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759 Threads found on Current Source Circuit
I understand that we use an NMOS to form a constant current source. My question is, can we create a constant current sink using a similar approach with PMOS? Is constant current sink even a thing?
Are you certain that you wired the actual circuit correctly? You may have the MOSFET body diode voltage drops to account for (2) when current is flowing in RL, e.g. the pin "2" of RL is not actually at ground (potential of the negative plate of the DC source) but diode drop above it). Take a DMM and measure voltage drops around the loop.
Are you saying that through this spiral does an electric current pass (ie the wiring is part of some circuit consuming power), or is it just a helical-like antenna ? If you want a 'stable' 50Hz noise source, I would recommend to make some circuit that you could predict the electromagnetic flow and even tune it. An open (...)
It depends on the loudspeaker and how much power you want. Some NE555 manufacturers specify as much as 200mA sink/source current which is enough to drive a medium to high impedance loudspeaker directly. The mass of the loudspeaker cone will be enough to average the PWM back to an analog level. For higher power all you need to do is ensure enough '
Hi! I am designing a PFC circuit(in boost configuration, inductor is CCM, switching frequency is 100kHz), and it has a high current spike during on and off of the MOSFET switch. I used a bulb as its load. I am not sure if these high spikes are results of the MOSFET parasitic noise or a common mode noise injected at the input of the PFC (...)
Because you are looking to run two equal currents through devices at two unequal current densities. So you need unequal areas. 1:N ratioing is the IC designer's best way to get a maximally consistent ratio. Drawing two different device geometries (like a single 1X emitter, and a single 16X-area emitter) puts you at the mercy of various lithogr
Hello, I build some project which use a constant power supply of 30V 30A, and i want to limit the current because i'm not use such a huge current and i want to promise that my project will never get 30A in 100%. I want to limit my project circuit current to 1A, what is the easiest way to do it? 136031
The transistors in red boundary are nothing but a simple single stage opamp. The final transistors(common source ones to the right) are used to add the current from the pMOS and nMOS differential inputs.
I have a simple low side switch using a mosfet for an Inductive load. All works quite fine. Now I need to add over current protection, and for this I need to add current sensing which will notify the driver or any other IC to switch off the mosfet if current is, for example, above 1A. 135546 I read many articles about it
Problem Statement:- We are current working on testing of different benchmark circuit using Tessent , DFT Advisor, Fastscan (Mentor Graphics) tool to calculate Test coverage, Fault coverage and ATPG effectiveness, We have calculated above parameters using default ATPG , but we unable to apply external test patterns to improve TC and FC. Whether
Since you seem to have a semi-infinite series of the most basic questions I think a textbook is right for you. But the textbook isn't going to teach you to recognize, for example, that "Vb" in the lower is the exact same thing as M3:M4 common gate node in the upper, only difference being whether or not the biasing is shown and how complicated i
It looks like an erroneous schematic. Presumed Q1 is a regular NMOSFET as claimed by the schematic symbol, drain and source terminals are interchangeable, and in this case, just drawn wrongly. After fixing the symbol, you get a regular current mirror with an additional resistor R2 draining part of the reference current. Wonder if the (...)
The obvious choice will be something like the LM317, but if you don't have one at hand, you can make a very simple current source like the circuit shown below. If you make R1 or R3 variable, you could adjust it between 10 mA and 20 mA. The switch is just for illustration of the minimum and maximum range.
currently have a relay thats rated for 15 amps for a 5amp AC PSU power source (high capacitive inrush current). I have it wired so that its in the NC state, and when the relay is powered it cuts power to the PSU (reason I want it like this is if the relay control logic fails on boot/power on, the AC circuit will still be (...)
One way is to use a programmable current source to vary the slew rates as shown below. A lot will depend on required frequency, level, etc.
If you overload your voltage source and it does not have current limiting then the circuit will smoke and burn or blow a fuse.
The "problem" is that even if the FET turns off instantly, the rise time of VDS will be determined by its drain source capacitance (Coss) and the load current. If your load is just a 1K resistor, this will result in a fairly slow rise time of VDS. You need to increase the load current greatly to see the true switching times of the FET. (...)
Hi All, I am looking for a commercial VCCS product, which include one current source and one current sink, with the same amplitude and can be controlled by a external DC voltage in generating uA level DC current. Would anyone give me some recommensation in finding this kind of product? My application is to use the (...)
hi, A P MOSFET requires negative voltages on the Gate and Drain with respect to the source in order to control source to Drain current conduction. E
Hello! Just a first hint for you. A thermocouple does not deliver a voltage but a current. You should search for a current/voltage conversion circuit. Dora.
You could use "Step-Up Voltage Regulator Module" like LM2577 with below circuit: 133170 For your application you need to change several thing: 1-Remove 7805, C11 and C12 . 2-Replace Zener diodes by 1N4746A (18V,1W); If circuit current consumption is higher than 100mA ,you should increase the maximum Power Dissipation of dio
Hello. In another thread of mine I talked about building a device to measure the saturation circuit of inductor cores, I was shown a to me unknown better circuit which I intend to build but I have manage to score perfectly in the ADD arena and haven't been able to finalize the order for the sensor I need:-) Anyway I have realized this (...)
Hai, I am designing a BLDC motor driver by using TLP250 using STM32f402 micro-controller. Now i have been stuck with optocoupler output,after reading hall sensor output i have triggered one high level mosfet and one low level mosfet. But when i read gate voltage there is no such gate trigg
Put together a bilateral current source circuit incorperating LM102 and LM107 and, unfortunately LTSpice doesn't carry them:thumbsdown:. Please let me know equivalent LT variants OR SPICE models for aforementioned IC's :sad: I did search around the web for spice models and found nothing.
