If I need to generate +/- 15 volts for a circuit, 2 single SMPS or 1 dual?

[VermontEE]

If I need to generate +/- 15 volts for a circuit, is there any benefit to choosing a dual DC-DC converter (like the ADP5071 or LT8471) versus tying two single output SMPS, one at +15 and the other at -15V together with a common ground?

The circuit in question is part of an current source feedback for a laser driver

Assuming the % regulation, ripple, etc... of each supply needs to be equal


Things that I can think of that might drive the decision.

Cost
PCB space
Thermal management of two single vs a dual solution
EMI switching noise
inductance introduced from the trace between the grounds of the individual SMPS chips
Availability of a second source should the dual go obsolete or on allocation

Thanks

[Neilm]

Buy one with a dual output and a standard footprint. You will never match commercial supplies for their economies of scale and size. I only ever spin my own if I need something special (very high voltage isolation for instance)

[VermontEE]

Whats the source and whats the load. You could do a flybuck or a flyback for dual outputs, depends how comfortable you are with doing your own magnetics.

AcHmed99

The source will be a AC-DC converter brick something like this but not necessarily this exact model

http://www.cui.com/product/power/ac-dc-power-supplies/external/desktop/sdi120-u-series

The load...that is a great question. I will have to get back to you. I assume you mean the nominal load in terms of amps and the maximum and minimum draw during operation. I don't have those figures in front of me as somebody else designed that part of the circuit. I also assume by load you don't mean impedance. I have worked with flybacks a lot but from the standpoint of troubleshooting for EMI output and noise reduction for RF design. I think that rolling my own transformer will be a no go as I'm not willing to take the risk in design time to get this right. I'm sure somebody with proper experience could knock it out of the park but I'm not there yet.

[VermontEE]

Buy one with a dual output and a standard footprint. You will never match commercial supplies for their economies of scale and size. I only ever spin my own if I need something special (very high voltage isolation for instance)

This is an intriguing option. I'll have to see if the budget will allow for this level of integration. It would accelerate the project timeline significantly but the first one that I looked at was $50 USD so I might have look around for a cheaper option. I'd have to go through the gauntlet of naysayers based on price and then I'd have to face my engineering peers who would look at me like I was not up to the task of doing the job out of IC's. I agree with you that this solution would be a no brainer if the product can support it.

Thanks

[VermontEE]

Too funny - too bad it's true

[Kleinstein]

Using two separate SPMS close together can sometimes cause extra low frequency noise, if the frequencies are similar, but not synchronized. The dual converter avoids this, as usually they use just one clock.

Unless special requirements are needed, the ready made isolated DCDC converters are relatively cheap and easy to use.