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between two different clock phases. The LTC3676 is also capable of providing considerable power, in excess of 10W. This can result in substantial circulating currents and so it is imperative to provide an uninterrupted path for this current to circulate. In particular, slots in the ground plane, which force the large circulating currents to flow around them, create slot antennas. But other obstacles, such as changing layers, contribute some energy in the EMI signature and should be minimized. Ideally the top and bottom layers should be all, or mostly, ground plane, with the signal layers flowing internally. Since this is usually not practical, some thought needs to go into how the ground plane will be connected prior to commencing layout. For example, it is not a good idea to put the LTC3676 into a corner or tab on the PCB. This will make it very difficult to properly route the ground plane. However, it is a good idea to route the high circulating current areas of the LTC3676 first, to ensure the most optimum layout possible. If EMI control is planned and executed with the concepts of source suppression and antenna elimination in mind, it is possible Fig. 3: The LTC3676 power-down sequence. to create a full power system that is a good EMI neighbor BE CONNECTED EVERYWHERE The LTC3676 also includes easily programmable powerdown sequence control. The IC includes two registers for initializing a power down sequence configuration which will be followed at the next turn-off event or overpower fault condition. Each regulator (DC-DC and LDO) can be pre-set to any one of four time slots for shutdown. Each regulator output includes an internal pull-down resistor that is engaged when disabled to guarantee the controlled discharges as shown in figure 3 and a low starting point for the next turn-on sequence. Bluetooth Low Energy Module – PAN17xx Series Bluetooth® Low Energy technology reduces power consumption down to a tenth of a Classic Bluetooth® device. It is only activated for events such as sending fi les, and otherwise stays in sleep mode. Bluetooth® Smart devices are designed to gather a specifi c type of information and send it to a Bluetooth® Smart Ready device. Features: • Rapid connection and disconnection (few ms), which allows to build multiple connections even so scatternet is not supported • For small, discrete data transfer Products: • PAN1720 (P/N ENW89820A3KF) • PAN1721 (P/N ENW89835A3KF) • Supported Firmware: nBlue™ by BlueRadios Inc. Applications: • 2.4 GHz Bluetooth low energy systems • Proprietary 2.4 GHz systems • Human Interface Devices • Sports and leisure equipment • Remote control for computers, MP3 players • Consumer Electronics • USB dongles • Health Care and Medical Please sign up to our webinar “Bluetooth Smart Integration Made Easy!“ on http://www.element14.com/community/events/3782 without increasing product cost or weight. The LTC3676 supports simple and effective power sequencing which can be handled through serial communications or via pin strapping where power supply output voltages are tied to enable pins in the desired turn-on sequence. Internally each enable is delayed micro seconds to further time stagger the startup sequence. This feature is supported with precision low voltage enable thresholds so the sequencing is possible even with output voltages as low as 0.43V. Each supply voltage output is also soft-started to limit inrush current and produce clean voltage transitions - see figure 2. panasonic_anz_pan1720_21_be_connected_190x136_v02.indd 1 24.09.13 10:05 www.electronics-eetimes.com Electronic Engineering Times Europe November 2013 27


EETE NOV 2013
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