This page contains a Flash digital edition of a book.
Power Supplies

for which no software programming knowledge is required. Being software programmable allows system power designers to answer questions and fill in boxes with information to create a successful initial design – the I2C interface on the IC allows continuous communications with the system so dynamic changes with operational system needs can be adjusted on the fly. Since no compensation network is needed with the usual resistors and capacitors – initial accuracy and drift over time and temperature high accuracy is reduced greatly. Additionally complex slew rate control delays and sequencing is simple to

implement. Importantly as system needs change, the power system can be reconfigured without any hardware changes, even remotely.

One of the benefits of the system level

approach to power implemented in this way is that the hardware is completely re- usable. The hardware design stays constant and reusability is easier than ever before – differentiation is achieved by defining the power system in simple software and saving it on the IC. Additionally if 3-4 or 20 or more channels are needed it’s a simple matter to daisy chain more channels and extend the system via I2C to control more channels by adding essentially more of the

same and repeating the design until the desired numbers of channels are achieved in hardware. Current levels per channel are defined in software and component selection. Differentiation is done via software so, the implementation can be reused across multiple products and product lines, and economies of scale are possible where reusing the hardware is accomplished and different products are differentiated only in software.

Power system solution approach While the needs of VLSI devices are undeniably becoming more complex, a

power system solution approach can make implementation easier. Customer benefits include the opportunity to save energy by allowing the system to modulate and optimise its own power supply to extract the best performance per watt as well as adding new features and functions. Devices like the PowerXR can be used to simplify the design of DDR3 and soon four memory systems as the programmability of the system can create the necessary delays, ramp rates on power up as well as power down. The PowerXR system can also generate the required voltages for using any termination scheme which might be desired either passive or active components which need the VTT voltage – this voltage is usually required to be precise and accurate over temperature and time. It can be seen that today’s processors also need complex accurate precise power and can also benefit from PowerXR programmable power technology. The flexibility of this approach is that channels can be added and daisy chained together to enable a system where each channel can be controlled individually regardless of how many channels are added. Channels can be added in 3 -4 channel increments. Thus an 8-channel implementation would consist of two 4-channel devices where each channel is independently designed and controlled for its unique task. A software GUI is available as well as evaluation boards and complete design assistance.

Exar Corporation | Kevin Parmenter is a member of Exar Corporation’s technical staff






 UL/GS/SAA/CB/K mark approved  CE/RoHS/FCC Class B compliant  From £7.45/unit for 1,000 pcs (12V 60W)  Available in quantities of 50 off upwards  12V 3.5A, 4.0A or 5.0A versions  Other models, Voltages & Power available

For the ideal solution to your power requirements call us on: T. 0845 260 3400 Components in Electronics July/August 2011 31

Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52