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Buck controllers (external switch)

LM5085

ACTIVE

4.5-75V Wide Vin, Constant On-Time Non-Synchronous PFET Buck Controller

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Data sheet

LM5085

ACTIVE
Data sheet Order now

Product details

Vin (Min) (V) 4.5 Vin (Max) (V) 75 Vout (Min) (V) 1.25 Vout (Max) (V) 75 Iout (Max) (A) 10 Iq (Typ) (uA) 1300 Switching frequency (Min) (kHz) 50 Switching frequency (Max) (kHz) 1000 Features Adjustable Current Limit, Enable, Frequency Synchronization Operating temperature range (C) -40 to 125 Regulated outputs (#) 1 Number of phases 1 Rating Catalog
Vin (Min) (V) 4.5 Vin (Max) (V) 75 Vout (Min) (V) 1.25 Vout (Max) (V) 75 Iout (Max) (A) 10 Iq (Typ) (uA) 1300 Switching frequency (Min) (kHz) 50 Switching frequency (Max) (kHz) 1000 Features Adjustable Current Limit, Enable, Frequency Synchronization Operating temperature range (C) -40 to 125 Regulated outputs (#) 1 Number of phases 1 Rating Catalog
HVSSOP (DGN) 8 9 mm² 3 x 3 VSSOP (DGK) 8 15 mm² 3 x 4.9 WSON (NGQ) 8 9 mm² 3 x 3
  • LM5085-Q1 is an Automotive Grade Product that
    is AEC-Q100 Grade 1 Qualified (–40°C to 125°C
    Operating Junction Temperature)
  • Wide 4.5-V to 75-V Input Voltage Range
  • Adjustable Current Limit Using RDS(ON) or a
    Current Sense Resistor
  • Programmable Switching Frequency to 1MHz
  • No Loop Compensation Required
  • Ultra-Fast Transient Response
  • Nearly Constant Operating Frequency with Line
    and Load Variations
  • Adjustable Output Voltage from 1.25 V
  • Precision ±2% Feedback Reference
  • Capable of 100% Duty Cycle Operation
  • Internal Soft-start Timer
  • Integrated High Voltage Bias Regulator
  • Thermal Shutdown
  • Package:
    • HVSSOP-8
    • VSSOP-8
    • WSON-8
  • LM5085-Q1 is an Automotive Grade Product that
    is AEC-Q100 Grade 1 Qualified (–40°C to 125°C
    Operating Junction Temperature)
  • Wide 4.5-V to 75-V Input Voltage Range
  • Adjustable Current Limit Using RDS(ON) or a
    Current Sense Resistor
  • Programmable Switching Frequency to 1MHz
  • No Loop Compensation Required
  • Ultra-Fast Transient Response
  • Nearly Constant Operating Frequency with Line
    and Load Variations
  • Adjustable Output Voltage from 1.25 V
  • Precision ±2% Feedback Reference
  • Capable of 100% Duty Cycle Operation
  • Internal Soft-start Timer
  • Integrated High Voltage Bias Regulator
  • Thermal Shutdown
  • Package:
    • HVSSOP-8
    • VSSOP-8
    • WSON-8

The LM5085 is a high efficiency PFET switching regulator controller that can be used to quickly and easily develop a small, efficient buck regulator for a wide range of applications. This high voltage controller contains a PFET gate driver and a high voltage bias regulator which operates over a wide 4.5-V to 75-V input range. The constant on-time regulation principle requires no loop compensation, simplifies circuit implementation, and results in ultrafast load transient response. The operating frequency remains nearly constant with line and load variations due to the inverse relationship between the input voltage and the on-time. The PFET architecture allows 100% duty cycle operation for a low dropout voltage. Either the RDS(ON) of the PFET or an external sense resistor can be used to sense current for over-current detection.

