MLX75030 Datasheet, PDF (24/72 Pages) Melexis Microelectronic Systems – Universal ActiveLight Sensor Interface

MLX75030 Universal ActiveLight Sensor Interface
Datasheet
7.1.3.3. Diagnostics Mode Operation
In diagnostics mode, the status of the external photodiodes is checked. The following checks are performed for each
ambient light channel X where X is C or D:
• X disconnected
• GNDAMB disconnected
• X shorted to GNDA/GNDD/GNDAMB
• X shorted to VCCA/VCCD
• GNDAMB shorted to GNDA/GNDD
• GNDAMB shorted to VCCA/VCCD
• X shorted to other ambient light channel
Note that in spite of the ability to detect any error by the ambient diagnostics, an error on an ambient pin might still have
other unwanted effects.
• Shorting any channel to GNDA/GNDD/GNDAMB will make the readout of the whole ambient block useless. At this
time a maximum current of 14mA might be constantly pulled from the supply, independent of the amount of
channels that is shorted to GNDA/GNDD/GNDAMB.
• During normal operation, node GNDAMB should be considered a ground pin. Shorting this pin to any other voltage
might result in a short current of max 800mA!
• Because of such unwanted effects, a detection of an error in diagnostics mode should be followed by a disabling of
the ambient channels in order to avoid disturbing the operation of other blocks in the system.
• Note that unused channels should be connected with an external resistance (~60kOhm) to GNDAMB. Doing so will
avoid disturbing the other channels, but will give a constant error on the channel connected to GNDAMB.
7.1.4. Temperature Sensor
The on-chip temperature sensor measures the IC temperature. The output voltage of the sensor is converted by the 16-bit
ADC. The sensor will be trimmed for the best result during the production. This trimming value is not applied to the
temperature sensor internally, but is available to the customer through two on-chip registers Calib1 and Calib2, see 7.4.11.
The Calib1 register contains the slope of the temperature curve in LSB/K. The Calib2 register contains the offset of the curve
at a defined temperature at which the chip is tested in production.
The temperature is calculated from the temperature readout (tempout) and the gain and offset calibration data (calibration
data measured at 30°C) according to the formula:
T_K
= 303.15K + ^{(11775 + 67 (calib2 − 32)) − tempout}
67 + (calib1−16)
K
or in °C:
T = 30°C + ^{(11775 + 67 (calib2 − 32)) − tempout} °C
67 + (calib1−16)
Where:
• tempout: digital temperature readout (16 Bit)
• calib1: contents of calib1 register (5 Bit)
• calib2: contents of calib2 register (6 Bit)
REVISION 005 – DECEMBER 2013
3901075030
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