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Question regarding Orientation of P-Mosfet in Arduino/Microcrontrollers
I was wondering why in the Arduino schematic, and other microcontroller schematics, the P-Mosfet is connected such that the Drain is to the USB while the Source is to the input of the LDO, and not the...
View ArticleDiscrete MOSFET driver control IC
I am building a Marx bank, which consists of multiple MOSFETs connected in parallel when charging and in series when discharging. I have each stage of the pulse generator designed, including isolated...
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PFET to turn on/off system power
I have a Raspberry PI board connected to some external circuitry, and am using Microchip MCP23008 I2C GPIO expander chips to control external LEDs and motor circuitry. One important part of this...
View ArticleWhat happpens to the Vgs in the Miller plateau region during MOSFET turn-ON?
During my mosfet switching power dissipation I went through the Vgs curves of the MOSFET during its turn-ON state.Here i found that the Vgs curve remains flat during the miller plateau region. Why is...
View Articlepicking the right Vgs th based on VOH and VOL
My microcontroller has a VOH min of 2.4V and a VOL max of 0.4V. How do I spec the right Vgs th for a transistor switch? At first I thought, aim for the middle and go 1.5V. But then I was thinking about...
View ArticleMOSFET source to drain Current
Similar kinds of questions have been asked before it but they don’t clarify how one can use this aspect in circuit. I’m aware that a MOSFET is a bidirectional device and in one direction current can...
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Bi-directional High-side NFET switches — drains or sources connected together?
TL;DR: When using two N-FETs to implement a high-side switch should the FETs be arranged so the drains are connected together, or the sources? Some additional facts about the current design: 1) A boost...
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DC current amplification
i’m trying to design a battery charger for 5Ah li-ion battery. Due to cost management problems, i am not able to use advanced 5A charger controller ICs; instead, i am going to use a 1A controller with...
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Microcontroller soft off circuit not working – why?
I was making a board with an atmega328 mcu (to be used with Arduino libraries) to do some one wire communication stuff. Since I was etching the board anyway, I decided to try and implement a simple...
View ArticleWhy pulsed drain current is higher than continuous drain current in MOSFETs?
Why is pulsed drain current higher than continuous drain current in MOSFETs? In MOSFET data-sheets, pulsed drain current is much higher than (by at least 2x) continuous drain current. What is the...
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Choosing R when designing CMOS Amplifier
I am trying to design a two stage amp like the one pictured above. I want the overall small-signal gain, |Av| = vo / vid = 240 V/V = (47.6 dB). I know in theory how to achieve this but am having...
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AC-DC voltage doubler rectifier
I designed a 50 Watt voltage doubler rectifier with rated input 12 VAC and output 48 VDC. The circuit configuration and simulation result are presented in figure below. 2 unit IRFP460 power MOSFET...
View Articletransistor level design of Op-amps
How do we realize the design of a simple Op-amp with Bipolar Junction Transistors or MOS Field Effect Transistors alone? I mean I understand the need for differential amplifiers for providing a...
View Articleusage of bidirectional mosfet
In the schematic of arduino due there’s a mosfet between of “USBVCCU2″ and 5V line. http://arduino.cc/en/uploads/Main/arduino-Due-schematic.pdf I refered to T2 (FDN340P) P-Channel Mosfet. What’s the...
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Burnt MOSFET in the following circuit. Why?
I made the following circuit. As the test load I used 10cm of a standard 12V LED strip to be sure I don’t sink too much current. Used 5V from uC to drive the circuit, toggling it on and off every...
View ArticleLatching solenoid control
I am working on a personal project that will involve driving a latching 9V/DC solenoid from an arduino. The circuit I’ve come up with is dependent on two things, that I haven’t quite figured out yet:...
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Simple ESD protection for MOSFETS
I’m designing a MOSFET (FQP30N06L) circuit to drive a (50V, 3.4ohm) pinball solenoid controlled by a PWM pin on an Arduino DUE: simulate this circuit – Schematic created using CircuitLab The MOSFET...
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Purpose of gate driver in Class D amplifier
Can somebody explain to me why we need MOSFET gate driver in class D amplifier like in the picture below(common class D schematics)? What I don’t understand is if we for example have 9V rails, then the...
View ArticleDesigning a motor driver for my robot
I’m new to electronics and i have a task at hand : to design a motor driver board for my turtlebot(an open source robot) . Having said that , im using a johnson gear side shaft motor that draws at max...
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Why a MOSFET in accumulation mode is not conducting?
In accumulation mode, the channel is not conducting, whereas in inversion mode it is conduting. But if in both cases I have free charge carriers in the channel, why isn’t there conduction in both...
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