C8051F502-IMR Silicon Laboratories Inc, C8051F502-IMR Datasheet - Page 175

• Manufacturer Part Number: C8051F502-IMR
• Description: MCU 8-Bit C8051F50x 8051 CISC 64KB Flash 2.5V/3.3V/5V 32-Pin QFN EP T/R
• Manufacturer: Silicon Laboratories Inc

Specifications of C8051F502-IMR

• Package: 32QFN EP
• Device Core: 8051
• Family Name: C8051F50x
• Maximum Speed: 50 MHz
• Ram Size: 4.25 KB
• Program Memory Size: 64 KB
• Operating Supply Voltage: 2.5|3.3|5 V
• Data Bus Width: 8 Bit
• Program Memory Type: Flash
• Number Of Programmable I/os: 25
• Interface Type: I2C/SPI/UART
• On-chip Adc: 32-chx12-bit
• Operating Temperature: -40 to 125 °C
• Number Of Timers: 4

19.4.2. 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 19.1, 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 19.6, the required XFCN setting is 010b.
19.4.3. External Capacitor Example
If a capacitor is used as an external oscillator for the MCU, the circuit should be configured as shown in
Figure 19.1, 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 19.2, where f = the frequency of
oscillation in MHz, C = the capacitor value in pF, and V
Figure 19.3. External 32.768 kHz Quartz Crystal Oscillator Connection Diagram
3
)/RC = 1.23(10
22pF*
* Capacitor values depend on
Equation 19.1. RC Mode Oscillator Frequency
3
)/[246 x 50] = 0.1 MHz = 100 kHz
crystal specifications
32.768 kHz
10M
f
=
1.23 10
Rev. 1.2

22pF*
DD
3

= the MCU power supply in Volts.

R C

XTAL1
XTAL2

C8051F50x/F51x
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