Questions tagged [switch-mode-power-supply]

A switch-mode power supply (SMPS) switches been fully-on and fully-off states quickly to maintain voltage regulation. They offer lower power dissipation and run cooler than linear regulators that continually dissipate power through a transistor.

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60 views

P-Channel MOSFET With a Floating Gate

I'm troubleshooting a boost/inverting converter that was built using a TPS65131. Below is the circuit I'm working on: U37 in the schematics is an SI2323DS P-channel MOSFET. By mistake, the gate of ...
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38 views

Mains Power Supply for STM32F407 chip

I'm planning to build/design my own STM32F407 chip based board for controlling a DIY audio amplifier. I will have attached to this board some devices like LAN8720, SSD1309 based display and 3/4 LEDs. ...
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55 views

How does the inductor current ripple influence a switch-mode power supply?

I am looking into several DC/DC switching controllers. When talking about component selection, many datasheets and application notes say that inductor ripple should be kept around 20-40% of the ...
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38 views

Buck regulator transient response explanation

I am using TPS5450 buck regulator and trying to measure the transient response but seem to see a weird triangular adjustment before it settles. I can't see anything in the datasheet that would explain ...
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24 views

SMPS mode power supply for 868 MHz operation in S2LP

I am trying to design a PCB for 868 MHz operations using S2LP, referring to the schematic from steval fki868v2. I have attached the same here. I would like to use SMPS mode and BALUN for the operation....
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87 views

12VDC from two different 230Vac voltage sources

I want 12VDC from two different AC source such as Main and DG supply. At a time only one source will be present. Right now I am using the circuit as shown below. Is there a way to replace two ...
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18 views

What Happens when PWM Period register and Compare register is also loaded with same value

Consider, PWM engine based on timers, PWM period register is loaded with 0x3FF (10bit, specifies the period of pwm frequency) and compare register( to vary the duty cycle , when timer count = cmp ...
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1answer
70 views

How can i convert my PWM signal into digital pot?

I have a PWM signal and i wanted to control a high voltage by changing the Feedback resistance of that power supply using optocoupler. But its not working. So i am thinking to convert it into analog ...
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1answer
30 views

the characteristic impedance leakage inductor and lump capacitor

In a flyback converter, how is the characteristic impedance of the leakage inductor and lumped capacitor derived to be \$Z_0=\sqrt{\frac{L_{LEAK}}{C_{LUMP}}}\$?
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43 views

What could be burning the schottky diode in this synchronous rectifier?

I have this TV PSU which has one supply circuit for the TV motherboard, which it calls "standby" in the scheme (AO3). Here's a portion of the AO3 circuit where most of the components I'll ...
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3answers
45 views

Adjustable output power supply for DC DC converter - Custom IC or Digipot?

I want to make a DC/DC supply that outputs between 10V and 28V from a 12V input, the system will need to output up to 20W. Should I use a digipot to adjust the feedback voltage divider, or are there ...
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73 views

What is this burnt, green, capacitor like, protective component marked TH on this switching power supply, and what can I replace it with?

This 220VAC to 24VDC 2.5A switching power supply stopped working. I've found the culprit (or at least one of the culprits) but I've no idea what it is. It is marked TH101. I think it may be a ...
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Question relating to components in SMPS

Why is the ESR (Equivalent Series Resistance) of the electrolytic capacitors important?
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What would be a normal voltage in the voltage feedback pin of a PWM controller?

Several SMPS use a topology that employs an optocoupler to close the control loop for the PWM controller that drives the primary of the ferrite transformer. However, I'm not sure and I can't find ...
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79 views

How to avoid current spike through the MOSFET of push-pull converter at low duty cycle?

I have designed a Push-pull converter as shown: The input is 30V and the output is 400V with the power of 400W. I have designed the MPPT algorithm, magnetic components, etc and the circuit is ...
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79 views

What type of SMPS is this?

What specific type of SMPS is this? I'm working on troubleshooting no power out. I'm having trouble finding comparable circuits so I can learn how it works. It appears to be some sort of resonant ...
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1answer
26 views

Design problem with current mode boost converter with the PAM2423 comp?

