ATMEGA324A-PU Atmel, ATMEGA324A-PU Datasheet - Page 39

• Manufacturer Part Number: ATMEGA324A-PU
• Description: IC MCU AVR 32K 20MHZ 40PDIP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA324A-PU

• 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: 32
• Program Memory Size: 32KB (16K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 1K x 8
• Ram Size: 2K x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 40-DIP (0.600", 15.24mm)
• Controller Family/series: Atmega
• No. Of I/o's: 32
• Eeprom Memory Size: 1KB
• Ram Memory Size: 2KB
• Cpu Speed: 20MHz
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

8.9
8.10
8272A–AVR–01/10
Timer/Counter Oscillator
Clock Output Buffer
Table 8-14.
Table 8-15.
When applying an external clock, it is required to avoid sudden changes in the applied clock fre-
quency to ensure stable operation of the MCU. A variation in frequency of more than 2% from
one clock cycle to the next can lead to unpredictable behavior. If changes of more than 2% is
required, ensure that the MCU is kept in Reset during the changes.
Note that the System Clock Prescaler can be used to implement run-time changes of the internal
clock frequency while still ensuring stable operation. Refer to
40
ATmega164A/164PA/324A/324PA/644A/644PA/1284/1284P uses the same type of crystal
oscillator for Low-frequency Crystal Oscillator and Timer/Counter Oscillator. See
quency Crystal Oscillator” on page 35
The device can operate its Timer/Counter2 from an external 32.768 kHz watch crystal or a exter-
nal clock source. See
Applying an external clock source to TOSC1 can be done if EXTCLK in the ASSR Register is
written to logic one. See
uously compared with the counter value (TCNT2). A match can be used to generate an Output
Compare interrupt, or to generate a waveform output on the OC2B pin.” on page 158
description on selecting external clock as input instead of a 32.768 kHz watch crystal.
The device can output the system clock on the CLKO pin. To enable the output, the CKOUT
Fuse has to be programmed. This mode is suitable when the chip clock is used to drive other cir-
cuits on the system. The clock also will be output during reset, and the normal operation of I/O
pin will be overridden when the fuse is programmed. Any clock source, including the internal RC
Oscillator, can be selected when the clock is output on CLKO. If the System Clock Prescaler is
used, it is the divided system clock that is output.
164A/164PA/324A/324PA/644A/644PA/1284/1284P
BOD enabled
Fast rising power
Slowly rising power
for details.
Power Conditions
Crystal Oscillator Clock Frequency
Start-up Times for the External Clock Selection
Nominal Frequency
”Clock Source Connections” on page 32
”The Output Compare Register B contains an 8-bit value that is contin-
0 - 20 MHz
Start-up Time from Power-
down and Power-save
Reserved
for details on the oscillator and crystal requirements.
6 CK
6 CK
6 CK
Additional Delay from
”System Clock Prescaler” on page
Reset (V
for details.
14CK + 4.1 ms
14CK + 65 ms
14CK
CC
CKSEL3..0
= 5.0V)
0000
”Low Fre-
for further
SUT1..0
00
01
10
11
39