Questions tagged [ripple-current]

Small unwanted residual periodic variation of the direct current (dc) output

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1answer
85 views

Can we use electrolytic capacitors on IC power rails?

Can we use bulk electrolytic capacitors on the power rails of an IC? I know that we will use bulk capacitors in switching regulators at input. Can anyone explain why or why not and how to find ripple ...
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1answer
75 views

Spike and Ripple Currents in PWM-driven DC Motor

I intend to drive a DC motor through an H-Bridge with PWM Control. Therefore I'm using only NMOS powerfets to drive the bridge. However I'm facing an issue with the current at the MOS gates. As you ...
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1answer
732 views

Calculate peak input current of switch mode power supply

I have the following problem. MY ATTEMPT The switch-mode power supply looks like it's a boost converter. I found that the DC-transfer functions for the boost converter to be: \$\frac{V_C}{V_{...
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73 views

Techniques for measuring the ripple current of SMD electrolytic capacitors

I am currently creating a test plan for an AC/DC converter (90VAC...264VAC -> 12VDC) I've been working on. Since the output electrolytic capacitors are of SMD type, I am trying to come up with ...
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2answers
1k views

Capacitor specifications, ripple current and life

What does the "Ripple current" and the "Life (in Hours)" in electrolytic capacitors specifications mean? My intuition says it's the highest current it can handle and it can operate for that hours (...
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3answers
556 views

SMPS Input/Output ripple current and ripple voltage

I found a presentation regarding SMPS and found this slide. I am not totally able to grasp the concept of the input and output ripple current. In the above image I have the following questions : I ...
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5answers
3k views

Are all linear regulators bad at filtering input ripple? (or really as bad as Dave suggests)?

Background In EEVBlog #1116, Dave discusses a method to remove power supply ripple, and goes on to show (see 5:17 to 6:15) that you cannot count on linear regulators to remove your input ripple. He ...
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1answer
76 views

PT4115, where should I put output capacitor?

The PT4115E datasheet states: Peak to peak ripple current in the LED(s) can be reduced below 30% of the average current, if required, by adding a capacitor across the LED(s). Can you confirm ...
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1answer
305 views

Ripple current at output capacitors

I was reading about the selection of output capacitors at the output of buck converters and found this Link The accepted answer states that before I select an output capacitor, we must fix the ...
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1answer
101 views

Measuring Output Ripple Voltage Problem

This is a followup of my previous question. Boost IC = NCV3063 Vin = 8V Vout = 23V Iout(max) = 250mA - (Load is a constant current circuit which is enabled at 200Hz) Schematic Mentioned the ...
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1answer
351 views

Bulk Capacitor Ripple Current as a Function of Capacitance

When you have a bulk capacitor on a time varying load, what is the relationship between the capacitance of the bulk capacitor, the ESR of the bulk capacitor and the ripple current through the bulk ...
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1answer
126 views

Selecting capacitor for SEPIC converter

I'm looking for an advice how to select capacitors for my SEPIC converter. I have done calculations, but I haven't find Cin, Cs and Cout yet. What seems like a problem is that there are few work ...
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2answers
239 views

Inductor current ripple ratio of buck boost converters

I have a question about this paper: https://ieeexplore.ieee.org/document/1210630 I have always thought that the maximum current ripple of a buck converter occurs with a duty cycle of 0.5. The paper ...
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3answers
146 views

Boost LED driver output spikes

I designed a boost LED driver based on TPS92691. It drives 56V 5A COB LED from 22-50V input. It works ok. Oscilloscope shows small spikes on input (100mV), but large spikes on output (3V). The spikes ...
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1answer
299 views

What might this term (N sub C) be, calculating ripple current for a buck converter output capacitor?

I'm reading through the datasheet for TI's TPS54302 step-down converter, and determining values for support components. There is a calculation to determine ripple current for the output capacitor ...
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2answers
423 views

Understanding inductor and LED ripple current in LM3409

I am reading the datasheet of the LM3409, specifically section 9 "Application and implementation". My intent is to understand how to calculate the values of the components needed for my specific ...
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2answers
1k views

What causes SMPS voltage ripple?

In many datasheets and application guides there is always an equation for ripple current, because it is fundamental to the operation of a buck or boost converter, but I never see a direct equation for ...
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0answers
109 views

How to convert Ripple Current spec to ESR?

