TSL2572

LIGHT-TO-DIGITAL CONVERTER

TAOS132 − MARCH 2012

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Copyright

E 2012, TAOS Inc.

The LUMENOLOGY

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www.taosinc.com

Functional Block Diagram

SDA

INT

SCL

CH1

ADC

ALS Control

CH1

Data

Wait Control

CH0

ADC

CH0

Data

CH0

CH1

Upper Limit

Lower Limit

Interrupt

GND

Detailed Description

The TSL2572 light-to-digital device provides on-chip photodiodes, integrating amplifiers, ADCs, accumulators,

photodiode (CH0), which is responsive to both visible and infrared light, and a channel 1 photodiode (CH1),

which is responsive primarily to infrared light. Two integrating ADCs simultaneously convert the amplified

photodiode currents into a digital value providing up to 16 bits of resolution. Upon completion of the conversion

cycle, the conversion result is transferred to the data registers. This digital output can be read by a

microprocessor through which the illuminance (ambient light level) in lux is derived using an empirical formula

to approximate the human eye response.

connection to a microcontroller or embedded controller. The digital output of the device is inherently more

immune to noise when compared to an analog interface.

The device provides a separate pin for level-style interrupts. When interrupts are enabled and a pre-set value

is exceeded, the interrupt pin is asserted and remains asserted until cleared by the controlling firmware. The

interrupt feature simplifies and improves system efficiency by eliminating the need to poll a sensor for a light

intensity value. An interrupt is generated when the value of an ALS conversion exceeds either an upper or lower

threshold. In addition, a programmable interrupt persistence feature allows the user to determine how many

consecutive exceeded thresholds are necessary to trigger an interrupt.