TSL201R

64 y 1 LINEAR SENSOR ARRAY

TAOS030B – AUGUST 2002

2

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Copyright

E 2002, TAOS Inc.

The

LUMENOLOGY

r Company

www.taosinc.com

Terminal Functions

TERMINAL

DESCRIPTION

NAME

NO.

DESCRIPTION

AO

3

Analog output.

CLK

2

Clock. The clock controls charge transfer, pixel output, and reset.

GND

6, 7

Ground (substrate). All voltages are referenced to the substrate.

SI

1

Serial input. SI defines the start of the data-out sequence.

4

Supply voltage. Supply voltage for both analog and digital circuits.

Detailed Description

The sensor consists of 64 photodiodes arranged in a linear array. Light energy impinging on a photodiode

generates photocurrent, which is 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 and the integration

time. The integration time is the interval between two consecutive output periods.

The output and reset of the integrators is controlled by a 64-bit shift register and reset logic. An output cycle is

is clocked through the 64-bit shift register, the charge on the sampling capacitor of each pixel is sequentially

connected to a charge-coupled output amplifier that generates a voltage output, AO. When the bit position goes

low, the pixel integrator is reset. On the 65th clock rising edge, the SI pulse is clocked out of the shift register

and the output assumes a high-impedance state. Note that this 65th clock pulse is required to terminate the

output of the 64th pixel and return the internal logic to a known state. A subsequent SI pulse can be presented

as early as the 66th clock pulse, thereby initiating another pixel output cycle.

The voltage developed at analog output (AO) is given by:

where:

is the analog output voltage for white condition

is the analog output voltage for dark condition

is the device responsivity for a given wavelength of light given in V/(

is the incident irradiance in

is integration time in seconds

AO is driven by a source follower that requires an external pulldown resistor (330-

Ω typical). The output is

nominally 0 V for no light input, 2 V for normal white-level, and 3.4 V for saturation light level. When the device

is not in the output phase, AO is in a high impedance state.

A 0.1