A voltage regulator is an analog circuit that produces a stable output voltage that doesn't vary with input voltage or load changes. Switching regulators are much more efficient than linear ones.
6
votes
2answers
130 views
Setting a part's VCC slightly lower than board's supply voltage
I'm interested in using the undervoltage detection feature (in addition to the primary function) of this chip. This IC draws 6 uA (microamps), and accepts any VCC between 1.6V and 5.5V.
The ...
2
votes
2answers
113 views
Need chargeable momentary 15 watt regulated voltage source
I'm working on a RF telemetry side-project that requires an amplifier IC to be run for about 5 seconds bursts between charges. The system is portable and runs off of a 3.3V battery that can supply ...
1
vote
3answers
427 views
Why does this 7905 giving -12V output?
I made myself a symmetric power supply for my lab projects using several 78xx and 79xx components. The PCB was ready and I was testing it. I saw that 7905 is giving -12V output.
(See full image.)
...
2
votes
2answers
724 views
What is the difference between level shifter, voltage regulator and dc-dc converter?
What is the difference between level shifter, voltage regulator and dc-dc converter?
As I know, voltage regulator is used to produce constant output voltage from high voltage; level shifter is used to ...
1
vote
3answers
226 views
What parameters effect on voltage regulator's temprature?
What parameters effect on voltage regulator's temperature? Is it current of output or another parameters effect on temperature? For example if a lm7805 is used for current output of 1A and 18 volt ...
7
votes
4answers
353 views
Do Linear regulators have a minimum current to maintain their output voltage?
When I was searching Digikey for a ~6V to 3.3V Linear regulators, there was a minimum current column in the listing results. This kind of threw me because I didn't know that there was such a thing, or ...
0
votes
1answer
146 views
going from 5volt 1A to equivalent from a 3V CR2 Battery
I have a small camera with wifi that runs off a 3V CR2 battery. I'm trying to run it from line voltage. Could not find any small transformers that go to 3volt 750mA.
I have an Apple transformer for ...
0
votes
1answer
214 views
Effect of decreasing input voltage of transformer on output voltage
I have designed a device which is controlled with a PIC micro controller.This micro's power is +5 volt. I have used a transformer for converting +220 volt to lower voltage +15 volt. Then a 7805 ...
3
votes
2answers
180 views
Stepping from 5 V / 1000 mA to 3 V / 750 mA
I'm trying to go from 5 V, 1000 mA, which is a USB transformer for Apple devices, to 3 V, 750 mA (which is a small camera I have). I have purchased a NTE1904 3 terminal volatage regulator which 3.3 V, ...
4
votes
1answer
2k views
Voltage regulator for linear constant-current (1.5A) LED driver?
I am considering building my own driver for a ~1.5A LED to power a microscope for my research.
For this application, efficiency isn't critical, but because exposure times to the camera can be short ...
4
votes
6answers
1k views
Proper use of a voltage regulator
I want to power a prototyping kit for an 8 pin picaxe micro-controller with a 9v battery (the board itself requires a 5v input).
I have the following regulator:
https://www.sparkfun.com/products/107
...
6
votes
1answer
430 views
Center tap split supply question
Lest's say that I have the following setup:
a split supply (using two voltage regulators: a positive and a negative one) connected to a center tapped transformer (12-0-12). The output of the ...
1
vote
1answer
98 views
Inverting the logic of the inhibit pin on TI PTR08100W
I'm using this TI PTR08100W switching regulatator, and want to use the inhibit pin to keep it turned off except when I am holding down a switch.
According to the datasheet:
The Inhibit pin is an ...
6
votes
4answers
131 views
Placement of undervoltage monitor and cutoff
Suppose I have a circuit running at 3.30V, supplied via an LDO regulator (e.g., ADP124), powered by a Li-ion battery. In other words:
Now, I would like to implement an undervoltage cutoff to "turn ...
2
votes
1answer
153 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 ...
6
votes
2answers
779 views
Critique of my Data logger's Power circuit design
I am laying out my first full device, a fairly simple sensor-data logger, with these specs in mind:
I'm running microcontroller and sensor @ 3.3V, with load varying from 10 mA to 400 mA
device will ...
-5
votes
1answer
186 views
diode nightmares
Let me start by saying I am a complete amateur trying to stumble my way through some pretty basic PCB design, and I have run into a problem selecting diodes. The PCB I am designing will be for some ...
