Synchronous-Rectified Buck MOSFET Drivers


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The RT9618/A are high frequency, dual MOSFET drivers specifically designed to drive two power N-MOSFETs in a synchronous-rectified buck converter topology. The drivers combined with Richtek's series of Multi-Phase Buck PWM controller form a complete core-voltage regulator solution for advanced micro-processors.
The RT9618/A drive both the lower/upper gate in a synchronous-rectifier bridge with 12V. This drive-voltage flexibility provides the advantage of optimizing applications involving trade-offs between switching losses and conduction losses.
RT9618A has longer UGATE/LGATE deadtime which can drive the MOSFETs with large gate RC value, avoiding the shoot-through phenomenon. RT9618 is targeted to drive low gate RC MOSFETs and performs better efficiency.
The output drivers in the RT9618/A can efficiently switch power MOSFETs at frequency up to 500kHz. Switching frequency above 500kHz has to take into account the thermal dissipation of the packages. RT9618/A are capable to drive a 3nF load with a 30ns rise time. RT9618/A implements bootstrapping on the upper gate with an external capacitor and an embedded diode. This reduces implementation complexity and allows the use of higher performance, cost effective N-MOSFETs. Adaptive shoot-through protection is integrated to prevent both MOSFETs from conducting simultaneously.


  • Core Voltage Supplies for Desktop, Motherboard CPU
  • High Frequency Low Profile DC-DC Converters
  • High Current Low Voltage DC-DC Converters
Key Spec.
RT9618 RT9618A
Recommended Alternative  RT9624B RT9624B
Number of Channels 1 1
Vcc (typ) (V) 12 12
UGATE Rise Time (typ) (ns) 27 27
UGATE Fall Time (typ) (ns) 32 32
LGATE Rise Time (typ) (ns) 35 35
LGATE Fall Time (typ) (ns) 27 27
UGATE Source Resistance (typ) (Ohm) 1.9 1.9
UGATE Sink Resistance (typ) (Ohm) 1.4 1.4
LGATE Source Resistance (typ) (Ohm) 1.9 1.9
LGATE Sink Resistance (typ) (Ohm) 1.1 1.1
Disable Pin Yes Yes
Built-In Bootstrap Diode Yes Yes
Iq (typ) (mA) 1 1
Features Tri-State Input Tri-State Input
Package Type WDFN3x3-8E;SOP-8 WDFN3x3-8E;SOP-8
  • Drives Two N-MOSFETs
  • Adaptive Shoot-Through Protection
  • Embedded Boot Strapped Diode
  • Support High Switching Frequency
  • Fast Output Rise Time
  • Small SOP-8 and 8-Lead WDFN Package
  • Tri-State Input for Bridge Shutdown
  • Supply Under Voltage Protection
  • Upper MOSFET Direct Shorted Protection
  • RoHS Compliant and 100% Lead (Pb)-Free
Title Last Update ShareDownload
Synchronous-Rectified Buck MOSFET Drivers 2015/05/19