Voltage rating on SMD capacitors

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • akis
    Member
    • Jun 2012
    • 20
    • UK

    #1

    Voltage rating on SMD capacitors

    I am using three SMD MLCC X7R 10uF/25V (total 30uF measured 40uF) at the output of a push-pull amp powered by +/-23V, the other side of the cap being a transformer.

    On a purely resistive load I think I'd be within the voltage levels of the cap.

    It is possible depending on the behaviour of the load on the transformer that higher voltages may develop even for very short periods of time.

    Can these theoretical (not observed, just academic) voltages harm the capacitor? How could I check a random capacitor for "good operation" other than plugging it on the cap meter?

    Thanks
  • akis
    Member
    • Jun 2012
    • 20
    • UK

    #2
    Re: Voltage rating on SMD capacitors

    /bump

    anyone?

    Comment

    • mariushm
      Badcaps Legend
      • May 2011
      • 3799

      #3
      Re: Voltage rating on SMD capacitors

      Never a good idea to get the voltage so close. Your voltage can go higher than +/- 23v for sure, depending on your mains voltage, load (transformers output more when there's little load usually)

      But the worst thing is ... those ceramic capacitors won't be 10uF with 23v on them, they're probably going to be 3-5 uF if you're lucky.

      Read up on it :

      * http://www.maximintegrated.com/en/ap...ex.mvp/id/5527
      *


      * video EEVblog #626 - Ceramic Capacitor Voltage Dependency : https://www.youtube.com/watch?v=2MQyQUkwmMk
      * video TDK Tech Tube : DC Bias Effect on Multilayer Ceramic Capacitors (MLCC) https://www.youtube.com/watch?v=weUrWSFJCgk


      You would probably have to use 100v rated capacitors and probably aim for more capacitance.
      Last edited by mariushm; 04-28-2015, 02:15 PM.

      Comment

      • akis
        Member
        • Jun 2012
        • 20
        • UK

        #4
        Re: Voltage rating on SMD capacitors

        Alright I am reading and will now run some tests on my caps to see how they behave! What I was worried about was that reaching or exceeding the voltage ratings might cause irreversible damage, maybe even unnoticeable. like temperature coefficient worsening, or ESR worsening or whatever the capacitor meter won't tell me.

        Comment

        Related Topics

        Collapse

        • quickname
          Cyberpower 1500AVR UPS repair
          by quickname
          I'd like to start out by thanking this forum for providing the info to be able to repair my 15 year old CP1500AVRLCD UPS. Here is all the info I gathered during my trouble-shooting and re-capping.

          Like clockwork, I've had to replace the SLA batteries every 4 years. It was about that time and the UPS was acting like it needed new batteries... randomly shutting off with AC present, not being able to charge fully, and poor runtime when AC was removed. So, I replaced the batteries but noticed that it was not charging properly.

          I decided to verify that the batteries were...
          11-12-2023, 09:57 AM
        • Instafixx
          Macbook A2179 820-01958
          by Instafixx
          Hi,
          Have a Macbook A2179 with liquid damage. Customer showed it some shop which has done an ultrasonic cleaning of the board.
          The board pulls 0V but doesnt turn on. No Fan SPIN. NOT IN DFU.

          I checked the Power Sequences below and found this -


          Once a valid external power source (Charger or battery) is connected, the following rails will come online.
          PPBUS_G3H: Normal voltage is ~12.6v on the charger with the battery disconnected. Produced from the ISL9240 (U7000, which uses PPDCIN_G3H as its VIN.
          PP3v3_G3H_RTC: Normal voltage is ~3.3v. Produced...
          05-20-2023, 05:19 AM
        • bimole
          Weird behavior on 3.3V rail of a CORSAIR CX600
          by bimole
          Hi,

          A colleague gave me an apparently ill CORSAIR CX600.
          He told me that he heard a banging noise, and smelt the magic smoke.
          After tearing down the PSU, no burnt component, everything seems OK, but the PSU often refuses to stay ON. When shorting PS_ON to GND, the fan spins a bit a finally stops. No output voltages.

          I tried to treat some apparently bad solder joins and finally it seems to work OK... on the 12V and 5V rails!
          It's another story on the 3.3V rail...

          I have some devices to test deeply PSUs (scope, AC source, electronic load)...
          02-13-2025, 04:49 AM
        • rddube
          Lenovo L490 Ram voltage circuit malfunction
          by rddube
          Hello friends,

          Looking for some guidance here. The RAM voltage circuit on this motherboard keeps burning out PU301 which is a RT8231AGQW. Copy of the board with the burnt chip attached with some voltage measurements and copy of the schematics also included.

          I think I've checked almost every component in the circuit, but when I change the RT8231, the laptop starts I have 1.2V on the inductor for about 10 seconds and then the RT8231 goes south and no more voltage on the inductor. All other voltages on the laptop are good, this is the only one conking out for a reason I...
          07-15-2025, 04:41 PM
        • Fernon@Repair
          Gigabyte Z490 Gaming X Motherboard No VCORE Voltage
          by Fernon@Repair
          i have Gigabyte Z490 Gaming X Motherboard .it has a power on no display fault .. no vcore voltage and debug led stuck CPU LED .

          VCCIO voltage ok
          VCCSA Voltage OK
          VCCPLL Voltage OK
          Ram Voltage ok
          RamVTT OK
          VPP 2.5 OK

          But No Core Voltage

          and i want to this vrm ic datasheet or pinout (ISL69269)
          anyone have this ic pinout voltages?...
          06-25-2025, 07:19 AM
        • Loading...
        • No more items.
        Working...