ATmega168A

Manufacturer Part NumberATmega168A
ManufacturerAtmel Corporation
ATmega168A datasheets
 


Specifications of ATmega168A

Flash (kbytes)16 KbytesPin Count32
Max. Operating Frequency20 MHzCpu8-bit AVR
# Of Touch Channels16Hardware Qtouch AcquisitionNo
Max I/o Pins23Ext Interrupts24
Usb SpeedNoUsb InterfaceNo
Spi2Twi (i2c)1
Uart1Graphic LcdNo
Video DecoderNoCamera InterfaceNo
Adc Channels8Adc Resolution (bits)10
Adc Speed (ksps)15Analog Comparators1
Resistive Touch ScreenNoTemp. SensorYes
Crypto EngineNoSram (kbytes)1
Eeprom (bytes)512Self Program MemoryYES
Dram MemoryNoNand InterfaceNo
PicopowerNoTemp. Range (deg C)-40 to 85
I/o Supply Class1.8 to 5.5Operating Voltage (vcc)1.8 to 5.5
FpuNoMpu / Mmuno / no
Timers3Output Compare Channels6
Input Capture Channels1Pwm Channels6
32khz RtcYesCalibrated Rc OscillatorYes
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Table 9-16.
Power Conditions
BOD enabled
Fast rising power
Slowly rising power
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
36
for details.
9.9
Clock Output Buffer
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.
9.10
Timer/Counter Oscillator
ATmega48A/PA/88A/PA/168A/PA/328/P uses the same crystal oscillator for Low-frequency
Oscillator and Timer/Counter Oscillator. See
details on the oscillator and crystal requirements.
ATmega48A/PA/88A/PA/168A/PA/328/P share the Timer/Counter Oscillator Pins (TOSC1 and
TOSC2) with XTAL1 and XTAL2. When using the Timer/Counter Oscillator, the system clock
needs to be four times the oscillator frequency. Due to this and the pin sharing, the Timer/Coun-
ter Oscillator can only be used when the Calibrated Internal RC Oscillator is selected as system
clock source.
Applying an external clock source to TOSC1 can be done if EXTCLK in the ASSR Register is
written to logic one. See
description on selecting external clock as input instead of a 32.768kHz watch crystal.
9.11
System Clock Prescaler
The ATmega48A/PA/88A/PA/168A/PA/328/P has a system clock prescaler, and the system
clock can be divided by setting the
ture can be used to decrease the system clock frequency and the power consumption when the
requirement for processing power is low. This can be used with all clock source options, and it
will affect the clock frequency of the CPU and all synchronous peripherals. clk
and clk
8271D–AVR–05/11
ATmega48A/PA/88A/PA/168A/PA/328/P
Start-up Times for the External Clock Selection
Start-up Time from Power-
down and Power-save
6 CK
6 CK
6 CK
Reserved
”Asynchronous Operation of Timer/Counter2” on page 157
”CLKPR – Clock Prescale Register” on page
are divided by a factor as shown in
FLASH
Additional Delay from
Reset (V
= 5.0V)
CC
14CK
14CK + 4.1ms
14CK + 65ms
”System Clock Prescaler” on page
”Low Frequency Crystal Oscillator” on page 33
I/O
Table 29-12 on page
324.
SUT1...0
00
01
10
11
for
for further
387. This fea-
, clk
, clk
,
ADC
CPU
36