This is a set of working notes – hopefully useful to illustrate the tests that have been made, but not intended as a real “presentation”. MPOD special parallel unit, ch 0/1/2 used here At first, according to “original” cable plan, test setup used 120 feet 12AWG cable (Belden #5000FE) 3x 150uF (T495D157K010ATE100) at load (at first – changed later, see below) Load is Agilent 6060B Sense connected with 107 feet Belden #9503 (3x 24AWG twisted pair w/ overall foil shield, one pair used here) Direct connect to sense terminals at PS (try other setups maybe too?) Setpoint 2.70V (I’m not sure of 6060B performance much lower than this, and this is I hope close enough to our lowest setpoint in system, 2.16V) “PWM offset” control set to 12.5V except as noted With all that, following pages show (at remote load / sense connection) the transient response with various 3A load steps (10 Hz square wave), from 6060B. iTOP LV DC Power Supply Tests at Indiana University

2A to 5A PWM offset: 12.5V

5A to 2A PWM offset: 12.5V

8A to 11A PWM offset: 12.5V

11A to 8A PWM offset: 12.5V

8A to 11A PWM offset: 12.5V (ref1), 8.0V (ch1)

11A to 8A PWM offset: 12.5V (ref1), 8.0V (ch1)

At this point, switched to 106 ft Belden # 5T00UP (10AWG, unshielded). This better approximates the revised and hopefully final cable design: 4C 10AWG 2C 16AWG (perhaps to 14AWG) 3pair 24AWG overall foil shield maximum length is expected to be 106ft (32.2m) according to measurements made at Belle-II 1/2015 For the test, sense line connected as before. Lack of shielding on test power lines is not likely to make a significant difference.

8A to 11A PWM offset: 12.5V

11A to 8A PWM offset: 12.5V

8A to 11A PWM offset: 12.5Vno cap at load

11A to 8A PWM offset: 12.5Vno cap at load

8A to 11A PWM offset: 12.5Vgeneric 1mF 63V aluminum axial

11A to 8A PWM offset: 12.5Vgeneric 1mF 63V aluminum axial

The large aluminum capacitor stabilizes it, but I think cannot really be used due to lifetime/reliability concerns. We have to use tantalum, or probably better now the niobium oxide capacitors which have a benign open-circuit failure mode. Next pages explore this. Some damping resistor seems to be necessary, but that’s fine.

11A to 8A PWM offset: 12.5Vref1: generic 1mF 63V aluminum axial ch1: 5x NOJD107M010RWB

11A to 8A PWM offset: 12.5Vref1: generic 1mF 63V aluminum axial ch1: 6x NOJD107M010RWB

11A to 8A PWM offset: 12.5Vref1: generic 1mF 63V aluminum axial ch1: 7x NOJD107M010RWB

11A to 8A PWM offset: 12.5Vref1: generic 1mF 63V aluminum axial ch1: 8x NOJD107M010RWB

11A to 8A PWM offset: 12.5Vref1: generic 1mF 63V aluminum axial ch1: 9x NOJD107M010RWB

11A to 8A PWM offset: 12.5Vref1: generic 1mF 63V aluminum axial ch1: 10x NOJD107M010RWB

8A to 11A PWM offset: 12.5Vch1: 10x NOJD107M010RWB

11A to 8A PWM offset: 12.5Vref1: generic 1mF 63V aluminum axial ch1: 3x NOJD107M010RWB || ((7x NOJD107M010RWB) + 60mΩ)

11A to 8A PWM offset: 12.5Vref1: generic 1mF 63V aluminum axial ch1: 3x NOJD107M010RWB || ((7x NOJD107M010RWB) + 60mΩ)

Now basically let’s assume that this load capacitance is what we’ll use. I looked into aluminum caps a bit, but reliability looks to be worse even for the long-life grades. And, although only one part instead of 8-10 are needed, it isn’t actually smaller. The niobium oxide caps look like the best option for us. So (for now) we use 3x NOJD107M010RWB || ((7x NOJD107M010RWB) + 60mΩ)

5A to 2A (ref1) & 4A to 1A (ch1) PWM offset: 12.5V Results seem consistent w/ ~2.5mF total output capacitance (ours + MPOD internal)

1A to 4A (ref1), 2A to 5A (ref2), 3A to 6A (ref3), 4A to 7A (ref4), 5A to 8A (ch1) PWM offset: 12.5V

6A to 9A (ref1), 7A to 10A (ref2), 8A to 11A (ref3), 9A to 12A (ref4), 10A to 13A (ch1) PWM offset: 12.5V

10A to 13A (ref1), 11A to 14A (ref2), 11.5A to 14.5A (ch1) PWM offset: 12.5V

PWM_offset=12.5V, no “PWM from Umod” (ref1), PWM_offset=12.5V, yes “PWM from Umod” (ch1) 11A to 14A

PWM_offset=12.5V, no “PWM from Umod” (ref1), PWM_offset=6V, no “PWM from Umod” (ch1) 11A to 14A

PWM_offset=12.5V, no “PWM from Umod” (ref1), PWM_offset=6V, yes “PWM from Umod” (ch1) 11A to 14A

PWM_offset=12.5V, no “PWM from Umod” (ref1), PWM_offset=15V, no “PWM from Umod” (ch1) 11A to 14A

