D4184 Mosfet

Description

General Description The AOD4185/AOI4185 uses advanced trench technology to provide excellent RDS(ON) and low gate charge. With the excellent thermal resistance of the DPAK/IPAK package, this device is well suited for high current applications.

This MOSFET module with optoisolation uses the D4184 N-Channel logic compatible MOSFET with low Rds(on) for moderate to higher current low-side switching applications.

PACKAGE INCLUDES:

D4184 MOSFET Control Module
3-pin Screw Terminal
2-pin Screw Terminal
Small male header strip

N-Channel 40-V (D-S) MOSFET V DS (V) I D (A) 53 49 Symbol Limit Units V DS 40 V GS ±20 Continuous Drain Current a T A =25°C I D 53 I DM 200 I S 44 A Power Dissipation a T A =25°C P D 50 W T J, T stg-55 to 150 °C Symbol Maximum Units RθJA 40 RθJC 3 Notes a. Surface Mounted on 1” x 1” FR4 Board. Pulse width limited by maximum.
MOSFET – Power, Single, P-Channel, Schottky Diode, Schottky Barrier Diode-30 V, -4.0 A, 20 V, 2.2A NTMD4184PF Features. FETKY Surface Mount Package Saves Board Space. Independent Pin−Out for MOSFET and Schottky Allowing for Design Flexibility. Low RDS(on) MOSFET and Low VF Schottky to Minimize Conduction Losses.

KEY FEATURES OF D4184 MOSFET CONTROL MODULE:

One switching output
Low 8.5mΩ Rds(on) resistance
2.5V – 20V input control voltage with optoisolation
6 – 36V output switching voltage
10A continuous current handling capability (See notes below)
3.3 and 5V logic compatible (See notes below)

The modules utilizes the D4184 N-channel MOSFET that has a low Rds(on) resistance of 8.5mΩ typical.

These modules support about 10A of continuous current with a load voltage of 12V. If driven with PWM, the maximum peak current can be greater up to 20A or more.

The design of these modules includes an optoisolator on the input so the input is biased from the output load voltage and is independent of logic levels used for the drive signal. A 3.3V input will drive as much current as a 5V input for instance.

Note that the module does not have a fly-back diode on the board. If using the module with inductive loads, an external fly-back diode should be used to avoid possible damage.

Theory of Operation

The module includes a PC817 optoisolator which provides electrical isolation between the high powered MOSFET side and the logic signals used to control the module. If something goes wrong and you burn up the MOSFET, it should not damage the MCU being used to control it.

The MCU PWM input to the module drives the internal LED side of the optoisolator. This input includes a 1K ohm series current limiting resistor to keep the current through the LED at safe levels which allows the input to be driven by up to a 20V input or even higher if you are not using an MCU.

When the PWM input signal is low or disconnected, the internal LED in the optoisolator is off which in turn keeps the phototransistor output turned off. With the phototransistor off, the gate of the MOSFET is pulled to ground by a 4.7K resistor. This keeps the MOSFET turned off and the load is disconnected from ground and disbled.

A logic high on the PWM input turns on the internal optoisolator LED which turns on the phototransistor. This creates a voltage divider composed primarily of two 4.7K resistors. This biases the gate at 50% of the power supply voltage which turns on the MOSFET. If a 12V power supply is used, the gate will be at 6V.

Since the maximum gate voltage available to turn on the MOSFET is 50% of the power supply voltage, that limits the power supply to a minimum of about 6V. Power dissipation in the MOSFET will be higher with lower power supply voltages and a minimum power supply of 9V is recommended if trying to draw more than a few amps through the module.

When the MOSFET conducts, the load is connected to ground to complete the circuit and the load is powered up. This also provides a ground for the on-board LED which lights to indicate that the MOSFET is turned on. A 4.7K resistor limits current through the on-board LED to safe levels over the 6-36V operating range.

Module Connections

The module requires 3 connections. A logic signal to turn the MOSFET on/off; a DC power supply to power the device (load) being controlled and finally the load itself. Connectors are provided that can be soldered to be the board, but these connections can also be made by direct wiring if desired.

