MLX90255BA Datasheet, PDF (4/10 Pages) List of Unclassifed Manufacturers – Linear Optical Array

Datasheet MLX90255BA
Linear Optical Array
General Description
(continued from page 1)
As the SI pulse is clocked through the shift
register, the charge stored on the sampling
capacitors is sequentially connected to a charge-
coupled output amplifier that generates a voltage
on the analog output AO. Two dummy pixel
values are shifted out first, then the 128 actual
pixel bits, followed by two additional dummy
pixel bits, for a total of 132 data bits. Although
there are only 132 pixels, 133 clock pulses are
necessary for a complete shift out. The final
pulse is used to re-initialize the shift register.
The integrator reset period ends 18 clock cycles
after the SI pulse is clocked in. So the light-
integration starts after the 18^th CLK pulse. The
light-integration ends at the next SI pulse.
Between the end of the 133^th clock pulse and the
next SI pulse, a minimum time of 10µs is
necessary for an effective S&H function. So the
minimum integration time of the MLX90255BA is
(133 -18) * Ts + 10µs and thus dependent on
clock speed. (Ts = clock period) After the 132
data bits are clocked out, the output becomes
high impedance. (see figure) The AO is driven
by a source follower that requires an external
pulldown resistor. (typically 330Ω) The output is
nominally 125mV for no light input and 2.4V for a
nominal full-scale output. The pixel gain is 15%
bigger at the edges than in the middle (cosine
correction) in order to get a flat output when
illuminating the device with a single LED light
source.
The MLX90255BA is intended for use in a wide
variety of applications, including: image
scanning, mark and code reading, optical
character recognition (OCR) and contact
imaging, edge detection and positioning, and
optical linear and rotary encoding. The
MLX90255BA is a replacement for the Texas
Instruments' TSL1301 and TSL1401 parts.
Absolute Maximum Ratings
Supply Voltage, Vdd
Digital Input Current Range
Operating Free-Air temperature
range, Ta
Storage temperature range,
Tstg
Lead Temperature
1.6mm (1/16 inch) from case for
10 seconds
+7V
-20 to 20 mA
-40°C to 125°C
(automotive compliant
optical package)
-40°C to 125°C
260°C
Stresses beyond those listed under "absolute
maximum ratings" may cause permanent
damage to the device.
These are stress ratings only, and functional
operation of the device at these or any other
conditions beyond those indicated under
"recommended operating conditions" is not
implied.
Exposure to absolute-maximum -rated
conditions for extended periods may affect
device reliability.
MLX90255BA Linear Optical Array
3901090255
Page 4
Rev 1.2 08-Aug-01