LM3311 Datasheet, PDF (1/29 Pages) National Semiconductor (TI) – Step-Up PWM DC/DC Converter with Integrated LDO, Op-Amp, and Gate Pulse Modulation Switch

September 2005
LM3311
Step-Up PWM DC/DC Converter with Integrated LDO,
Op-Amp, and Gate Pulse Modulation Switch
General Description
The LM3311 is a step-up DC/DC converter integrated with
an LDO, an Operational Amplifier, and a gate pulse modu-
lation switch. The boost (step-up) converter is used to gen-
erate an adjustable output voltage and features a low R_DSON
internal switch for maximum efficiency. The operating fre-
quency is selectable between 660kHz and 1.28MHz allowing
for the use of small external components. An external soft-
start pin enables the user to tailor the soft-start time to a
specific application and limit the inrush current. The LDO
also has an adjustable output voltage and is stable using
ceramic output capacitors. The Op-Amp is capable of
sourcing/sinking 135mA of current (typical). The gate pulse
modulation switch can operate with a VGH voltage of 5V to
30V. The LM3311 is available in a low profile 24-lead LLP
package.
Features
n Boost converter with a 2A, 0.18Ω switch
n Boost output voltage adjustable up to 20V
n Operating voltage range of 2.5V to 7V
n 660kHz/1.28MHz pin selectable switching frequency
n Adjustable soft-start function
n Input undervoltage protection
n Over temperature protection
n Adjustable low dropout linear regulator (LDO)
n Integrated Op-Amp
n Integrated gate pulse modulation (GPM) switch
n 24-Lead LLP package
Applications
n TFT Bias Supplies
n Portable Applications
Typical Application Circuit
© 2005 National Semiconductor Corporation DS201263
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