BC41B143A-DS-003PC Datasheet, PDF (49/94 Pages) List of Unclassifed Manufacturers – BlueCore 4-ROM Plug-n-Go Single Chip Bluetooth v2.0 + EDR System

Device Terminal Descriptions
10.3 Crystal Oscillator (XTAL_IN, XTAL_OUT)
This section describes the crystal mode. See section 10.2 for the description of the external reference clock mode.
10.3.1 XTAL Mode
BlueCore4-ROM Plug-n-Go contains a crystal driver circuit. This operates with an external crystal and capacitors to
form a Pierce oscillator.
g_m
-
C_trim
C_int
C_trim
C_t2
C_t1
Figure 10.5: Crystal Driver Circuit
Figure 10.6 shows an electrical equivalent circuit for a crystal. The crystal appears inductive near its resonant
frequency. It forms a resonant circuit with its load capacitors.
Figure 10.6: Crystal Equivalent Circuit
The resonant frequency may be trimmed with the crystal load capacitance. BlueCore4-ROM Plug-n-Go contains
variable internal capacitors to provide a fine trim.
BC41B143A-ds-003Pc
Advance Information
© Cambridge Silicon Radio Limited 2005
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