LM27402 (ACTIVE)

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

3-20V, Voltage Mode Synchronous Buck Controller with DCR Current Sensing - LM27402


The LM27402 is a voltage-mode, synchronous, DC-DC step-down controller with lossless inductor DCR current sensing capability. Sensing the inductor current eliminates the need to add resistive powertrain elements, which increases overall efficiency and facilitates accurate, continuous current sensing. A 0.6-V ±1% voltage reference enables high accuracy and low voltage capability at the output. An input operating voltage range of 3 V to 20 V makes the LM27402 suitable for a large variety of input rails.

The LM27402 voltage-mode control loop incorporates input voltage feed-forward to maintain stability throughout the entire input voltage range. The switching frequency is adjustable from 200 kHz to 1.2 MHz. Dual, high-current, integrated MOSFET drivers support large QG, low RDS(on) power MOSFETs. A power good indicator provides power rail sequencing capability and output fault detection. An adjustable external soft-start limits inrush current and provides monotonic output control during start-up. Other features include external tracking of other power supplies, integrated LDO bias supply, and synchronization capability.


  • Wide Input Voltage Range of 3 V to 20 V
  • Inductor DCR or Shunt Resistor Based
    Overcurrent Protection
  • 0.6-V Reference With ±1% FB Accuracy Across
    Full –40°C to 125°C Junction Temperature Range
  • Switching Frequency from 200 kHz to 1.2 MHz
  • Output Voltage as High as 95% of Input Voltage
  • Integrated High-Current MOSFET Drivers
  • Internal VDD Bias Supply LDO Subregulator
  • External Clock Synchronization
  • Adjustable Soft-Start With External Capacitor
  • Pre-Biased Start-up Capability
  • Power Supply Tracking
  • Voltage-Mode Control With Line Feedforward
  • Open-Drain Power Good Indicator
  • Precision Enable With Hysteresis
  • HTSSOP-16 and WQFN-16 Packages

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Parametrics Compare all products in Buck Controller (External Switch)

Vin (Min) (V)
Vin (Max) (V)
Vout (Min) (V)
Vout (Max) (V)
Iout (Max) (A)
Regulated Outputs (#)
Number of Phases
Switching Frequency (Min) (kHz)
Switching Frequency (Max) (kHz)
Iq (Typ) (mA)
Duty Cycle (Max) (%)
Operating Temperature Range (C)
Package Group
Control Mode
LM27402 LM27403 LM2748
3    3    1   
20    20    14   
0.6    0.6    0.6   
18.6    19    12   
30    30    20   
1    1    1   
1    1    1   
200    200    50   
1200    1200    1000   
4.5    3.5    1.7   
Frequency Synchronization
Power Good
Pre-Bias Start-Up
Synchronous Rectification
Frequency Synchronization
Power Good
Pre-Bias Start-Up
Remote Sense
Synchronous Rectification
Power Good
Synchronous Rectification
95    93    86   
-40 to 125    -40 to 125    -40 to 125   
Catalog    Catalog    Catalog   
Voltage Mode    Voltage Mode    Voltage Mode   
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WEBENCH® Designer LM27402

  Min   Max Range
Vin  V 3.0 to 20.0V
Vout  V 0.6 to 18.6V
Iout  A ≤ 30A
Ambient Temp  °C -40 to 125°C

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