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


Product details


Vin (Min) (V) 4.5 Vin (Max) (V) 42 Vout (Min) (V) 1.25 Vout (Max) (V) 42 Iout (Max) (A) 10 Iq (Typ) (mA) 1.25 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 open-in-new Find other Buck controllers (external switch)

Package | Pins | Size

HVSSOP (DGN) 8 15 mm² 3 x 4.9 VSSOP (DGK) 8 15 mm² 3 x 4.9 WSON (NGQ) 8 9 mm² 3 x 3 open-in-new Find other Buck controllers (external switch)


  • LM25085-Q1 is an Automotive Grade product that is
    AEC-Q100 Grade 1 Qualified (–40°C to 125°C
    Operating Junction Temperature)
  • 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 1.25V
  • Precision ±2% Feedback Reference
  • Capable of 100% Duty Cycle Operation
  • Internal Soft-Start Timer
  • Integrated High Voltage Bias Regulator
  • Thermal Shutdown
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The LM25085 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

Design & development

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Hardware development

document-generic User guide

The LM25085 evaluation board provides the design engineer with a fully functional buck regulator, employing the LM25085 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 42V. The circuit (...)

Design tools & simulation

SNVM302.ZIP (99 KB) - PSpice Model
SNVMAF8.ZIP (3 KB) - PSpice Model
LM(2)5085 Quick Start Calculator

CAD/CAE symbols

Package Pins Download
HVSSOP (DGN) 8 View options
VSSOP (DGK) 8 View options
WSON (NGQ) 8 View options

Ordering & quality

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