®
MicroConverter , Dual-Channel
16-/24-Bit ADCs with Embedded FLASH MCU
a
ADuC824
FEATURES
FUNCTIONAL BLOCK DIAGRAM
High Resolution Sigma-Delta ADCs
Two Independent ADCs (16- and 24-Bit Resolution)
Programmable Gain Front End
24-Bit No Missing Codes, Primary ADC
13-Bit p-p Resolution @ 20 Hz, 20 mV Range
18-Bit p-p Resolution @ 20 Hz, 2.56 V Range
AVDD
AVDD
ADuC824
AIN1
AIN2
PRIMARY
24-BIT ꢂ-ꢃ ADC
PGA
BUF
MUX
CURRENT
SOURCE
MUX
IEXC1
IEXC2
AGND
AIN3
AIN4
AIN5
Memory
12-BIT
VOLTAGE O/P
DAC
AUXILIARY
16-BIT ꢂ-ꢃ ADC
MUX
8 KB On-Chip Flash/EE Program Memory
640 Bytes On-Chip Flash/EE Data Memory
Flash/EE, 100 Year Retention, 100 Kcycles Endurance
256 Bytes On-Chip Data RAM
DAC
BUF
8051-BASED MCU WITH ADDITIONAL
PERIPHERALS
TEMP
SENSOR
8 KBYTES FLASH/EE PROGRAM MEMORY
640 BYTES FLASH/EE DATA MEMORY
256 BYTES USER RAM
8051-Based Core
INTERNAL
BANDGAP
VREF
PROG.
CLOCK
DIVIDER
8051-Compatible Instruction Set (12.58 MHz Max)
32 kHz External Crystal, On-Chip Programmable PLL
Three 16-Bit Timer/Counters
26 Programmable I/O Lines
11 Interrupt Sources, Two Priority Levels
Power
ON-CHIP MONITORS
POWER SUPPLY
MONITOR
3 ꢁ 16 BIT
TIMER/COUNTERS
1 ꢁ TIME INTERVAL
COUNTER
WATCHDOG TIMER
OSC
AND
PLL
EXTERNAL
VREF
DETECT
2
I C-COMPATIBLE
UART AND SPI
SERIAL I/O
4ꢁ PARALLEL
PORTS
REFIN– REFIN+ XTAL1 XTAL2
Specified for 3 V and 5 V Operation
Normal: 3 mA @ 3 V (Core CLK = 1.5 MHz)
Power-Down: 20 ꢀA (32 kHz Crystal Running)
On-Chip Peripherals
On-Chip Temperature Sensor
12-Bit Voltage Output DAC
Dual Excitation Current Sources
Reference Detect Circuit
Time Interval Counter (TIC)
low-level signals). The ADCs with on-chip digital filtering are
intended for the measurement of wide dynamic range, low-frequency
signals, such as those in weigh scale, strain-gauge, pressure trans-
ducer, or temperature measurement applications. The ADC output
data rates are programmable and the ADC output resolution will
vary with the programmed gain and output rate.
The device operates from a 32 kHz crystal with an on-chip PLL
generating a high-frequency clock of 12.58 MHz. This clock is,
in turn, routed through a programmable clock divider from
which the MCU core clock operating frequency is generated. The
microcontroller core is an 8052 and therefore 8051-instruction-
set-compatible. The microcontroller core machine cycle consists
of 12 core clock periods of the selected core operating frequency.
8 Kbytes of nonvolatile Flash/EE program memory are provided
on-chip. 640 bytes of nonvolatile Flash/EE data memory and
256 bytes RAM are also integrated on-chip.
UART Serial I/O
I2C®-Compatible and SPI® Serial I/O
Watchdog Timer (WDT), Power Supply Monitor (PSM)
APPLICATIONS
Intelligent Sensors (IEEE1451.2-Compatible)
Weigh Scales
Portable Instrumentation
Pressure Transducers
4–20 mA Transmitters
The ADuC824 also incorporates additional analog functionality
with a 12-bit DAC, current sources, power supply monitor,
and a bandgap reference. On-chip digital peripherals include a
watchdog timer, time interval counter, three timers/counters,
and three serial I/O ports (SPI, UART, and I2C-compatible).
GENERAL DESCRIPTION
The ADuC824 is a complete smart transducer front-end, inte-
grating two high-resolution sigma delta ADCs, an 8-bit MCU,
and program/data Flash/EE Memory on a single chip. This low
power device accepts low-level signals directly from a transducer.
On-chip factory firmware supports in-circuit serial download and
debug modes (via UART), as well as single-pin emulation mode
via the EA pin. A functional block diagram of the ADuC824 is
shown above with a more detailed block diagram shown in
Figure 12.
The two independent ADCs (Primary and Auxiliary) include a
temperature sensor and a PGA (allowing direct measurement of
MicroConverter is a registered trademark of Analog Devices, Inc.
SPI is a registered trademark of Motorola, Inc.
I2C is a registered trademark of Philips Semiconductors, Inc.
The part operates from a single 3 V or 5 V supply. When operating
from 3 V supplies, the power dissipation for the part is below
10 mW. The ADuC824 is housed in a 52-lead MQFP package.
REV.B
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, norforanyinfringementsofpatentsorotherrightsofthirdpartiesthat
may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices.
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Tel: 781/329-4700
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© Analog Devices, Inc., 2002