TSL3301CL

102 × 1 LINEAR OPTICAL SENSOR ARRAY

WITH ANALOG-TO-DIGITAL CONVERTER

TAOS141 − JULY 2011

2

r

r

Copyright

E 2011, TAOS Inc.

The LUMENOLOGY

r Company

www.taosinc.com

Terminal Functions

TERMINAL

I/O

DESCRIPTION

NAME

NO.

I/O

DESCRIPTION

GND

6, 7

Ground

SCLK

1

I

System clock input for serial I/O and all internal logic.

SDIN

3

I

Serial data input. Data is clocked in on the rising edge of SCLK.

SDOUT

4

O

Serial data output. Data is clocked out on the falling edge of SCLK.

2

Positive supply voltage.

Detailed Description

The TSL3301CL is a 102

× 1 linear optical array with onboard A/D conversion. It communicates over a serial

digital interface and operates over a 3 V to 5.5 V range. The array is divided into three 34-pixel zones (left, center,

and right), with each zone having programmable gain and offset (dark signal) correction.

The sensor consists of 102 photodiodes, also called pixels, arranged in a linear array. Light energy impinging

on a pixel generates a photocurrent, which is then integrated by the active integration circuitry associated with

that pixel. During the integration period, a sampling capacitor connects to the output of the integrator through

an analog switch. The amount of charge accumulated at each pixel is directly proportional to the light intensity

approximately 300 electrons.

Integration, sampling, output, and reset of the integrators are performed by the control logic in response to

commands input via the SDIN pin. Data is read out on the SDOUT pin. A normal sequence of operation consists

of a pixel reset (RESET), start of integration (STARTInt), integration period, sampling of integrators

(SAMPLEInt), and pixel output (READPixel). Reset sets all the integrators to zero. Start of integration releases

the integrators from the reset state and defines the beginning of the integration period. Sampling the integrators

ends the integration period and stores the charge accumulated in each pixel in a sample and hold circuit.

Reading the pixels causes the sampled value of each pixel to be converted to 8-bit digital format and output on

the SDOUT pin. All 102 pixels are output sequentially unless interrupted by an abort (ABORTPixel) command

or reset by a RESET command.

Gain adjustment is controlled by three 5-bit DACs, one for each of the the three zones. Table 1 lists the gain

settings and the corresponding pixel values. Offset is affected by the gain setting and may have to be adjusted

after gain changes are made.

to the digital conversion. There is a separate offset DAC for each of the three zones. Codes 0h − 7Fh correspond

to positive offset values and codes 80h – FFh correspond to negative offset values.

The offset correction is proportional to the gain setting. At minimal gain, one LSB of the offset DAC corresponds

to approximately 1/3 LSB of the device output, and at maximum gain, to about 1 LSB of the device output.

Note that the gain and offset registers are in indeterminate states after power up and must be set by the controller

as required.

remaining bits representing the magnitude. An MSB of 1 indicates a negative number.