MLX75031 Datasheet, PDF (20/67 Pages) Melexis Microelectronic Systems – Optical Gesture & Proximity Sensing IC

MLX75031
Optical Gesture & Proximity Sensing IC
with Integrated LED Drivers
Datasheet
input threshold level
20%
light response time
80%
light response time
time
corresponding output
threshold level
time
Figure 3 : Ambient response time explanation
8.2.5. Diagnostics Mode Operation
In diagnostics mode, the status of the external photodiodes is checked.
A set of switches controls the different possible error conditions by running through the different tests. At
the end of this check, all switches go back into the initial position to allow normal ambient light detection.
Table 11 lists the possible error modes for detector C and pin GNDAMB.
The error modes for detectors D are equivalent.
Failure
Detected How
detC disconnected
Diagnostics If checkC == 0: error!
GNDAMB disconnected Diagnostics Identical test as detC disconnected.
detC shorted to
GNDA/GNDD/GNDAMB
normal mode
Diagnostics
• Ambient detector shows incredible high light input
• ADC response is much likely saturated, anyway the
output is far beyond the allowed operation range
If checkC == 0: error!
detC shorted to
VCCA/VCCD
Diagnostics If checkC == 1: error!
• This is no problem for normal operation
GNDAMB shorted to
GNDA/GNDD
Various
• This CAN be a problem in testmode if short is strong and
pin GNDAMB pulled to VDDA: a maximum current of 50mA
can be pulled during 10µs
• If so, test for detC disconnected will show an error
GNDAMB shorted to
VCCA/VCCD
normal mode
Diagnostics
A maximum current of 800mA can be pulled from this driver
If the current can be supplied by the module, an error will
be flagged similar to detC shorted to VCCA/VCCD
detC shorted to detD
Diagnostics
• If checkC == 0: error!
• If checkD == 1: error!
Table 11 : List of possible failures on the ambient pins – projected on channel C.
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.
•
REVISION 001 – JANUARY, 2013
39010xxxxx
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