LM5088 Datasheet, PDF (1/26 Pages) National Semiconductor (TI) – Wide Input Range Non-Synchronous Buck Controller

LM5088
June 8, 2009
Wide Input Range Non-Synchronous Buck Controller
General Description
The LM5088 high voltage non-synchronous buck controller
features all the necessary functions to implement an efficient
high voltage buck converter using a minimum number of ex-
ternal components. The LM5088 can be configured to operate
over an ultra-wide input voltage range of 4.5V to 75V. This
easy to use controller includes a level shifted gate driver ca-
pable of controlling an external N-channel buck switch. The
control method is based upon peak current mode control uti-
lizing an emulated current ramp. The use of an emulated
control ramp reduces noise sensitivity of the pulse-width mod-
ulation circuit, allowing reliable control of very small duty
cycles necessary in high input voltage/low output voltage ap-
plications. The LM5088 switching frequency is programmable
from 50 kHz to 1 MHz.
The LM5088 is available in two versions: The LM5088-1 pro-
vides a +/-5% frequency dithering function to reduce the
conducted and radiated EMI, while the LM5088-2 provides a
versatile restart timer for overload protection. Additional fea-
tures include a low dropout bias regulator, tri-level enable
input to control shutdown and standby modes, soft-start and
oscillator synchronization capability. The device is available
in a thermally enhanced TSSOP-16EP pin package.
Features
■ ^{Emulated current mode control}
■ ^{Drives external high-side N-channel MOSFET}
■ ^{Ultra-wide input voltage range from 4.5V to 75V}
■ ^{Low I}_Q ^{Shutdown and Standby modes}
■ ^{High duty cycle ratio feature for reduced dropout voltage}
■ ^{Spread spectrum EMI reduction (LM5088-1)}
■ ^{Hiccup timer for overload protection (LM5088-2)}
■ ^{Adjustable output voltage from 1.205V with 1.5% feedback}
reference accuracy
■ ^{Wide bandwidth error amplifier}
■ ^{Single resistor oscillator frequency setting}
■ ^{Oscillator synchronization capability}
■ ^{Programmable soft-start}
■ ^{High voltage, low dropout bias regulator}
■ ^{Thermal shutdown protection}
Package
■ ^TSSOP-16EP
Simplified Application Schematic
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