I'm looking for a replacement for an old bridge rectifier and I've found one (Vishay B80C1500G), but I'm curious about two parameters of the bridge rectifier:

  1. Maximum load capacitance
  2. Rating for fusing

As far as I know the more capacitance connected to the bridge, the more peak current occurs when the capacitor is being charged. Am I right? Other producers of bridge rectifiers don't specify this parameter in their datasheets. Does this parameter depend on Peak forward surge current (IFRM) and maximum peak working voltage (VRWM)?

How to understand the second parameter: rating for fusing? For what is this used?

bridge rectifier datasheet


1 Answer 1


Gosh, I can't remember when, or if, I've ever seen limiting impedance specs on a rectifier, aside from vacuum tube types. How...old fashioned?

Yes, IFRM, IFSM and I2t are equivalent ratings; meet or exceed these with a replacement and you're fine.

Excellent resources are available to explain fusing, see for example:
Eaton - Fuseology
Digi-Key - Fuse I2T Rating, Melting Point, and Interrupt Rating
How do I use the I2T rating of a fuse?

In particular, the active phrase in the first link:

Typically the semiconductor data sheet specifies a maximum I2 t withstand for a semiconductor device. To offer short circuit protection to the semiconductor device, the fuse selected should have an I2t let-through less than the I2t withstand rating of the semiconductor device.

  • \$\begingroup\$ Thank you, very useful links. I'm still curious why "rate for FUSING" parameter is given for the BRIDGE RECTIFIER that it isn't even works as a fuse \$\endgroup\$
    – Krystepan
    Commented Apr 6, 2023 at 9:27
  • \$\begingroup\$ Added in the edit. \$\endgroup\$ Commented Apr 6, 2023 at 10:00

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