Questions tagged [ldo]
A Low Drop-Out or LDO regulator is a DC linear voltage regulator which can operate with a very small input–output differential voltage.
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Could you provide feedback on my LTC2954 and TPS61090 Schematic?
I am a hobbyist diving a bit deeper into designing more complex PCBs. In the past, I have created basic ESP32 based 2 layer PCBs with basic LDOs for supplying power. I am currently working on a more ...
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Simplifying a complex power setup
I'm working on an STM32F407 PCB for a flight simulator that has the following conditions:
Normally powered via 12V and an AMS1117-3.3 to power the MCU.
Needs to provide 5V for certain peripherals ...
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LDO voltage regulator malfunctioning as passthrough after 24/7 usage
I have designed a custom pcb utilizing the ENC28J60 ethernet chip to be used with raspberry pi. The board has 5V in which powers both the ENC28J60 (through a AMS1117-3.3 LDO regulator) and the pi. ...
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Powering ESP32-WROOM-32E using LM1117S-3.3 LDO voltage regulator
I want to power my ESP32-WROOM-32E module with an 3.7V Li-Po battery. To reduce the voltage to 3.3V I'd like to use LM1117S-3.3 LDO. As far as I know, the most ESP32 developing boards use AM1117 ...
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What is the general rule for LDO thermal considerations at various voltages?
This question isn't so much about my specific case, but rather, I'm looking for a general rule for estimating the max current that can be pulled from heatsink-less LDOs at some voltage difference.
I ...
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What is the best way to get 5V from USB?
If we need to make a board that use two voltage levels (3.3V and 5.0V) and the board can be powered both from the USB or from an external 5V power bus, then good practice is setting a diode on the USB ...
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LDO stability with resistor in the feedback path
I am working on a circuit for measuring very low and very "fast" currents (think: measuring power consumption of an MCU). I found out that I can measure what I want with a sense amp and a ...
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Check of PDN for RF Amplifier - Revised
This is an update to my previous post. I was recommended to post it again.
For optimal working conditions, HMC863ALC4TR needs Vdd = 5.5 V and Vgg = -0.75 V. I have tried to design such a network to ...
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Trade off between output ripple and switching frequency for DC-DC converters
DC-DC converters datasheets generally specify their output ripple and the switching frequency.
From what I understand, the output ripple goes down as the switching frequency goes up.
When using a ...
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Capacitor at output of component followed by capacitor at input of another component
I am new to electronics; I want to have an isolated power supply. To do so I use a DC/DC converter followed by a low dropout voltage regulator.
Both components recommend a certain layout, the DC/DC ...
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Auto power switching between USB and a range of Lipos (1S-3S)
I'm designing a circuit used in a portable device. I want the option of powering the device over USB or from a range of different Lipo batteries (1S-3S).
I want the circuit to auto negotiate between ...
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Can I use an LDO voltage regulator as current limiter?
Like this, connect the ADJ and Vout of an LDO directly.
The principle of an LDO is to make Vout 1.25 V higher than ADJ. As they are connected, Vout can never be 1.25 V higher than ADJ, and the LDO ...
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Voltage Dropout plot in LTSpice
I am trying to achieve this plot in LTspice from the datasheet of LT1762. (I am a beginner trying to understand how this works)
My schematic is as follows:
The output I get is this.
What am I doing ...
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Best way to control RGB LEDs with wireless MCU
I am working on a project that involves using 5050 package RGB LEDs (specifically, the ones in this datasheet: link to datasheet). Currently, I have successfully controlled one of these LEDs with an ...
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Why do MCU dev boards include multiple voltage regulators?
I was examining the Adafruit ESP32-S3 feather board and noticed that it contains 2 voltage regulators.
It appears that one is used for powering the MCU itself, and the other is for powering I2C ...
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Overshoot on dc/dc converter
Any idea on what would the level of overshoot that this LDO can provide?
Would that data/information on overshoot would be provided in the datasheet? If not, how should I understand that?
I am using ...
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Check of PDN for RF Amplifier
I would like to ask you for help with the power delivery network (PDN) design.
For optimal working conditions, HMC863ALC4TR needs Vdd = 5.5 V and Vgg = -0.75 V. I have tried to design such a network ...
