A Low Drop-Out or LDO regulator is a DC linear voltage regulator which can operate with a very small input–output differential voltage.
0
votes
2answers
35 views
NCP59302 resistor question
What resistors do I need to get 5V on this chip? Sorry, I don't understand the reference to the Iadj in the formula. The section on the Iadj in Adjustable Voltage Design seems circular.
...
2
votes
1answer
68 views
Can a linear regulator in shutdown mode have the output in parallel with a switching regulator
I am trying to design an efficient battery powered circuit using a 3.3V microcontroller (NXP LPC1343). One of the requirements is that the microcontroller periodically read a value from an ADC and ...
2
votes
1answer
71 views
How step-down voltage regulators behave when their input drops below their output voltage?
How do the common low-dropout LP2950 and buck LM2596 regulators behave when their input voltage drops below their output voltage?
I'm driving a micro-controller board rated for 3.7-5.5 V with a 4.8V ...
5
votes
4answers
353 views
Arduino Uno R3: Directly supply regulated 5V to 5V pin?
I'd like to use an Arduino Uno R3 battery powered a datalogger. I want do supply it directly with a Step-Up regulated 5V rechargable battery powersource at power ...
1
vote
1answer
38 views
Regulated power supply from thermostat to zigbee module
I have a thermostat that outputs a DC power supply for a communication daughter board. When I read it with the voltmeter, it reads ~3.9v, but the zigbee module that I want to use requires 3.3v ...
2
votes
1answer
136 views
Question about the Inrush Current in LDO
I have a doubt with inrush current limiting for an LDO. To understand that, I referred old literature of capacitors and others. I have some conflicting arguments which I need to clear out:
This is ...
1
vote
2answers
145 views
FT230X 3V3OUT pin connected to 3.6V, Safe?
The FTDI ft230X datasheet states that, for the output pin of the internal LDO:
When VCC is 3V3; pin 8 is an input pin and should be connected to pin 10. page 7.
Meaning that 3V3OUT of the ...
0
votes
3answers
149 views
Are “fixed voltage” LDOs adjustable too? [duplicate]
I have a quick question...
I have purchased a 5VDC fixed voltage LDO. P/N: MC7805CT-BP
I was wondering if I can still use a voltage divider to set the output to a higher voltage.
If yes... does ...
0
votes
2answers
151 views
LDO or switching Regulator
My requirement is 3.3V 1A output from 5V (this 5V is derived from DC-DC regulator 24v to 5V 1.5A)
i have chosen NCP5662DS33 LDO , but which is best one to use for this current requiremnt ?
i have ...
1
vote
1answer
153 views
Obtaining +- 1.5V, +- 20V, and 3V from single LiPo [closed]
I want to use a 3.7 volt LiPo to power a portable device. What's the best (efficient and small) way to get ± 1.5V, ± 20V, and 3V from a single cell LiPo?
Here are some specs about the ...
1
vote
2answers
117 views
What happens when I connect the GND of a LDO in a Diode to the real GND?
A friend of mine told me to put a diode between the LDO's GND pin and the circuit's GND. He said the LDO will regulate it's fixed voltage plus the diode drop. Is it true? How does it work?
I am using ...
0
votes
0answers
115 views
Dual Power the PIC18F2550 with USB and LP2992 LDO
I have seen some examples of how to dual power the PIC18F2550, even in the datasheet. But are there any things to look after for a equivalent circuit using the LP2992? I guess there is the problem of ...
0
votes
1answer
52 views
LDO LP2992 5V Naming
Some one could explain to me please the difference between the LP2992IM5-5.0/NOPB, LP2992IM5X-5.0/NOPB, LP2992AIM5X-5.0, LP2992AIM5-5.0? They all seems to be the same thing.
0
votes
0answers
105 views
Atmel UC3L/SAM4L + 2.8V peripherals li-pol charger and power rails (PMU/PMIC ?)
I am designing a very tiny low-power Atmel UC3L (or SAM4L) project and I need the smallest solution for safe Li-Pol charging and to provide 2.8V and 1.8V power rails.
I found some LTC parts with dual ...
2
votes
3answers
131 views
Voltage modulation with an LDO
I am trying to build a voltage modulation circuit using an adjustable LDO and a uC switchable resistor network (to provide different Vout levels). I need the circuit to provide 4.9, 5.1 and 5.3V at ...
6
votes
5answers
457 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 ...
4
votes
2answers
392 views
Solving input noise
I built a very simple circuit so I could use my Bose headphones in the noisy server room without wasting batteries. I however feel silly that I did not know how noisy USB power was, thus the V(L) ...
8
votes
4answers
692 views
Layout advice for LDOs
I'm developing a four layer board which is powered by 3 voltages - 1.8V, 3.3V and 5.0V. The board has the following stackup:
Signals
Ground
3.3V
Signals
The ground and 3.3V plane are completely ...
4
votes
2answers
212 views
Choosing a Tantalum based on Min. ESR - LDO Stability
How does one go about choosing a capacitor for a LDO regulator which specifies a min. ESR? Capacitor datasheets that I've seen only contain the Max. ESR parameter. One could just choose a cap with a ...
1
vote
1answer
147 views
Noise on simple proto
I am trying to evaluate a component (OpAmp) and built this simple circuit. I didn't use a breadboard due to high capacitance and noise, I just soldered stuff over the air thinking this would be low ...
5
votes
3answers
426 views
Why LDO regulators have so big voltage drop?
I wonder, why LDO linear regulators does not use MOSFETs as main component to be able to have minimal dropout=0 (well, depending on current, must be still few mV)?
Or can one expect to build ...
2
votes
2answers
1k views
LDO with low-voltage cutoff?
I'm building a circuit powered by a small Li-Ion battery. The battery will be connected to a 3.3V LDO, which then powers the entire circuit.
Li-Ion batteries are damaged if they are allowed to drain ...
0
votes
3answers
273 views
Voltage rating and tantalum capacitors
I was originally considering using a 10u 6.3V 0603 ceramic capacitor for stabilising the onboard voltage regulator on my microcontrollers. However, it may not be capable because of temperature ...
1
vote
1answer
144 views
Choosing regulator for gyro's and accelerometer
Should I choose a linear regulator that has good transient response? or ultra low Vrms noise? or high accuracy?
I am using digital accelerometers and gyros (BMA180 and ITG3200).
7
votes
2answers
1k views
Tantalum capacitors vs. ceramic capacitors
I have a negative LDO (-5V from -5.5V to -10V) which requires a tantalum or aluminum capacitor. I'm wondering why it can't use a ceramic capacitor? Is there any specific reason for this?
Regulator is ...
3
votes
4answers
415 views
3.3V @ 10mA from 5V - 35V
Any ideas on how to get 3.3V from 5V - 35V at a low 10mA current level? 3.3V need not be precise. It can be 3.5V or 3V, it is powering a small microcontroller.
I'm looking for a small and cost ...
7
votes
6answers
1k views
For a small Vin-Vout difference, is it worth using an LDO vs a buck regulator?
I want to step down 5V to 3.3V at around 250mA.
As far as I see it, there are two options to consider:
Buck: more space, higher cost
LDO: less space, lower cost, more difficult to remove heat(?), ...
8
votes
3answers
715 views
Best solution to get 3.3V from 5V-20V @ 250mA
For my Super OSD project, I need a +3.3V supply at 250mA from a variable input of 5.5V to 20V. Cost is a concern, as is size. Originally, I considered an LM317 in a SOT-223 package, due to the small ...
