ATmega168A Atmel Corporation, ATmega168A Datasheet - Page 29

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ATmega168A

Manufacturer Part Number
ATmega168A
Description
Manufacturer
Atmel Corporation
Datasheets

Specifications of ATmega168A

Flash (kbytes)
16 Kbytes
Pin Count
32
Max. Operating Frequency
20 MHz
Cpu
8-bit AVR
# Of Touch Channels
16
Hardware Qtouch Acquisition
No
Max I/o Pins
23
Ext Interrupts
24
Usb Speed
No
Usb Interface
No
Spi
2
Twi (i2c)
1
Uart
1
Graphic Lcd
No
Video Decoder
No
Camera Interface
No
Adc Channels
8
Adc Resolution (bits)
10
Adc Speed (ksps)
15
Analog Comparators
1
Resistive Touch Screen
No
Temp. Sensor
Yes
Crypto Engine
No
Sram (kbytes)
1
Eeprom (bytes)
512
Self Program Memory
YES
Dram Memory
No
Nand Interface
No
Picopower
No
Temp. Range (deg C)
-40 to 85
I/o Supply Class
1.8 to 5.5
Operating Voltage (vcc)
1.8 to 5.5
Fpu
No
Mpu / Mmu
no / no
Timers
3
Output Compare Channels
6
Input Capture Channels
1
Pwm Channels
6
32khz Rtc
Yes
Calibrated Rc Oscillator
Yes

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Company
Part Number
Manufacturer
Quantity
Price
Part Number:
ATmega168A-AU
Manufacturer:
ATMEL
Quantity:
464
Part Number:
ATmega168A-PU
Manufacturer:
ATMEL
Quantity:
1 000
9.3
8271D–AVR–05/11
Low Power Crystal Oscillator
selectable delays are shown in
dependent as shown in
Table 9-2.
Main purpose of the delay is to keep the AVR in reset until it is supplied with minimum V
delay will not monitor the actual voltage and it will be required to select a delay longer than the
V
used. A BOD circuit will ensure sufficient V
can be disabled. Disabling the time-out delay without utilizing a Brown-Out Detection circuit is
not recommended.
The oscillator is required to oscillate for a minimum number of cycles before the clock is consid-
ered stable. An internal ripple counter monitors the oscillator output clock, and keeps the internal
reset active for a given number of clock cycles. The reset is then released and the device will
start to execute. The recommended oscillator start-up time is dependent on the clock type, and
varies from 6 cycles for an externally applied clock to 32K cycles for a low frequency crystal.
The start-up sequence for the clock includes both the time-out delay and the start-up time when
the device starts up from reset. When starting up from Power-save or Power-down mode, V
assumed to be at a sufficient level and only the start-up time is included.
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
crystal or a ceramic resonator may be used.
This Crystal Oscillator is a low power oscillator, with reduced voltage swing on the XTAL2 out-
put. It gives the lowest power consumption, but is not capable of driving other clock inputs, and
may be more susceptible to noise in noisy environments. In these cases, refer to the
Crystal Oscillator” on page
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
ues given by the manufacturer should be used.
CC
Typ Time-out (V
rise time. If this is not possible, an internal or external Brown-Out Detection circuit should be
4.1ms
65ms
0ms
Number of Watchdog Oscillator Cycles
CC
ATmega48A/PA/88A/PA/168A/PA/328/P
= 5.0V)
”Typical Characteristics” on page
31.
Table 9-3 on page
Table
Typ Time-out (V
9-2. The frequency of the Watchdog Oscillator is voltage
CC
4.3ms
69ms
before it releases the reset, and the time-out delay
0ms
30. For ceramic resonators, the capacitor val-
CC
= 3.0V)
Figure 9-2 on page
332.
Number of Cycles
8K (8,192)
30. Either a quartz
512
0
”Full Swing
CC
. The
CC
29
is

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