TSL2571

LIGHT-TO-DIGITAL CONVERTER

TAOS117A − FEBRUARY 2011

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Copyright

E 2011, TAOS Inc.

The LUMENOLOGY

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www.taosinc.com

Detailed Description

The TSL2571 light-to-digital device includes on-chip photodiodes, integrating amplifiers, ADCs, accumulators,

(CH0), which is responsive to both visible and infrared light, and one 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. Interrupt thresholds and persistence

settings are configured independently.