ATMEGA48-20MJ Atmel, ATMEGA48-20MJ Datasheet - Page 30

• Manufacturer Part Number: ATMEGA48-20MJ
• Description: IC AVR MCU 4K 5V 20MHZ 32-QFN
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA48-20MJ

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 23
• Program Memory Size: 4KB (2K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 512 x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 32-VQFN Exposed Pad, 32-HVQFN, 32-SQFN, 32-DHVQFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: ATMEGA48-24MJ; ATMEGA48-24MJ

8.4
30
Full Swing Crystal Oscillator
ATmega48/88/168
Table 8-4.
Notes:
Pins XTAL1 and XTAL2 are input and output, respectively, of an inverting amplifier which can be
configured for use as an On-chip Oscillator, as shown in
ceramic resonator may be used.
This Crystal Oscillator is a full swing oscillator, with rail-to-rail swing on the XTAL2 output. This is
useful for driving other clock inputs and in noisy environments. The current consumption is
higher than the
Oscillator will only operate for V
C1 and C2 should always be equal for both crystals and resonators. The optimal value of the
capacitors depends on the crystal or resonator in use, the amount of stray capacitance, and the
electromagnetic noise of the environment. Some initial guidelines for choosing capacitors for
use with crystals are given in
the manufacturer should be used.
The operating mode is selected by the fuses CKSEL3..1 as shown in
Table 8-5.
Notes:
Oscillator Source /
Power Conditions
Crystal Oscillator, BOD
enabled
Crystal Oscillator, fast
rising power
Crystal Oscillator, slowly
rising power
Frequency Range (MHz)
1. These options should only be used when not operating close to the maximum frequency of the
2. These options are intended for use with ceramic resonators and will ensure frequency stability
1. If 8 MHz frequency exceeds the specification of the device (depends on V
0.4 - 20
device, and only if frequency stability at start-up is not important for the application. These
options are not suitable for crystals.
at start-up. They can also be used with crystals when not operating close to the maximum fre-
quency of the device, and if frequency stability at start-up is not important for the application.
Fuse can be programmed in order to divide the internal frequency by 8. It must be ensured
that the resulting divided clock meets the frequency specification of the device.
Start-up Times for the Low Power Crystal Oscillator Clock Selection (Continued)
Full Swing Crystal Oscillator operating modes
“Low Power Crystal Oscillator” on page
Start-up Time from
Table
Power-down and
CC
Power-save
= 2.7V - 5.5 volts.
16K CK
16K CK
16K CK
8-6. For ceramic resonators, the capacitor values given by
Capacitors C1 and C2 (pF)
Recommended Range for
12 - 22
Additional Delay
14CK + 4.1 ms
14CK + 65 ms
(V
from Reset
Figure
CC
28. Note that the Full Swing Crystal
14CK
(1)
= 5.0V)
8-2. Either a quartz crystal or a
Table
CKSEL3..1
CKSEL0
8-5.
CC
1
1
1
), the CKDIV8
2545S–AVR–07/10
011
SUT1..0
01
10
11