C8051F709-GQR Silicon Labs, C8051F709-GQR Datasheet - Page 173

• Manufacturer Part Number: C8051F709-GQR
• Description: 8-bit Microcontrollers - MCU 8kB 32B EEPROM Cap Sense
• Manufacturer: Silicon Labs

Specifications of C8051F709-GQR

• Rohs: yes
• Core: 8051
• Processor Series: C8051
• Data Bus Width: 8 bit

27.2. Programmable Internal High-Frequency (H-F) Oscillator
All C8051F70x/71x devices include a programmable internal high-frequency oscillator that defaults as the
system clock after a system reset. The internal oscillator period can be adjusted via the OSCICL register
as defined by SFR Definition 27.2.
On C8051F70x/71x devices, OSCICL is factory calibrated to obtain a 24.5 MHz base frequency.
The internal oscillator output frequency may be divided by 1, 2, 4, or 8, as defined by the IFCN bits in reg-
ister OSCICN. The divide value defaults to 8 following a reset.
The precision oscillator supports a spread spectrum mode which modulates the output frequency in order
to reduce the EMI generated by the system. When enabled (SSE = 1), the oscillator output frequency is
modulated by a stepped triangle wave whose frequency is equal to the oscillator frequency divided by 384
(63.8 kHz using the factory calibration). The maximum deviation from the center frequency is ±0.75%. The
output frequency updates occur every 32 cycles and the step size is typically 0.25% of the center fre-
quency.
SFR Definition 27.2. OSCICL: Internal H-F Oscillator Calibration
SFR Address = 0xBF; SFR Page = F
Name
Reset
Bit
6:0 OSCICL[7:0] Internal Oscillator Calibration Bits.
Type
Bit
Name
Varies
7
These bits determine the internal oscillator period. When set to 00000000b, the H-F
oscillator operates at its fastest setting. When set to 11111111b, the H-F oscillator
operates at its slowest setting. The reset value is factory calibrated to generate an
internal oscillator frequency of 24.5 MHz.
Varies
6
Varies
5
Varies
Rev. 1.0
4
OSCICL[6:0]
R/W
Function
Varies
3
Varies
C8051F70x/71x
2
Varies
1
Varies
0
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