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The 2008 power supply circuit uses the same switching topology as the 2007 system with some changes, most notably a jump in system voltage to 12V from 9V to support the new motors. Another change is more analysis in the design phase including looking at possible interference with the radio and other devices that use oscillators.


  • [X] Finalize specs on voltages, maximum current draw, and allowable frequencies
  • [X] Select a part based on the spec
  • [X] Determine how to mount batteries
  • [X] CAD the design
  • [X] Verify the design
  • [X] Fabricate Prototype


Power Supply

  • 12V operation
  • Small package
  • Low inductance
  • High allowable RL (so we can use smaller inductors)
  • Frequency does not interfere with other electronics
  • Protection Circuitry (TVS:Transient Voltage Suppression)


Part VBatt 5V 3.3V 2.5V 1.8V 1.2V
FPGA 1 mA + 12*n mA
n pins high
8 mA typ
12 mA max
8 mA typ
27 mA max
ARM 15 mA max 15 mA max
FET Drivers (each) 9mA
FET Drivers (total) 45mA
Maxon Halls ??
Micro Mo Halls ??
Kicker Board 4A (when

The FPGA has between a 2.5K and a 10K pullup, and between a 4K and 34.5K pulldown. Thus, the bus pins (D0-D7) are expected to draw max ~1 mA when driven into the FPGA.

Parts and Supplies

  • 3V3 @ 3 A supplies all linear regulators
  • 2V5
  • 1V8
  • 1V2


  • Packs need to be configured to give out 12V
  • Orientation and number need to be spec'd by both EE and ME
  • Possible on-board charger? maybe in 2009
  • Battery health monitor
  • Affordable

Similar to last year, we will probably go with NiMh batteries because we cannot afford Li*.

Quick notes on available batteries

Tenergy Batteries have done well (enough) in tests, and the internet seems to think they are ok.

Supposedly these coupons "tenergy2547" and "septspecials" can save us 10% from this slickdeals post.

This coupon "tenergydeals" will supposedly get free shipping.



Power Supply

Quick Specs
Data Sheet


Quick Specs
Data Sheet