Skip to main content

Questions tagged [derating]

The tag has no usage guidance.

Filter by
Sorted by
Tagged with
3 votes
2 answers
500 views

Super capacitors derating

I want to use supercaps in a system for minimal power interruption backup (1-2 seconds). My systems works at - 40 to 85°C. I have seen that supercaps are usually rated for 1000 - 2000 hours at max ...
Uriel Katz's user avatar
2 votes
1 answer
349 views

X2 Capacitor rating

For a power supply circuit, I need to add an X2 capacitor. I have space constrains - so, considering choosing a very small SMD component. The product will be connected to 230V 50Hz mains voltage. The ...
user14665305's user avatar
3 votes
2 answers
185 views

LED limit to short pulse and high power

I’m studying the viability of a small footprint distance detector that relies on a LED, a photodetector and some lenses. It’s meant for a distance above 150m, where the light beam travel time is ...
PDuarte's user avatar
  • 1,399
0 votes
1 answer
135 views

Fuse/PTC voltage derating

For safe operation of a PCB design, do I need to derate the voltage of a Fuse / PTC? Can I for example assume, that a femtoASMDC008F can be used in a circuit with a nominal voltage of 12V (but ...
KarlKarlsom's user avatar
  • 1,822
3 votes
6 answers
3k views

Filters: what kind of capacitor?

Until recently, I (foolishly) believed that the capacitance of a given capacitor was the capacitance given by the datasheet +- the tolerance. I recently learned about the DC derating of MLCC (multi-...
Sandro's user avatar
  • 7,502
1 vote
1 answer
476 views

For calculating inrush current in a ceramic capacitor , do we need to consider the effective capacitance after derating for dc-bias effect?

Inrush current happens when capacitor is initially charged from 0V to the intended rail voltage. What should be the effective capacitance to be considered during this charging? -Since the voltage ...
Dynamic_equilibrium's user avatar
0 votes
2 answers
207 views

Resistor power rating and circuit stability

I've read the following excerpt from a book (Passive Circuit Analysis with LTSpice by Colin May page 96) but am not sure what that means (with no relevant explanation before nor after): On Fixed ...
KMC's user avatar
  • 1,430
0 votes
1 answer
182 views

Do touchstone (s2p) files for capacitors from include the ESR/ESL, or do I need to add an ideal R/L for simulation?

Manufacturers like muRata and AVX provide .s2p files for their RF capacitors. When modeling for simulation in my EDI software, do I need to include the ESR graphed in the datasheet for the frequency ...
KJ7LNW's user avatar
  • 1,922
-3 votes
1 answer
745 views

surge voltage characteristics of ceramic capacitors

I am reading a datasheet from Murata for a ceramic capacitor. According to the datasheet: When AC voltage or pulse voltage is applied, the peak-to-peak voltage shall not exceed the rated DC ...
user15847's user avatar
  • 113
1 vote
2 answers
1k views

Zener temperature derating

Can someone explain what the Ta line on this zener diode temperature derating graph means please. The diode is an MCC SMBJ5338B 5.1V 5W zener. I understand the lead temperature (TL) line means ...
PhilS's user avatar
  • 11
9 votes
2 answers
6k views

Ceramic Capacitors vs DC Bias - Derating rule of thumb misleading?

Premise Ceramic capacitors with Class 2 dielectrics (such as X5R and X7R) usually show a reduction of its capacitance value as the applied bias voltage increases. This behavior is more prominent in ...
FlyerDragon's user avatar
0 votes
1 answer
95 views

Determining Absolute Maximums for IC Output Current and Power

I'm having a small gap in understanding with a project I'm working on. The project is reliability related and requires looking at the absolute maximum values for some 54ALS family logic (Max Vcc, ...
bladpart's user avatar
2 votes
1 answer
730 views

X5R capacitor derating and highpass filters

X5R capacitors derate to about roughly 85% when DC voltage is applied, from what I have been told. Does this have an effect on high pass filters, even though HF filters off DC (0Hz)? If I wanted to ...
Vinh Trung Thai's user avatar
1 vote
1 answer
8k views

Calculating SMD resistor temperature rise

I am interested in knowing the actual power dissipation of an SMD resistor at a 70C ambient temperature. I am looking at a 10kOhm 2512 1Watt resitor RMCF2512JT10K0. from the electrical specifications ...
fhlb's user avatar
  • 1,470
0 votes
1 answer
236 views

