C8051F336-GMR Silicon Laboratories Inc, C8051F336-GMR Datasheet - Page 118

• Manufacturer Part Number: C8051F336-GMR
• Description: Microcontrollers (MCU) 16KB 10ADC 10DAC 768Ram MCU Lead Free
• Manufacturer: Silicon Laboratories Inc

Specifications of C8051F336-GMR

• Processor Series: C8051F3x
• Core: 8051
• Data Bus Width: 8 bit
• Program Memory Type: Flash
• Program Memory Size: 16 KB
• Data Ram Size: 768 B
• Interface Type: I2C, SPI, UART
• Maximum Clock Frequency: 25 MHz
• Number Of Programmable I/os: 17
• Number Of Timers: 4
• Operating Supply Voltage: 2.7 V to 3.6 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: QFN-20
• 3rd Party Development Tools: KSK-SL-TOOLSTICK, PK51, CA51, A51, ULINK2
• Development Tools By Supplier: C8051F336DK
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 10 bit
• On-chip Dac: 10 bit
• Package: 20QFN
• Device Core: 8051
• Family Name: C8051F336
• Maximum Speed: 25 MHz
• Ram Size: 768 Byte
• Operating Temperature: -40 to 85 °C
• Lead Free Status / Rohs Status: Details

C8051F336/7/8/9
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
= the MCU power supply in Volts.
DD
Equation 19.2. C Mode Oscillator Frequency
(
)
⁄
(
×
)
f
=
KF
R V
DD
For example: Assume V
= 3.0 V and f = 150 kHz:
DD
f = KF / (C x VDD)
0.150 MHz = KF / (C x 3.0)
Since the frequency of roughly 150 kHz is desired, select the K Factor from the table in SFR Definition 19.5
(OSCXCN) as KF = 22:
0.150 MHz = 22 / (C x 3.0)
C x 3.0 = 22 / 0.150 MHz
C = 146.6 / 3.0 pF = 48.8 pF
Therefore, the XFCN value to use in this example is 011b and C = 50 pF.
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