1
vote
1answer
458 views
LM7812 power regulator 28v to 12 dc-dc converter wrong output
Hello I have an LM7812CT power regulator and I want to use it to convert a 28V dc to a 12V dc.
I am using the circuit provided in the data-sheet using 2 capacitors, one 0.33uF connected to the input ...
1
vote
1answer
282 views
LT3080 regulator question
The datasheet of the LT3080 voltage regulator says that "For true zero voltage output operation, this 1mA load current must be returned to a negative supply voltage."
What exactly does this mean? How ...
3
votes
1answer
2k views
TTL voltage shift from 5 to 3.3 Volts “UART”
I want to make serial communication with a device which works on 0-5 Volt TTL level. But my serial chip uses 3.3 Volt logic. (this is an UART communication)
I know that I need a step down at least ...
0
votes
2answers
159 views
LM3524D as a StepUp regulator
I am using LM3524D IC configured like Figure 8:
I am supposed to get a 10V output with a 5V input using 20kHz Fosc. I am pretty sure about my connections and the values but I can't seem to reach ...
-1
votes
1answer
325 views
setting the output for l200c - am I correct in how it works
I'm trying to use a L200C voltage regulator as a pre-regulator for my PSU since that all I have. I noticed it has a voltage divider between the pin 2 and 4. Am I correct in saying the limiting pin ...
6
votes
3answers
3k views
Regulated 3.3V from a Lithium-ion (or LiPo) battery
Background
I wish to power my circuit with a Lithium-ion or LiPo battery (likely a battery with around 1000 mAh capacity). These batteries have a voltage that goes from 4.2V to 2.7V typically during ...
1
vote
1answer
279 views
Providing power to additional load (PN532 Board)
SETUP: I've put together a board comprised of:
24 V DC Supply voltage connected to 60 Ohm (10 W) Resistor that is in series with a LM7805C (5V Regulator). The LM7805C has a .33 uF cap on the Vin ...
4
votes
4answers
543 views
Efficient low-power buck (step-down) regulator IC for Li-Ion - 3.3V conversion?
It's not easy for electronics novice to find good element base, so I hope this suitable question.
Requirement: Efficiently power a lean, 3.3V-based MCU design from a Li-Ion battery. "Efficient" ...
11
votes
2answers
600 views
Why is a lower switching frequency more efficient?
I'm designing a 10V to 3.3V step-down converter. Looking at the LT8610, the applications example shows two similar circuits that have different switching frequencies.
The Efficiency vs Frequency plot ...
1
vote
0answers
112 views
Datasheet for this switch-mode DC-DC regulator
I'm trying to regulate a 6-cell NiMH battery pack (7.2V) to supply a constant 5V to a Raspberry Pi. I've ordered this DC-DC regulator after reading a suggestion on another website.
I want the ...
2
votes
3answers
188 views
Regulating Voltage
I want to rectify my input voltage from AC to DC in the range of 90 vin min to 270 vin max. I was thinking about a buck converter design due to the efficiency however I cannot find one that can take ...
2
votes
3answers
395 views
L7805CV 5V Voltage Regulator 1.5A
I seem to be having some problems with hooking up the L7805CV Regulator. When i provide it 12v @2A i seem to be getting an output value of 10.xxV???
What could i be doing incorrectly? Does it matter ...
3
votes
1answer
216 views
effect of output capacitance
I am wondering if anybody has more information about the effect of an output capacitor on a circuit? I.e. Does an output capacitor with (parallel) resistive load contribute any poles or zeroes, and ...
1
vote
2answers
184 views
Simplest way to control the speed of 4 identical fans
Hi, my computer has 4 fans in it running on 12v from the PSU.
How can I control their speed?
Maybe a potentiometer?
3
votes
3answers
288 views
Isolating power for an infrared receiver
I am using this IR receiver in a circuit, and I have noticed that sometimes the unit generates an oscillating output when it is not being activated by a remote - I am guessing that this is due to the ...
-1
votes
1answer
174 views
How to power a motherboard from a 24V source?
I would like to power a ATX motherboard from a 12V or 24V power source.
Does anybody have some circuit?
