# How much current can be drawn from 1N4007 based bridge rectifier

I am not an electronics expert. Hence little confused with the current rating of 1N4007 diode. I know it's rated for 1 Amp and 1000 V. But I want to use 4 of them in a bridge rectifier circuit which is supposed to rectify 200 Volt AC to DC. How much max current can I draw from this rectifier safely? I'll be glad, if someone can help me understand the calculation as well.

If those diodes were sold as a bridge, it would be rated at 2A average current (when rectifying AC, since only one pair conducts at a time).

However that's under some (fairly reasonable) operating conditions, and if you are outside those conditions you may need to derate the maximum current. If you want good reliability you may choose to derate the maximum current. See, for example the datasheet diode derating and conditions such as lead length and pad size:

Typically you should derate 20% or more for a capacitive load as well, since the RMS current will be higher.

• @TonyM The average current per series pair is 1A, 50% duty cycle. Total average current is 2A. Of course if it's possible to have DC input then you can't assume 50% duty cycle. Commented Dec 16, 2021 at 23:51
• I thought I was probably falling into an obvious pitfall when I asked :-) But the Vishay datasheet (and the Diodes Inc datasheet) specifies IF(AV) as 1 A, defined as Maximum average forward rectified current, 0.375" (9.5 mm) lead length at TA = 75 °C. I'd interpret that as giving the average: 1 A, not 2 A. In other words, haven't you taken their figure with allowance for AC average then subjected it to another allowance for AC average? Commented Dec 16, 2021 at 23:58
• @TonyM "average forward rectified current" is obviously half-wave and is 1A. The two diodes in series have the same current, so the rating is the same (thermal considerations aside). The second pair also has average 1A so the total is the sum of the two. Maybe worth pointing out that the peak current in each diode will be much higher than 1A, about 3.1A if I did the math right. Some of the comments in this question touch on the issue. Commented Dec 17, 2021 at 0:08
• I can see what you're driving at and I'd first looked at the typical diode current: short spikes, once per cycle per diode, topping off the reservoir capacitor across the bridge. It's the exact meaning of the terminology that I'm seeing differently to you. (Incidentally, I'll delete this comment chain later, it'll not be needed or I can summarise it better.) Commented Dec 17, 2021 at 0:16
• This answer ignores the major design consequences at this voltage. (-1) for inrush current , ripple voltage vs RMS rating of the diode. Commented Dec 17, 2021 at 14:04

I want to use 4 of them in a bridge rectifier circuit which is supposed to rectify 200 Volt AC to DC. How much max current can I draw from this rectifier safely?

This is a common beginner goal but let me explain why it is not a good one.

1. Diodes are really sturdy dynamic nonlinear switches that can rectify from microamps to 30 Amps for 1 half cycle at 60Hz absolute MAXIMUM. Yet voltage is even more dynamic and when the bulk capacitor starts at 0V and goes up to sqrt(2)=1.414 times the RMS AC voltage the diode and capacitor current is only limited by the loop resistance. In theory, the grid is 0 and the caps are 0 while the diode depends on bulk size and thus peak current becomes V/R=I which can easily burst both diode and/or capacitor. So chokes and resistance must be added for high voltage to limit the current. This causes a few cost penalties.
1. the power current limiting resistor must waste about 10% of the load power and ends up costing a lot more than a dozen 1N400x diodes and is still boiling hot.
1. the capacitor also has foil-dielectric interface resistance called effective series resistance (ESR) and must also dissipate heat except it is unavoidably thermally and by design, electrically insulated. So the bulk capacitor for a low ESR Cap at high voltage that can supply the 1A RMS rating of the diode in question will cost again, more than a dozen of these diodes.