Hi, Hard to guess, for me. Perhaps it just means that the voltage referred to ground before the shunt, from ground to the resistor positive terminal, is the full supply voltage, the "Vcm - Vshunt" means the voltage referred to ground minus the shunt resistor's voltage drop when measured at the resistor negative terminal. Presumably the differenc
Hi guys, Can we do the thevenin equivalent on a voltage divider where the voltage drop controls a voltage controlled current source? The circuit comes from two BJT small signal circuits with their emitter connected together. So I was thinking if it is possible to apply the thevenin equivalente at that input. Reagrds.
Yeah, I forgot the negative sign, because the current k*V1 enters in the negative polarity of the R3. Regards.
It could be measurement error. Your scope probe needs to be using tip and barrel only across Vcc and Gnd .... ~ 1cm or less apart without gnd clip. since ESR rises with C, the RC time constant is 10us for LOW ESR and about >>100us for standard. So when cable capacitance is switched current pulse causes a voltage spike at source due to ESR. BIt m
Comments: The time constant of 3.3K across 0.22uF is too short, you will get quite a lot of ripple. I would suggest you use a higher voltage capacitor before the voltage divider (after the bridge rectifier) maybe with a low value resistor (~1K) between the bridge and cap to limit surge current. That cures the time constant problem without making
Substrate diodes and dedicated protection diodes are forward biased with inverted power supply. If the supply source is able to exceed the maximum diode current, the device is destroyed.
Hi, I am designing a circuit that has GPRS communication. The modem has an STATUS output but datasheet mentions only how to put a LED as in indicator (standard connection when LED is in collector side with an 300ohm resistor and emitter is connected to GND). I asked manufacturer if I can connect STATUS pin to the microcontroller PIN configured a
Hi i have encounter an problem, how to set the unit for parameter sweep in the dc sweep controller. in this case i wanted to set it to "uA" as shown in my IBB current source. 130410 thanks
Hi, i want to make a digitally(FPGA) controlled negative current source. C1 capacitor is the load. - i want that current change equally for every single bit , for istance 1110 = Ix 1101 = 2Ix 1100 = 3Ix... but in my circuit current doesnt change propartional. i arrange resistor values to make it 2Ix (...)
Some external circuit will be needed - current source loaded to capacitor.
Hi, Attached is a current mirror design I am a little bit confused about. I do not know what this kind of topology is called and thus cannot find any external information. I do understand that this is a cascade current mirror, but I don't know what are the two external transistors doing and what is the benefit of having them in design.
In first place I thought that this would't work, because you're forcing the current and by definition gm = did / dvgs. If id is constant gm is equal to zero. The same goes for the gds = did / dvds. Even though I tried to simulate that circuit and I get a completly different plot: 129410 The devices I am using are 1.
Hi Everyone, I am using MCU C8051F972-A-GM in my project . I have 6 LEDs in my board connected to the GPIO pins of the MCU. I want to design a circuit for constant current control with supply current in uA(when all LEDs are OFF) and with PWM dimming. I searched for the Constant current LED drivers with PWM control, but (...)
Hi, assume there is a simple connection of an ideal voltage source with a resistor. on the other hand, there is a current source connection with a resistor. I want to measure the resistance in each circuit. now, 1- for measuring resistance of a 10k or higher, it is preferred to use voltage source or (...)
I use LTS 25-NP current sensor to measure ac current grid. I just built it. I tried to calibrate it using simple circuit consists of a single phase source and high power resistor. The current is flowing when I change the source voltage as appearing in the Ammeter but the output voltage from (...)
Yes, you cam make your own A/D converter, and it's not too dificult to understand. With a constant current source and a small capacitor, you can generate a saw teeth waveform, which can be used to compare with measured signal. The time elapsed to reach the same value is proportional to the voltage.
There's no Vin, gain (transimpedance in this case) is measured with current source I1. Seriously I have no idea how the circuit is intended to work as oscillator, respectively don't know which transimpedance value you want to achieve.
What is I1? Are you really supplying the DC bus with a current source? That's weird.
Hi i want to add noise to the input current source of my multiplier circuit and i want to run the DC analysis. Can anyone tell me can is there any noise file already written that i can obtain from cadence or do it have to write a file of my own and include the txt file. Also once obtained can anyone pls tell me how to include it. In the (...)
Hi, All this depends on your circuit. You should give at least your example circuit. * Supply voltage? * output current? source only? or sink too? gain: How much gain do you need? What is the input voltage? I estimate it should be a unity gain buffer, am I right? BW: For me a reference voltage could be considered to be (...)
Ideally, SW3 should not be open, otherwise I current source would generate an "infinite" voltage accross its terminals.
To know the inverter power (magnitude and direction), you'll multiply and voltage and current (instantaneous power) and average the product. Under circumstances, it's sufficient to form sign(P) = sign(V) xor sign (I), needs only two comparators. The inverter can also "source" or "sink" reactive power, in this case sign (P) will flicker with doub
"Pulse" refers to the square wave current waveform in case b, I presume. It has been already explained that the waveform is cause by connecting a current source as load, which is more a theoretical model than a real load case. You can however come quite near to it by using a large inductor with series resistance as load.
for these super low frequencies, use a current source/capacitor ramp generator circuit. Start the ramp at the positive going zero crossing of the input sine wave, and reset the capacitor to 0 Volts at the negative going zero crossing. Save the peak ramp voltage value in a simple diode/hold capacitor and read off the voltage from that hold (...)
I presume you are referring to the circuit linked in post #1 126146 I would suggest some modifications. If no FET is available, you should at least use a Darlington (e.g. BC517 for the NPN configuration) to keep the base current error negligible. Secondly, the output transistor involves a voltage gain for Rsens < 5
Yes the internal resistance will limit the current in addition to any external resistance. Frank