C8051F502-IMR Silicon Laboratories Inc, C8051F502-IMR Datasheet - Page 176

• 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

C8051F50x/F51x
Equation 19.2. C Mode Oscillator Frequency






f
=
KF
R V
DD
For example: Assume V
= 2.1 V and f = 75 kHz:
DD
f = KF / (C x VDD) 
0.075 MHz = KF / (C x 2.1)
Since the frequency of roughly 75 kHz is desired, select the K Factor from the table in SFR Definition 19.6
(OSCXCN) as KF = 7.7:
0.075 MHz = 7.7 / (C x 2.1) 
C x 2.1 = 7.7 / 0.075 MHz 
C = 102.6 / 2.0 pF = 51.3 pF
Therefore, the XFCN value to use in this example is 010b.
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Rev. 1.2