It used to be that vendors like Digikey gave a cap's ESR value and not ripple current. Nowadays, it seems more report only ripple current and not ESR. What gives with that? So what are we supposed to ...
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1answer
464 views

How to measure 120 Hz ripple current at the output of an LED driver?

I have a 50W LED driver and a programmable load. Please suggest a way to measure 120Hz ripple current! I have an oscilloscope and multi-meters.
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0answers
161 views

What will be the output ripple current per capacitor buck regulator?

I have a existing buck regulator design. Converter part number: TPS54340Q1. Input voltage = 5 V. Output voltage = 3.3 V RMS ripple current is calculated as = 108 mA. (Don't worry too much about ...
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2answers
1k views

Ripple Current in Boost Converter for Nixies

I'm trying to design a power supply for 6 IN-8 Nixie Tubes (driven individually, not multiplexed). Each tube has a current draw of 2.5-4.5mA, so they pull around 30mA(max) total. The input voltages is ...
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1answer
324 views

Buck-Boost power supply I_ripple calculation

I'm not looking to get torn apart, just looking for a hand. I can't remember exactly how to calculate the RMS Current required from the output capacitors or a Buck-Boost power supply and I was hoping ...
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1answer
2k views

How do you identify what capacitor to use to filter DC voltage ripples from a bridge rectifier? (capacitance, etc.)

Let's say I have reduced 220V 60Hz AC to 1.5V 750mA AC with a step-down transformer and used a bridge rectifier consisting of 4 IN4007 diodes to convert it to DC. How do I math this down?
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2answers
310 views

Is this inductor and caps a good choice for a buck converter?

I wanted to get together a simple and efficient 12V to 5V switching power regulator using only through-hole components that can be soldered to a nice protoboard. For my purposes, I need to provide 0....
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2answers
10k views

capacitor voltage ripple in buck converter

I am struggling with output voltage ripple calculation of the buck converter below. Firstly, I don't understand the following statement from the lecture. Can anyone explain it? If the capacitor ...
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4answers
5k views

Ground plane directly underneath physically large 100 µH inductor?

I plan to use a physically large ferrite core inductor (Murata part "1410478C", 100 µH at 1 kHz) in a 12 V, 7 A DC filter circuit. It will be mounted on topside of a four-layer PCB ...
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1answer
1k views

Determining the input capacitance for a SMPS [closed]

I'm attempting to layout a SMPS using the LTC3703 chip, however the datasheet doesn't talk about the AMOUNT of input capacitance, just that it be low esr. However, it does talk about "bulk ...
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3answers
163 views

Ripple flowing through probes connected to the same point!

While trying to filter the ripple of my switching PSU, I've come to a phenomenon that is probably well known to professionals, but seems absurd to me. Admittedly, my scope is not of the highest ...
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1answer
431 views

How to protect constant LED current from ripples & clamps?

I need to develope a constant current LED Driver. The product must be portable and as small as possible. So I can not use SMPS, I have use AC/DC adapter as source. This is the AC/DC adapters output: ...
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2answers
748 views

Ultra low ripple constant-current LED driver design

I designed a LED driver(SMPS configuration) with ILD6150XUMA1 and below is the circuit. I used it with AC/DC adapter. The thing is, th optical system is ultra sensitive and ripple from the LED ...
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4answers
768 views

Measure indcutor ripple current in a SMPS

I need to measure the ripple current in a buck converter. In general, I add leads to the inductor and use a current probe. My issue now is that the inductor I am using has such a low inductance that ...
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0answers
290 views

How to estimate ripple current for PWM loads?

I'm buying some caps for a PCB which I'm designing, and I'm not quite sure how to estimate the ripple current they need to be. This PCB is intended to switch about ~15A from 12V to 24V at ~100kHz. ...
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5answers
1k views

What is the problem with charging a (lead-acid) car battery with AC power?

The closest thread I've found (which didn't show up in the automated suggestions) was What happens if an AC voltage is applied to a battery?. Unfortunately, I felt like the answers were more aimed at ...
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1answer
163 views

Where can I find a stable AC to DC switching power supply?

I've purchased multiple 3V switching power regulators form Amazon and they all have spikes in the ripple. Here's an O-scope capture: The spikes increase frequency depending on the load. Are these ...
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1answer
3k views

Capacitor Ripple Current - Frequency coefficient

I am designing a motor controller with a 11A max start load and 3A max continuous load. Looking for capacitors I found in this datasheet a "Frequency coefficient for ripple current", what is that and ...