ADUC812 Analog Devices, ADUC812 Datasheet - Page 18

• Manufacturer Part Number: ADUC812
• Description: Precision Analog Microcontroller: 1.3MIPS 8052 MCU + 8kB Flash + 8-Ch 12-Bit ADC + Dual 12-Bit DAC
• Manufacturer: Analog Devices

Specifications of ADUC812

• Mcu Core: 8052
• Mcu Speed (mips): 1.3
• Sram (bytes): 256Bytes
• Gpio Pins: 34
• Adc # Channels: 8

ADuC812
and the gain calibration coefficient is divided into ADCGAINH
(six bits) and ADCGAINL (eight bits). The offset calibration
coefficient compensates for dc offset errors in both the ADC and
the input signal.
Increasing the offset coefficient compensates for positive offset,
and effectively pushes the ADC transfer function DOWN. De-
creasing the offset coefficient compensates for negative offset,
and effectively pushes the ADC transfer function UP. The
maximum offset that can be compensated is typically ±5% of
V
Similarly, the gain calibration coefficient compensates for dc gain
errors in both the ADC and the input signal.
Increasing the gain coefficient compensates for a smaller analog
input signal range and scales the ADC transfer function UP,
effectively increasing the slope of the transfer function. Decreasing
the gain coefficient compensates for a larger analog input signal
range and scales the ADC transfer function DOWN, effectively
decreasing the slope of the transfer function. The maximum analog
input signal range for which the gain coefficient can compensate
is 1.025
which equates to ±2.5% of the reference voltage.
Calibration
Each ADuC812 is calibrated in the factory prior to shipping, and
the offset and gain calibration coefficients are stored in a hidden
area of FLASH/EE memory. Each time the ADuC812 powers up,
an internal power-on configuration routine copies these coefficients
into the offset and gain calibration registers in the SFR area.
The MicroConverter ADC accuracy may vary from system
to system due to board layout, grounding, clock speed, and so
on. To get the best ADC accuracy in your system, perform
the software calibration routine described in Application Note
uC005, available from the MicroConverter homepage at
www.analog.com/microconverter.
NONVOLATILE FLASH MEMORY
Flash Memory Overview
The ADuC812 incorporates Flash memory technology on-chip
to provide the user with a nonvolatile, in-circuit reprogrammable
code and data memory space.
Flash/EE memory is a relatively new type of nonvolatile memory
technology based on a single transistor cell architecture.
This technology is basically an outgrowth of EPROM technology
and was developed in the late 1980s. Flash/EE memory takes the
flexible in-circuit reprogrammable features of EEPROM and
combines them with the space efficient/density features of EPROM
(see Figure 14).
Because Flash/EE technology is based on a single transistor cell
architecture, a Flash memory array, like EPROM, can be imple-
mented to achieve the space efficiencies or memory densities
required by a given design.
Like EEPROM, Flash memory can be programmed in-system
at a byte level, although it must first be erased in page blocks.
Thus, Flash memory is often and more correctly referred to as
Flash/EE memory.
REF
, which equates to typically ±125 mV with a 2.5 V reference.
V
REF
, and the minimum input range is 0.975
V
REF
,
–18–
Overall, Flash/EE memory represents a step closer to the ideal
memory device that includes nonvolatility, in-circuit programma-
bility, high density, and low cost. Incorporated in the ADuC812,
Flash/EE memory technology allows the user to update program
code space in-circuit without replacing one-time programmable
(OTP) devices at remote operating nodes.
Flash/EE Memory and the ADuC812
The ADuC812 provides two arrays of Flash/EE memory for user
applications. 8K bytes of Flash/EE program space are provided
on-chip to facilitate code execution without any external discrete
ROM device requirements. The program memory can be pro-
grammed using conventional third party memory programmers.
This array can also be programmed in-circuit, using the serial
download mode provided.
A 640 byte Flash/EE data memory space is also provided on-chip
as a general-purpose nonvolatile scratchpad area. User access to
this area is via a group of six SFRs.
ADuC812 Flash/EE Memory Reliability
The Flash/EE program and data memory arrays on the ADuC812
are fully qualified for two key Flash/EE memory characteristics:
Flash/EE Memory Cycling Endurance and Flash/EE Memory
Data Retention.
Endurance quantifies the ability of the Flash/EE memory to be
cycled through many program, read, and erase cycles. In real
terms, a single endurance cycle is composed of four independent
sequential events:
In reliability qualification, every byte in the program and data
Flash/EE memory is cycled from 00H to FFH until the first fail is
recorded, signifying the endurance limit of the on-chip Flash/EE
memory.
As indicated in the Specification tables, the ADuC812 Flash/EE
Memory Endurance qualification has been carried out in accor-
dance with JEDEC Specification A117 over the industrial
temperature ranges of –40°C, +25°C, and +85°C. The results
allow the specification of a minimum endurance figure over supply
and temperature of 10,000 cycles, with an endurance figure of
50,000 cycles being typical of operation at 25°C.
Retention quantifies the ability of the Flash/EE memory to retain
its programmed data over time. Again, the ADuC812 has been
qualified in accordance with the formal JEDEC Retention Lifetime
Specification (A117) at a specific junction temperature (T
As part of this qualification procedure, the Flash/EE memory is
cycled to its specified endurance limit described above, before data
retention is characterized. This means that the Flash/EE memory
is guaranteed to retain its data for its full specified retention
lifetime every time the Flash/EE memory is reprogrammed.
a. Initial Page Erase Sequence
b. Read/Verify Sequence
c. Byte Program Sequence
d. Second Read/Verify Sequence
SPACE EFFICIENT/
Figure 14. Flash Memory Development
DENSITY
TECHNOLOGY
EPROM
FLASH/EE MEMORY
TECHNOLOGY
TECHNOLOGY
REPROGRAMMABLE
EEPROM
IN-CIRCUIT
J
= 55°C).
REV. E