C8051F560-TB Silicon Laboratories Inc, C8051F560-TB Datasheet - Page 165

• Manufacturer Part Number: C8051F560-TB
• Description: BOARD PROTOTYPE W/C8051F560
• Manufacturer: Silicon Laboratories Inc
• Type: MCUr

Specifications of C8051F560-TB

• Contents: Board
• Processor To Be Evaluated: C8051F56x
• Processor Series: C8051F56x
• Interface Type: USB
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Operating Supply Voltage: 1.8 V to 5.25 V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: C8051F55x, C8051F56x, C8051F57x
• For Use With: 336-1691 - KIT DEVELOPMENT FOR C8051F560
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 336-1694

18.4.2. External RC Example
If an RC network is used as an external oscillator source for the MCU, the circuit should be configured as
shown in Figure 18.1, Option 2. The capacitor should be no greater than 100 pF; however for very small
capacitors, the total capacitance may be dominated by parasitic capacitance in the PCB layout. To deter-
mine the required External Oscillator Frequency Control value (XFCN) in the OSCXCN Register, first
select the RC network value to produce the desired frequency of oscillation, according to Equation , where
f = the frequency of oscillation in MHz, C = the capacitor value in pF, and R = the pull-up resistor value in
k  .
For example: If the frequency desired is 100 kHz, let R = 246 k  and C = 50 pF:
f = 1.23(10
Referring to the table in SFR Definition 18.6, the required XFCN setting is 010b.
18.4.3. External Capacitor Example
If a capacitor is used as an external oscillator for the MCU, the circuit should be configured as shown in
Figure 18.1, Option 3. The capacitor should be no greater than 100 pF; however for very small capacitors,
the total capacitance may be dominated by parasitic capacitance in the PCB layout. To determine the
required External Oscillator Frequency Control value (XFCN) in the OSCXCN Register, select the capaci-
tor to be used and find the frequency of oscillation according to Equation , where f = the frequency of oscil-
lation in MHz, C = the capacitor value in pF, and V
Figure 18.3. External 32.768 kHz Quartz Crystal Oscillator Connection Diagram
3
)/RC = 1.23(10
22pF*
* Capacitor values depend on
Equation 18.1. RC Mode Oscillator Frequency
3
)/[246 x 50] = 0.1 MHz = 100 kHz
crystal specifications
32.768 kHz
10M
f
=
1.23 10
Rev. 1.1

DD
22pF*
= the MCU power supply in Volts.
3


R C

XTAL1
XTAL2
C8051F55x/56x/57x

165