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Does it matter when I step down the voltage in a two part conversion?
I’m designing a 3.3V board using 328P that I want to program via usb, meaning I need a usb to serial conversion. My question is, does it matter if I regulate the voltage (MIC5129 LDO) between the USB ...
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Which topology of power regulator gives a stable voltage output, linear or switching?
I am experimenting on the stability parameter of switching vs linear regulators. By stability I mean how much the output voltage ripple is changing.
A lot of online reading has made me understand that ...
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Two LDOs influencing each other despite only being connected through Vcc
I'm currently writing my bachelor thesis and running into a problem with two of my LDOs nut running as intended. I'm not sure if I'm allowed to share the schematic so I will draw the parts of the ...
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Can I power a circuit from the balance cable of a lipo battery?
Hello I want to power a circuit (that runs at 3.3v) with the balancing cable of a 3s Lipo Battery, my plan is to use only 1 cell through an LDO to power my circuit.
My question is can I power it ...
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Determining feedback resistors for the BD00FC0WFP LDO voltage regulator
I'm trying to configure the regulator to output 4.5V. From what I gather, the output voltage is governed by the voltage divider between Vo and GND where the device's FB pin reads the voltage dropped ...
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Connecting MCP130T-460 and RT9013-33GB together
I have a problem connecting the reset pin of the voltage supervisor directly to the EN pin on the fixed LDO 3.3V voltage regulator (RT9013-33GB).
The MCP130T-460 has an open drain output connecting ...
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Can I cascode 2 positive LDOs generate both positive and negative power rails?
I looked this circuit:
I have a idea,
Can I cascode 2 positive LDOs generate both positive and negative power rails?
For instance, the input is 5.1 Vusb, I cascode 2 TPS7A2050 generating +/-5V:
Can ...
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Gate-source connected MOSFETs for voltage division
Currently, I am engaged in the design of a Thermal Shutdown circuit for an LDO regulator. In this endeavor, I have obtained a circuit schematic from a senior colleague, which utilizes three NMOS ...
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Selecting a low dropout regulator for 5-8.5 V input, 3.3 V output
I need to select a LDO with output voltage of 3.3V for my design.
My load requirement is 300 mA maximum.
The LDO is powered by either USB 5 V (VBUS) or by an external power source ranging from 6 V to ...
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PSRR in LDO system
I have a question about PSRR.
For example, in an LDO PMOS structure why can we increase the PSRR if the output capacitor is the dominant pole? Generally, for ICs, we prefer to not use big capacitors ...
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Is charge pump with DC/DC LDO suitable for low-noise amplifier?
I use LTC6268-10 as a pre-amplifier with the gain of 500. I would like to implement the positive and negative power supply. Could someone give me the idea whether the charge pump DC/DC with LDO is ...
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LDO self-latching circuit review
I am putting together a latching circuit and just want to make sure I am not missing something obvious that would prevent this from working. Circuit:
Note: the actual LDO in the design is XC6701B502PR ...
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LDO PSRR output impedance
Image source: Toshiba Application Note - Simple Guide to Improving Ripple Rejection Ratio of LDO Regulators
Here they are showing that the PSRR can be calculated by a voltage divider at the output ...
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Designing dual tracking regulator low noise PSU
I want to design a power supply with the following constraints
Inputs 19 V - 0 - 19 V secondary & 9.5 V secondary - A transformer I have
ready for the project, primary 230V
. Output +15 & -...
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How to step down DC 19~17V to DC 6V? [closed]
Please help me to looking for a cheap and simple chip or circuit that can step down DC 19~17V to DC 6V with a load of about 200 mA.
I have tried to use an LDO like AMS1117 to drop it violently, but it ...
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Quiescent current in battery circuit
In this circuit I'm using an MCP73832 for battery charging and an AP2210 LDO. The mosfet is a DMP3099L. With the USB disconnected, VBAT set to 4.2V and the MCU (STM32F030F4P6) in standby mode (drawing ...
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Power Regulation
I have a Li-Ion 3S1P Battery Pack with built in BMS rated:
Typ. Capacity: 5000 mAh
Nominal Voltage: 10.8V – 11.1V
Charging Voltage: 12.6V
Discharging Voltage: 9V
I need to power an STA540 in stereo ...
