MonsonPeer Review – 24 October 2013 SPP/FIELDS LNPS PEER REVIEW Steven Monson University of Minnesota 1

MonsonPeer Review – 24 October D View of Main Electronics Package 2

MonsonPeer Review – 24 October 2013 SPP FIELDS Instrument Block Diagram 3

MonsonPeer Review – 24 October 2013 LNPS Requirements Operate from 22 to 35 VDC Operate over the range of -25 to +65 degrees C base plate temperature Must sync at 150 kHz but operate nominally without sync Provide ten DC voltage supplies –1.8V, 3.3V, 4V, 5V, +/- 6V, +/- 12V, +/- 100V –+/-100V supply to be delayed by 100ms from 5V supply (AEB) Total secondary power to be approx. 7w for LNPS1 and 4w for LNPS2 Monitor and multiplex 10 voltages, LNPS temp and one SCM temp Provide sense circuit and control for SCM heater Provide pass through of some additional lines –Primary heater power for MAG and Preamps –Temperature feedback for MAG and Preamps 4

MonsonPeer Review – 24 October 2013 Comparison STEREO/WAVESSPP/FIELDS 15 watts primary11 watts primary LNPS1 (14w hot) 7 watts primary LNPS2 (9w hot) 100 kHz150 kHz LTC1149 switching regulatorMSKennedy 5055RH (plastic)(LT3845A rad hard dice) HS1825ARH pulse width modulator same 25 degree C55 degree C 5

MonsonPeer Review – 24 October 2013 LNPS Block Diagram 6

MonsonPeer Review – 24 October 2013 LNPS1 Customers DCBRFSDFBAEBSCMMAG (mA)(mA)(mA)(mA)(mA)(mA) 1.8V250 (500)364 (728) 3.3V300 (450)285 (428) 1 4V170 5V150 +6V V V V V V.5 Total 11.3 watts primary (14.5 hot) 7

MonsonPeer Review – 24 October 2013 LNPS2 Customers TDSAEB2MAG (mA)(mA)(mA) 1.8V250 (500) 3.3V300 (450) 1 5V111 +6V V V V V V.3 Total 6.7 watts primary (8.3 hot) 8

MonsonPeer Review – 24 October 2013 Risk - High Currents When Hot The current LNPS design does not have enough margin to accommodate the doubling of FPGA power when hot –Could add more transformers Add two transformers dividing 1.8V and 3.3V into two each –Would take a lot more space for two extra transformers and associated diodes and filters. –Separates DCB and DFB supplies (positive) I have never ran three transformers off of one pair of FETs –FETs would need to be larger also –May be better to go to third PWM (take even more board space) Board space will not be known for a couple more weeks –Could make transformers larger Would increase box height by about.15 inches Would take more space but not as much as above Are high temperature predictions correct? 9

MonsonPeer Review – 24 October 2013 SYNC at 150 kHz Pre-Regulator and PWMs free run at 135kHz 600 kHz square wave clock –generated by DCB for LNPS1 –generated by TDS for LNPS2 Binary counter (HC4024) makes 150kHz for Pre-Regulator and 300kHz for first PWM Second PWM slaved from the first All 3 operate in sync from 16V to 40V input. In the event of sync failure, all 3 free run at 135kHz whether sync stops up, stops down, or is removed completely. 10

MonsonPeer Review – 24 October % efficient at 11 watts 1 watt change causes only 1 mV change in output 11 12V Pre-Regulator

MonsonPeer Review – 24 October V / 3.3V Voltage Variations FPGA currents will go up when hot (LNPS1) –614 mA could go to 1228 mA for 1.8V supply Transformer output will drop.1V Two diode drops will decrease output.25V Filter inductor looses.05V CMC for +V and RTN drops another.24V Total change could be.64V –Need 1.84V minimum –Will need 2.48V out of transformer for quiet room-temperature conditions Can we eliminate CMCs on the 1.8V and 3.3V supplies? 12

MonsonPeer Review – 24 October 2013 Turn On Delay Flight instrument will have AEB +/-100V delayed from +5V by 100ms Top: 12V Pre-Regulator 10V/div Middle: 3.3V 2V/div –Comes from first PWM Bottom: 4V 2V/div –Comes from 2 nd PWM Time: 25 ms/div 13

MonsonPeer Review – 24 October 2013 Voltage Ripple Not able to measure until we have a working EM in box Will depend on how much loads vary Measurements from STEREO/WAVES of complete operating instrument with true RMS meter (300kHz bandwidth): –12V Pre-Regulator25 mV –+/- 8V 20mV –+5V30 mV –+5V DPU100 mV 14

MonsonPeer Review – 24 October 2013 Low Voltage Turn 0n 15 Tested a breadboard with the Pre-regulator and both PWMs Turned on instrument in 1/3 volt increments from 0 to 28V No evidence of a high current mode where two FETS were on at the same time

MonsonPeer Review – 24 October 2013 Inrush current 16 SPP has same specs as STEREO SPP/FIELDS will be very similar to STEREO/WAVES which was well within spec 100ms delay of 2 nd PWM will lower first spike and make a second smaller peak at 100ms 1 ms / div 1 amp / div STEREO/WAVES SPP Requirements