international rectifier IRDC2085S-S d emo b oard e valuation p rocedure international rectifier ? 233 kansas street, el segundo, ca 90245 usa overview this document describes how to connect and evaluate the supplied irdc2085s-df demo board. the demo board incorporates a new dc bus converter chipset in a fi xed-frequency, open-loop isolated half-bridge dc-dc converter with 6:1 input to output volta ge conversion ratio. the chipset consis ts of a primary side ic (ir2085s), two 80v primary side fets (irf7493), two 30v secondary side fets (irf 7832), a primary side biasing fet (irf7380) and a secondary side gate clamp fet (irf9956). the fr ont side of the demo board is shown in fig. 1. fig. 1 front side of the dc bus converter demo board wi th ir2085s chipset with marked input and output pins. this version of the demo board employs irf7832 pow er mosfets for secondary synchronous rectification * IRDC2085S-S quick evaluation procedure to evaluate the operation and performance of the irdc2085s -s demo board, connect a power supply to its input terminals, and a power load to its output terminals. input and output terminals are marked in fig. 1. to duplicate the performance data reported on page two, approximately 400 lfm of airflow is needed across the module. the circuit will start to operate as soon as the primary v cc reaches about 9v C typically at 12vin. at this low input voltage, the output voltage will be only about 2v , and the secondary vcc will be insufficient to fully enhance the secondary side synchronous rectifier mo sfets. to avoid excessive body diode conduction losses, output current during slow input voltage ra mp-up should be set at less than 2a. IRDC2085S-S demo board description and circuit capability the circuit is designed to deliver continuous 20a output current in 36v C 60v input voltage range, with 400 lfm of airflow. output voltage for this input voltage range will vary from 6v to 10v, and the total available output power from the module will range from around 120w at 36v to up to 200w at 60v input. the circuit design is optimized in order to demonstrate true performance of the ir2085s control ic, irf7493 primary fets and irf7832 secondary fets. therefore, no t est pins are available on the board. to probe the circuit waveforms use an oscilloscope probe with minima l length for the ground pin a nd connect directly to the pins of the ic / mosfet device. to measure circuit efficiency, voltage and current at the i nput and output of the demo board need to be accurately measured. use of calibrated shunts for input and output current measurements is strongly recommended, as is use of a thermal camera for thermal performance evaluation. * irdc2085s - s 150w dc bus demo board + vout + vin - vout - vin downloaded from: http:///
international rectifier a complete schematic of the demo board is shown in fig. 2. typical efficiency and a thermal image for 150w output power at 48vin are shown in fig. 3. inputs and outputs of two or more modules can be connected in parallel to provide required output po wer higher than 150w. due to natural output voltage droop associated with open-loop operation, no additional circui try is required for relatively accurate current sharing (in the range of +/- 10%). 36~60vinput c1 3.3u rb9 39k vdd c7 22u db3 nm4 irf6603 or irf7832 nm3 irf6603 or irf7832 nm1 irf7493 nm2 irf7493 c8 22u rb2 200 c2 3.3u nm5 irf9956 t c31u vdd cs ct g lo vcc vb vs ho ic1 ir2085s r156k d1 l cb2 .1u db2 9v c41u c51u c647 rg2 100k rg3 10k rg4 10k vdd 36~60vinput cb1 .1u rb10 39k rb1 200 db4 nm6 irf7380 db1 15v db5 3v d4 romote shutdown 6~10vout fig. 2 complete schematic of IRDC2085S-S demo board fig. 3 efficiency and thermal image at 48vin, 150w out max *ir2085s demo board has (2) versions: - irdc2085s-df (uses irf6603 directfet mosfets for secondary synchronous rectifiers nm3 & nm4) - IRDC2085S-S (uses irf7832 so8 mosfet for secondary synchronous rectifiers nm3 & nm4) 62.2c 59.4c 61.5c 66.7c 64.5c 94.5 95 95.5 96 96.5 97 5.0 7.5 10.0 12.5 15.0 17.5 20.0 output load current, io [a] electrical efficiency [%] irf7832 irf6603 downloaded from: http:///
international rectifier IRDC2085S-S demo board pcb layout (total of 8 layers) top layer bottom layer layer #1 layer #2 layer #3 layer #4 layer #5 layer #6 note : the above gerber f ile is available upon request downloaded from: http:///
international rectifier IRDC2085S-S dc bus converter demo board bom list item no ref. designator description part number value package vendor 1 ic1 controller ic ir2085s 100v, +/- 1.0a so8 ir 2 nm1, nm2 single n-channel power mosfet irf7493 80vn, 15mohm so8 ir 3 nm3, nm4 single n-channel power mosfet irf7832 30vn, 4mohm so8 ir 4 nm5 dual n-channel power mosfet irf9956 30vn, 100mohm so8 ir 5 nm6 dual n-channel power mosfet irf7380 80vn, 73mohm so8 ir 6 db4 dual rectifier diode bat54s 30v sot23 ir 7 d, db3 rectifier diode bav16wdict 75v sod123 digi-key 8 db1, db6 zener diode dz23c116dict-nd 15v sod323 digi-key 9 db2 zener diode bzt52c9v15dict 9v sod323 digi-key 10 db5 zener diode bzt52v3v0sdict-nd 3v sod323 digi-key 11 c1, c2 ceramic cap thcr50e1h335zt 3.3u, 50v 1812 digi-key 12 c3 ceramic cap ecj5yb2a105m 1u, 100v 1812 panasonic 13 c7, c8 ceramic cap grm43e61c 226ke01b 22u, 16v 1210 digi-key 14 cb1,cb2 ceramic cap pcc1840ct- nd 0.1u, 25v 805 digi-key 15 c4,c5 ceramic cap pcc2224ct-nd 1u, 16v 805 digi-key 16 c6 ceramic cap pcc1470acvct-nd 47pf 603 digi-key 17 rg3, rg4 resistor p10kgct 10k 603 digi-key 18 rb9, rb10 resistor p39kact 39k 805 digi-key 19 r resistor p51kgct 51k 603 digi-key 20 rg2 resistor p100kgct 100k 603 digi-key 21 rb1, rb2 resistor p200ect 200 1206 digi-key 22 tr_a, tr_ pq transformer core, grinded pq20/16-3f3 window width = 2.4mm grinded feroxube 23 0.5 mil gap pq core center gaped(cut to fit) ma terial 200fn919 kapton polyimide film dupont 24 lo_a inductor core, non-gaped half e14/3.5/5-3f3 feroxube 25 lo_a inductor core, gapped half e14/3.5/5-3f3-axx-e feroxube 26 pcb pcb (8 layers: 3 oz cu top & bottom layers, 4 oz cu center layers, 2.125"x0.8125") 27 tab for input & output connection 3125-2-00-01-00-00-08-0 mill-max 28 connector banana jack, insulated nylon, red & black j151-nd digi-key downloaded from: http:///
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