bc41b143a07 ETC-unknow, bc41b143a07 Datasheet - Page 56

• Manufacturer Part Number: bc41b143a07
• Description: Single Chip Bluetooth
• Manufacturer: ETC-unknow

The BlueCore4-ROM driver circuit is a transconductance amplifier. A voltage at XTAL_IN generates a current at
XTAL_OUT. The value of transconductance is variable and may be set for optimum performance.
9.3.2
For resonance at the correct frequency the crystal should be loaded with its specified load capacitance, which is
defined for the crystal. This is the total capacitance across the crystal viewed from its terminals. BlueCore4-ROM
provides some of this load with the capacitors C
labelled C
swing, hence, slew rate at XTAL_IN (to which all on-chip clocks are referred). Crystal load capacitance, C
with Equation 9.4:
Where:
Note:
CS-101564-DSP12
Frequency
Initial Tolerance
Pullability
C
C
C
trim
int
int
= 1.5pF
does not include the crystal internal self capacitance; it is the driver self capacitance.
= 3.4pF nominal (mid-range setting)
t1
Load Capacitance
and C
t2
. C
t1
should be three times the value of C
8MHz
Min
-
-
Equation 9.4: Load Capacitance
Table 9.4: Crystal Specification
C
I
Production Information
trim
=
© CSR plc 2003-2007
C
int
and C
+
C
trim
2
int
. The remainder should be from the external capacitors
t2
+
for best noise performance. This maximises the signal
C
C
±20ppm/pF
1 t
±25ppm
1 t
26MHz
+
•
C
Typ
C
2 t
2 t
Device Terminal Descriptions
32MHz
Max
-
-
l
Page 56 of 97
is calculated