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N-channel depletion mode MOSFET

Depletion MOSFETs are in an on-state at zero voltage of gate-to-source (VGS), normally-on. This makes them a perfect constant current source.

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Overview

Infineon's range of depletion mode MOSFET switches offers fast switching and small and compact design. Infineon offers depletion MOSFETs in SOT-223 and SOT-23 packages, with breakdown voltages ranging from 60 V to 600 V. Together with a low negative voltage to turn off and a Strong Safe Operating Area, these products also offer the benefit of reduced design complexity.

Key Features

  • Available from 60 V up to 600 V
  • Higher efficiency and ruggedness
  • Wide operating range available
  • Fast switching and compact design

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About

N-Channel Depletion mode MOSFET features

For a MOSFET, the gate-to-source voltage (VGS) should be higher than the gate-to-source threshold voltage (VGS(th)) in order to conduct current through it. For an N-channel enhancement MOSFET, VGS(th) is above 0 V. Therefore, even at VGS?of 0 V, a Depletion mode MOSFET can conduct current. To turn off a Depletion-mode MOSFET, the VGS?should be lower than the (negative) VGS. The N-channel Depletion mode MOSFET operation results in a load current independent of the applied drain-to-source input voltage. These N-channel Depletion MOSFET characteristics are ideal for power supply startup power, overvoltage protection, in-rush-current limiter, and offline voltage reference applications.

One important parameter when selecting a Depletion-mode MOSFET is the minimum drain current when the gate voltage is zero. Because the Depletion MOSFET is used as a current source, the minimum current capability of a gate voltage of 0 V is necessary to design the Depletion-mode MOSFET circuit for the required current levels. Infineon¡¯s range of N-channel Depletion-mode MOSFETs are available with the VGS?indicator on the reel, and are RoHS compliant as well as qualified according to AEC Q101.

NMOS Depletion-mode conduction

NMOS Depletion-mode MOSFETs use electrons as the current carrier allowing conduction if there is a positive charge. On the other hand, PMOS MOSFETs use holes, so a negative charge attracts positively charged holes to the channel allowing it to conduct. However, NMOS Depletion mode is activated when using a negative voltage to repel the free carriers so the Depletion device can no longer conduct. This is how to turn off a Depletion-mode MOSFET.

Automotive applications

All N-channel Depletion MOSFET products are suitable for automotive applications. In order to meet special requirements, N-channel Depletion mode MOSFETs are available with VGS(th) indicator on reel.

Industrial applications

Areas of Depletion-mode MOSFET applications include power supply startup power, overvoltage protection, in-rush-current limiter, and offline voltage reference. With one single component, it is possible to realize a simple current regulator.

N-Channel Depletion mode MOSFET features

For a MOSFET, the gate-to-source voltage (VGS) should be higher than the gate-to-source threshold voltage (VGS(th)) in order to conduct current through it. For an N-channel enhancement MOSFET, VGS(th) is above 0 V. Therefore, even at VGS?of 0 V, a Depletion mode MOSFET can conduct current. To turn off a Depletion-mode MOSFET, the VGS?should be lower than the (negative) VGS. The N-channel Depletion mode MOSFET operation results in a load current independent of the applied drain-to-source input voltage. These N-channel Depletion MOSFET characteristics are ideal for power supply startup power, overvoltage protection, in-rush-current limiter, and offline voltage reference applications.

One important parameter when selecting a Depletion-mode MOSFET is the minimum drain current when the gate voltage is zero. Because the Depletion MOSFET is used as a current source, the minimum current capability of a gate voltage of 0 V is necessary to design the Depletion-mode MOSFET circuit for the required current levels. Infineon¡¯s range of N-channel Depletion-mode MOSFETs are available with the VGS?indicator on the reel, and are RoHS compliant as well as qualified according to AEC Q101.

NMOS Depletion-mode conduction

NMOS Depletion-mode MOSFETs use electrons as the current carrier allowing conduction if there is a positive charge. On the other hand, PMOS MOSFETs use holes, so a negative charge attracts positively charged holes to the channel allowing it to conduct. However, NMOS Depletion mode is activated when using a negative voltage to repel the free carriers so the Depletion device can no longer conduct. This is how to turn off a Depletion-mode MOSFET.

Automotive applications

All N-channel Depletion MOSFET products are suitable for automotive applications. In order to meet special requirements, N-channel Depletion mode MOSFETs are available with VGS(th) indicator on reel.

Industrial applications

Areas of Depletion-mode MOSFET applications include power supply startup power, overvoltage protection, in-rush-current limiter, and offline voltage reference. With one single component, it is possible to realize a simple current regulator.

Documents

Documents

Design resources

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