ATTINY25-20SUR Atmel, ATTINY25-20SUR Datasheet - Page 130

• 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

130
ATtiny25/45/85
When initiating a single ended conversion by setting the ADSC bit in ADCSRA, the conversion
starts at the following rising edge of the ADC clock cycle.
A normal conversion takes 13 ADC clock cycles. The first conversion after the ADC is switched
on (ADEN in ADCSRA is set) takes 25 ADC clock cycles in order to initialize the analog circuitry,
as shown in
Figure 17-4. ADC Timing Diagram, First Conversion (Single Conversion Mode)
The actual sample-and-hold takes place 1.5 ADC clock cycles after the start of a normal conver-
sion and 13.5 ADC clock cycles after the start of an first conversion. When a conversion is
complete, the result is written to the ADC Data Registers, and ADIF is set. In Single Conversion
mode, ADSC is cleared simultaneously. The software may then set ADSC again, and a new
conversion will be initiated on the first rising ADC clock edge.
Figure 17-5. ADC Timing Diagram, Single Conversion
When Auto Triggering is used, the prescaler is reset when the trigger event occurs. This assures
a fixed delay from the trigger event to the start of conversion. In this mode, the sample-and-hold
takes place two ADC clock cycles after the rising edge on the trigger source signal. Three addi-
tional CPU clock cycles are used for synchronization logic.
Cycle Number
ADC Clock
ADSC
ADIF
ADCH
ADCL
Cycle Number
ADC Clock
ADEN
ADSC
ADIF
ADCH
ADCL
Figure 17-4
1
1
2
MUX and REFS
Update
2
MUX and REFS
Update
below.
12
3
13
Sample & Hold
4
14
5
15
6
Sample & Hold
16
First Conversion
7
17
One Conversion
18
8
19
9
20
10
Conversion
Complete
21
11
22
Conversion
Complete
23
12
24
13
25
Sign and MSB of Result
Sign and MSB of Result
LSB of Result
Next Conversion
1
Next
Conversion
1
LSB of Result
2586M–AVR–07/10
2
MUX and REFS
Update
2
MUX and REFS
Update
3
3