DA6503.005
14 December 2016
OPERATING MODES
After connecting the power supply the device is
reset by on-chip power on reset (POR) circuit and
then set to standby mode. The POR circuit works
only for supply voltage rise rates faster than max
1ms rise time. To provide reset in all supply rise
conditions it is recommended to reset the device
manually after every power up (VDD rise) either via
the XCLR pin or via the serial bus using the reset
register.
control registers a new A/D conversion is started.
MAS6503 includes a 256-bit EEPROM memory for
storing trimming and calibration data on chip. 16-
bits of EEPROM are reserved for internal oscillator
trimming and programmable I2C device address
but the remaining 240-bits are free for calibration
and other data.
The stored calibration data should comprise of
calibration
and
temperature
compensation
MAS6503 has three operating modes, pressure,
temperature and VDD level monitoring mode. In the
pressure mode the pressure dependent sensor
bridge voltage is connected to the ADC input. In the
temperature measurement mode the resistive
sensor bridge is connected into a Wheatstone
bridge configuration together with four internal
coefficients which can be used to calculate
accurate calibrated pressure and temperature
measurement results from the non-calibrated
measurement results. All calculations need to be
done in the external micro controller unit (MCU).
A calibrated MAS6503 sensor system is operated
as illustrated in figure 2. The calibration and
compensation coefficients need to be read to the
MCU memory only once. From each pair of
pressure and temperature measurements results
the accurate pressure and temperature values are
then calculated by using the external MCU.
resistors
(see
Temperature
Measurement
Configuration in the Application Information
chapter). The formed Wheatstone bridge output
voltage is connected to the ADC input. It is
proportional to absolute temperature. In the VDD
level monitoring mode an internal bandgap voltage
is connected to the ADC input but the ratiometric
ADC references are allowed to follow supply
voltage by disabling the internal regulator. The
supply voltage monitoring can be useful feature
especially in battery operated systems.
All communication with MAS6503 is done using a
4-wire SPI bus or a 2-wire I2C bus. Starting an A/D
conversion, reading out the conversion result and
reading and writing data from and to the EEPROM
memory are all accomplished via serial bus
communication.
Switching between pressure, temperature and VDD
level monitoring modes is done via the single ADC
control register. The measurement configuration
includes selection of over sampling ratio, input
signal range, offset and sensor resistance. By
writing two 8-bit configuration data to two ADC
In addition to the serial bus the digital interface
includes also end-of-conversion (EOC) and master
reset (XCLR) pins. See Serial interface in the
following Serial Data Interface Control chapter.
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MAS [ MICRO ANALOG SYSTEMS ]
