Contact us

A new window will open A new window will open

Case 2: Selection of a MOSFET to increase the withstand voltage margin: Power supply product
Keywords: 45-V MOSFET, latest MOSFET, low RDS(ON), low Qoss, power supply development


Voltage surge transients exceeded the available margin.
There seemed no alternative but to place an order for a MOSFET with custom specifications...
45-V devices in the U-MOSIX-H series that meet your requirements for “a little more voltage margin”

Product Overview

U-MOSIX-H series available with five VDSS points: 30 V, 40 V, 45 V, 60 V and 100 V


  • Industry’s best trade-off between on-resistance and output charge*1
  • Low output loss due to low QOSS*2
  • Extensive product lineup

*1  As of November 2017 for MOSEFTs with equivalent ratings (as surveyed by Toshiba)
*2  QOSS: Output charge

Problem-Solving Examples

Solution for Company F, an industrial equipment manufacturer (Employee population: 1,500)

Company F was developing a new power supply product, applying a 20% derating factor to the in-house specification requirements. At first, its design team used typical 40-V MOSFETs for the power supply unit with a 12-V output. The 20% derating means that the maximum allowable voltage for the 40-V MOSFETs is 32 V . An evaluation indicated, however, that the power supply unit could generate voltage surge transients as high as 34 V, i.e., 2 V higher than the maximum allowable voltage.
The design could not be modified in such a manner as to keep surge voltage below 32 V because doing so caused the circuit’s switching speed to become too slow. In contrast, using 60-V MOSFETs, for example, was inconceivable because of high on-resistance. Another alternative was to place an order for a customized MOSFET rated at 43 V, but it was unjustifiable in terms of cost.
Company F faced a tough decision of whether to use standard MOSFETs or order customized MOSFETs.

Solving the dilemma with Toshiba’s latest U-MOSIX-H series

It was just at that time when F’s engineer heard about Toshiba’s MOSFET from an agent. In addition to 30-V and 40-V MOSFETs, 45-V MOSFETs are available in Toshiba’ latest U-MOSIX-H series.

Latest U-MOSVIX-H Series

Latest U-MOSVIX-H Series
Features of U-MOSIX-H (VDSS = 40 V)

  • Industry’s lowest-class RDS(ON):
    RDS(ON)*3=0.65mΩ typical (VGS=10V)

  • Low output loss due to low QQSS:
    RDS(ON) × QOSS = 56mΩ・nC(VDS=20V)

  • Guaranteed up to a channel temperature (Tch) of 175°C

*3 RDS(ON): Drain-source on-resistance

Toshiba’s 45-V MOSFETs of the U-MOSIX-H series, which have the same size and footprint as 40-V MOSFETs, serve as an easy replacement for 40-V MOSFETs. In addition, the 45-V MOSFETs have an on-resistance, RDS(ON), close to that of the 40-V MOSFETs. Therefore, when derated by 20%, the 45-V MOSFETs tolerate surge transients of up to 36 V.
By using Toshiba’s 45-V MOSFETs of the U-MOSIX-H series, Company F met the customer requirements and managed to deliver a power supply unit to the customer.

List of Problem-Solving Examples

Case 1: Selection of a MOSFET to meet power supply specifications: DC-DC converter

Low-voltage MOSFET, Qoss reduction, low on-resistance, double-sided-cooling package, reducing the size of a DC-DC converter

Case 3: Selection of a MOSFET to improve the efficiency of a server power supply

High-voltage MOSFET, super-junction MOSFET, standard switching speed, high switching speed, high-speed diode

Case 4: EMI noise solutions based on the results of simulation

EMI noise problem, documents on the resolution of EMI problems, causes of gate oscillation, maintaining high efficiency, development of a new product 

Case 5: Using a photocoupler to solve a problem of an industrial robot caused by overcurrent

Photocoupler for IGBT/MOSFET drive, optical isolation, alleviating an overcurrent problem, design support by specialized engineers

Case 6: Using a solid-state relay to reduce the size and prolong the service life of power supply units for Programmable Logic Controller

Reducing the size of a control relay unit, semiconductor, long service life, board size reduction, countermeasure for the effects of magnetic fields 


If you have any questions, click one of these links:

Technical queries
Questions about purchasing, sampling and IC reliability
To Top
·Before creating and producing designs and using, customers must also refer to and comply with the latest versions of all relevant TOSHIBA information and the instructions for the application that Product will be used with or for.