PIC18F6621-I/PT Microchip Technology Inc., PIC18F6621-I/PT Datasheet - Page 26

• Manufacturer Part Number: PIC18F6621-I/PT
• Description: 64 PIN, 64 KB FLASH, 3840 RAM, 52 I/O
• Manufacturer: Microchip Technology Inc.

Specifications of PIC18F6621-I/PT

• A/d Inputs: 12-Channel, 10-Bit
• Comparators: 2
• Cpu Speed: 10 MIPS
• Eeprom Memory: 1024 Bytes
• Input Output: 54
• Interface: I2C/SPI/UART/USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 64-pin TQFP
• Programmable Memory: 64K Bytes
• Ram Size: 3.8K Bytes
• Speed: 40 MHz
• Timers: 2-8-bit, 3-16-bit
• Voltage, Range: 2-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

PIC18F6525/6621/8525/8621
2.6
The PIC18F6525/6621/8525/8621 devices include a
feature that allows the system clock source to be
switched from the main oscillator to an alternate low
frequency clock source. For the PIC18F6525/6621/
8525/8621 devices, this alternate clock source is the
Timer1 oscillator. If a low-frequency crystal (32 kHz, for
example) has been attached to the Timer1 oscillator
pins and the Timer1 oscillator has been enabled, the
device can switch to a low-power execution mode.
FIGURE 2-7:
DS39612B-page 24
Oscillator Switching Feature
T1OSO
T1OSI
OSC2
OSC1
DEVICE CLOCK SOURCES
Timer1 Oscillator
Main Oscillator
PIC18F6X2X/8X2X
T1OSCEN
Enable
Oscillator
Sleep
Clock Source Option
for Other Modules
4 x PLL
Figure 2-7 shows a block diagram of the system clock
sources. The clock switching feature is enabled by
programming
(OSCSEN) bit in the CONFIG1H Configuration register
to a ‘0’. Clock switching is disabled in an erased device.
See Section 12.0 “Timer1 Module” for further details
of the Timer1 oscillator. See Section 24.0 “Special
Features of the CPU” for Configuration register
details.
T
T
T
OSC
1
P
T
OSC
/4
the
Source
Clock
Oscillator
 2005 Microchip Technology Inc.
T
SCLK
Switching
Enable