ATmega168A Atmel Corporation, ATmega168A Datasheet - Page 33

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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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9.5
8271D–AVR–05/11
Low Frequency Crystal Oscillator
The Low-frequency Crystal Oscillator is optimized for use with a 32.768kHz watch crystal. When
selecting crystals, load capacitance and crystal’s Equivalent Series Resistance, ESR must be
t a k e n i n t o c o n s i d e r a t i o n . B o t h v a l u e s a r e s p e c i f i e d b y t h e c r y s t a l v e n d o r .
ATmega48A/PA/88A/PA/168A/PA/328/P oscillator is optimized for very low power consumption,
and thus when selecting crystals, see
9.0pF and 12.5pF crystals
Table 9-7.
Note:
The Low-frequency Crystal Oscillator provides an internal load capacitance, see
each TOSC pin.
Table 9-8.
The capacitance (Ce+Ci) needed at each TOSC pin can be calculated by using:
where:
Crystals specifying load capacitance (CL) higher than 6 pF, require external capacitors applied
as described in
The Low-frequency Crystal Oscillator must be selected by setting the CKSEL Fuses to “0110” or
“0111”, as shown in
shown in
Table 9-9.
C
ATmega48A/PA/88A/PA/168A/PA/3
=
SUT1...0
– Ce - is optional external capacitors as described in
– Ci - is the pin capacitance in
– CL - is the load capacitance for a 32.768kHz crystal specified by the crystal vendor
– CS - is the total stray capacitance for one TOSC pin.
2 CL
00
01
10
11
1. Maximum ESR is typical value based on characterization
Table
C
s
Device
Maximum ESR Recommendation for 32.768kHz Crystal
Capacitance for Low-frequency Oscillator
Start-up Times for the Low-frequency Crystal Oscillator Clock Selection
28/P
Additional Delay from Reset (V
Figure 9-2 on page
9-9.
Crystal CL (pF)
Table 9-10 on page
ATmega48A/PA/88A/PA/168A/PA/328/P
12.5
6.5
9.0
4 CK + 4.1ms
4 CK + 65ms
4 CK
Table 9-8
30.
32kHz Osc. Type
System Osc.
Table
Timer Osc.
34. Start-up times are determined by the SUT Fuses as
CC
for maximum ESR recommendations on 6.5pF,
= 5.0V)
Reserved
Recommended Usage
Fast rising power or BOD enabled
Slowly rising power
Stable frequency at start-up
Cap(Xtal1/Tosc1)
Figure 9-2 on page 30
18pF
18pF
Max ESR [kΩ]
75
65
30
Cap(Xtal2/Tosc2)
(1)
Table 9-8
8pF
8pF
33
at