Hi Guys,
I'm a student at a faculty of electrical engineering and recently I got fascinated with avionics hardware. One of the standards involved is the DO-160G which gives the mechanical and electrical requirements. The longest section is about power supply and I got really interested in that. For a 28 Vdc system, the electronics needs to handle 80V spikes. I have already build a power supply input stage which is capable of handling such surges (basically a mosfet voltage limiter), but I have no way of testing if it actually works. Here's where I need your input.
So the standard specifies the power supply waveform in the attachment. The device needs to handle 80V for 100ms, then 48V for 1sec and then back to 28Vdc normal (see attachment). The rise time needs to be < 1ms and fall time < 5ms. The suggested test circuit is in the attachment. The standard also says that pull down resistors might be added to meet the 5ms fall time requirement. The thing is, that this surge generator is quite boring and not very adjustable. You need three power supplies and more or less you need three adjustable power supplies. For instance, in some categories you only need to test up to 60V surges.
I was thinking that it would be a better idea to build like a power B-class type amplifier, but for DC. That way I could generate the waveform with an arbitrary waveform generator and have the amplifier amplify the amplitude by 10x. I did a few quick simulations in LT-spice and the problem I'm getting is that the B class amplifier overshoots by a lot when a capacitive load is added to the output. Of course, the DUT will always have some capacitance on it's power supply input. Does anyone have any experiences in this field, or maybe a different suggestion on how to build such a surge generator? Any input is more then welcome.
Regards
Ivo