Rainbow Electronics ATtiny15L - Manual (Page 41)

41
ATtiny15L
1187E–AVR–06/02
The Analog-to-Digital
Converter, Analog
Multiplexer, and Gain
Stages
Features • 10-bit Resolution
• ±2 LSB Absolute Accuracy
• 0.5 LSB Integral Non-linearity
• Optional Offset Cancellation
• 65 - 260 µs Conversion Time
• Up to 15 kSPS
• 4 Multiplexed Single-ended Input Channels
• 1 Differential Input Channel with Optional Gain of 20x
• 2.56V Internal Voltage Reference
• 0 - 2.56V Differential Input Voltage Range
• 0 - V
CC
Single-ended Input Voltage Range
• Optional Left Adjustment for ADC Result Readout
• Free Running or Single Conversion Mode
• Interrupt on ADC Conversion Complete
• Sleep Mode Noise Canceler
The ATtiny15L features a 10-bit successive approximation ADC. The ADC is connected
to a 4-channel Analog Multiplexer that allows one differential voltage input and four sin-
gle-ended voltage inputs constructed from the pins of Port B. The differential input (PB3,
PB4) is equipped with a programmable gain stage, providing amplification step of 26 dB
(20x) on the differential input voltage before the A/D conversion. The single-ended volt-
age inputs at PB2..PB5 refer to 0V (GND).
The ADC contains a Sample and Hold Amplifier that 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 25.
An internal reference voltage of nominally 2.56V is provided On-chip and this reference
can optionally be externally decoupled at the AREF (PB0) pin by a capacitor for better
noise performance. Alternatively, V
CC
can be used as reference voltage for single-
ended channels. There is also an option to use an external voltage reference and turn
off the internal voltage reference. These options are selected using the REFS1..0 bits of
the ADMUX Control Register.