CC2544 Datasheet, PDF (22/30 Pages) Texas Instruments – System-on-Chip for 2.4-GHz USB Applications

CC2544
SWRS103D – JUNE 2011 – REVISED MAY 2012
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Crystal
An external 32-MHz crystal with two loading capacitors is used for the 32-MHz crystal oscillator. The load
capacitance seen by the 32-MHz crystal is given by:
C_L =
1
11
+ C_parasitic
C₁₇₁ ⁺ C₁₈₁
(1)
A series resistor may be used to comply with ESR requirement.
On-Chip 1.8-V Voltage Regulator Decoupling
The 1.8-V on-chip voltage regulator supplies the 1.8-V digital logic. This regulator requires a decoupling capacitor
(C311) for stable operation.
On-Chip 5-V to 3.3-V USB Voltage Regulator Decoupling
The 5-V to 3.3-V on-chip voltage regulator supplies the 1.8-V on-chip voltage regulator. This regulator requires a
decoupling capacitor (C41) for stable operation.
Power-Supply Decoupling and Filtering
Proper power-supply decoupling must be used for optimum performance. The placement and size of the
decoupling capacitors and the power supply filtering are very important to achieve the best performance in an
application. TI provides a compact reference design that should be followed very closely.
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