4.5-35V, Hysteretic Non-Synchronous PFET Buck Controller


Product details


Vin (Min) (V) 4.5 Vin (Max) (V) 35 Vout (Min) (V) 1.242 Vout (Max) (V) 35 Iout (Max) (A) 4 Iq (Typ) (uA) 250 Switching frequency (Min) (kHz) 50 Switching frequency (Max) (kHz) 1000 Features Enable Operating temperature range (C) -40 to 125 Regulated outputs (#) 1 Number of Phases 1 Rating Catalog open-in-new Find other Buck controllers (external switch)

Package | Pins | Size

VSSOP (DGK) 8 15 mm² 3 x 4.9 open-in-new Find other Buck controllers (external switch)


  • Easy-to-Use Control Methodology
  • No Control-Loop Compensation Required
  • 4.5-V to 35-V Wide Input Range
  • 1.242-V to VIN Adjustable Output Range
  • High Efficiency 93%
  • ±1.3% (±2% Over Temp) Internal Reference
  • 100% Duty Cycle
  • Maximum Operating Frequency > 1 MHz
  • Current Limit Protection
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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 ultralow 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 RDS(ON) of the PFET, 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.

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Technical documentation

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Type Title Date
* Datasheet LM3485 Hysteretic PFET Buck Controller datasheet (Rev. H) Dec. 28, 2015
Selection guide Power Management Guide 2018 (Rev. R) Jun. 25, 2018
Selection guide Control-Mode Quick Reference Guide (Rev. A) Sep. 14, 2017
Application note Reduce buck-converter EMI and voltage stress by minimizing inductive parasitics Jul. 21, 2016
User guide AN-1227 LM3485 Evaluation Board (Rev. B) Apr. 25, 2013
User guide AN-1392 LM3485 LED Demo Board (Rev. B) Apr. 25, 2013

Design & development

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Hardware development

document-generic User guide

Hysteretic PFET Buck Controller

  • 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
  • (...)
document-generic User guide

The LM3485 LED driver board is a buck regulator derived controlled current source designed to drive high power, high brightness LEDs (HBLEDs) such as the Luxeon™ Emitter at dissipations of 1W to 5W. The board can accept an input voltage ranging from 5V to 30V and can control the output current (...)

Design tools & simulation

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  • Leverages Cadence PSpice Technology
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CAD/CAE symbols

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VSSOP (DGK) 8 View options

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