3-20V, Voltage Mode Synchronous Buck Controller with Temperature-Compensated DCR Current Sensing - LM27403

LM27403 (ACTIVE)

3-20V, Voltage Mode Synchronous Buck Controller with Temperature-Compensated DCR Current Sensing


The LM27403 is a feature-rich, easy-to-use, synchronous buck controller offering exceptional levels of integration and performance for superior efficiency in high power density, point-of-load (POL) DC-DC regulator solutions. The resistor-programmable switching frequency from 200 kHz to 1.2 MHz and integrated, high-current MOSFET gate drivers with adaptive deadtime offer flexibility to optimize solution size and maximize conversion efficiency.

High precision and low output voltage are easily obtained with a 0.6-V, 1% accurate voltage reference together with a 30-ns high-side MOSFET minimum controllable on-time. Using lossless inductor dc resistance (DCR) current sensing and an inexpensive 2N3904 BJT to sense temperature remotely at the inductor, the LM27403 supports accurate and thermally compensated overcurrent protection (OCP).

The LM27403 has a conventional voltage-mode control loop with high gain-bandwidth error amplifier and PWM input voltage feedforward to simplify compensation design and enable excellent transient response throughout the full line voltage and load current ranges. Forced-PWM (FPWM) operation eliminates frequency variation to minimize EMI in sensitive applications. An open-drain Power Good circuit provides power-rail sequencing and fault reporting. Other features include programmable system-level thermal shutdown with automatic recovery, output voltage remote sense, configurable soft-start, monotonic start-up into prebiased loads, an integrated bias supply low-dropout (LDO) regulator, external power supply tracking, precision enable with customizable hysteresis for programmable line undervoltage lockout (UVLO), and synchronization capability for beat frequency sensitive and multiregulator applications. The LM27403 is offered in a 4-mm x 4-mm thermally enhanced WQFN-24 package with 0.5-mm pitch.


  • Up to 97% Efficiency and 93% Duty Cycle
  • Wide Input Voltage Range of 3 V to 20 V
  • Switching Frequency From 200 kHz to 1.2 MHz
  • Inductor-DCR-Based Overcurrent Protection With
    Thermal Compensation
  • 0.6-V Reference With 1% Feedback Accuracy
  • 30-ns Min On-Time for Low VOUT
  • Integrated High-Current MOSFET Drivers
    • Adaptive Deadtime Control
  • Ultrafast Line and Load Transient Response
    • High GBW Error Amplifier
    • PWM Line Feedforward
  • Integrated VDD Bias Supply LDO Subregulator
  • Programmable System-Level OTP
  • Precision Enable With Hysteresis
  • Frequency Synchronization
  • Monotonic Prebiased Start-up
  • Programmable Soft-Start With Tracking
  • Output Remote Sense
  • Open-Drain Power Good Indicator
  • 4-mm x 4-mm WQFN-24 PowerPAD™ Package

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Parametrics Compare all products in Step-Down (Buck) Controller

Vin (Min) (V)
Vin (Max) (V)
Vout (Min) (V)
Vout (Max) (V)
Iout (Max) (A)
Switching Frequency (Min) (kHz)
Switching Frequency (Max) (kHz)
Iq (Typ) (mA)
Duty Cycle (Max) (%)
Regulated Outputs (#)
Market Segment
Control Mode
Special Features
Operating Temperature Range (C)
Approx. Price (US$)
LM27403 LM27402
3     3    
20     20    
0.6     0.6    
19     18.6    
200     200    
1200     1200    
3.5     4.5    
93     95    
1     1    
Buck     Buck    
Communications & Telecom     Communications & Telecom
Computing & Multimedia    
Voltage Mode     Voltage Mode    
Frequency Synchronization
Power Good
Pre-Bias Start-Up
Synchronous Rectification
Frequency Synchronization
Power Good
Pre-Bias Start-Up
Synchronous Rectification
Catalog     Catalog    
-40 to 125     -40 to 125    
0.95 | 1ku     1.10 | 1ku    

Related end equipment

  • DC-DC Converters and POL Modules
  • Telecommunications Infrastructure
  • Embedded Computing, Servers, Storage

All trademarks are the property of their respective owners.

    Min   Max   Range  
  Vin V    3.00 – 20.00V  
  Vout V    0.60 – 18.60V  
  Iout A    ≤ 40A  
  Ambient Temp °C    -40 – 125°C  
Footprint BOM Cost Efficiency
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Companion parts

Part # Name Product Family Comments
LM10011   1% Accuracy 4/6-Bit VID Voltage Programmer for Point of Load Regulator w/ Adj Start-Up Current   POWER SUPPLY SUPPORT - FEEDBACK SIGNAL GENERATOR    6-Bit VID Control  
CSD87350Q5D   Synchronous Buck NexFET™ Power Block MOSFET Pair   POWER MOSFET - POWER MOSFET MODULE    Power MOSFET  
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