MLX75030 Datasheet, PDF (65/72 Pages) Melexis Microelectronic Systems – Universal ActiveLight Sensor Interface

MLX75030 Universal ActiveLight Sensor Interface
Datasheet
10. Application Comments
The MLX75030 is featuring very sensitive current inputs on the pins 9 and 10 for active light detection and on the pins 11 and
12 for ambient light measurements in a range over several orders of magnitude. In order to achive optimum results in the
application it is recommended to consider the following hints for the design of the PCB:
1. The both supply voltage pins 16 (VDDA for analog circuit parts) and 23 (VDDD for digital circuit parts) shall be star-
connected to the local (external) regulator output (3.0V-3.6V) in order to avoid digital disturbance injection into the
analog supply.
2. Note that the device works with two separate ground connections: Pin 15 works as analog ground for the sensitive input
circuitry whereas pin 24 works as digital ground and as ground connection of the LED path, which carries high pulse
currents.
3. The Exposed Pad of the package should be star-connected to the local (external) ground pin of the regulator.
4. The external blocking capacitors C1 and C2 shall be placed as close as possible to the corresponding pins of the device.
5. The external photodiodes on the active light channel inputs as well as on the ambient light inputs shall be placed as
close as possible to the corresponding pins of the device. If this is not possible due to constructive reasons, the
connections shall be shielded by a noise-free analog ground plane in order to avoid performance-loss due to disturbance
coupling.
6. Notice that GNDAMB must not be connected to any GND line on the PCB. This terminal is actively switched to supply
voltage during diagnosis mode.
7. Note that not connected input channels (ActiveLight, ambient light) must be disabled in the EnChan register.
8. For diagnosis purposes on pin DIAGAMB a current of 10uA is recommended. For a current in this range the diagnosis
result is least sensitive to temperature.
REVISION 005 – DECEMBER 2013
3901075030
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