LM3485EVAL Datasheet, PDF (1/22 Pages) Texas Instruments – LM3485 Hysteretic PFET Buck Controller

LM3485
www.ti.com
SNVS178F – MAY 2004 – REVISED SEPTEMBER 2009
LM3485 Hysteretic PFET Buck Controller
Check for Samples: LM3485
FEATURES
1
•2 Easy to use control methodology
• No control loop compensation required
• 4.5V to 35V wide input range
• 1.242V to V_IN adjustable output range
• High Efficiency 93%
• ±1.3% (±2% over temp) internal reference
• 100% duty cycle
• Maximum operating frequency > 1MHz
• Current limit protection
• MSOP-8
APPLICATIONS
• Set-Top Box
• DSL/Cable Modem
• PC/IA
• Auto PC
• TFT Monitor
• Battery Powered Portable Applications
• Distributed Power Systems
• Always On Power
DESCRIPTION
The LM3485 is a high efficiency PFET switching regulator controller that can be used to quickly and easily
develop a small, low cost, switching buck regulator for a wide range of applications. The hysteretic control
architecture provides for simple design without any control loop stability concerns using a wide variety of external
components. The PFET architecture also allows for low component count as well as ultra-low dropout, 100%
duty cycle operation. Another benefit is high efficiency operation at light loads without an increase in output
ripple.
Current limit protection is provided by measuring the voltage across the PFET’s R_DS(ON), thus eliminating the
need for a sense resistor. The cycle-by-cycle current limit can be adjusted with a single resistor, ensuring safe
operation over a range of output currents.
Typical Application Circuit
Connection Diagram
Figure 1. 8 Lead Plastic MSOP-8
Top View
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
All trademarks are the property of their respective owners.
2
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2004–2009, Texas Instruments Incorporated