ADUC834 Analog Devices, ADUC834 Datasheet - Page 24

• Manufacturer Part Number: ADUC834
• Description: Precision Analog Microcontroller: 1MIPS 8052 MCU + 62kB Flash + 16/24-Bit ADC + 12-Bit DAC
• Manufacturer: Analog Devices

Specifications of ADUC834

• Mcu Core: 8052
• Mcu Speed (mips): 1
• Sram (bytes): 2304Bytes
• Gpio Pins: 34
• Adc # Channels: 4
• Other: PWM

ADuC834
Auxiliary ADC
The auxiliary ADC is intended to convert supplementary inputs
such as those from a cold junction diode or thermistor. This ADC
is not buffered and has a fixed input range of 0 V to 2.5 V
(assuming an external 2.5 V reference). The single-ended inputs
can be driven from AIN3, AIN4, or AIN5 Pins, or directly from
the on-chip temperature sensor voltage. A block diagram of the
auxiliary ADC is shown in Figure 8.
Analog Input Channels
The primary ADC has four associated analog input pins (labelled
AIN1 to AIN4) that can be configured as two fully differential input
channels. Channel selection bits in the ADC0CON SFR detailed
in Table VI allow three combinations of differential pair selection
as well as an additional shorted input option (AIN2–AIN2).
TEMPERATURE
ON-CHIP
SENSOR
CONVERSION CYCLE. CHOPPING
ANALOG INPUT CHOPPING
THE INPUTS ARE ALTERNATELY
THE MULTIPLEXER IS CONTROLLED
AIN3
AIN4
AIN5
EXTERNAL SINGLE ENDED INPUTS
OR THE ON-CHIP TEMP. SENSOR.
OFFSET AND OFFSET DRIFT
ALLOWS SELECTION OF THREE
A DIFFERENTIAL MULTIPLEXER
REVERSED THROUGH THE
VIA THE CHANNEL SELECTION
YIELDS EXCELLENT ADC
ANALOG MULTIPLEXER
PERFORMANCE.
BITS IN ADC1CON.
MUX
MU
X
CHOP
REFIN(–) REFIN(+)
REFERENCE VOLTAGE IS SELECTED
THE EXTERNAL REFERENCE INPUT
TO THE ADuC834 IS DIFFERENTIAL
DIFFERENTIAL REFERENCE
AND FACILITATES RATIOMETRIC
VIA THE XREF1 BIT IN ADC1CON.
CIRCUITRY TESTS FOR OPEN OR
SHORTED REFERENCE INPUTS.
OPERATION. THE EXTERNAL
STREAM (THE OUTPUT OF WHICH
THE MODULATOR PROVIDES A
HIGH FREQUENCY 1-BIT DATA
REPRESENTS THE SAMPLED
THE DUTY CYCLE OF WHICH
REFERENCE DETECT
IS ALSO CHOPPED) TO THE
ANALOG INPUT VOLTAGE.
Figure 8. Auxiliary ADC Block Diagram
- MODULATOR
DIGITAL FILTER,
MODULATOR
-
- ADC
PROGRAMMABLE
DIGITAL FILTER
–24–
The auxiliary ADC has three external input pins (labelled AIN3 to
AIN5) as well as an internal connection to the on-chip temperature
sensor. All inputs to the auxiliary ADC are single-ended inputs
referenced to the AGND on the part. Channel selection bits in
the ADC1CON SFR previously detailed in Table VII allow
selection of one of four inputs.
Two input multiplexers switch the selected input channel to the
on-chip buffer amplifier in the case of the primary ADC and
directly to the - modulator input in the case of the auxiliary
ADC. When the analog input channel is switched, the settling
time of the part must elapse before a new valid word is available
from the ADC.
ENSURES 16 BITS NO MISSING
CODES. THE ENTIRE -
IS CHOPPED TO REMOVE
THE - ARCHITECTURE
QUANTIZATION NOISE INTRODUCED
BY THE MODULATOR. THE UPDATE
DRIFT ERRORS.
PROGRAMMABLE DIGITAL
RATE AND BANDWIDTH OF THIS
FILTER ARE PROGRAMMABLE
THE SINC 3 FILTER REMOVES
- ADC
VIA THE SF SFR.
CHOP
FILTER
ADC
AVERAGE
OUTPUT
AS PART OF THE CHOPPING
SUMMED AND AVERAGED
WITH ITS PREDECESSOR
IMPLEMENTATION, EACH
TO NULL ADC CHANNEL
OUTPUT AVERAGE
DATA-WORD OUTPUT
FROM THE FILTER IS
OFFSET ERRORS.
DIGITAL FILTER IS SCALED BY
THE OUPUT WORD FROM THE
THE CONVERSION RESULT.
SCALING
OUTPUT
COEFFICIENTS BEFORE
OUTPUT SCALING
BEING PROVIDED AS
THE CALIBRATION
RESULT WRITTEN
TO ADC1H/L SFRs
DIGTAL OUTPUT
REV. A