The LM5085 is a high efficiency PFET switching regulator controller that can be used to quickly and easily develop a small, efficient buck regulator for a wide range of applications. This high voltage controller contains a PFET gate driver and a high voltage bias regulator which operates over a wide 4.5-V to 75-V input range. The constant on-time regulation principle requires no loop compensation, simplifies circuit implementation, and results in ultrafast load transient response. The operating frequency remains nearly constant with line and load variations due to the inverse relationship between the input voltage and the on-time. The PFET architecture allows 100% duty cycle operation for a low dropout voltage. Either the RDS(ON) of the PFET or an external sense resistor can be used to sense current for over-current detection.
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Technical documentation

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Type Title Date
* Data sheet LM5085/-Q1 75-V Constant On-Time PFET Buck Switching Controller datasheet (Rev. I) PDF | HTML 12 Aug 2015
Technical article Crafty idea: Create a 150V non synchronous buck solution with a lower Vin rated controller 25 Aug 2017
Analog Design Journal Reduce buck-converter EMI and voltage stress by minimizing inductive parasitics 21 Jul 2016
Technical article How to design for EMC and isolation with Fly-Buck™ converters 28 Jul 2015
Application note Transient Response versus Ripple – An Analysis of Ripple Injection Techniques 28 Apr 2014
Technical article How to dynamically control the output voltage with a COT regulator 19 Dec 2013
Technical article Eight switching circuits to power wide VIN applications - brought to you by Vijay Choudhary and presented by Santa’s reindeer 18 Dec 2013
White paper Wide VIN power management ICs simplify white paper (Rev. A) 19 Sep 2013
EVM User's guide AN-1878 LM5085 Evaluation Board (Rev. B) 30 Apr 2013
Application note Constant Current Constant Voltage Buck Converter w/LM25085 (Rev. A) 23 Apr 2013
Application note Designing Non-Invert Buck-Boost (Zeta) Cnvrts w/a Buck P-FET Cntrl 22 Apr 2011

Design & development

For additional terms or required resources, click any title below to view the detail page where available.

Evaluation board

LM5085EVAL — LM5085 - 75V Wide Vin Constant On-Time PFET Buck Switching Controller Evaluation Module

The LM5085 evaluation board provides the design engineer with a fully functional buck regulator, employing the LM5085 PFET switching controller which uses the constant on-time (COT) operating principle. The evaluation board provides a 5V output over an input range of 5.5V to 55V. The circuit (...)

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Simulation model

LM5085 PSpice Transient Model (Rev. A)

SNVM213A.ZIP (135 KB) - PSpice Model
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Simulation model

LM5085 PSpice Unencrypted Transient Model (Rev. B)

SNVM213B.ZIP (147 KB) - PSpice Model
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Simulation model

LM5085 TINA-TI Load Transient Reference Design (Rev. A)

SNVM496A.TSC (135 KB) - TINA-TI Reference Design
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Simulation model

LM5085 TINA-TI Startup Reference Design (Rev. A)

SNVM497A.TSC (136 KB) - TINA-TI Reference Design
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Simulation model

LM5085 TINA-TI Transient Spice Model (Rev. A)

SNVM498A.ZIP (20 KB) - TINA-TI Spice Model
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Simulation model

LM5085 Unencrypted PSpice Transient Model

SNVM955.ZIP (3 KB) - PSpice Model
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Simulation tool

PSPICE-FOR-TI — PSpice® for TI design and simulation tool

PSpice® for TI is a design and simulation environment that helps evaluate functionality of analog circuits. This full-featured, design and simulation suite uses an analog analysis engine from Cadence®. Available at no cost, PSpice for TI includes one of the largest model libraries in the (...)
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Calculation tool

LM25085-5085QUICK-CALC — LM(2)5085 Quick Start Calculator

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Reference designs

PMP9103 — Low Cost Buck Provides 24V@2A from 32Vin for Wireless Base Station Reference Design

This hysteretic buck converter delivers greater than 97% efficiency, low cost and small area. Additional benefits are very low output ripple voltage and excellent load transient response.
Package Pins Download
HVSSOP (DGN) 8 View options
VSSOP (DGK) 8 View options
WSON (NGQ) 8 View options

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