Embedded Systems Design - July 2008 - (Page 32) This board layout includes the optically-isolated portion of the Figure 3 power supply circuit. Figure 4 plement a precision reference. That option is not available in this case, because the resulting voltage (VA-Kmin = VREF = 2.5 V, plus drops in the U45 LED and in R124) is too close to the desired 3.6-V output. One alternative is the MAX8515A shunt regulator from Maxim. It includes a voltage refNEW erence of only APPROACHES 0.6 V, with This IC is the best option for 1% tolerance TO FURTHER REDUCE in the range applications in which the CURRENT 40ºC to circuit must provide lower Several alterna+85°C. This output voltages, because it tives, based on IC is the best Texas Instruoption for apdoesn’t have a “large” ments’ plications in reference voltage. UCC38C41 or which the cirMaxim’s cuit must MAX5021 provide lower PWM controller and TI’s TLV431C or output voltages, because it doesn’t Maxim’s MAX8515A precision referhave the limitation mentioned above ence, can further reduce current drawn (a “large” reference voltage of 2.5 V). by the converter. The associated compoAnother option for this example is nents are selected for minimum possithe TLV431C shunt regulator. Availble power consumption. able from several manufacturers, it also meets the requirement of VREF = Error comparator 1.24 V, with 1% tolerance from 0°C to The classic TL431 can sometimes im+70°C. Current through the output dimust also take care that the RC filter formed with C53 doesn’t affect the current signal. Power consumption in the oscillator components (R126 and C46) is unavoidable, because the voltage output must be maintained at all times. No-load current for different input voltages. VIN (V) IIN (mA) VO(V) 10.0 12.0 15.0 Table 2 IO(A) 0.06 0.06 0.06 6.12 5.78 5.44 3.612 3.612 3.612 http://www.embeddedarm.com
Table of Contents Feed for the Digital Edition of Embedded Systems Design - July 2008 Embedded Systems Design - July 2008 Contents #Include Parity Bit Programming Pointers Interactive C-code Cleaning Tool Supports Multiprocessor SoC Design Building a Power Supply for Discontinuous Transmission Wireless Networks An Exception Primer Advertising Index Break Points Marketplace Embedded Systems Design - July 2008 Embedded Systems Design - July 2008 - Embedded Systems Design - July 2008 (Page Cover1) Embedded Systems Design - July 2008 - Embedded Systems Design - July 2008 (Page Cover2) Embedded Systems Design - July 2008 - Embedded Systems Design - July 2008 (Page 1) Embedded Systems Design - July 2008 - Embedded Systems Design - July 2008 (Page 2) Embedded Systems Design - July 2008 - Contents (Page 3) Embedded Systems Design - July 2008 - Contents (Page 4) Embedded Systems Design - July 2008 - Contents (Page 5) Embedded Systems Design - July 2008 - Contents (Page 6) Embedded Systems Design - July 2008 - #Include (Page 7) Embedded Systems Design - July 2008 - #Include (Page 8) Embedded Systems Design - July 2008 - Parity Bit (Page 9) Embedded Systems Design - July 2008 - Programming Pointers (Page 10) Embedded Systems Design - July 2008 - Programming Pointers (Page 11) Embedded Systems Design - July 2008 - Programming Pointers (Page 12) Embedded Systems Design - July 2008 - Programming Pointers (Page 13) Embedded Systems Design - July 2008 - Programming Pointers (Page 14) Embedded Systems Design - July 2008 - Programming Pointers (Page 15) Embedded Systems Design - July 2008 - Programming Pointers (Page 16) Embedded Systems Design - July 2008 - Programming Pointers (Page 17) Embedded Systems Design - July 2008 - Interactive C-code Cleaning Tool Supports Multiprocessor SoC Design (Page 18) Embedded Systems Design - July 2008 - Interactive C-code Cleaning Tool Supports Multiprocessor SoC Design (Page 19) Embedded Systems Design - July 2008 - Interactive C-code Cleaning Tool Supports Multiprocessor SoC Design (Page 20) Embedded Systems Design - July 2008 - Interactive C-code Cleaning Tool Supports Multiprocessor SoC Design (Page 21) Embedded Systems Design - July 2008 - Interactive C-code Cleaning Tool Supports Multiprocessor SoC Design (Page 22) Embedded Systems Design - July 2008 - Interactive C-code Cleaning Tool Supports Multiprocessor SoC Design (Page 23) Embedded Systems Design - July 2008 - Interactive C-code Cleaning Tool Supports Multiprocessor SoC Design (Page 24) Embedded Systems Design - July 2008 - Interactive C-code Cleaning Tool Supports Multiprocessor SoC Design (Page 25) Embedded Systems Design - July 2008 - Interactive C-code Cleaning Tool Supports Multiprocessor SoC Design (Page 26) Embedded Systems Design - July 2008 - Building a Power Supply for Discontinuous Transmission Wireless Networks (Page 27) Embedded Systems Design - July 2008 - Building a Power Supply for Discontinuous Transmission Wireless Networks (Page 28) Embedded Systems Design - July 2008 - Building a Power Supply for Discontinuous Transmission Wireless Networks (Page 29) Embedded Systems Design - July 2008 - Building a Power Supply for Discontinuous Transmission Wireless Networks (Page 30) Embedded Systems Design - July 2008 - Building a Power Supply for Discontinuous Transmission Wireless Networks (Page 31) Embedded Systems Design - July 2008 - Building a Power Supply for Discontinuous Transmission Wireless Networks (Page 32) Embedded Systems Design - July 2008 - Building a Power Supply for Discontinuous Transmission Wireless Networks (Page 33) Embedded Systems Design - July 2008 - Building a Power Supply for Discontinuous Transmission Wireless Networks (Page 34) Embedded Systems Design - July 2008 - An Exception Primer (Page 35) Embedded Systems Design - July 2008 - An Exception Primer (Page 36) Embedded Systems Design - July 2008 - An Exception Primer (Page 37) Embedded Systems Design - July 2008 - An Exception Primer (Page 38) Embedded Systems Design - July 2008 - An Exception Primer (Page 39) Embedded Systems Design - July 2008 - An Exception Primer (Page 40) Embedded Systems Design - July 2008 - An Exception Primer (Page 41) Embedded Systems Design - July 2008 - An Exception Primer (Page 42) Embedded Systems Design - July 2008 - An Exception Primer (Page 43) Embedded Systems Design - July 2008 - Advertising Index (Page 44) Embedded Systems Design - July 2008 - Break Points (Page 45) Embedded Systems Design - July 2008 - Break Points (Page 46) Embedded Systems Design - July 2008 - Marketplace (Page 47) Embedded Systems Design - July 2008 - Marketplace (Page 48) Embedded Systems Design - July 2008 - Marketplace (Page Cover3) Embedded Systems Design - July 2008 - Marketplace (Page Cover4)
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