LM25117

(ACTIVE) 4.5-42V Wide Vin, Current Mode Synchronous Buck Controller with Tracking

Diagrams

Functional Diagram

Typical Application

Typical Performance

Description

The LM25117 is a synchronous buck controller intended for step-down regulator applications from a high voltage or widely varying input supply. The control method is based upon current mode control utilizing an emulated current ramp. Current mode control provides inherent line feed-forward, cycle-by-cycle current limiting and ease of loop compensation. The use of an emulated control ramp reduces noise sensitivity of the pulse-width modulation circuit, allowing reliable control of very small duty cycles necessary in high input voltage applications.

The operating frequency is programmable from 50 kHz to 750 kHz. The LM25117 drives external high-side and low-side NMOS power switches with adaptive dead-time control. A user-selectable diode emulation mode enables discontinuous mode operation for improved efficiency at light load conditions. A high voltage bias regulator that allows external bias supply further improves efficiency. The LM25117’s unique analog telemetry feature provides average output current information. Additional features include thermal shutdown, frequency synchronization, hiccup mode current limit and adjustable line undervoltage lockout.

Features

  • LM25117-Q1 is Qualified for Automotive Applications
  • AEC-Q100 Qualified With the Following Results:
    • Device Temperature Grade 1: -40°C to 125°C Ambient Operating Temperature Range
  • Emulated Peak Current Mode Control
  • Wide Operating Range from 4.5 V to 42 V
  • Robust 3.3 A Peak Gate Drives
  • Adaptive Dead-time Output Driver Control
  • Free-run or Synchronizable Clock up to 750 kHz
  • Optional Diode Emulation Mode
  • Programmable Output from 0.8 V
  • Precision 1.5% Voltage Reference
  • Analog Current Monitor
  • Programmable Current Limit
  • Hiccup Mode Over Current Protection
  • Programmable Soft-start and Tracking
  • Programmable Line Undervoltage Lockout
  • Programmable Switch-over to External Bias Supply
  • Thermal Shutdown

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Parametrics

Vin (Min) (V) 4.5    
Vin (Max) (V) 42    
Vout (Min) (V) 0.8    
Vout (Max) (V) 41    
Iout (Max) (A) 20    
Regulated Outputs (#) 1    
Number of Phases 1    
Switching Frequency (Min) (kHz) 50    
Switching Frequency (Max) (kHz) 750    
Iq (Typ) (mA) 4.8    
Features Adjustable Current Limit^Enable^Frequency Synchronization^Light Load Efficiency^Synchronous Rectification^Tracking^UVLO Adjustable    
Duty Cycle (Max) (%) 98    
Operating Temperature Range (C) -40 to 125    
Rating Catalog    
Package Group HTSSOP^WQFN    
Control Mode Current Mode    

Companion Products

Technical Documents

Datasheet (1)

Application notes (4)

User guides (2)

Selection guides (3)

White papers (2)

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