23800

·  Easy to use control methodology
·  No control loop compensation required
·  4.5V to 35V wide input range
·  1.242V to VIN 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

·  Set-Top Box
·  DSL/Cable Modem
·  PC/IA
·  Auto PC
·  TFT Monitor
·  Battery Powered Portable Applications
·  Distributed Power Systems
·  Always On Power Typical Application Circuit 20034608

If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales ffice/Distributors for availability and specifications.
VIN Voltage ....................................−0.3V to 36V
PGATE Voltage ...............................−0.3V to 36V
FB Voltage .......................................−0.3V to 5V
ISENSE Voltage .............................−1.0V to 36V
ADJ Voltage ...................................−0.3V to 36V
Maximum Junction Temp. ..........................150
Power Dissipation ..............417mW @ TA =25
ESD Susceptibilty
Human Body Model (Note 3) ......................2kV
Lead Temperature
Vapor Phase (60 sec.).............................215
Infared (15 sec.).....................................220
Storage Temperature ..............−65 to 150
Operating Ratings (Note 1)
Supply Voltage ............................4.5V to 35V
Operating Junction
Temperature .......................−40 to +125

The LM3485 is a high efficiency PFET switching regulator controller that a system designer can use to quickly and easily develop a small, low cost, switching buck regulator for a wide range of applications. The use of a hysteretic control scheme provides for simple design without any control loop stability concerns using a wide variety of external components.

The LM3485 also allows for low component count as well as ultra-low dropout operation. Another benefit is high efficiency operation at light loads without an increase in output ripple. Current limit protection circuit is provided by measuring the voltage across the PFET's RDSON thus eliminating a costly sense resistor. The current limit can be adjusted allowing for designs at various output currents and costs.