PWM_offset=12.5V, no “PWM from Umod” (ref1), PWM_offset=15V, yes “PWM from Umod” (ch1) 11A to 14A

PWM_offset= 15V (ref1), 13V (ref2), 11V (ref3), 9V (ref4), 7V (ch1) 11A to 14Aall cases no “PWM from Umod”

PWM_offset= 7V (ref1) as before, 6V (ref2), 5V (ref3), 4V (ch1) 11A to 14Aall cases no “PWM from Umod”

MUSEcontrol screenshots, in steady-state operation (maybe not fully warmed up, but close) with 14.5A load (nominal from 6060B front panel entry / readout)

I plan to check still the waveforms at PS terminals under the various 3A transient steps quick comparison of performance at 5V regulated instead of 2.7V – any difference in stability efficiency check (although it isn’t very meaningful with so little overall load on the crate, we can probably still get some useful info from it, by looking at AC input delta with load 0A, 14.5A) cable temperature measurement (qualitative impression is, it is much cooler than the 12AWG cable…) And then I have to return the MPOD mainframe to Wiener. Next testing will be by them, with PL512. If that looks good, we should buy one for our prototype.

load (ref1), PS terminal (ref2), independently acquired! PWM offset: 12.5V1A to 4A

1A to 4A (ref1), 2A to 5A (ref2), 3A to 6A (ref3), 4A to 7A (ref4), 5A to 8A (ch1) PWM offset: 12.5V PS terminal voltage scope offset adjusted to overlay traces, same V/div

PWM offset: 12.5V PS terminal voltage scope offset adjusted to overlay traces, same V/div 6A to 9A (ref1), 7A to 10A (ref2), 8A to 11A (ref3), 9A to 12A (ref4), 10A to 13A (ch1)

PWM offset: 12.5V PS terminal voltage scope offset adjusted to overlay traces, same V/div 10A to 13A (ref1), 11A to 14A (ref2), 11.5A to 14.5A (ch1)

PWM offset: 12.5V 11A to 14A PS terminal voltage scope offset adjusted to overlay traces, same V/div Vset=2.7V (ref1), Vset=3.7V (ref2), Vset=4.7V (ch1)

PWM offset: 12.5V 6.4A to 9.4A PS terminal voltage scope offset adjusted to overlay traces, same V/div Vset=13.85V (ref1), Vset=13.35V (ch1) ref1 scale is offset +500mV This was a check that we can run right up to the voltage limit of the supply and still hold regulation. Success. Unfortunately, scope offset range limitations get in the way here. But that isn’t important.

PWM offset: 12.5V 6.4A to 9.4A PS terminal voltage scope offset adjusted to overlay traces, same V/div Vset=13.85V (ref1), Vset=15.00V (ch1) ref1 on same scale (no offset) In fact, we can go beyond the nameplate 16V limit. MUSEcontrol allows max terminal voltage to be set to 17.6V, did that, we can run right up to it and it works well as seen here.

3A to 4A (ref1), 3A to 5A (ref2), 3A to 6A (ref3), 3A to 7A (ref4), 3A to 8A (ch1) PWM offset: 12.5V

3A to 3.2A (ref1), 3A to 3.4A (ref2), 3A to 3.6A (ref3), 3A to 3.8A (ref4), 3A to 4A (ch1) PWM offset: 12.5V

Now a look at if we can do any better using “fast” remote sense setting (i.e. “medium” box unchecked in MUSEcontrol) together with some external network to stabilize. First revisited the load capacitance, I find can get just as good, maybe slightly better, performance from 60mΩ+(10x NOJD107M010RWB). So that’s what’s there now. Also, find that sense input to MPOD is pretty high impedance, and we can connect sense lines with up to few hundred Ohms and have no change in performance. (Tested at MPOD, not at load side, need to re- check.) “Fast” regulation stabilized with 450 Ω to load sense cable, 400 nF to PS out terminal, on each PS sense terminal (i.e. one of these networks on positive and one on negative). This was done with substitution boxes and values optimized by a bit of experimentation. But performance that way is not as good as “medium” regulation mode with no network (or with only 50 Ω resistors and no caps), see next slide. That’s fine, “medium” regulation mode looks good for us. This was just a test to see what happens; note that we use a similar network to make long distance remote sense work on Excelsys unit under test.

“medium” (ref1), “fast” w/ 450 Ω, 400nF (ch1) PWM offset: 12.5V 3A to 6A

I confirmed, the 50 Ω or even up to a few hundred Ohm resistors can be used to connect the sense lines at the load. I think we will probably do this rather than use polyfuses. Resistors should be more reliable and convenient. Final circuit (showing only one of the three PS circuits that feed each FEE (“boardstack”) is below: Note that (owing to space constraints) the final 1.2m of the circuit is run on lighter gauge wire and remote sense is placed at the junction point not at the FEE.

Question: We may be able to use 8V modules (and so 2 ch parallel for 20A capability, rather than 3 ch parallel for 15A). On the 16V unit, max terminal voltage is 17.6V according to MUSEcontrol. It doesn’t seem to be specified on the datasheet. From my testing, this really works… Is the exact value universal, or it depends on specific module’s calibration? What is guaranteed minimum value of this, if it varies. And most importantly, what is corresponding value for the 8V 10A MPOD module????