N-Channel Depletion Mode MOSFET
The features of a single current regulator in one component
Infineon is one of the few semiconductor manufacturers worldwide to offer N-channel depletion mode MOSFETs. Compared to enhancement mode transistors, known as normally-off, depletion MOSFETs are in an on-state at zero voltage of gate-to-source (VGS), normally-on. This makes N-channel depletion MOSFETs a perfect constant current source.
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 type MOSFET can conduct current. To turn off a depletion-mode MOSFET the VGS should be lower than the (negative) VGS(th). The N-channel depletion mode MOSFET operations 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, over-voltage protection, in-rush-current limiter, and off-line 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, a 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 MOSFET are available with VGS(th) indicator on the reel, and are RoHS compliant as well as qualified according to AEC Q101.
Explore Infineon’s range of depletion mode MOSFETs and discover which N-channel depletion type MOSFET characteristics will best fit your requirements.
N-channel depletion mode MOSFET portfolio
Infineon’s range of N-channel depletion mode MOSFETs are available in voltages from 60 V up to 600 V. Thanks to the depletion type MOSFET's special characteristics, it provides higher efficiency and ruggedness as well as a wider operating range for SMPS and LED lighting. A depletion power MOSFET can also be used as a voltage regulator.
NMOS depletion mode MOSFETs use electrons as the current carrier allowing conduction if there is a positive charge. PMOS MOSFETs on the other hand 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.
Infineon’s range of depletion mode MOSFET switches offer fast switching and small and compact design.
N-channel depletion mode MOSFET applications
Areas of depletion MOSFET application include power supply startup power, over-voltage protection, in-rush-current limiter, and off-line voltage reference. With one single component it is possible to realize a simple current regulator.