C8051T617-GM Silicon Laboratories Inc, C8051T617-GM Datasheet - Page 106

• Manufacturer Part Number: C8051T617-GM
• Description: IC 8051 MCU 16K BYTE-PROG 24-QFN
• Manufacturer: Silicon Laboratories Inc
• Series: C8051T61xr

Specifications of C8051T617-GM

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 25MHz
• Connectivity: SMBus (2-Wire/I²C), SPI, UART/USART
• Peripherals: POR, PWM, WDT
• Number Of I /o: 21
• Program Memory Size: 16KB (16K x 8)
• Program Memory Type: OTP
• Ram Size: 1.25K x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 3.6 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 24-QFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Data Converters: -
• Other names: 336-1438-5

C8051T610/1/2/3/4/5/6/7
20. Oscillators and Clock Selection
C8051T610/1/2/3/4/5/6/7 devices include a programmable internal high-frequency oscillator and an exter-
nal oscillator drive circuit. The internal high-frequency oscillator can be enabled/disabled and calibrated
using the OSCICN and OSCICL registers, as shown in Figure 20.1. The system clock can be sourced by
the external oscillator circuit or the internal oscillator. The internal oscillator also offers a selectable post-
scaling feature.
OSCICL
OSCICN
RC Mode
VDD
EXTCLK
EN
Programmable
n
Internal Clock
Generator
SYSCLK
C Mode
Input
EXTCLK
EXTCLK
OSC
Circuit
CMOS Mode
EXTCLK
OSCXCN
CLKSEL
Figure 20.1. Oscillator Options
20.1. System Clock Selection
The CLKSL0 bit in register CLKSEL selects which oscillator source is used as the system clock. CLKSL0
must be set to 1 for the system clock to run from the external oscillator; however the external oscillator may
still clock certain peripherals (timers, PCA) when the internal oscillator is selected as the system clock. The
system clock may be switched on-the-fly between the internal oscillator and external oscillator, so long as
the selected clock source is enabled and running.
The internal high-frequency oscillator requires little start-up time and may be selected as the system clock
immediately following the register write which enables the oscillator. The external RC and C modes also
typically require no startup time.
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Rev 1.0