ADUC831BS Analog Devices Inc, ADUC831BS Datasheet - Page 18

• Manufacturer Part Number: ADUC831BS
• Description: IC ADC/DAC 12BIT W/MCU 52-MQFP
• Manufacturer: Analog Devices Inc
• Series: MicroConverter® ADuC8xxr

Specifications of ADUC831BS

• Rohs Status: RoHS non-compliant
• Core Processor: 8052
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: EBI/EMI, I²C, SPI, UART/USART
• Peripherals: PSM, Temp Sensor, WDT
• Number Of I /o: 34
• Program Memory Size: 62KB (62K x 8)
• Program Memory Type: FLASH
• Eeprom Size: 4K x 8
• Ram Size: 2.25K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 8x12b, D/A 2x12b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 52-MQFP, 52-PQFP
• For Use With: EVAL-ADUC831QSZ - KIT DEV FOR ADUC831 QUICK START

ADuC831
ADC CIRCUIT INFORMATION
General Overview
The ADC conversion block incorporates a fast, 8-channel,
12-bit, single supply ADC. This block provides the user with
multichannel mux, track/hold, on-chip reference, calibration
features, and ADC. All components in this block are easily
configured via a 3-register SFR interface.
The ADC consists of a conventional successive-approximation
converter based around a capacitor DAC. The converter accepts
an analog input range of 0 to V
and factory calibrated 2.5 V reference is provided on-chip. An
external reference can be connected as described later. This
external reference can be in the range of 1 V to AV
Single step or continuous conversion modes can be initiated in
software or alternatively by applying a convert signal to an exter-
nal pin. Timer 2 can also be configured to generate a repetitive
trigger for ADC conversions. The ADC may be configured to
operate in a DMA Mode whereby the ADC block continuously
converts and captures samples to an external RAM space without
any interaction from the MCU core. This automatic capture facility
can extend through a 16 MByte external data memory space.
The ADuC831 is shipped with factory programmed calibration
coefficients that are automatically downloaded to the ADC on
power-up ensuring optimum ADC performance. The ADC core
contains internal offset and gain calibration registers, that can
be hardware calibrated to minimize system errors.
A voltage output from an on-chip band gap reference propor-
tional to absolute temperature can also be routed through the
front end ADC multiplexor (effectively a ninth ADC channel
input) facilitating a temperature sensor implementation.
REF
. A high precision, low drift,
DD
.
–18–
ADC Transfer Function
The analog input range for the ADC is 0 V to V
range, the designed code transitions occur midway between
successive integer LSB values (i.e., 1/2 LSB, 3/2 LSBs,
5/2 LSBs, . . ., FS –3/2 LSBs). The output coding is straight
binary with 1 LSB = FS/4096 or 2.5 V/4096 = 0.61 mV when
V
the 0 to V
Typical Operation
Once configured via the ADCCON 1-3 SFRs the ADC will
convert the analog input and provide an ADC 12-bit result word in
the ADCDATAH/L SFRs. The top four bits of the ADCDATAH
SFR will be written with the channel selection bits so as to identify
the channel result. The format of the ADC 12 bit result word is
shown in Figure 8.
REF
TOP 4 BITS
= 2.5 V. The ideal input/output transfer characteristic for
CH–ID
000...010
111...111
111...110
111...101
111...100
000...011
000...001
000...000
OUTPUT
REF
CODE
range is shown in Figure 7.
Figure 7. ADC Transfer Function
0V 1LSB
Figure 8. ADC Result Format
1LSB =
4096
FS
VOLTAGE INPUT
LOW 8 BITS OF THE
ADC RESULT WORD
HIGH 4 BITS OF
ADC RESULT WORD
ADCDATAH SFR
ADCDATAL SFR
+FS
–1LSB
REF
. For this
REV. 0