C8051F902-GM Silicon Laboratories Inc, C8051F902-GM Datasheet - Page 179

• 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

19. Clocking Sources
C8051F91x-C8051F90x devices include a programmable precision internal oscillator, an external oscillator
drive circuit, a low power internal oscillator, and a SmaRTClock real time clock oscillator. The precision
internal oscillator can be enabled/disabled and calibrated using the OSCICN and OSCICL registers, as
shown in Figure 19.1. The external oscillator can be configured using the OSCXCN register. The low
power internal oscillator is automatically enabled and disabled when selected and deselected as a clock
source. SmaRTClock operation is described in the SmaRTClock oscillator chapter.
The system clock (SYSCLK) can be derived from the precision internal oscillator, external oscillator, low
power internal oscillator, or SmaRTClock oscillator. The global clock divider can generate a system clock
that is 1, 2, 4, 8, 16, 32, 64, or 128 times slower that the selected input clock source. Oscillator electrical
specifications can be found in the Electrical Specifications Chapter.
The proper way of changing the system clock when both the clock source and the clock divide value are
being changed is as follows:
If switching from a fast “undivided” clock to a slower “undivided” clock:
a. Change the clock divide value.
b. Poll for CLKRDY > 1.
c. Change the clock source.
If switching from a slow “undivided” clock to a faster “undivided” clock:
a. Change the clock source.
b. Change the clock divide value.
c. Poll for CLKRDY > 1.
VDD
Option 2
XTAL2
Option 1
Option 4
10M
XTAL2
Option 3
XTAL2
XTAL1
XTAL2
Figure 19.1. Clocking Sources Block Diagram
OSCICL
Internal Oscillator
Drive Circuit
Oscillator
Precision
External
OSCXCN
EN
OSCICN
Internal Oscillator
Low Power
Rev. 1.0
C8051F91x-C8051F90x
Low Power Internal Oscillator
Precision Internal Oscillator
SmaRTClock
Oscillator
SmaRTClock Oscillator
External Oscillator
CLKSEL
Clock Divider
n
CLKRDY
SYSCLK
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