5
votes
1answer
278 views
Voltage regulator minimum voltage input
I have a device (a Raspberry Pi) with the voltage regulator SE8117T33 for 3.3V. From the datasheet it says that the dropout voltage is 1.1V, so the minimum input voltage should be 4.4V, right? I'm a ...
2
votes
2answers
455 views
Capacitor sizing on a voltage regulator output
I have an application in which an RFID reader demands 200 mA of current when it attempts to read an RFID tag. For some reason the current switcher power supply either can't supply enough current or ...
3
votes
3answers
322 views
Can the outputs of 3 different voltage regulators be tied together?
I'm working on a variable power supply board. It will take 9-35VDC input and output either 3.3V, 5V or an adjustable output that's jumper-selected. If I hook the outputs of all 3 regulators together ...
6
votes
5answers
467 views
Adjustable LDO Regulator
I'm using Microchip TC1071 in a circuit to provide an adjustable output voltage (appears to be pin compatible with LT1761-SD). My plan is to use a digital potentiometer (Microchip MCP4251) to control ...
0
votes
1answer
589 views
Does Arduino use step down voltage regulators?
I am designing my first "permanent" Arduino application, and I would like to know if the voltage regulator is linear or step down.
The reason I would like to know is because I am currently powering ...
5
votes
2answers
339 views
What does frequency foldback do in a switching regulator?
I'm looking into using the LT3759. One of the features that they advertise is frequency foldback.
Frequency Foldback
When VOUT is very low during start-up or a short-circuit fault on the ...
2
votes
3answers
377 views
Basic wattage and volt conversion when using solar panel
I have a basic electronic question or two I need to ask.
I want to use a solar panel which delivers 5.2W and is rated for "8V open voltage and 650mA short circuit". If I connect a 5V voltage ...
4
votes
3answers
494 views
Proper behavior for USB and +5V
I have a batch of Sanguino 1.3a RepRap boards, with the following "bug" listed:
The USB 5V VBUS is connected to the output of the 5V regulator. This is bad for the regulator and bad for the PC. ...
2
votes
1answer
370 views
Why are the output voltages way too high on this stacked LM317 circuit?
I'm making a circuit that is intended to "simulate" a stack of 6 Li-Ion cells, for testing a BMS. Here's the schematic:
Schematic of cell simulator circuit
The ICs in red boxes are LM317 voltage ...
2
votes
3answers
699 views
Why is the voltage regulator's output current not what I'm expecting?
I've recently bought a couple of Sanyo LA5003 voltage regulators (datasheet). From the datasheet, I understood that the highest possible current on the output can be 60mA. However, when I connect it ...
5
votes
4answers
360 views
What capacitance should be added over the inputs and outputs of a voltage regulator?
Is there a nice rule/formula for this or do we always need to go off of the datasheet? I read today (in a datasheet, no less) that the capacitance should be customized for a given application (no ...
0
votes
1answer
439 views
Increasing the output current of LM7805 [closed]
Supply Voltage +-15 V to +-24 V
Goal:To have an adjustable single low voltage output (-0.5 V to 0.5 V ) from dual supply voltage.
What I want to do is to have dual voltage output which will be ...
5
votes
2answers
626 views
Explaining a car voltage regulator circuit
I need to come up with a solution for a voltage regulator to be used in a vehicle, regulating ~12V from the car battery to 5V used by Atmel AVR microcontroller.
I've found this schematic on the ...
2
votes
2answers
295 views
PWM speed controller with rectifier as voltage regulator?
I was looking around for a voltage regulator when I thought of this, so it might be completely crazy. And I'm sorry if it is.
BUT...
Could I use a PWM speed controller as a voltage regulator if I ...
1
vote
5answers
642 views
How to make 95%+ efficiency voltage regulator?
I need to make an 11 volt voltage regulator. I would really like this to be step-down, not a linear voltage regulator because I am going to be drawing between 1-2 amps at 11 volts, and if I was using ...
1
vote
1answer
702 views
L200C voltage regulation
I have a battery that's designed to power a MacBook Pro (it's not an internal battery, it's an external battery meant to act in place of a charger, so it's got all the monitoring electronics ...
1
vote
1answer
251 views
Buck Regulator Output is too Small
I'm making a buck regulator using L4970A using circuit from this application note figure 60 , except for the inductor. I change i to 180 uH
I wanna make it to be a power adaptor for laptop with solar ...