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Safe Operating Area
This is my LDO. 3A part.
Input is 12V
Output is 5V.
Load current is 2A.
As per Figure 2-41 on page 15, at 85degC, I am limited to 0.2A of max load current.
How can I get the 2A load current with the ...
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Why is this regulator circuit unstable?
I'm trying to use a LDO with higher current (5 A in my case) than what it's rated for. I derived for this the following circuit
V is a noisy voltage source between 16 and 22 V (mainly 50 Hz 1 Vpp ...
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Effect of source/input impedance on LDO regulator stability
The datasheet for the MCP1700 family of LDO voltage regulators, in section 5.1 (p.13) states:
...As with all LDO circuits, a relatively low source impedance (10\$\Omega\$) is needed to prevent the ...
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Low drop out regulator
For an LDO (Low drop-out regulator) I am having below two questions but couldnt find a good reference to answer them.
What determines Bandwidth of an LDO? For e.g. for a change in load current what ...
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Issue with LDO in a PWM high current circuit for heating element
I’m building a circuit to control a heating element using a ESP32 as MCU.
The circuit is simple. A 2S lipo battery (8.4 V) as power source and 2 N-channel MOSFETs controlled by PWM in order to ...
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How to choose a "good" 3.3 V LDO and FET for low power applications?
I am trying to design my first low-power PCB using an ESP32 to switch a 12 V 1.2 A LED Strip.
I purchased this module that charges a Lithium battery using a solar panel here. Hence that is where the 5 ...
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Selecting the current rating of a LDO linear voltage regulator
I'm prototyping with a development board which has a 3.3 V rail and I have an IC that needs to be partially powered at 1.9 V. From my research, LDO linear voltage regulators are ideal for this ...
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Power-Input protection
i need a little help with designing a power input "stage" for a product with the following requirements:
Input-Voltage 5V +-10%
Output-Voltage with two independent 1V8 rails (150mA max with ...
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Thermal issues when converting high power using a low drop out linear regulator
We are looking to develop a circuit that will reduce 12 V to 5 V @ 5 A using a low drop out (LDO) linear regulator.
The best device that I found is the MIC29751-5.0WWT.
The heat parameters for this ...
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Filtering USB +5V and filtering battery (also +5V) before and after LDO
I have a development board project where I want to use USB as the power source when plugged in and then switch off the battery - and vice versa. Then I am running it through a 3.3V fixed LDO (AMS1117-...
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Best method of reducing transient current spikes in LDO
I'm using a sensor (U3) that essentially switches an LED on and off using (Q3). The led is fed 5V through an LDO (U4) that steps 12V -> 5V. My current issue is that the switching is causing the ...
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Need advice on LDOs that can take ceramic caps on Vin (8.4 V) and Vout (5 V) at 50 mA of current draw [closed]
I´m designing a really small circuit based on an ATtiny85 and a laser ranger sensor. The PCB is really small, 30 mm by 20 mm, so I need to use smaller and fewer components.
I need a recommendation for ...
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How do I minimize oscillation in this 2-wire electret MEMS microphone interface?
Circuit is as follows:
Ignoring the ground/shield separation at the audio jack, you get a two-wire interface at the plug. The FET does double duty as a minimum drop source follower power supply (DC) ...
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LDO: Is it OK if the input voltage is lower than the output voltage?
I'd like to adopt the TPS7A20-5V as LDO for USB input and output in my analog circuit:
[Datasheet here ]
...
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Is it reasonable to use two LDOs in parallel for redundancy?
I'm trying to have redundancy in part of my design.
I want to use two LDOs in parallel before an OR-controller (specifically, an LM66100-Q1.) One LDO is enough to feed the system, so it will not be ...
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Can a VCC line of a 3W led being PWM'd on the CAT4101 LED Driver be used to power other circuits?
I'm designing a circuit where I'll run a 3W LED using the CAT4101 Led driver, like in the in picture below. VCC will be a 2s Li-Ion battery, at 8.4 - 7.2V DC.
As I'll use PWM to DIM the led, there'll ...
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