ATmega48 Atmel Corporation, ATmega48 Datasheet - Page 241

• Manufacturer Part Number: ATmega48
• Manufacturer: Atmel Corporation

Specifications of ATmega48

• Flash (kbytes): 4 Kbytes
• Pin Count: 32
• Max. Operating Frequency: 20 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 12
• 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: No
• Crypto Engine: No
• Sram (kbytes): 0.5
• Eeprom (bytes): 256
• Self Program Memory: NO
• 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

23. Analog comparator
23.1
23.2
2545T–AVR–05/11
Overview
Analog comparator multiplexed input
The Analog Comparator compares the input values on the positive pin AIN0 and negative pin
AIN1. When the voltage on the positive pin AIN0 is higher than the voltage on the negative pin
AIN1, the Analog Comparator output, ACO, is set. The comparator’s output can be set to trigger
the Timer/Counter1 Input Capture function. In addition, the comparator can trigger a separate
interrupt, exclusive to the Analog Comparator. The user can select Interrupt triggering on com-
parator output rise, fall or toggle. A block diagram of the comparator and its surrounding logic is
shown in
The Power Reduction ADC bit, PRADC, in
disabled by writing a logical zero to be able to use the ADC input MUX.
Figure 23-1. Analog comparator block diagram
Notes:
It is possible to select any of the ADC7..0 pins to replace the negative input to the Analog Com-
parator. The ADC multiplexer is used to select this input, and consequently, the ADC must be
switched off to utilize this feature. If the Analog Comparator Multiplexer Enable bit (ACME in
ADCSRB) is set and the ADC is switched off (ADEN in ADCSRA is zero), MUX2..0 in ADMUX
select the input pin to replace the negative input to the Analog Comparator, as shown in
23-1. If ACME is cleared or ADEN is set, AIN1 is applied to the negative input to the Analog
Comparator.
Table 23-1.
ACME
0
1
1
ADC MULTIPLEXER
1. See
2. Refer to
Figure
REFERENCE
ACME
ADEN
BANDGAP
OUTPUT
placement.
Analog comparator multiplexed input.
Table
(1)
23-1.
ADEN
ACBG
x
1
0
Figure 1-1 on page 2
23-1.
MUX2..0
000
xxx
xxx
and
Table 14-9 on page 84
“Minimizing power consumption” on page 41
Analog comparator negative input
AIN1
AIN1
ADC0
(2)
.
ATmega48/88/168
for analog comparator pin
must be
Table
241