AuxPower1U: Power Supply Selection

This is post 5 in the series (next: Cooling, previous: Dell Trigger).


When it comes to power supplies for embedded electronics, it’s really hard to beat Meanwell. They are easily available, they have a wide selection, and they are reasonably priced. Thus, my search for power supply started with the first Meanwell catalog I found.

After testing the Dell trigger board, my power supply setup crystallized to 48/55V (for my routers), 15/20V for computers, and lastly (optionally) 12V for a modem. Why do I say “optionally”? Well, the option of using a buck regulator for the modem is always open. Since I have my case dimensions predetermined, the choice on whether to use 2 or 3 power supplies will be mostly driven by their dimensions.

As 1U severely restricts the height, my choice fell onto four power supply families:

I wanted to get as small as possible (can I fit 3?), a reasonable amount of power at each voltage (100W+, especially for 15V needed by computers), a reasonably small ripple (less than 200mA, if possible), tight voltage tolerance (1%, ideally), high efficiency (90%+ desired), and lastly robust overload controls (ideally with auto-recovery). Looking at the catalog, I placed the following power supplies on the short list:

ModelOutputPowerTolRippleEffDimensions
LRS-35-1212 V 3.0 A35 W±1%120 mV86%99 x 82 x 30
LRS-50-1212 V 4.2 A50 W±1%120 mV86%99 x 82 x 30
LRS-100-1515 V 7.0 A105 W±1%120 mV90%129 x 97 x 30
LRS-100-4848 V 2.3 A100 W±1%200 mV91%129 x 97 x 30
LRS-150-2424 V 6.5 A150 W±1%200 mV89%159 x 97 x 30
LRS-150-4848 V 3.3 A150 W±1%200 mV90%159 x 97 x 30
RS-50-1212 V 4.2 A50 W±1%120 mV84%99 x 97 x 36
RSP-150-2424 V 6.3 A150 W±1%150 mV89%199 x 99 x 30
RSP-150-4848 V 3.2 A150 W±1%250 mV90%199 x 99 x 30
RSP-320-4848 V 6.7 A320 W±1%240 mV90%215 x 115 x 30
UHP-200-1212 V 16.7 A200 W±1%240 mV93%194 x 55 x 26
UHP-200-1515 V 13.4 A200 W±1%240 mV94%194 x 55 x 26
UHP-200-2424 V 8.4 A200 W±1%240 mV94%194 x 55 x 26
UHP-200-4848 V 4.2 A200 W±1%240 mV94%194 x 55 x 26

ModelInputC OverloadV OverloadPFCFanCost
LRS-35-1285-264 VacY (auto)Y (repower)NN$13
LRS-50-1285-264 VacY (auto)Y (repower)NN$14
LRS-100-1585-264 VacY (auto)Y (repower)NN$17
LRS-100-4885-264 VacY (auto)Y (repower)NN$19
LRS-150-2485-264 VacY (auto)Y (repower)NN$19
LRS-150-4885-264 VacY (auto)Y (repower)NN$25
RS-50-1288-264 VacY (auto)Y (auto)NN$19
RSP-150-2485-264 VacY (auto)Y (repower)YN$39
RSP-150-4885-264 VacY (auto)Y (repower)YN$43
RSP-320-4888-264 VacY (auto)Y (repower)YY$54
UHP-200-1290-264 VacY (auto)Y (repower)YN$58
UHP-200-1590-264 VacY (auto)Y (repower)YN$54
UHP-200-2490-264 VacY (auto)Y (repower)YN$57
UHP-200-4890-264 VacY (auto)Y (repower)YN$59

After tinkering with a couple of combinations, including using power supplies from different families, I decided on a homogenous UHP-200-XX setup. They have ridiculously low profile, high power, and high efficiency. On the downside, they do have a bit of a ripple and their cost is quite a hit.

Another setup I could go with would still have UHP-200-15, but combined with LRS-50-12 and LRS-100-48. The downside of this approach would be a bit of a crowded central setup and less robust power supply.

The three power supplies I ended up with are UHP-200-12, UHP-200-15, and UHP-200-55. While the last one might be a surprise since I was leaning more toward 48V, the 55V version has unusually wide adjustment range (45-58V). This means it covers both 48V and 55V thus allowing me some flexibility.

If you look into their datasheet carefully, one will notice that these power supplies require quite a big heatsink. But alas, we cannot solve everything today; there needs to be something for a future me to deal with too. For now, I need to order these three before I change my mind again.