SWRS046H – NOVEMBER 2006 – REVISED MARCH 2015
6.2.4
Crystal
An external crystal with two loading capacitors (C4 and C5) is used for the crystal oscillator. See
for details.
6.2.5
Additional Filtering
Additional external components (for example, RF, LC, or SAW filter) may be used in order to improve the
performance in specific applications. See
for further information.
6.2.6
Power Supply Decoupling and Filtering
Power supply decoupling and filtering must be used (not shown in the application circuit). The placement
and size of the decoupling capacitors and the power supply filtering are very important to achieve the
optimum performance for narrowband applications. TI provides a reference design that should be followed
very closely.
6.3
PCB Layout Recommendations
The top layer should be used for signal routing, and the open areas should be filled with metallization
connected to ground using several vias.
The area under the chip is used for grounding and must be connected to the bottom ground plane with
several vias. In the TI reference designs we have placed 9 vias inside the exposed die attached pad.
These vias should be “tented” (covered with solder mask) on the component side of the PCB to avoid
migration of solder through the vias during the solder reflow process.
Do not place a via underneath CC1020 at “pin #1 corner” as this pin is internally connected to the exposed
die attached pad, which is the main ground connection for the chip.
Each decoupling capacitor should be placed as close as possible to the supply pin it is supposed to
decouple. Each decoupling capacitor should be connected to the power line (or power plane) by separate
vias. The best routing is from the power line (or power plane) to the decoupling capacitor and then to the
CC1020 supply pin. Supply power filtering is very important, especially for pins 23, 22, 20 and 18.
Each decoupling capacitor ground pad should be connected to the ground plane using a separate via.
Direct connections between neighboring power pins will increase noise coupling and should be avoided
unless absolutely necessary.
The external components should ideally be as small as possible and surface mount devices are highly
recommended.
Precaution should be used when placing the microcontroller in order to avoid noise interfering with the RF
circuitry.
A CC1020/1070DK Development Kit with a fully assembled
Evaluation Module is available.
It is strongly advised that this reference layout is followed very closely in order to get the best
performance. The layout Gerber files are available from the
product folder.
86
Applications, Implementation, and Layout
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