Logic Signal Connections: The 2-pin connector on the right side is for making connections to the MCU. It has two holes on 4mm centers which support a 2 position screw terminal as well as two holes on 0.1″ centers that can alternatively support a standard male header which may be handy in a breadboard setup. The pins are labeled PWM for the signal and GND for the signal ground.

DC Load Power Supply: is connected to the 3-pin screw terminals marked + / LOAD / – on the back of the module. The positive lead of the power supply connects to + and the ground connection is hooked up to –. The module supports a load power supply of 6-36VDC

Load: The load which is being driven is connected to the screw terminals marked + and Load on the back of the module. The positive lead of the load connects to the + terminal and the negative lead of the load connects to – terminal.

The signal ground and the load ground connections are not connected together on the module due to the optoisolator being used to provide isolation between the MOSFET power circuit and the MCU.

1 x 2 Screw Terminal / Header (Logic Signal Input)

PWM = Signal input (active HIGH).
GND = Signal ground

1 x 3 Screw Terminal (Load Power Supply Connections)

+ = Connect to power supply (6-36V) being used to power the load
– = Connect to power supply ground

1 x 3 Screw Terminal (Load Connections)

+ = Connect to positive lead of load (motor, LEDs, fan, etc)
LOAD = Connect to negative lead of load

Physical Mounting: There are two 2mm diameter holes at the signal end of the board spaced 12mm apart if it is desired to physically mount it.

OUR EVALUATION RESULTS:

These modules work well for basic ON/OFF operation such as for driving a solenoid or PWM control such as for dimming an array of LEDs and can handle a surprising amount of power given the small size. It is also possible to parallel these modules to further increase the power handling capability. Though the maximum current spec for the MOSFET is 50A, do not expect to run 50A through this small module as it will quickly overheat due to minimal heatsink capability of the small PCB.

One important point to take note of is that if an inductive load is being controlled, an external fly-back diode should be used to prevent possible damage when the load is switched off.

The chart to the right from the datasheet shows the effect of the drive (Gate) voltage on the maximum potential current through the MOSFET device. Since the gate is driven off the load power supply at a 50% level, for a 10V power supply, the current handling will be similar to the 5V curve.

The chart below shows some example temperature measurements of the MOSFET with a load varying from 2.5A to 20A @ 12V. The logic drive signal varies from 100% duty cycle (always on) to 50% duty cycle or 25% duty cycle. The measurements are being taken with no airflow over the module and an ambient temperature of 22C. Since a 12V power supply is being used, the gate voltage is around 6V which gives pretty good performance.

In general, you should keep the MOSFET under about 100°C to keep it happy. For long-term use, 80°C or lower would be a better target.

Load Amps	12V Input @ 100% duty cycle	12V Input @ 50% duty cycle	12V Input @ 25% duty cycle
2.5A	32°C
5A	39°C	30°C
10A	69°C	47°C
12.5A	102°C	63°C	43°C
15A	X	78°C	48°C
20A	X	115°C+	74°C

Aod4148

BEFORE THEY ARE SHIPPED, THESE MODULES ARE:

Sample tested per incoming shipment

Notes:

None

Technical Specifications

Maximum Ratings
V_DS	Drain-Source Voltage	40V max (36V recommended)
I_D	Drain Current Max (Continuous)	10A @ 12V
R_DS(on)	Drain-Source On-Resistance	8.5mΩ
Dimensions	(L x W x H)	35 x 16 x 14mm (1.38 x 0.63 x 0.55″)
Datasheet	AOD4184

Power MOSFET

The Power MOSFET is a type of MOSFET. The operating principle of power MOSFET is similar to the general MOSFET. The power MOSFETS are very special to handle the high level of powers. It shows the high switching speed and by comparing with the normal MOSFET, the power MOSFET will work better. The power MOSFETs is widely used in the n-channel enhancement mode, p-channel enhancement mode, and in the nature of n-channel depletion mode. Here we have explained about the N-channel power MOSFET. The design of power MOSFET was made by using the CMOS technology and also used for development of manufacturing the integrated circuits in the 1970s.

What is a Power MOSFET?

