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.
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.
