C8051T322-GQR Silicon Labs, C8051T322-GQR Datasheet - Page 125

• Manufacturer Part Number: C8051T322-GQR
• Description: 8-bit Microcontrollers - MCU USB-OTP-16K-LQFP32
• Manufacturer: Silicon Labs

Specifications of C8051T322-GQR

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

21.3. Programmable Internal High-Frequency (H-F) Oscillator
All C8051T620/621/320/321/322/323 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 21.2.
On C8051T620/621/320/321/322/323 devices, OSCICL is factory calibrated to obtain a 48 MHz base fre-
quency. Note that the system clock may be derived from the programmed internal oscillator divided by 1, 2,
4, or 8 after a divide by 4 stage, as defined by the IFCN bits in register OSCICN. The divide value defaults
to 8 following a reset, which results in a 1.5 MHz system clock.
21.3.1. Internal Oscillator Suspend Mode
When software writes a logic 1 to SUSPEND (OSCICN.5), the internal oscillator is suspended. If the sys-
tem clock is derived from the internal oscillator, the input clock to the peripheral or CIP-51 will be stopped
until one of the following events occur:




When one of the oscillator awakening events occur, the internal oscillator, CIP-51, and affected peripherals
resume normal operation, regardless of whether the event also causes an interrupt. The CPU resumes
execution at the instruction following the write to the SUSPEND bit.
Note: The prefetch engine can be turned off in suspend mode to save power. Additionally, both Voltage
Regulators (REG0 and REG1) have low-power modes for additional power savings in suspend mode. See
Section “13. Prefetch Engine” on page 74 and Section “11. Voltage Regulators (REG0 and REG1)” on
page 59 for more information.
SFR Definition 21.2. OSCICL: Internal H-F Oscillator Calibration
SFR Address = 0xB3
Name
Reset
Bit
6:0 OSCICL[6:0] Internal Oscillator Calibration Bits.
Type
7
Bit
Port 0 Match Event.
Port 1 Match Event.
Timer3 Overflow Event.
USB0 Transceiver Resume Signalling
Unused
Name
R
7
0
Unused. Read = 0; Write = Don’t Care
These bits determine the internal oscillator period. When set to 0000000b, the H-F
oscillator operates at its fastest setting. When set to 1111111b, the H-F oscillator
operates at its slowest setting. The reset value is factory calibrated to generate an
internal oscillator frequency of 48 MHz.
Varies
6
Varies
5
C8051T620/621/320/321/322/323
Varies
Rev. 1.1
4
OSCICL[6:0]
Function
Varies
R/W
3
Varies
2
Varies
1
Varies
0
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