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Questions tagged [current-sink]

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3answers
64 views

MAX485 Receive Output pin current sufficient for optocoupler LED?

I want to recreate a project found at this link where an optocoupler's LED is a driven by the receiver output of a MAX485. Now, my question is, the LED series resistor (R5) value is 470ohms, if my ...
1
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2answers
75 views

current sink/source in ADS114S06B analog/digital converter

Here is the datasheet. It seems from the graphs on page 17 that the I/O pins will sink or source as much as 7.5 mA: However on page 9 the table indicates an expected sourcing of 1 mA (I say expected ...
0
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2answers
55 views

Current drawn by a motor driver

Only interested in the binary logic part, not the motor side. The datasheet specifies a few absolute max ratings: Table 4. Absolute maximum rating IIN Input current (INA and INB pins) +/...
-1
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1answer
106 views

Current source with op amp and transistor

I'm building current source with OP AMP LM358 and MOSFET transistor IRF5305. Here's schematic diagram of the circuit: I have two questions about it: 1) Maximal gate-source voltage of IRF5305 is +/-...
1
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1answer
104 views

Testing regulated power supply: 100 mA current sink

Disclaimer: I'm trying to learn about circuits on my own. I'm reading as much as possible to avoid any basic mistakes, but if there's any, please point it out and I'll investigate further in that ...
2
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2answers
124 views

Reducing noise on a voltage reference

I need a stable, low noise voltage reference that I can adjust between 1.4V and 1.8V. The output should source or sink up to 0.25mA @150Hz max. The output will provide a +1.65V bias for a bipolar ...
-2
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2answers
88 views

Pulling Current From a Cell Phone Port

I have a Samsung Galaxy S9 that I am trying to pull current from via power resistors. I have been able to pull 0.927 Amps from the USB-C port but every time I get above that, the phone stops ...
2
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1answer
118 views

~40 uA current sink… what current mirror topology to use?

I need to sink a constant 20-60 microamps from the inverting input terminal of an op-amp in order to shift the output voltage upwards a bit. This is a pretty low-speed circuit, with little spectral ...
1
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1answer
53 views

Connect DAC IC to current sinking controller

I want to supply a 0-5V signal to this process controller using the DAC8555. The DAC8555 datasheet states: Each output buffer amplifier is capable of [...] driving a load of 2kΩ in parallel with ...
1
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2answers
148 views

Supply for sinking current

;) I want to use an amplifier circuit powered by a +/-15V supply (DC-DC converter IC with one or two Watts) to interface an ADC. I want to use clamping diodes to prevent the ADC input from leaving ...
0
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1answer
67 views

Inverting regulators and sinking current

I have a circuit to drive a simple resistive load, and it works quite well. On the high side is 2.5V from a regulator, and the low side is 0V (taken as reference to a battery's negative terminal which ...
1
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3answers
119 views

Current sink for microcontroller port not constant

I have designed a two-transistor current sink for my application. I need it to keep the current constant which flows through an IR-LED: simulate this circuit – Schematic created using ...
1
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3answers
277 views

What decides that an IC will be able to sink or source current?

Correct me if I am wrong but so far, I've learnt that some ICs can source current while some can only sink (open-collector) while others can do both. And it is decided by looking at the datasheet, Ioh ...
0
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1answer
45 views

High output voltage or sink?

As I recently learned, LED driver output voltage stands for what the pin can handle after the last cathode of LED strip. However, I am interested in this chip HV5812, that is a high voltage shift ...
5
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3answers
378 views

microamp constant current sink

I'm trying to put together a constant current sink circuit for discharging small Lithium-Ion coin cells. I need to be able to sink from about 200 uA to 12 mA. My first thought was to use some voltage ...
0
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2answers
86 views

Help with design of current DAC

I am required to design a current DAC (64 element NMOS) that sinks the current of another current DAC (16 element PMOS). The specs are as follows: 1. The smallest current output from the PMOS DAC is ...
0
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2answers
298 views

