DigiKey-eMag-Robotics-Vol 22

Why and how to use a component-based distributed power architecture for robotics

can also contribute to higher PDN efficiencies. Vicor offers DC/DC converters that are capable of supporting designers’ needs in a wide range of component-based distributed power delivery architectures, including the four outlined above. The following discussion focuses on specific devices that can be used in a power delivery system similar to the one described for campus and consumer delivery robots, as shown in Figure 2. DC/DC converters for robot power systems The DCM3623TA5N53B4T70 is an example of a DCM isolated and regulated DC/DC converter that can produce the 48 volt intermediate bus voltage from 100 volt battery power (Figure 5). This converter uses zero voltage switching (ZVS) technology to deliver a 90.7% peak efficiency and a 653 watts per cubic inch power density. It provides 3,000 volts dc isolation between the input and output.

Leveraging the thermal and density benefits of Vicor’s Converter- housed-in-Package (ChiP) packaging technology, the DCM module offers flexible thermal management options with very low top and bottom side thermal impedances. ChiP-based power components enable designers to achieve cost-effective power system solutions with previously unattainable system size, weight and efficiency attributes, quickly and predictably. To start exploring the capabilities of the DCM3623TA5N53B4T70 , designers can use the DCM3623EA5N53B4T70 evaluation board (Figure 6). The DCM evaluation board can be configured for various enabling and fault monitoring schemes, as well as to exercise various modes of trimming depending upon the application requirements. The DCM3623EA5N53B4T70 can be used to evaluate DCMs in either a stand-alone configuration, or as an array of modules. It also supports evaluation of various enable, trim and fault monitoring options: Enable options: ■ On-board mechanical switch (default) ■ External control Trim options: ■ Fixed trim operation (default): the TR pin is permitted to float at initial startup. The DCM disables

output trimming and the output trim is programmed to the nominal rated VOUT ■ Variable trim operation, on- board variable resistor: The trim pin voltage is ratiometric, with a rheostat working against a pull-up resistor inside the DCM to VCC ■ Variable trim operation, off- board control: The trim pin voltage is controlled via external programming control, which is referenced to the –IN of each specific DCM in the system Fault monitor options: ■ On-board LED: the FT pin drives a visible LED for visual feedback on fault status ■ On-board optocoupler: the FT pin drives an on-board optocoupler to bring fault status across the primary-secondary isolation boundary

respectively. It is a high efficiency, wide input and output range ZVS converter. This high-density system-in-package (SiP) integrates a controller, power switches, and support components (Figure 7). It features a peak efficiency up to 96%, as well as good light-load efficiency. The PI3740-00 requires an external inductor, resistive divider, and minimal capacitors to form a complete buck-boost regulator. The 1 megahertz (MHz) switching frequency reduces the size of the external filtering components, improves power density, and enables fast dynamic response to line and load transients. To kickstart design with the PI3740- 00, Vicor provides the PI3740-00- EVAL1 to evaluate the PI3740-00 in constant voltage applications where VOUT is above 8 volts. The board operates from an input voltage between 8 and 60 volts dc and supports output voltages up to 50 volts dc. Features of this eval board include:

■ Input and output lugs for source and load connections ■ Location to place a through- hole input aluminum electrolytic capacitor ■ Input source filter ■ Oscilloscope probe jack for accurate, high-frequency output and input voltage measurements ■ Signal pin test points and wire connectors ■ Kelvin voltage test points and sockets for all of the PI3740 pins ■ Jumper selectable high-side/ low-side current sensing ■ Jumper selectable float voltage Finally, the PI3526-00-LGIZ buck regulator from Vicor can be used to provide 12 volt power for a computer and wireless subsystems in the PDN (Figure 8). This DC/ DC converter provides efficiency up to 98%, and support for user- adjustable soft start and tracking that includes fast and slow current- limit capabilities. These ZVS regulators integrate the controller, power switches, and support components in a SiP configuration. The PI3526-00-EVAL1 evaluation board from Vicor can be configured to experiment with the PI3526- 00-LGIZ buck regulator in a stand-alone or a remote sense configuration. Sockets are provided to permit quick probing and placement of a bulk input capacitor. The evaluation board provides lugs, bottom layer banana jack footprints for input and output connections, signal connectors and test points, and Kelvin Johnson-Jacks for

accurate power node voltage measurements.

Conclusion Robotic system power conversion needs become more challenging as load capacities, visual recognition, and user functionality increase the complexity of robots. Existing power solutions can suffer from performance limitations in terms of size, efficiency, weight and scalability, making them less suitable for robotics applications. For robotics applications, designers can turn to component- based distributed power delivery architectures to power the motors, CPUs and other systems. As shown, this approach can result in a lighter weight power system, enabling further performance gains for battery-powered robotics. Flexibility is also enhanced as power conversion components can be paralleled to easily scale as power demands increase, allowing the same power architecture to be deployed across a platform of various sized robotic systems.

Vicor’s PI3740-00 buck-boost DC/DC converter can be used to produce 44 volt and 24 volt power for LED floodlights and high-definition (HD) cameras,