MLX75031 Datasheet, PDF (22/67 Pages) Melexis Microelectronic Systems – Optical Gesture & Proximity Sensing IC

MLX75031
Optical Gesture & Proximity Sensing IC
with Integrated LED Drivers
Datasheet
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
+ ^{(11781+ 67(calib2 − 32))− tempout}
67 + (calib1−16)
K
or in °C:
T = 30°C + ^{(11781+ 67(calib2 − 32))− tempout} °C
67 + (calib1−16)
• tempout : digital temperature readout (16Bit)
• calib1 : contents of calib1 register (5Bit)
• calib2 : contents of calib2 register (6Bit)
8.4. Analog to Digital Conversion
The ADC converts all MUX signals in a 16 bit word which is passed in a register in the digital block and can be
read out through the SPI interface.
8.5. Output Stage
8.5.1. DAC
For the MLX75031 Active Light application, the DAC has been designed to generate a pulse voltage signal
from 1mV to 1V, so that LED current driven by the LED driver can be 1mA to 150mA, if a 6.6Ώ external
resistor is used.
A logarithmic DAC was used.
A piece-wise linear DAC with four zones is implemented as approximation for the logarithmic DAC.
DAC piece
(DACx[7:6])
00
Steps in
each piece
(6LSBs
DACx[5:0] )
64
Step size
for 1 bit (V)
1.00E-04
Trasfer function
Vdac (V) =
1.00E-04*DACx[7:0] + 1.03E-3
Range
start (V)
1.03E-03
Range
end (V)
7.43E-03
01
64
5.10E-04 5.10E-04*DACx[7:0] - 2.491E-2 7.56E-03 3.952E-02
10
64
2.52E-03 2.52E-03*DACx[7:0] - 2.820E-01 4.022E-02 1.988E-01
11
64
1.224E-02 1.224E-02*DACx[7:0] - 2.145 2.057E-01 9.769E-01
Table 12 : The DAC voltage values based on the DAC codes (DACx[7:0], x=A or B) at VDD=3.3V
REVISION 001 – JANUARY, 2013
39010xxxxx
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