ATMEGA168-20PU Atmel, ATMEGA168-20PU Datasheet - Page 349

• Manufacturer Part Number: ATMEGA168-20PU
• Description: IC AVR MCU 16K 20MHZ 28DIP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA168-20PU

• 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: 16KB (8K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 6x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 28-DIP (0.300", 7.62mm)
• Processor Series: ATMEGA16x
• Core: AVR8
• Data Bus Width: 8 bit
• Data Ram Size: 1 KB
• Interface Type: 2-Wire, SPI, USART, Serial
• Maximum Clock Frequency: 20 MHz
• Number Of Programmable I/os: 23
• Number Of Timers: 3
• Operating Supply Voltage: 2.7 V to 5.5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: Through Hole
• 3rd Party Development Tools: EWAVR, EWAVR-BL
• Development Tools By Supplier: ATAVRDRAGON, ATSTK500, ATSTK600, ATAVRISP2, ATAVRONEKIT
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 10 bit, 6 Channel
• A/d Inputs: 6-Channel, 10-Bit
• Cpu Speed: 20 MIPS
• Eeprom Memory: 512 Bytes
• Input Output: 23
• Interface: I2C/SPI/UART/USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 28-pin PDIP
• Programmable Memory: 16K Bytes
• Timers: 2-8-bit, 1-16-bit
• Voltage, Range: 4.5-5.5 V
• Controller Family/series: AVR MEGA
• No. Of I/o's: 23
• Eeprom Memory Size: 512Byte
• Ram Memory Size: 1KB
• Rohs Compliant: Yes
• For Use With: ATSTK600-TQFP32 - STK600 SOCKET/ADAPTER 32-TQFPATSTK600 - DEV KIT FOR AVR/AVR32770-1007 - ISP 4PORT ATMEL AVR MCU SPI/JTAGATAVRDRAGON - KIT DRAGON 32KB FLASH MEM AVRATAVRISP2 - PROGRAMMER AVR IN SYSTEMATJTAGICE2 - AVR ON-CHIP D-BUG SYSTEM
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

32.3
32.3.1
32.3.2
32.3.3
2545E–AVR–02/05
Errata ATmega168
Rev A
Rev B
Rev C
The revision letter in this section refers to the revision of the ATmega168 device.
•
•
1. Wrong values read after Erase Only operation
At supply voltages below 2.7 V, an EEPROM location that is erased by the Erase Only operation
may read as programmed (0x00).
If it is necessary to read an EEPROM location after Erase Only, use an Atomic Write operation
with 0xFF as data in order to erase a location. In any case, the Write Only operation can be used
as intended. Thus no special considerations are needed as long as the erased location is not
read before it is programmed.
2. Part may hang in reset
Some parts may get stuck in a reset state when a reset signal is applied when the internal reset
state-machine is in a specific state. The internal reset state-machine is in this state for approxi-
mately 10 ns immediately before the part wakes up after a reset, and in a 10 ns window when
altering the system clock prescaler. The problem is most often seen during In-System Program-
ming of the device. There are theoretical possibilities of this happening also in run-mode. The
following three cases can trigger the device to get stuck in a reset-state:
- Two succeeding resets are applied where the second reset occurs in the 10ns window before
the device is out of the reset-state caused by the first reset.
- A reset is applied in a 10 ns window while the system clock prescaler value is updated by
software.
- Leaving SPI-programming mode generates an internal reset signal that can trigger this case.
The two first cases can occur during normal operating mode, while the last case occurs only dur-
ing programming of the device.
The first case can be avoided during run-mode by ensuring that only one reset source is active.
If an external reset push button is used, the reset start-up time should be selected such that the
reset line is fully debounced during the start-up time.
The second case can be avoided by not using the system clock prescaler.
The third case occurs during In-System programming only. It is most frequently seen when using
the internal RC at maximum frequency.
If the device gets stuck in the reset-state, turn power off, then on again to get the device out of
this state.
No errata.
No errata.
Wrong values read after Erase Only operation
Part may hang in reset
Problem Fix/Workaround
Problem Fix/Workaround
ATmega48/88/168
349