LM25085A

ACTIVE

4.5-42V Wide Vin, Constant On-Time Non-Synchronous PFET Buck Controller with 0.9V Reference

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LM25148 ACTIVE 42-V synchronous buck DC/DC controller with ultra-low IQ Improved EMI performance with QFN package and dual random spread spectrum.

Product details

Vin (min) (V) 4.5 Vin (max) (V) 42 Iout (max) (A) 10 Operating temperature range (°C) -40 to 125 Control mode Constant on-time (COT) Topology Buck Controller Rating Catalog Vout (min) (V) 0.9 Vout (max) (V) 42 Features Adjustable current limit, Frequency synchronization Iq (typ) (µA) 1250 Duty cycle (max) (%) 100 Number of phases 1
Vin (min) (V) 4.5 Vin (max) (V) 42 Iout (max) (A) 10 Operating temperature range (°C) -40 to 125 Control mode Constant on-time (COT) Topology Buck Controller Rating Catalog Vout (min) (V) 0.9 Vout (max) (V) 42 Features Adjustable current limit, Frequency synchronization Iq (typ) (µA) 1250 Duty cycle (max) (%) 100 Number of phases 1
HVSSOP (DGN) 8 14.7 mm² 3 x 4.9 VSSOP (DGK) 8 14.7 mm² 3 x 4.9 WSON (NGQ) 8 9 mm² 3 x 3
  • Wide 4.5V to 42V 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 0.9V
  • Precision ±2% Feedback Reference
  • Capable of 100% Duty Cycle Operation
  • Internal Soft-Start Timer
  • Integrated High Voltage Bias Regulator
  • Thermal Shutdown

All trademarks are the property of their respective owners.

  • Wide 4.5V to 42V 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 0.9V
  • Precision ±2% Feedback Reference
  • Capable of 100% Duty Cycle Operation
  • Internal Soft-Start Timer
  • Integrated High Voltage Bias Regulator
  • Thermal Shutdown

All trademarks are the property of their respective owners.

The LM25085A is a functional variant of the LM25085 COT PFET Buck Switching Controller. The functional differences of the LM25085A are: The feedback reference voltage is 0.9V, the forced off-time after current limit detection is longer, and the soft-start time is shorter (1.8 ms).

The LM25085A 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 4.5V to 42V input range. The constant on-time regulation principle requires no loop compensation, simplifies circuit implementation, and results in ultra-fast 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 LM25085A is a functional variant of the LM25085 COT PFET Buck Switching Controller. The functional differences of the LM25085A are: The feedback reference voltage is 0.9V, the forced off-time after current limit detection is longer, and the soft-start time is shorter (1.8 ms).

The LM25085A 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 4.5V to 42V input range. The constant on-time regulation principle requires no loop compensation, simplifies circuit implementation, and results in ultra-fast 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 42V Constant On-Time PFET Buck Switching Controller with 0.9V Reference datasheet (Rev. B) 06 Mar 2013
Selection guide Power Management Guide 2018 (Rev. R) 25 Jun 2018
Analog Design Journal Reduce buck-converter EMI and voltage stress by minimizing inductive parasitics 21 Jul 2016
EVM User's guide AN-1933 LM25085A Evaluation Board (Rev. B) 26 Apr 2013
Application note Constant Current Constant Voltage Buck Converter w/LM25085 (Rev. A) 23 Apr 2013

Design & development

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Evaluation board

LM25085AMYEEVAL — LM25085AMYEEVAL 42V Constant On-Time PFET Buck Switching Controller with 0.9V Reference

The LM25085AMYE evaluation board provides the design engineer with a fully functional buck regulator, employing the LM25085A PFET switching controller which uses the constant on-time (COT) operating principle. This evaluation board provides a 1V output over an input range of 4.5V to 24V. The (...)

User guide: PDF
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Simulation model

LM25085 PSpice Transient Model

SNVM302.ZIP (99 KB) - PSpice Model
Simulation model

LM25085 Unencrypted PSpice Transient Model

SNVMAF8.ZIP (3 KB) - PSpice Model
Calculation tool

LM25085AQUICK-CALC — LM25085A Quick Start Calculator

Package Pins CAD symbols, footprints & 3D models
HVSSOP (DGN) 8 Ultra Librarian
VSSOP (DGK) 8 Ultra Librarian
WSON (NGQ) 8 Ultra Librarian

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