ATTINY25-20SUR Atmel, ATTINY25-20SUR Datasheet - Page 29

• Manufacturer Part Number: ATTINY25-20SUR
• Description: MCU AVR 2KB FLASH 20MHZ 8SOIC
• Manufacturer: Atmel
• Series: AVR® ATtinyr

Specifications of ATTINY25-20SUR

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: USI
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 6
• Program Memory Size: 2KB (1K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 128 x 8
• Ram Size: 128 x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 4x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

6.2.4
6.2.5
2586M–AVR–07/10
Internal 128 kHz Oscillator
Low-Frequency Crystal Oscillator
The 128 kHz internal Oscillator is a low power Oscillator providing a clock of 128 kHz. The fre-
quency is nominal at 3V and 25°C. This clock may be select as the system clock by
programming the CKSEL Fuses to “0100”.
When this clock source is selected, start-up times are determined by the SUT Fuses as shown in
Table
Table 6-9.
Note:
To use a 32.768 kHz watch crystal as the clock source for the device, the Low-frequency Crystal
Oscillator must be selected by setting CKSEL fuses to ‘0110’. The crystal should be connected
as shown in
the manufacturer’s datasheet.
When this oscillator is selected, start-up times are determined by the SUT fuses as shown in
Table
Table 6-10.
Note:
The Low-frequency Crystal Oscillator provides an internal load capacitance, see
each TOSC pin.
Table 6-11.
SUT[1:0]
SUT[1:0]
00
01
10
11
00
01
10
11
ATtiny25/45/85
6-9.
6-10.
1. If the RSTDISBL fuse is programmed, this start-up time will be increased to 14CK + 4 ms to
1. These options should be used only if frequency stability at start-up is not important.
Device
ensure programming mode can be entered.
Figure
Start-up Time from
Start-up Times for the 128 kHz Internal Oscillator
Start-up Times for the Low Frequency Crystal Oscillator Clock Selection
Capacitance of Low-Frequency Crystal Oscillator
32K (32768) CK
1K (1024) CK
1K (1024) CK
Power Down
Start-up Time from
6-5. To find suitable load capacitance for a 32.768 kHz crysal, please consult
Power-down
6 CK
6 CK
6 CK
(1)
(1)
32 kHz Osc. Type
System Osc.
Additional Delay from
Reset (V
64 ms
64 ms
4 ms
Additional Delay from
CC
= 5.0V)
Reserved
Reserved
14CK + 64 ms
14CK + 4 ms
14CK
Reset
Cap (Xtal1/Tosc1)
(1)
Recommended usage
Fast rising power or BOD enabled
Slowly rising power
Stable frequency at start-up
16 pF
BOD enabled
Fast rising power
Slowly rising power
Recommended Usage
Cap (Xtal2/Tosc2)
Table 6-11
6 pF
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