MLX90314 Datasheet, PDF (9/26 Pages) List of Unclassifed Manufacturers – Programmable Sensor Interface

MLX90314AB
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 MLX90314 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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