ATMEGA325A-AUR Atmel, ATMEGA325A-AUR Datasheet - Page 34

• Manufacturer Part Number: ATMEGA325A-AUR
• Description: IC MCU AVR 32K FLASH 64TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA325A-AUR

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: SPI, UART/USART, USI
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 54
• Program Memory Size: 32KB (16K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 1K x 8
• Ram Size: 2K x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 64-TQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Table 8-9.
34
ATmega165A/165PA/325A/325PA/3250A/
3250PA/645A/645P/6450A/6450P
ATmega165A/165PA/325A/325PA/3250A/3250PA/645A/645P/645
Capacitance for Low-Frequency Crystal Oscillator
Device
Table 8-8.
Note:
The capacitance (Ce + Ci) needed at each TOSC pin can be calculated by using:
where:
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.
C
Crystals specifying load capacitance (CL) higher than the ones given in the
34, 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
Table
Table 8-10.
Table 8-11.
Note:
S
CKSEL3...
SUT1..0
- is the total stray capacitance for one TOSC pin.
0110
0111
00
01
10
11
0
8-10.
(1)
1. Maximum ESR is typical value based on characterization
1. This option should only be used if frequency stability at start-up is not important for the
application
Maximum ESR Recommendation for 32.768kHz Watch Crystal
ATmega325A/325PA/3250A/3250PA/645A/645P/6450A/6450P
Start-up Times for the Low-frequency Crystal Oscillator Clock Selection
Start-up Times for the Low-frequency Crystal Oscillator Clock Selection
Additional Delay from Reset (V
Crystal CL (pF)
32kHz Osc. Type
Table
Power-down and Power-save
System Osc.
12.5
Timer Osc.
6.5
9.0
Start-up Time from
8-11. Start-up times are determined by the SUT Fuses as shown in
14 CK + 65ms
14 CK + 4ms
Table 8-9 on page 34
32K CK
1K CK
14 CK
Ce
+
Ci
CC
=
Cap (Xtal1/Tosc1)
= 5.0V)
2 CL
⋅
Reserved
Figure 8-2 on page 32
16pF
16pF
–
Figure 8-2 on page
C
s
Recommended Usage
Fast rising power or BOD enabled
Slowly rising power
Recommended Usage
Stable frequency at start-up
Stable frequency at start-up
Max ESR [kΩ]
75
65
30
Cap (Xtal2/Tosc2)
32.
Table 8-9 on page
(1)
6pF
6pF
8285B–AVR–03/11