C8051F236 Silicon Laboratories Inc, C8051F236 Datasheet - Page 97

• Manufacturer Part Number: C8051F236
• Description: IC 8051 MCU 8K FLASH 48TQFP
• Manufacturer: Silicon Laboratories Inc
• Series: C8051F2xxr

Specifications of C8051F236

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 25MHz
• Connectivity: SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, WDT
• Number Of I /o: 32
• Program Memory Size: 8KB (8K x 8)
• Program Memory Type: FLASH
• Ram Size: 1.25K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 3.6 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 48-TQFP, 48-VQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -
• Data Converters: -

13. Oscillator
The MCU includes an internal oscillator and an external oscillator drive circuit, either of which can generate
the system clock. The MCU boots from the internal oscillator after any reset. This internal oscillator can
be enabled/disabled and its frequency can be set using the Internal Oscillator Control Register (OSCICN)
as shown in SFR Definition 13.1. The internal oscillator's electrical specifications are given in Table 13.1.
Both oscillators are disabled when the RST pin is held low. The MCU can run from the internal oscillator
permanently, or it can switch to the external oscillator if desired using CLKSL bit in the OSCICN Register.
The external oscillator requires an external resonator, crystal, capacitor, or RC network connected to the
XTAL1/XTAL2 pins (see Figure 13.1). The oscillator circuit must be configured for one of these sources in
the OSCXCN register. An external CMOS clock can also provide the system clock by driving the XTAL1
pin. The XTAL1 and XTAL2 pins are NOT 5 V tolerant.
opt. 4
XTAL1
opt. 3
XTAL1
XTAL2
VDD
opt. 2
XTAL1
Figure 13.1. Oscillator Diagram
opt. 1
XTAL1
XTAL2
Rev. 1.6
Circuit
Input
OSCXCN
Internal Clock
OSCICN
Generator
EN
OSC
C8051F2xx
SYSCLK
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