Bt848EVK Hardware Reference Guide
Mechanical Description
8
UG848_2A
Bt848
Hardware Reference Guide
Brooktree
®
Power Block
There is one power plane (+5 V) and one ground plane in the Bt848EVK. There also exists a DC to
DC converter that takes the
±
12 VDC from the PCI bus and c33 VDC, as needed by some
TV tuner models.
Digital Power
Power supply for Bt848 digital circuitry. All VDD pins are connected together as close to the Bt848
as possible.
Analog Power
Power supply for Bt848 analog circuitry. All VAA pins and VPOS are connected together as close
to the Bt848 as possible.
PCI Power
Power supply for PCI bus signals. All VDDP pins are connected together.
TV Tuner Power
The
±
12 VDC from the PCI bus is connected to the DC to DC converter that c30 VDC to
+33 VDC at 2.0 mA maximum. This output must not exceed 10 mV peak to peak ripple (up to 500
KHz spectrum). The output of the DC to DC converter is passed to the tuning supply pin of the TV
tuner through a 22 K
Ω
resistor. The circuitry in this section is not necessary if a TV tuner with an
internal DC to DC converter is used.
GPIO Power
Power supply for GPIO port signals. All VDDG pins are connected together.
Grounding
There is one continuous ground plane for all digital circuits, analog circuits, PCI ground, and chas-
sis ground. Chassis ground connects all input connector cases and the front panel.
Mechanical Description
The Bt848EVK board’s physical dimensions are 6.875 inches in length and 4.2 inches in width.
Power Consumption
Less than 7.5 Watts.