SWRS046H – NOVEMBER 2006 – REVISED MARCH 2015
4.8
Crystal Oscillator
All measurements were performed using the two-layer PCB CC1020EMX reference design. See
. The electrical
specifications given for 868 MHz are also applicable for 902 to 928 MHz. T
A
= 25°C, AVDD = DVDD = 3.0 V,
f
C
= 14.7456 MHz if nothing else stated.
PARAMETER
MIN
TYP
MAX
UNIT
CONDITION
Recommended frequency is
Crystal Oscillator Frequency
4.9152
14.7456
19.6608
MHz
14.7456 MHz. See
for
details.
±5.7
ppm
433 MHz (EN 300 220)
868 MHz (EN 300 220)
Must be less than ±5.7 / ±2.8 ppm to
±2.8
ppm
Reference frequency
comply with EN 300 220 25 kHz channel
accuracy requirement
(1) (2)
spacing at 433/868 MHz.
Must be less than ±4 ppm to comply with
±4
ppm
Japanese 12.5 kHz channel spacing
regulations (ARIB STD-T67).
C4 and C5 are loading capacitors. See
Crystal operation
Parallel
for details.
4.9 to 6 MHz, 22 pF
12
22
30
pF
recommended
Crystal load
6 to 8 MHz, 16 pF
12
16
30
pF
capacitance
recommended
8 to 19.6 MHz, 16 pF
12
16
16
pF
recommended
4.9152 MHz, 12 pF load
1.55
ms
7.3728 MHz, 12 pF load
1.0
ms
9.8304 MHz, 12 pF load
0.90
ms
Crystal oscillator
start-up time
14.7456 MHz, 16 pF load
0.95
ms
17.2032 MHz, 12 pF load
0.60
ms
19.6608 MHz, 12 pF load
0.63
ms
The external clock signal must be
connected to XOSC_Q1 using a DC
block (10 nF). Set XOSC_BYPASS = 0 in
External clock signal drive, sine wave
300
mVpp
the INTERFACE register when using an
external clock signal with low amplitude
or a crystal.
The external clock signal must be
connected to XOSC_Q1. No DC block
External clock signal drive, full-swing digital
0 – VDD
V
shall be used. Set XOSC_BYPASS = 1 in
external clock
the INTERFACE register when using a
full-swing digital external clock.
(1)
The reference frequency accuracy (initial tolerance) and drift (aging and temperature dependency) will determine the frequency
accuracy of the transmitted signal.
(2)
Crystal oscillator temperature compensation can be done using the fine step PLL frequency programmability and the AFC feature. See
for details.
Copyright © 2006–2015, Texas Instruments Incorporated
Specifications
13
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