Rainbow-electronics ATmega64C1 Manuale Utente Scaricare il pdf (Pagina 227)

227

7647A–AVR–02/08

ATmega32/64/M1/C1

18. Analog to Digital Converter - ADC

18.1 Features

• 10-bit Resolution

• 0.5 LSB Integral Non-linearity

• ± 2 LSB Absolute Accuracy

• 8- 250 µs Conversion Time

• Up to 120 kSPS at Maximum Resolution

• 11 Multiplexed Single Ended Input Channels

• 3 Differential input channels with accurate (5%) programmable gain 5, 10, 20 and 40

• Optional Left Adjustment for ADC Result Readout

• 0 - V

ADC Input Voltage Range

• Selectable 2.56 V ADC Reference Voltage

• Free Running or Single Conversion Mode

• ADC Start Conversion by Auto Triggering on Interrupt Sources

• Interrupt on ADC Conversion Complete

• Sleep Mode Noise Canceler

• Temperature Sensor

• LiN Address Sense (ISRC Voltage Measurement)

• Vcc Voltage Measurement

The ATmega32/64/M1/C1 features a 10-bit successive approximation ADC. The ADC is con-

nected to an 15-channel Analog Multiplexer which allows eleven single-ended input. The single-

ended voltage inputs refer to 0V (GND).

The device also supports 3 differential voltage input amplifiers which are equipped with a pro-

grammable gain stage, providing amplification steps of 14dB (5x), 20 dB (10x), 26 dB (20x), or

32dB (40x) on the differential input voltage before the A/D conversion. On the amplified chan-

nels, 8-bit resolution can be expected.

The ADC contains a Sample and Hold circuit which ensures that the input voltage to the ADC is

held at a constant level during conversion. A block diagram of the ADC is shown in Figure 18-1.

The ADC has a separate analog supply voltage pin, AV

. AV

must not differ more than ±

0.3V from V

. See the paragraph “ADC Noise Canceler” on page 234 on how to connect this

pin.

Internal reference voltages of nominally 2.56V or AV

are provided On-chip. The voltage refer-

ence may be externally decoupled at the AREF pin by a capacitor for better noise performance.

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Rainbow-electronics ATmega64C1 Manuale Utente Pagina 227