I'm trying to a boost conveter PAM2423 which workd at 520kHz for the first time(using a high quality breadboard from jameco for prototyping) following the manufacturer ref schematic: My Setup: I've ...
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75 views

how this equation is obtained for calculating input capacitor of a fly back presented in UC3842 datasheet?

i know that it refers to stored energy formula for a capacitor according to voltage variations. but i dont have any idea about the specified part. where did this part come from? https://www.ti.com/lit/...
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38 views

Dual ouput switching power supply - NEGATIVE VOLTAGE?

I am trying to power an opamp with a negative and positive voltage however I have a qeustion.. Can I take a negative voltage from this power supply? I would take V1 and COM just as normal for my ...
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24 views

Differential Mode EMI Filter Position

In the AC input power supplies; input EMI filters(common + differential) are connected between mains and the rectifier. In some low power power supplies; only differential mode filter is used and this ...
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1answer
41 views

Smps connecting negative output to earth ground

I design a circuit and I need a 3A 12V power supply and want to use a 40W myrra smps but the datasheet mentions this : Now I need to connect the (-) output to GND of the circuit and to Earth Ground (...
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36 views

How can I increase the output current while using LLC topology ? (see details)

I am using a DC-DC LLC topology for my power supply. My input voltage is 400V DC (after PFC boosting.) I need 60VDC 20A, but I only get 12A. I have tried: My switching frequency is at the resonance. ...
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2answers
33 views

How can the output current be programmed in Step-Down Regulators?

I use analog device's LTC3649 regulator as step down regulators. It is said that there is a programmable output current in the datasheet, but I have no idea how to do this. Anyone have an idea or ...
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71 views

Applications for Constant Power Source

Consider a SMPS with a control loop that uses an analog multiplier to control its output voltage in order to maintain a constant power output. I am trying to figure out some of the applications where ...
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1answer
48 views

Understanding RF spectrum of SMPS power supply

I have a (third-party) device that has failed EMI testing, and have been asked to investigate the cause and fix the issues. The device is an automobile accessory, and has 12 V DC power input. ...
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1answer
35 views

Bode Plot of Type 3 Compensator

I've designed a Type 3 compensator and wanted to see it's bode plot on matlab. Here is the transfer function of type 3 compensator: My values are: wp0=203 wp1=6657000 wp2=31400 wz1=5024 wz2=5024 The ...
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81 views

Boost Converter/ Inverting Converter Noise Measurement

I built a boost/inverting converter using TPS65130. The output voltage is +15V and - 15V. Below is a picture of the schematics: I know the schematics shows a zener diode symbol, but that's just a ...
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1answer
35 views

CCM flyback or DCM flyback

Recently, I have been working on a battery charger design based on a flyback DC-DC converter and I am curious about one thing: the flyback converter can work in CCM (continuous conduction mode) and ...
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68 views

1.8kVdc to 700Vdc voltage dropper

I'm trying to get some ideas for dropping 1.8kVdc to 700Vdc using simple voltage dropping techniques/topologies. I am using a SMPS (Switched Mode Power Supply) to regulate the low voltage outputs from ...
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74 views

LTC3862 GATE Pin always high and switch on?

Switch Mode Power SupplyLTC3862-1 GATE PIN(1-2) ALWAYS HIGH and MOSFET Gate Pın ON We are using a LTC3862 for a SMPS (switching mode power supply, 24V to 130V, 0.5A). Firstly, we modelled the design ...
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49 views

Voltage rating for DIY power supply

This is the first time I am building a DIY variable DC power supply using a SMPS and LTC3780 DC-DC Buck/Boost converter (5-32V input to 1V-30V 10A output). For most of my hobby projects 5-10A and 25-...
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1answer
78 views

SMPS grounding interference … ground loop maybe?

I am experiencing a weird phenomenon with my class 1, 15 Volt, 1000 watt SMPS with an isolated input and output grounds. The AC input (PE) ground connection has continuity to the SMPS chassis. When ...
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1answer
37 views

Inverting SMPS - tantalum and part selection | Monolithic controller getting hot

I'm designing a circuit to provide a negative voltage rail in a battery for an ADC. I've decided to use a particular monolithic BCD Chip that can work as a step up/down/inverting controller and has an ...
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68 views

How can i use my power supply ( 24VDC 5A ) in redundant mode ? I need to design it

In redundant mode, if one of my power supply goes off or faulty, my standby power supply shall overtake. I am thinking to use SPDT Relay (24VDC) both in Input as well as Output. secondary power supply ...
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1answer
40 views

Which topology is best to design a DC DC 120W Power Supply? Kindly go through details

My requirement is as follows: Input Supply 110+-30% VDC i.e., 77VDC to 138VDC. output need to be 24VDC 5A. All the basic protections like short circuit, Reverse polarity. No power consumption when no ...
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4answers
621 views

Why do buck converters end up in steady state?

