C8051F930DK Silicon Laboratories Inc, C8051F930DK Datasheet - Page 190

• Manufacturer Part Number: C8051F930DK
• Description: KIT DEV C8051F920,F921,F930,F931
• Manufacturer: Silicon Laboratories Inc
• Type: MCUr

Specifications of C8051F930DK

• Contents: Target Board, Power Adapter, USB Debug Adapter, Cables, Batteries, and Software
• Processor To Be Evaluated: C8051F930
• Processor Series: C8051F9xx
• Data Bus Width: 8 bit
• Interface Type: I2C, UART, SPI
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Operating Supply Voltage: 0.9 V to 3.6 V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: C8051F920, F921, F930, F931
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 336-1473

C8051F93x-C8051F92x
19.3.2. External RC Mode
If an RC network is used as the external oscillator, the circuit should be configured as shown in
Figure 19.1, Option 2. The RC network should be added to XTAL2, and XTAL2 should be configured for
analog I/O with the digital output drivers disabled. XTAL1 is not affected in RC mode.
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. The resistor should be no smaller than
10k  . The oscillation frequency can be determined by the following equation:
To determine 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. For example, if the
frequency desired is 100 kHz, let R = 246 k  and C = 50 pF:
Referencing Table 19.2, the recommended XFCN setting is 010.
190
f
where 
f = frequency of clock in MHz
V
where 
f = frequency of clock in MHz
V
f
=
DD
DD
XFCN
=
000
001
010
100
101
011
110
111
1.23 10
------------------------ -
= power supply voltage in Volts
= power supply voltage in Volts
1.23 10
------------------------ -
R C
R



Table 19.2. Recommended XFCN Settings for RC and C modes

C
3
3
=
Frequency Range (RC
800 kHz  f  1.6 MHz
1.6 MHz  f  3.2 MHz
100 kHz  f  200 kHz
200 kHz  f  400 kHz
400 kHz  f  800 kHz
50 kHz  f  100 kHz
1.23 10
------------------------ -
25 kHz  f  50 kHz
246 50
and C Mode)
Approximate


f  25 kHz
3
=
100 kHz
R = pull-up resistor value in k 
R = pull-up resistor value in k 
C = capacitor value on the XTAL2 pin in pF
C = capacitor value on the XTAL2 pin in pF
K Factor (C Mode)
Rev. 1.1
K Factor = 1590
K Factor = 0.87
K Factor = 180
K Factor = 664
K Factor = 2.6
K Factor = 7.7
K Factor = 22
K Factor = 65
Typical Supply Current/ Actual
242 µA, f = 890 kHz, C = 46 pF
1.0 mA, f = 2.0 MHz, C = 46 pF
4.6 mA, f = 6.8 MHz, C = 46 pF
32 µA, f = 270 kHz, C = 33 pF
82 µA, f = 310 kHz, C = 46 pF
5.5 µA, f = 33 kHz, C = 33 pF
3.0 µA, f = 11 kHz, C = 33 pF
13 µA, f = 98 kHz, C = 33 pF
(C Mode, VDD = 2.4 V)
Measured Frequency