De-rating/re-rating criteria/theory for frequency in circuit breakers

I'm trying to spec a circuit breaker for a system that will be performing in the 3 kHz range, and am not finding much info on how to calculate a new rating based on frequencies in this range (where ...
Matt McNair's user avatar
0 votes
1 answer
881 views

common mode choke and derating vs current

I have a CMC that has is rated at about 1kR at 100Mhz at 3A However my circuit uses only 1A. Do I need to derate my inductance since there is less current flowing through it ?
Johan B.'s user avatar
  • 359
1 vote
2 answers
912 views

How fast do tantalum capacitors self-heal? [closed]

I am troubleshooting a design that uses a 47 µF 20 V tantalum SMD cap across a 15 Vdc rail. While the derating guidelines I follow dictate a 50% voltage derating for tantalum caps, the design I'm ...
Bort's user avatar
  • 1,094
2 votes
1 answer
755 views

Correct LED derating

I am currently looking at the datasheet of a LED and have snipped out the passage of interest. The question is how do I find out the intensity I can reach at a specific temperature/current by using ...
Junius's user avatar
  • 1,021
1 vote
3 answers
2k views

EEE-INST-002 Wire Derating - Single Wire vs. Bundle/Multi-Conductor

We have an aerospace application and are having trouble defining EEE-INST-002's current derating guidelines in regards to wire. The issue that I have isn't about stranded versus solid. MIL-W-22759 ...
depwl9992's user avatar
15 votes
3 answers
4k views

Resistor surge rating

I have a circuit with a 220uF capacitor and a resistor is used to limit the inrush current I stupidly fitted the wrong power rating resistor and (no surprise it failed) its taken me a while to realise ...
Jamie Lamb's user avatar
9 votes
1 answer
15k views

How to derate a ceramic capacitor for DC bias

I understand that the capacitance of a ceramic cap is very dependent on the DC bias applied to the terminals. At rated voltage, I've measured a decrease of up to 70%, and I've heard it can go higher. ...
Jason_L_Bens's user avatar
1 vote
1 answer
265 views

Using a COTS common mode choke on DC

Are commercially available common-mode chokes, such as one you'd pull out of a dead switching supply, suitable for DC service up to their rated current, or will they saturate/do other baleful things ...
ThreePhaseEel's user avatar
4 votes
1 answer
236 views

How do I derate paralleled diodes with negative temperature coeffecients?

In my application, my load current is 1.4 amps, and for reasons of cost, availability, and recovery time, I want to use this particular 1 amp diode. Like many diodes, this one has a negative ...
Stephen Collings's user avatar
0 votes
1 answer
737 views

Power resistor derating

I'm going to use a power resistor which needs to dissipate around 2.5W. I will use a resistor rated at 3W. I have a thermal impedance of 88°C/W. If the ambient is at 40°C, I assume that the resistor ...
thexeno's user avatar
  • 1,305
4 votes
2 answers
158 views

Have bypass cap recommendations already taken derating into consideration?

Datasheets often specify specific values for bypass caps. My assumption is that these values reflect the actual value (after derating), however, I often see on evaluation boards the same nominal value ...
mhz's user avatar
  • 1,010
1 vote
2 answers
553 views

Busbar calculation

I am looking formula and factor involved in calculating DCDB and ACDB busbar calculation in string combiner box. Please share link or example calculating bus bar. choosing proper bus bar effect of ...
Ajit's user avatar
  • 25
0 votes
1 answer
122 views

Which BJT-parameters need to be derated at raised ambient temperature?

I am designing a discrete MOSFET-driver stage based on BJTs in simple push-pull configurations and wondering, which of the values under absolute maximum ratings I have to derate at higher ambient ...
christoph's user avatar
  • 720
1 vote
1 answer
2k views

How to do derating analysis

I need help in learning derating analysis for a vienna rectifier circuit (may be anything). Do you guys suggest any material to do the derating analysis by hand for each component understanding the ...
D_T's user avatar
  • 13
12 votes
3 answers
16k views

What does derating mean?

Derating as the Wiki and other Google articles says operating the part at lower values than rated specifications to prolong its life. Can some please explain "What exactly is Derating?" How it is ...
AKR's user avatar
  • 2,303