A power MOSFET is a special type of metal oxide semiconductor field effect transistor. It is specially designed to handle high-level powers. The power MOSFET’s are constructed in a V configuration. Therefore, it is also called as V-MOSFET, VFET. The symbols of N- channel & P- channel power MOSFET are shown in the below figure.

Basic Statures of Power MOSFET

There is three basic status in the power MOSFET which is following.

On sate resistance
Breakdown voltage
Body diode

On State Resistance

If the power MOSFET is in ON sate, then it produces the resistive behavior in-between the drain & source terminals. We can see in the following figure, that the resistance is the sum of many elementary contributions. The RS resistance is the source resistance. It will show all resistance between the source terminals of the package to the channel of the MOSFET.

The Rch resistance is the channel resistance and this resistance is inversely proportional to the channel width & for a given die size, to the channel density. This resistance is very important contributors to the RDSon of the low voltage MOSFET. The intensive work has done to reduce their cell size with respect to increase the channel density.

The access resistance is represented by the Ra. The access resistance shows the resistance of the epitaxial zone directly to the gate electrode. The current direction is changed from the channel to the vertical.

RJFET is the detrimental effect of the cell size reduction. The P implantation is observed from the gate of a parasitic JFET transistor and it has reduced the width of the current flow.

Rn represents the epitaxial layer and it is used for sustaining the blocking voltage. This resistance is directly related to the voltage rating of the device. The high voltage MOSFET requires a thick low dependent layer which is highly resistive and a low voltage transistor requires a thin layer with the higher doping layer which is very less resistive. This is the main factor for the resistance of high voltage MOSFET.

The RD resistance is the equivalent of resistance of the RS for the drain. The RD resistance, represent the transistor substrate and the package connections.

Break Down Voltage

The power MOSFET is equivalent to the PIN diode, if it is in the OFF state and it is initiated by the P+ diffusion, the N- epitaxial layer and the N+ substrate. This structure is reverse biased when it is highly nonsymmetrical structure and the space charge region extends principally to the lightly doped side, which is the N- layers.

Even though, when the MOSFET is in the ON state, there is a no function of the N- layers. Moreover, it is lightly doped rejoin, intrinsic resistivity is non-negligible and it is added to the MOSFET ON- state drain to source resistance.

There are two important parameters to run both the breakdown voltage and the RDSon of the transistor, which is the doping level and the thickness of the N- epitaxial layer. If the layer is thicker, it has low doping level and the breakdown voltage is high. Similarly, thicker the layer, it has the high doping level and the radon is low. Hence we can observe that there is a trade-off in the design of the MOSFET, between the voltage rating and the ON state resistance.

Body Diode

The body diode can be seen in the following figure that the source metallization is connected to both the N+ and P implantations. Even though the basic principle of the MOSFET requires only that the source should be connected to the N+ zone. Thus, this would result in a floating P zone between the N-doped source and drain. It is equivalent to an NPN transistor with a nonconnected base. Under some conditions like high drain current, in the order of the same volts of an on-state drain to source voltage, this parasitic transistor of NPN should be triggered and make the MOSFET uncontrollable.

The connections of the P implantation to the source metallization short the base terminal of the transistor parasitic to its emitter and it prevents the latching. Hence this solution creates a diode between the cathode & anode of the MOSFET and the current blocks in one direction.

For inductive loads, the body diodes utilize the freewheeling diodes in the configuration of H Bridge & half bridge. Generally, these diodes will have a high forward voltage drop, the current is high. They are sufficient in many applications like reducing part count.

Working of Power MOSFET and Characteristics

The construction of the power MOSFET is in V-configurations, as we can see in the following figure. Thus the device is also called as the V-MOSFET or V-FET. The V- the shape of power MOSFET is cut to penetrate from the device surface is almost to the N+ substrate to the N+, P, and N – layers. The N+ layer is the heavily doped layer with a low resistive material and the N- layer is a lightly doped layer with the high resistance region.

Both the horizontal and the V cut surface are covered by the silicon dioxide dielectric layer and the insulated gate metal film is deposited on the SiO2 in the V shape. The source terminal contacts with the both N+ and P- layers through the SiO2 layer. The drain terminal of this device is N+.

