ATMEGA165-16AI Atmel, ATMEGA165-16AI Datasheet - Page 31

• Manufacturer Part Number: ATMEGA165-16AI
• Description: IC AVR MCU 16K 16MHZ 64TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA165-16AI

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: SPI, UART/USART, USI
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 54
• 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 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 64-TQFP, 64-VQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Switching Time
2573G–AVR–07/09
Table 13. Clock Prescaler Select
When switching between prescaler settings, the System Clock Prescaler ensures that
no glitches occur in the clock system and that no intermediate frequency is higher than
neither the clock frequency corresponding to the previous setting, nor the clock fre-
quency corresponding to the new setting.
The ripple counter that implements the prescaler runs at the frequency of the undivided
clock, which may be faster than the CPU’s clock frequency. Hence, it is not possible to
determine the state of the prescaler – even if it were readable, and the exact time it
takes to switch from one clock division to another cannot be exactly predicted.
From the time the CLKPS values are written, it takes between T1 + T2 and T1 + 2*T2
before the new clock frequency is active. In this interval, 2 active clock edges are pro-
duced. Here, T1 is the previous clock period, and T2 is the period corresponding to the
new prescaler setting.
CLKPS3
1
1
1
CLKPS2
1
1
1
CLKPS1
0
1
1
CLKPS0
1
0
1
ATmega165/V
Clock Division Factor
Reserved
Reserved
Reserved
31