20090528 c20090515 [60].pdf 18192KB May 29 2009 05:10:11 PM

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Breaking Through Performance Barriers Speedster is the World’s Fastest FPGA New Speedster 1.5 GHz FPGAs Breaking through the speed barriers of traditional FPGAs, fully reprogrammable Speedster devices from Achronix Semiconductor are capable of operating at 1.5 GHz peak performance. Speedster’s unique 40 lanes of 10.3 Gbps embedded SerDes and four independent 1066 Mbps DDR2/DDR3 controllers enable extremely high I/O throughput to match the device’s outstanding internal performance. At 3X faster, Speedster opens up new worlds of application design previously unavailable to engineers using traditional FPGAs. Familiar Silicon. Familiar Tools. Fast Time-to-Market. Speedster uses familiar LUT-based fabric and standard synthesis and simulation tools, so designers can use standard RTL. High-Performance Applications See what’s possible: www.achronix.com/speedster
EDITED BY MARTIN ROWE designideas AND FRAN GRANVILLE READERS SOLVE DESIGN PROBLEMS Current-sense monitor and MOSFET boost output current Gyula Diószegi and János Nagy, Divelex Ltd, Budapest, Hungary V IN 4 2 0.125k 8 4 2 1 9 0 1 2 8 7 0.25k 0.5k 1k 6 V IN GND R 1 100 5 R SENSE 4 3 100 TO 900 mA ZXCT1010 1.25k LOAD I OUT 8 4 2 1 8 7 2.5k 5k 10k 9 6 5 0 1 2 5 Figure 1 Passing current through a MOSFET and regulating it with a currentsense monitor bypasses the BCD switches, letting you increase load current. 4 3 3 10 TO 90 mA V OUT 12.5k V REF 8 4 2 1 8 IRF520 7 25k 50k 100k 9 6 0 1 2 5 TLC271 4 4.7 nF 3 1 TO 9 mA 10k R LOAD DIs Inside 47 Multiplexed, programmablegain, track-and-hold amplifier has instrumentation inputs 48 Simple circuit smoothly drives stepper motors 52 Excel spreadsheet yields RLC best-fit calculator 54 Automatically turn secondary lamp on or off To see all of EDN's Design Ideas, visit www.edn.com/design ideas. A previous Design Idea describes a programmable current source that used a three-terminal National Semiconductor (www.national. com) LM317 adjustable regulator (Reference 1). Although that circuit lets you program the output current, the load current flowed through the BCD (binary-coded-decimal) switches. However, you may find it difficult to purchase BCD switches that can handle more than 25 mA, limiting the circuit’s output current. By applying the simple, four-pin Zetex (www. zetex.com) ZXCT1010 current-sensemonitor chip, you can boost current because it doesn’t flow through BCD switches (Figure 1). The load current results in a voltage on the sense resistor R SENSE . The voltage on R 1 , the 100 resistor, is the same as that on R SENSE , generating an output current on R 1 : I OUT 100I LOAD R SENSE , and V OUT I OUT R OUT , where I OUT is the output current, I LOAD is the load current, and V OUT is the output voltage. You can apply the output voltage as a control voltage to regulate the load current. One application for this circuit would be to refill accumulators in portable devices. In this case, the circuit works at 18V. The Fairchild Semiconductor (www.fairchildsemi. com) IRF520 is an N-channel, power- MOSFET chip in an aluminum heat sink with as much as 9.2A current and 0.27 drain-to-source resistance to connect the load current. An op amp controls the IRF520 in the feedback of the load current. In this application, the maximum output current is 1A, and the value of the sense resistor is 0.1. The PCB (printed-circuit board) can also have this small resistance value, which you calculate using 44 EDN | MAY 28, 2009
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Page 5 and 6: 5.28.09 contents Stress out; strain
Page 7 and 8: contents 5.28.09 DC-DC Converters u
Page 9 and 10: New! LPD3015 and LPD4012 miniature
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Page 60: 48 V : 12 V Bus Converter for Serve

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