The V-MOSFET is an E-mode FET and there is no exists of the channel in between the drain & source till the gate is positive with respect to the source. If we consider the gate is positive with respect to the source, then there is a formation of the N-type channel which is close to the gate and it is in the case of the E-MOSFET. In the case of E-MOSFET, the N-type channel provides the vertical path for the charge carriers. To flow between the drain and source terminals. If the VGS is zero or negative, then there is no channel of presence and the drain current is zero.

D41A

The following figures show the drain & transfer characteristics for the enhancement mode of N-channel power MOSFET is similar to the E-MOSFET. If there is an increase in the gate voltage then the channel resistance is reduced, therefore the drain current ID is increased. Hence the drain current ID is controlled by the gate voltage control. So that for a given level of VGS, ID is remaining constant through a wide range of VDS levels.

The channel length of the power MOSFET is in the diffusion process, but in the MOSFET the channel length is in the dimensions of the photographic masks employed in the diffusion process. By controlling the doping density and diffusion time, the channel length will become shorter. The shorter channels will give, the more current densities which will contribute again to larger power dissipation. It also allows a larger transconductance gm to be attained in the V-FET.

In the geometry of power MOSFET, there is an important factor which is the presence of lightly doped, N- epitaxial layer which is close to the N+ substrate. If the VGS is at zero or negative, then the drain is positive with respect to the source and there is a reverse biased between the P- layer & N- layer. At the junction the depletion region penetrates into the N- layer, therefore it punch-through the drain to the source are avoided. Hence, relatively high VDS are applied without any danger of device breakdown.

In the power MOSFET, there is available of P-channel. The characteristics are similar to the N-channel MOSFET. The direction of the current and voltage polarities are in reverse direction.

MOSFET Power Amplifier

There are different types of MOSFET power amplifiers like 300W MOSFET power amplifier, 240W MOSFET power amplifier, 160W MOSFET power amplifier and 100W MOSFET power MOSFET amplifier. But here we are explaining about the 100W MOSFET power amplifier with its circuit.

100W MOSFET Power Amplifier Circuit Operation

The circuit operation of 100w MOSFET amplifier consists of PNP transistor from the differential amplifier circuit. The AC input signal is sent to one of the transistors and the other transistor gets the output signal from the feedback. The AC signal is a coupled to the base terminal of the transistor Q1 with the help of the coupling capacitor and the feedback signal. The feedback signal is fed into the base terminal of the second transistor Q2 with the help of resistor R5 & R6. The potentiometer is used to set the output of the amplifier.

D4184 MOSFET Control Module - ProtoSupplies

The first stage differential output amplifier is fed to the second stage differential amplifier input. In the case of the first differential amplifier, when the input voltage is more than the feedback voltage than the input voltage of the two transistors Q3 and Q4 of second differential amplifier differs from each other. The current mirror circuit of the transistors is Q5 & Q6. This circuit ensures the flowing of output current in the push-pull amplifier circuit is constant.

Thus, this circuit can be achieved because, when the collector current of transistor Q3 is increased, the collector current of Q4 decreases is to maintain the flow of constant current through the universal point of the emitter terminal of the transistors Q3 &Q4. There is an equal output current in between the current mirror circuit & collector current of the Q3 transistor. The potentiometer R12 protects the applications of DC biasing to each MOSFET because the two MOSFETs are in the balancing to each other.

If the positive voltage is applied to the gate terminal of the Q7 transistor then it will conduct. Correspondingly transistor Q8 will conduct for the negative threshold voltage. To prevent the MOSFET output from the oscillating the gate resistors are used.

Applications of Power MOSFET

The power MOSFET’s are used in the power supplies

D4184 Mosfet

DC to DC converters
Low voltage motor controllers
These are widely used in the low voltage switches which are less than the 200V

MOSFET – Power, Single, P-Channel, Schottky Diode, Schottky ...

This article will give the information on the working principle of power MOSFET circuit and its applications. We hope by reading this article you have gained some basic knowledge and understanding about the power MOSFET. Here is the question for you, what are the functions of the power MOSFET?