Need suggestions for SMPS ICs for a DIY Lab power Suipply

and maybe another member of the sci.electronics.deign group has some favori te SMPS ICs for this type of application.

wow, 2A at 15Vdc

If you want great performance and not have to concentrate on the design, I'd use SMPS followed by the variable SMPS's, followed by 'tracking' LDO followed by the most humongous RFI/EMI filtering you've ever seen. That way you have efficiency and quiet. Note the tracking LDO means transitory inefficiency. Once you set the Vdc, the tracking takes the LDO up near the value and you keep the efficiency but gain over 10:1 on the output noise.

If you're going to use this as a lab supply, I'd not free run the SMPS, but use sync mode and then vary the frequency while watching the effects on the breadboard as a check to make usre the PS is NOT the problem. It gives you a 'handle' to work with.

I may be preaching to the choir, but WATCH OUT FOR MAGNETIC PICKUP! Use small loops, copper tape shielding etc. Noise goes around all your filtering by either capacitive pickup [which pepole understand] or by magnetic pickup [which most forget about]

I'd concentrate on the vendor: First, I lean towards Linear as a source of IC's that have support. LTC1871 use LTspice to see what's going on. Completely simulate the supply and store with your documentation. LTC1871 I think they have AppNotes that take these up to 10A.

If you're really brave look at the TI line, I found high quality, and now they're going after high performance like some really knock your socks off LDO's.

I hope you come back and share the project with all of us. May be post it on the DIY website too.

Hello Robert,

Thank you for sharing your experience and knowledge. However, it is not obv ious to me why you recommend using a SMPS with a fixed output as a pre-regu lator and connecting the inputs of the variable output SMPS to the output o f the fixed SMPS. What advantages are gained by adding a pre-regulator to this DIY Lab supply.

Howard

bvious to me why you recommend using a SMPS with a fixed output as a pre-re gulator and connecting the inputs of the variable output SMPS to the output of the fixed SMPS.  What advantages are gained by adding a pre-regulator to this DIY Lab supply.

vary the output of the second one.

with the first one fixed, the second one's range of output is lessened: input Vac +/15%, including 'brownout'? input ratio 1.35 output 2:15Vdc? output ratio 7.5:1

no fixed 'input' ratio is then over 10:1 Yes, not sure why tandem occurred to me, but, this is a lab supply, one of a kind, and the overall efficiency suffers with two in series, but blocks with simpler requirements in a system are easier to design seems better to have a lower ratio, you can count on what's going on. Especially when you get into current limiting.

Plus, the filtering at the output won't need to get rid of AC mains modulation, well as much.

When you do design your filtering, watch out for the Zseries to spike at 'cross-over' The damage that can do is to make you 'think' you have an excellent filter because the noise you look at on the scope is so low. But, when you attach an active load with some clock harmonics right on top of that Z spike; you no longer have a low Zimpedance looking back into your power supply, you have something like over 10 ohms! and now you can't understand why the BBD is acting wonky. Easy to use LTspice to see the effect. I've often had to NOT follow the parts list given in vendors' AppNotes, because that effect was not looked at. Make your own filtering, and watch out for PCB layout getting in there. A little bit of magnetic field coupling can undo your best filtering.