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754 Threads found on Current Source Circuit
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
Dear All Recently I faced a problem in calculating the output current in a circuit which is similar to current mirror circuit. I wanted to ask for your ideas on how to solve this circuit problem . In this circuit we supposed Vdd as Vreference. the schematic is as below : 134906 (...)
can any one help me out for Vf=7 volt I=10 to 20mA (variable) constant current control circuit for UV LED 134762
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.
for an ideal voltage source the voltage across it's terminal will be constant for any load, for a practical source however will have a limit on the max current it can supply(also will have some internal resistance). so suppose for a smaller load if the current has reached to its max value. so my two doubts are 1. once (...)
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
I think the circuit may be from "Op Amp circuit Collection", AN-31, attached is the schematic which uses LM102 and LM107 for a "Bilateral current source."
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
I now see the reason for the arrow in the current source. It is negative conventional current produced by a current source that must have a negative supply voltage since the base of the NPN transistor is at ground. If the gate of an enhancement N-channel Mosfet is also at ground then the (...)
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.
Sorry,I forgot to update the current diagram and thanks for your "wish" erikl :popcorn:. After done some reading, I try to make some changes to the circuit. As I know, oscillator circuit need 180 phase shift (at least two poles). What I did actually is I'm connecting the first block of the circuit to another (...)
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 (...)
Hello all! I am using gpdk180nm CMOS lib for designing BGR circuit. I have designed the circuit using current mirror. But to improve this circuit I am using op-amp. I need to know what type of op-amp should I use for getting 1.12 V const ref voltage for temp range -40 to 125? What should be the gain, BW, PSRR, CMRR of (...)
Ideally, SW3 should not be open, otherwise I current source would generate an "infinite" voltage accross its terminals.
Any circuit diagram to measure direction of AC current using PIC microcontroller (18Family) ? i.e, If direction of current changes the output of circuit should be changed from (high to low) OR (low to high) Thanks
Hello , Can someone please explain why the current at the output is considered to a pulse?? I don't understand how this the case if out input voltage is sinusoidal, or is the pulse obtained not necessarily the output? Please refer to the document and the schematic attached htt
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
If I induce a voltage v in a circuit with resistance r, will I get current V/R? I've always assumed there were some exceptions to this rule since 9V batteries have high voltage but do not give out high current... but rather than being an exception to the rule was this due to its internal resistance?
Not sure what you are trying to do there. If you are trying to turn the current source on and off, I don't think that circuit is the way to go. If you're trying to do something totally different, then you're on the right track. If you're trying to pulse the current from 0 to 1A, then drive the INPUT of the opamp. In (...)
I'm trying to replicate this circuit for a 2W laser diode engraver. I could understand most of the other components except the current source schematic (Pg. 5, Fig 4). I understand that the TLC271 is being operated in high-bias mode (cause the
I think it's a 'long tailed pair' inverter with a constant current source in the combined emitter connection so it gives maximum voltage gain. Exactly why that is necessary isn't clear unless it's to ensure the drive signals to the IR2110 switch abruptly between logic levels. Brian.
Make model as CCVS(current Control Voltage source) or CCCS(current Control current source).
... For proper operating point a large inductor i.e. 10^9 should be connected at output with a voltage source. I am confused what changes will this bring to the circuit simulation. As said in the following text (by Tietze-Schenk), this is a method for simulation to keep the outputs (of a fully differential