Op-Amp output not stabilizing in precision current sink

I am creating a precision 3A current sink which functions when connected to 12+ volts. I am using the following circuit: The voltage reference is created by a 0.4V precision reference chip (LT6650CS5)...
0
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1answer
163 views

Circuit to boost PWM voltage using ULN2803a

I am trying to convert 5v PWM signal to 10v using ULN2803a IC. My target device (a dual channel LED light)expects two 10v pwm signal and GND via a 3.5mm audio connector. The part I am struggling with ...
1
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1answer
250 views

precision current sink for battery discharge

I'm trying to build a precision computer-controlled current sink to discharge a battery. The maximum discharge current is to be 2mA (at the moment; I might go to larger currents later) and the battery ...
0
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2answers
83 views

Convert logic signals to be able to supply/sink higher currents [closed]

I am making a LED matrix and have the required logic in place to drive the unit. My problem lies in the fact that my matrix is 80x56 diodes large and requires a fair amount of current. Each diode is ...
3
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1answer
197 views

RLC circuit: unexpected behaviour

I see some unexpected behaviour from (what I thought) is a relative straight forward RLC oscillator circuit: The idea is that a coil is charged over a certain period of time (during this pulse the ...
2
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3answers
882 views

OpAmp based constant current source/sink produces high peak current when load voltage is pulsed

I'm trying to build an OpAmp based high constant current source/sink based on the analog devices application note 968. In the first step I designed it for maximum of 1A, but later up to 10A is planed....
1
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1answer
147 views

How can I current-limit a current mode DAC?

I have an OLED display with a current reference input to control brightness. Absolute maximum brightness is achieved by sinking 12.5uA, which is usually accomplished by a resistor to ground. I wish ...
0
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1answer
185 views

Power Supply Response to Sinking Current/Overvoltage

Please consider the following circuit where voltage sources V1 and V2 are regulated linear DC power supplies: From the simulation V1 will sink 2.5A of current provided by V2. Questions: What will ...
0
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2answers
1k views

MOSFET current source / current limiter request for review

I need a small (somewhat) voltage independent current (about 10 mA), with a voltage range of 3-30V. I came up with the following circuit. simulate this circuit – Schematic created using ...
3
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2answers
661 views

PIC Micro - Can I use both sinking and sourcing maximum current ratings if some pins sink while others source?

I intend to drive 6 LEDs with the PIC12F519 microcontroller if I am able to do so. On page 61 of the datasheet the maximum current ratings are given: Max current sourced per pin ....... 25 mA Max ...
2
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2answers
542 views

Saving a resistor on an NPN transistor current source (sink) when driving LEDs

The typical circuit to drive an LED from a low-power microcontroller digital output pin, using a transistor, might look something like this (assume a 20mA/2V LED): simulate this circuit – ...
2
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2answers
250 views

Understanding sink currents for IO expanders

I'm looking at using a GPIO expander to control some LEDs. I plan to sink the LED current through the GPIO expander (so configure port to output and set to 0 to switch LED on). I'm looking at using ...
0
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1answer
758 views

AC Current sink with op amp and transistor

I want to create an AC load for testing high capacity battery (200Ah) using the circuit below: Can I put an AC voltage at Vin and get a AC load current through the FET? And why do they need LT1492 ...
0
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1answer
112 views

Relation or difference between Input clamp current and Sink current

I want to take input from external peripherals to PIC micro-controller(PIC18F66K22) through buffer IC(74HC541). My problem is o/p of buffer source current is +/-35mA and i/p of PIC18F66K22 PORTF pin ...
0
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3answers
668 views

OP amp PI controlled electrical load

I am building an electrical load, capable of "sinking" 0 - 3A on a maximum of 60VDC. I want to control the load with a microcontrollers ADC (0-3V). On the internet you find hundereds of circuit ...
1
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1answer
734 views

RS485 current source/sink

I'm looking at using the RS485 to communicate between two Arduinos. I'm trying to wrap my head around the current requirements though... If I connect a driver to a receiver through a differential pair,...
0
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2answers
134 views

Current step generator - ideas for completing the implementation?

