CC2541-Q1_15 Datasheet, PDF (25/35 Pages) Texas Instruments – CC2541-Q1 SimpleLink Bluetooth Low Energy Wireless MCU for Automotive

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CC2541-Q1
SWRS128 – JUNE 2014
An external 32-MHz crystal, XTAL1, with two loading capacitors (C221 and C231) is used for the 32-MHz
crystal oscillator. See Section 4.9 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
11
+ C_parasitic
+
C₃₂₁ C₃₃₁
(2)
A series resistor may be used to comply with the ESR requirement.
6.3 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 (C471) for stable operation.
6.4 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.
Copyright © 2014, Texas Instruments Incorporated
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