DA6505.005
11 June 2018
APPLICATION INFORMATION (continued)
OPTIONAL TEMPERATURE
SENSING DIODE
VDD
VDDIO
VDDIO
CVDD
10µF
CVDDIO
100nF
VDDIO
VDD
RP
4.7k
TD
VDD
OSC
EEPROM
VDDS
PI
RP
REG
VREFP
4.7k
GND
AFE
P
T
SENSOR
SDI
I/O
I/O
SDO
ADC
CONTROL
P
NI
I2C/
SPI
SCK
CSB
T
VDDS
GNDS
VREFN
R3
R1
TEST
MUX
SDO
R4
R2
MCU
T
P
T
MAS6505
GND
GND
GND
GND
NOTE: In I2C bus communication the CSB pin is unused and left unconnected (floating). It has an internal pull up to VDDIO.
Figure 15. Typical EEPROM read only application circuit in I2C bus communication
Together with a resistive pressure sensor, MAS6505
can be used in pressure measurement applications.
An external micro-controller can control the
MAS6505 via an I2C or a SPI serial interface. Note
that the I2C serial interface requires suitable pull-up
resistors connected to the SDI and SCK pins (see
Figure 15). If there is only a single master device
connected to the serial bus the master’s SCK output
can be of push-pull type making the SCK pull-up
resistor unnecessary.
through to the ADC. In the temperature
measurement mode, the switches marked “T” are
closed and the voltage at the ADC input is
determined by the internal resistor array and the
temperature-dependent resistance of the sensor. In
this configuration the sensor bridge is connected as
part of a Wheatstone resistor bridge circuit where the
other four resistors (R1, R2, R3, R4) are inside the
IC.
A decoupling capacitor of at least 10F should be
used at the supply voltage VDD for low noise
performance (see Figure 15).
The sensor is connected between regulated Sensor
bridge supply voltage (VDDS) and Sensor bridge
supply ground (GNDS) of MAS6505. The sensor
output is read as a differential signal through PI
(positive input) and NI (negative input) to the ΔΣ
converter in MAS6505.
In EEPROM read only application (EEPROM
calibration memory readily programmed) the supply
voltage operating range is VDD=1.71V…5.5V.
However if both EEPROM write and read are needed
in application level the 5V supply voltage is
necessary (VDD=4.5V…5.5V) as shown in Figure 4.
In the pressure measurement mode, the switches
marked “P” are closed and the sensor output is fed
39 (44)
MAS [ MICRO ANALOG SYSTEMS ]
