MLX75030 Datasheet, PDF (25/72 Pages) Melexis Microelectronic Systems – Universal ActiveLight Sensor Interface

MLX75030 Universal ActiveLight Sensor Interface
Datasheet
7.1.5. DAC
For active light sensor applications, the MLX75030 DAC has been designed to have the following features:
To generate a pulse voltage signal from 1mV to 1V, so that LED current driven by LED driver can be 1mA to 1A if a 1Ω shunt
resistor is used between pins 18 and 19. After controlling and slewing circuitry, the final output voltage over external shunt
resistor is like in Figure 6.
DAC piece (2MSBs
B[7:6] )
00
01
10
11
Steps each piece
(6LSBs B[5:0] )
64
64
64
64
step size for
1 bit (V)
1.00E-04
5.00E-04
2.50E-03
1.25E-02
Range covered
(V)
6.40E-03
3.20E-02
1.60E-01
8.00E-01
Range start (V)
1.05E-03
7.65E-03
4.07E-02
2.06E-01
Range end (V)
7.35E-03
3.92E-02
1.98E-01
9.93E-01
Table 11 : The DAC voltage values based DAC codes (B[7:6]) can refer to the following table
1.20E+00
1.00E+00
8.00E-01
6.00E-01
4.00E-01
2.00E-01
0.00E+00
0
50
100
150
200
250
300
Figure 5 : Piece Wise Linear DAC voltage VS DAC codes
Trising = 3u
1mV...1V
1mV
7.1.6. LED Driver
Tdc_pulse<1:0>
( max 400us)
t_{pulse_on}
Figure 6: Vshunt waveform
REVISION 005 – DECEMBER 2013
3901075030
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