ADUC7023 Analog Devices, ADUC7023 Datasheet - Page 34

• Manufacturer Part Number: ADUC7023
• Description: Precision Analog Microcontroller, 12-Bit Analog I/O, ARM7TDMI MCU
• Manufacturer: Analog Devices

Specifications of ADUC7023

• Mcu Core: ARM7 TDMI
• Mcu Speed (mips): 40
• Sram (bytes): 8192Bytes
• Gpio Pins: 20
• Adc # Channels: 12
• Other: PWM

ADuC7023
For system gain error correction, the ADC channel input
stage must be tied to V
conversion loop must be implemented to modify the value
in ADCGN until the ADCDAT reads Code 4094 to Code 4095.
If the ADCDAT value is less than 4094, ADCGN should be
incremented until ADCDAT reads Code 4094 to Code 4095.
Similar to the offset calibration, the gain calibration resolution
is 0.25 LSB with a range of ±3% of V
TEMPERATURE SENSOR
The ADuC7023 provides a voltage output from an on-chip
band gap reference that is proportional to absolute temperature.
This voltage output can also be routed through the front-end
ADC multiplexer (effectively an additional ADC channel
input), facilitating an internal temperature sensor channel,
measuring die temperature.
An ADC temperature sensor conversion differs from a standard
ADC voltage. The ADC performance specifications do not
apply to the temperature sensor.
Chopping of the internal amplifier should be enabled using the
TSCON register. To enable this mode, the user must set Bit 0 of
TSCON. The user must also take two consecutive ADC readings
and average them in this mode.
The ADCCON register must be configured to 0x37A3.
To calculate die temperature use the following formula:
where:
T is the temperature result.
T
V
conversions.
V
described in Table 1.
K is the gain of the ADC in temperature sensor mode as
determined by characterization data, K = 0.2262°C/mV. This
corresponds to 1/V TC specification as shown in Table 1.
Using the default values from Table 1 and without any calibra-
tion, this equation becomes
where:
V
For increased accuracy, perform a single point calibration at a
controlled temperature value.
REF
ADC
TREF
ADC
T − T
T – 25°C = (V
is in millivolts.
is 25°C.
is the average ADC result from two consecutive
is 1369 mV, which corresponds to T
REF
= (V
ADC
ADC
− V
− 1369) × 0.2262
REF
TREF
. A continuous software ADC
) × K
REF
.
REF
= 25°C as
Rev. B | Page 34 of 96
For the calculation shown without calibration, (T
(25°C, 1369 mV). The idea of a single point calibration is to use
other known (T
1369 mV) for every part.
For some users, it is not possible to get such a known pair. For
these cases, an ADuC7023 comes with a single point calibration
value loaded in the TEMPREF register. For more details on this
register, see the TEMPREF Register section.
During production testing of the ADuC7023, the TEMPREF
register is loaded with an offset adjustment factor. Each part
will have a different value in the TEMPREF register. Using this
single point calibration, use the same formula as shown:
where:
T
not guaranteed.
T
TSCON Register
Name:
Address:
Default value:
Access:
Table 28. TSCON MMR Bit Designations
Bit
7 to 1
0
TEMPREF Register
Name:
Address:
Default value:
Access:
REF
TREF
is 27°C when using the TEMPREF register method, but is
T − T
can be calculated using the TEMPREF register.
Description
Reserved.
Temperature sensor chop enable bit.
This bit is set to 1 to enable chopping of the internal
amplifier to the ADC.
This bit is cleared to disable chopping.
This bit is cleared by default.
REF
= (V
REF
ADC
, V
TSCON
0xFFFF0544
0x00
Read/write
TEMPREF
0xFFFF0548
Factory configured
Read/write
TREF
− V
) values to replace the common (25°C,
TREF
) × K
REF
, V
TREF
) =