I'm studying buck converters such as the one in the following simulation: I have learned that for buck converters that are in continuous conduction mode and at steady state, the following equation ...
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2answers
142 views

What is the purpose of this sense pin in dual MOSFET package? [duplicate]

No info available in datasheet http://www.aosmd.com/res/data_sheets/AONP36336.pdf After going through the answers I got some additional doubts: Why is the sense pin only there for high side MOSFET? ...
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72 views

DC AC Inverter topologies

I am trying to get a deeper understanding of sine wave inverters (like this one) and thereby came across different topologies like a Push pull inverter with a center taped transformer or a full bridge ...
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55 views

Self-Oscillating Flyback Converter

I am trying to design a self-oscillating flyback converter using the circuit below as a reference. I understand the ton time depends upon the values of Rst, Cf, and Rf and the switching mosfet, M1 ...
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2answers
40 views

Closed loop control ZVS buck converter

I have a buck converter of 400 V input, 200 V output, 300 kHz switching frequency, power output 100 W. I am trying to put it into closed loop voltage mode control. It is working DCM mode. Modelling ...
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1answer
48 views

Transformer Winding Resistance

I have a SMPS transformer and a LCR meter. I can measure 3 different resistance on a winding: R on a certain frequency(10kHz): 0.065R Rs: 0.086(I don't know what is this) DCR: 0.06 Which one is the ...
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57 views

Regarding connecting MOV and SMPS in parallel for electrical meter

We are working on development of a 3 phase electrical metering circuitry. All the 3 phases are connected to metering IC using resistor divider circuitry for voltage measurement (between phase and ...
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1answer
49 views

Power supply design - what safety mechanisms are needed?

When evaluating or designing a power supply for instrumentation (let's say a CT scanner b/c that's my field, and the environment is always changing), what safety mechanisms should I verify? What I can ...
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48 views

Failure Modes for Synchronous Boost Low-Side MOSFET?

I'm looking for some input on possible failure-modes for the low-side MOSFET in a synchronous BOOST converter. I am using LM5122: https://www.ti.com/lit/ds/symlink/lm5122.pdf Out of 50 units built, 2 ...
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2answers
61 views

Meanwell SMPS voltage regulation, changing the Trimmer (LRS series)

I needed a 19V-20V source so I ordered some 24V LRS series SMPSs but they offer 10% adjustability, the voltage range just below that is 15V, the adjustability is also the same there. So none of them ...
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1answer
71 views

The most efficient way to regulate unregulated 12V

I need to power a 12VDC device from an AGM battery, of which the voltage will vary from about 10.5 to 14.5V. The device's datasheet does not mention the tolerance on the supply voltage, I'll assume it ...
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1answer
48 views

What determines output voltage in a feedforward DC/DC converter?

I am designing system that includes a solar power stage with an MPP tracker. The DC/DC converter in the MPPT is feedforward, i.e. it regulates the input voltage of the solar panel to the maximum power ...
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46 views

PWM frequency and control system sampling frequency in dc-dc converters

I am trying to control the output voltage of a simple dc-dc buck converter, which is digitally controlled. The output voltage is sampled, and the control algorithm is run, at every \$T_s\$ seconds, ...
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1answer
58 views

What is magnetization resistance and how to calculate(or measure, or estimate) it?

What is magnetization resistance? How to calculate or measure or estimate it? Edit: I'm trying to build a smps simulation on simulink, in transformer block I have a parameter named magnetization ...
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1answer
50 views

Selecting 36V, 12V and 9V from 3 different PSUs

currently i am designing a system in a machine. One of the feature is it can select power supply between 36V (overvoltage), 12V and 9V (under-voltage). Max current would be 300mA @ 12, while 9V which ...

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