CC2541_15 Datasheet, PDF (25/34 Pages) Texas Instruments – 2.4-GHz Bluetooth™ low energy and Proprietary System-on-Chip

CC2541
www.ti.com
SWRS110D – JANUARY 2012 – REVISED JUNE 2013
Crystal
An external 32-MHz crystal, XTAL1, with two loading capacitors (C221 and C231) is used for the 32-MHz crystal
oscillator. See 32-MHz CRYSTAL OSCILLATOR for details. The load capacitance seen by the 32-MHz crystal is
given by:
C_L =
1
1
1
+ C_parasitic
+
C₂₂₁ C₂₃₁
(1)
XTAL2 is an optional 32.768-kHz crystal, with two loading capacitors (C321 and C331) used for the 32.768-kHz
crystal oscillator. The 32.768-kHz crystal oscillator is used in applications where both very low sleep-current
consumption and accurate wake-up times are needed. The load capacitance seen by the 32.768-kHz crystal is
given by:
C_L = ₁ ¹ ₁ + C_parasitic
+
C₃₂₁ C₃₃₁
(2)
A series resistor may be used to comply with the 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
(C401) 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.
References
1. Bluetooth® Core Technical Specification document, version 4.0
http://www.bluetooth.com/SiteCollectionDocuments/Core_V40.zip
2. CC253x System-on-Chip Solution for 2.4-GHz IEEE 802.15.4 and ZigBee^® Applications/CC2541 System-on-
Chip Solution for 2.4-GHz Bluetooth low energy Applications (SWRU191)
3. Current Savings in CC254x Using the TPS62730 (SWRA365).
Additional Information
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