MLX90308CAB Datasheet, PDF (9/26 Pages) List of Unclassifed Manufacturers – Programmable Sensor Interface

MLX90308CAB
Programmable Sensor Interface
Analog Features
Supply Regulator
A bandgap-stabilized supply-regulator is on-chip
while the pass-transistor is external. The bridge-type
sensor is typically powered by the regulated supply
(typically 4.75V). For ratiometric operation, the
supply-regulator can be disabled by connecting
together the unregulated and regulated supply pins.
Oscillator
The MLX90308 contains a programmable on-chip
RC oscillator. No external components are needed to
set the frequency (87.8 kHz +/-1%). The MCU-clock
is generated by a PLL (phase locked loop tuned for
614 kHz or 2.46 Mhz) which locks on the basic
oscillator.
The frequency of the internal clock is stabilized over
the full temperature range, which is divided into three
regions, each region having a separate digital clock
setting. All of the clock frequency programming is
done by Melexis during final test of the component.
The device uses the internal temperature sensor to
determine which temperature range setting to use.
Power-On Reset
The Power-On Reset (POR) initializes the state of the
digital part after power up. The reset circuitry is
completely internal. The chip is completely reset and
fully operational 3.5 ms from the time the supply
crosses 3.5 volts. The POR circuitry will issue another
POR if the supply voltage goes below this threshold for
1.0 us.
Test Mode
For 100% testability, a "TEST" pin is provided. If the
pin is pulled low, then the monitor program is entered
and the chip changes its functionality. In all other
applications, this pin should be pulled high or left
floating (internal pull-up).
Temperature Sense
The temperature measurement, TPO, is generated
from the external or internal temperature sensor. This
is converted to a 10-bit number for use in calculating
the signal compensation factors. A 2-bit coarse
adjustment GNTP[1:0] is used for the temperature
signal gain & offset adjustment.
A/D and D/A
Conversions using only one DAC
For saving chip area, the "Offset DAC" is multiplexed
in various ways. Both "fine offset" and "digital mode"
signals are stored on a capacitor. An ADC-loop is
available by using a comparator and SAR.
D/A
Before changing to another capacitor, the DAC
output should be settled to the new value. For
example, MODSEL moves the analog multiplexer to
the so-called "open state 0." At the same time, the 10
bit mux selects OF[9:0] for the offset-DAC. After the
DAC settling time, the analog multiplexer is moved to
its final state and the DAC-output is stored on a
capacitor.
A/D
The S/W-Signal MODSEL connects the SAR-output
to the DAC and the DAC-output to the comparator.
The SARegister is initialized by a rising edge of STC
(S/W signal). At the end of the A/D conversion, the
EOC flag is set to 1 and the controller can read the
ADC values.
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