MLX75031 Datasheet, PDF (26/67 Pages) Melexis Microelectronic Systems – Optical Gesture & Proximity Sensing IC

MLX75031
Optical Gesture & Proximity Sensing IC
with Integrated LED Drivers
Datasheet
8.9. Vstab Analog +Bandgap
This block generates all reference voltages and current sources for the analogue blocks.
These sources work as far as possible independent from the temperature.
The block is also switched off in standby and sleep mode and has a wake up functionality with the smallest
possible time.
8.10. Digital Control
The digital control is responsible for all clock and gating signals used within the IC. These signals control the
LED drive sequence, the sampling and conversion of the photo-diode inputs, and so on.
The digital control is also responsible for channeling data to and from the SPI interface.
8.11. SPI
8.11.1. General Description of the SPI Interface
After power-on, the sensor enters a reset state (invoked by the internal power-on-reset circuit). A start-up
time tstartup after power-on, the internal reference voltages have become stable and a first measurement
cycle can start. To indicate that the start-up phase is complete, the DR pin will go high (DR is low during the
start-up phase).
The control of this sensor is completely SPI driven. For each task to be executed, the proper command must
be uploaded via the SPI. The SPI uses a four-wire communication protocol. The following pins are used:
CS : when CS pin is low, transmission and reception are enabled and the MISO pin is driven. When the
CS pin goes high, the MISO pin is no longer driven and becomes a floating output. This makes it
possible that one micro-processor takes control over multiple sensors by setting the CS pin of the
appropriate sensor low while sending commands. The idle state of the chip select is high.
SCLK : clock input for the sensor. The clock input must be running only during the upload of a new
command or during a read-out cycle. The idle state of the clock input is high.
MOSI : data input for uploading the different commands and the data that needs to be written into
some registers. The idle state of the data input is low.
MISO : data output of the sensor.
A SPI timing diagram is given in Figure 8. This is the general format for sending a command. First the CS pin
must be set low so that the sensor can accept data. The low level on the CS pin in combination with the first
rising clock edge is used to start an internal synchronization counter that counts the incoming bits. Data on
the MOSI pin is clocked in at the rising clock edge. Data on the MISO pin is shifted out during the falling
clock edge. Note that the tri-state of the MISO pin is controlled by the state of CS.
After uploading a command, the CS pin must be set high for a minimum time of tcs_inter in order to reset
the internal synchronization counter and to allow new commands to be interpreted.
REVISION 001 – JANUARY, 2013
39010xxxxx
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