ADUC834 Analog Devices, ADUC834 Datasheet - Page 68

• 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
Typical System Configuration
A typical ADuC834 configuration is shown in Figure 66. It
summarizes some of the hardware considerations discussed in
the previous paragraphs.
Figure 66 also includes connections for a typical analog measure-
ment application of the ADuC834, namely an interface to an
RTD (Resistive Temperature Device). The arrangement shown
is commonly referred to as a 4-wire RTD configuration.
Here, the on-chip excitation current sources are enabled to excite
the sensor. The excitation current flows directly through the
RTD generating a voltage across the RTD proportional to its
200 A/400 A
EXCITATION
CURRENT
RTD
*EXTERNAL UART TRANSCEIVER INTEGRATED IN SYSTEM OR AS
5.6k
R
PART OF AN EXTERNAL DONGLE AS DESCRIBED IN uC006.
RS-232 INTERFACE*
REF
C1+
V+
C1–
C2+
C2–
V–
T2OUT
R2IN
AV
ADM3202
DD
R1OUT
R2OUT
T1OUT
Figure 66. Typical System Configuration
GND
R1IN
T1IN
T2IN
V
CC
P1.3/AIN5/DAC
P1.2/I
AV
AGND
REFIN–
REFIN+
P1.4/AIN1
P1.5/AIN2
52
DD
DV
51
EXC
DD
50
1/DAC
49
DV
–68–
48
DD
DV
ADuC834
47
STANDARD D-TYPE
DD
CONNECTOR TO
SERIAL COMMS
resistance. This differential voltage is routed directly to the positive
and negative inputs of the primary ADC (AIN1, AIN2 respec-
tively). The same current that excited the RTD also flows through
a series resistance R
V
in the excitation current do not affect the measurement system as
the input voltage from the RTD and reference voltage across
R
R
errors in the reference voltage over temperature. R
also be large enough to generate at least a 1 V voltage reference.
46
REF
REF
REF
PC HOST
45
. The ratiometric voltage reference ensures that variations
must, however, have a low temperature coefficient to avoid
DOWNLOAD/DEBUG
vary ratiometrically with the excitation current. Resistor
(NORMALLY OPEN)
1
7
8
ENABLE JUMPER
2
3
4
5
6
9
44
1k
43
ALL CAPACITORS IN THIS EXAMPLE ARE
0.1 F CERAMIC CAPACITORS
42
NOT CONNECTED IN THIS EXAMPLE
41
XTAL2
XTAL1
DGND
DV
1k
40
DD
REF
DV
39
38
37
36
35
34
33
32
31
30
29
28
27
DD
generating a ratiometric voltage reference
DV
32.768kHz
DD
2-PIN HEADER FOR
EMULATION ACCESS
(NORMALLY OPEN)
REF
must
REV. A