 40V
n 100kHz to 1MHz Adjustable and Synchronizable clock
frequency
n ±1.5% (over temperature) internal reference
n 5µA shutdown current (over temperature)
Features
n 8-lead Mini-SO8 (MSOP-8) package
n Internal push-pull driver with 1A peak current capability
n Current limit and thermal shutdown
n Frequency compensation optimized with a capacitor and
a resistor
n Internal softstart
n Current Mode Operation
n Undervoltage Lockout with hysteresis
Applications
n Distributed Power Systems
n Notebook, PDA, Digital Camera, and other Portable
Applications
n Offline Power Supplies
n Set-Top Boxes
Typical Application Circuit
Typical SEPIC Converter
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