# Questions tagged [derating]

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### 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 ...
107 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 ...
162 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 ...
47 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, ...
894 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 ...
85 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 3kHz range, and am not finding much info on how to calculate a new rating based on frequencies in this range (where ...
259 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 ?
443 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 ...
294 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 ...
621 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 ...
1k 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 ...
8k 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. ...
212 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 ...
498 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 ...
108 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 ...
120 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 ...
399 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 ...
77 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 ...