C8051F902-GM Silicon Laboratories Inc, C8051F902-GM Datasheet - Page 182

• Manufacturer Part Number: C8051F902-GM
• Description: IC MCU 8BIT 8KB FLASH 24QFN
• Manufacturer: Silicon Laboratories Inc
• Series: C8051F9xxr

Specifications of C8051F902-GM

• Program Memory Type: FLASH
• Program Memory Size: 8KB (8K x 8)
• Package / Case: 24-QFN
• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 25MHz
• Connectivity: SMBus (2-Wire/I²C), SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, Temp Sensor, WDT
• Number Of I /o: 16
• Ram Size: 768 x 8
• Voltage - Supply (vcc/vdd): 0.9 V ~ 3.6 V
• Data Converters: A/D 15x10/12b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Processor Series: C8051F9x
• Core: 8051
• Data Ram Size: 768 B
• Interface Type: UART
• Maximum Clock Frequency: 25 MHz
• Number Of Timers: 4
• Operating Supply Voltage: 0.9 V to 3.6 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: PK51, CA51, A51, ULINK2
• Development Tools By Supplier: C8051F912DK
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 12 bit
• Package: 24QFN EP
• Device Core: 8051
• Family Name: C8051F90x
• Maximum Speed: 25 MHz
• Data Bus Width: 8 Bit
• Number Of Programmable I/os: 16
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 336-1848-5

C8051F91x-C8051F90x
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
10 k. The oscillation frequency can be determined by the following equation:
where
f = frequency of clock in MHzR = pull-up resistor value in k
V
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 fre-
quency desired is 100 kHz, let R = 246 k and C = 50 pF:
where
f = frequency of clock in MHz
V
Referencing Table 19.2, the recommended XFCN setting is 010.
182
DD
DD
f
= power supply voltage in VoltsC = capacitor value on the XTAL2 pin in pF
= power supply voltage in Volts
f
=
XFCN
=
000
001
010
100
101
011
110
111
1.23 10
------------------------ -
1.23 10
------------------------ -
R C
R




C
3
Table 19.2. Recommended XFCN Settings for RC and C modes
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
C = capacitor value on the XTAL2 pin in pF
K Factor (C Mode)
Rev. 1.0
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