I'm working on a circuit that can act as a current sink or source. The goal is to control it using some digital means so it can output the required current. Right now I am not sure about the ...
6
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1answer
2k views

How do I build the current regulator circuit referred to on the LM337 datasheet?

What I would like to accomplish: I am trying to add current regulators into a home built dual rail linear regulated power supply. I previously asked this question about transformer fusing and ...
1
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1answer
712 views

Trouble splitting off LFO signal to drive LED

Background: I am trying to build a very simple noise box that doesn't need to be tuned to 1V/Oct or anything special. It simply has one VCO, two LFOs, and a VCA. The circuit is powered off of a dual ...
1
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1answer
103 views

Leftover current after current limiting resistor

This question is related to my another question here. In crux, I would like to sink current of TLP521 via 74HC595n shift register. The TLP521 is connected with a resistance such that the current is ...
2
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2answers
2k views

Programmable current sink

I need a current sink that I can control from a micro-controller. Should handle 5V up to 4mA or so in at least 256 steps (more is better). I'm looking for a design, not so much a complete product, due ...
0
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1answer
118 views

How to test/connect the CAP-150 capacitive sensor

I am evaluating a few sensors for an application at work, and I'm having some troubles figuring out the correct way to connect/test this sensor: Gems Sensors' CAP-150. Datasheet here. I want to ...
0
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2answers
129 views

What should I use for a 3.3 voltage reference that sinks maximum of 1mA?

I am in search for stable and precise 3.3 voltage reference IC. I am using it for the temperature sensor application which only sinks 1mA at max. Can someone suggest me a best component/IC for this ...
0
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1answer
288 views

Current sink - work in simulator, doesn't work in real

I've built current sink to drive wheatstone bridge. I've counted that I must reach current ~0.2mA to properly working whole measure system. Picture below present my current sink (I use MCP6001 op amp):...
0
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1answer
141 views

wheatstone bridge drive by small current, issues?

I've got question about Wheatstone bridge. I've designed device which contain NCP1210 pressure sensor and works with 3.0V power supply. I've did calculations and now I've got some questions. My ...
4
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2answers
1k views

Understanding 74LVC245 datasheet and current source/sink

I'm using a SN74LVC245A (datasheet) to shift 5V TTL down to 3.3V so I can read the signals with a Raspberry Pi. However I am getting really weird results (a 60Hz input signal is picked up by the Pi ...
1
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1answer
105 views

What if there's current INTO an output pin?

maybe my question is easy to answer and maybe I shouldn't have asked it, but I'm really not sure. I would like to connect an XBee ZigBee module (3.3 V) to a microcontroller (PIC, 5V) using the USARTs....
5
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1answer
5k views

How to build a voltage-controlled current sink / voltage-controlled resistor

I am trying to control a current through several current-mirror device (specifically the IREF pin on the TLC5940) using a single potentiometer. I've tried using a ...
0
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1answer
103 views

R-EXT connection on the STP16CP05MTR LED sink driver

I'm planning to use a STP16CP05MTR LED sink driver to drive some LEDs in a matrix. The STP16CP05MTR supports constant current by the use of an external resistor ...
6
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2answers
2k views

Sinking and Sourcing Current to and from a PIC24F Output Pin

Sinking and sourcing current refers to current going into and out of the MCU (respectively), right? If you configure a GPIO pin as an output, why would current ever go into the pin (since it's ...
4
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1answer
2k views

Increase 74LS TTL gate's output current to drive multiple high-power LEDs

If have several 1 watt LEDs that I want to drive off of a TTL gate's ouput. What can I do to increase a 74LS TTL logic chip's output fan-out (current) to be able to produce a true 5 V output that is ...
2
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2answers
5k views

application of current source and current sink concepts

The terms current source and sink, imply the direction of current flow. For a source circuit, there is a "switch" connected between the positive terminal and load, where it sources the current ...
4
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1answer
926 views

Are all voltage reference ICs able to sink as well as source current?

I'm looking at the REF30xx series of precision voltage references from TI. The datasheet lists a maximum output current of 25mA. Every specification and figure on the datasheet (e.g. load regulation ...