EVB90255 Melexis Inc, EVB90255 Datasheet - Page 3

• Manufacturer Part Number: EVB90255
• Description: EVAL BOARD FOR THE MLX90255
• Manufacturer: Melexis Inc

Specifications of EVB90255

• Sensor Type: Light, Photodiode Array
• Sensing Range: 128 x 1 Pixels
• Interface: Analog
• Sensitivity: 1.7 V @ 10 µW/cm² @ 0.7ms
• Voltage - Supply: 6 V ~ 10 V
• Embedded: Yes, MCU, 8-Bit
• Utilized Ic / Part: MLX90255
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: Q3625223A

appropriate SI pulse to the optical array. The
required pull-down resistors are also foreseen
on the board. All important signals (SI, CLK,
VOUT, 5V and GND) are connected to test
terminals, which makes it easy to visualize them
on an oscilloscope. One sensor in a SMD
package is soldered on the PCB (called B) while
an external sensor can be connected to the 5-
pins connector row (upper right corner) (called
A). Both output signals are connected to test
terminals,
VOUTA.
An external regulated DC power supply, with an
output voltage between 6 and 10V, needs to be
connected to the screw connector in the upper
left corner of the PCB. A regular 9V battery is
also possible. (Mind the sign!) As soon as the
power supply is switched on, a LED lights up
and the micro controller starts generating the
CLK and SI signals with the selected frequency
and integration time.
The frequency of the signal CLK can be chosen
with the rotary DIL switch on the right. The
frequencies corresponding to the 16 positions of
this switch are shown in the following table.
Positions 0, E and F correspond to frequencies
that are outside the device specification. Lighting
up a second LED indicates selecting one of
them.
For each SI pulse, 133 CLK pulses are
MLX90255 Linear Optical Array
Position
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
called
respectively
CLK frequency
36kHz
64kHz
77kHz
93kHz
112kHz
141kHz
170kHz
214kHz
284kHz
345kHz
435kHz
588kHz
909kHz
1.0MHz
1.25MHz
1.67MHz
VOUTB
and
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generated with the selected frequency, and after
them the CLK line is pulled low until the next SI
pulse. See further in this document for the
correct timings.
The light integration time can be selected with
the other rotary DIL switch. Again 16 positions
are possible, however now there is no one-to-
one relation with the corresponding integration
times. Actually the switch specifies a time which
starts only after the 133
integration time already starts after the 18
(see device specification), the total integration
time also depends on the selected frequency.
The following table shows for each position (of
the ‘integration time switch’) the minimal and the
maximal integration time, corresponding to
respectively the maximal and the minimal CLK
frequency.
The analog output voltage is directly proportional
to the light intensity and the integration time up
to the devices saturation level (3V typical). The
response of a pixel can be described with the
following formula:
VOUT = PR*P
where DC means the dark current.
The
responsivity
(V*cm2/µW*sec). Responsivity is wavelength
Position
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
proportionality
light
of
Total Integration Time
Minimal
79us
230us
380us
682us
985us
1.30ms
2.50ms
3.10ms
3.85ms
4.60ms
6.10ms
7.7ms
9.15ms
10.5ms
15ms
20ms
+ offset + PR
Linear Optical Array
the
MLX90255
constant
rd
device
Rev 1.0 31-May-01
CLK pulse. As the
error
*P
Maximal
3.17ms
3.33ms
3.48ms
3.77ms
4.09ms
4.40ms
5.60ms
6.20ms
6.95ms
7.70ms
9.15ms
10.7s
12.5ms
10.5ms
15ms
20ms
PR
light
given
+ DC
is
th
pulse
the
in