TSL2672

DIGITAL PROXIMITY DETECTOR

TAOS133 − MAY 2012

2

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Copyright

E 2012, TAOS Inc.

The LUMENOLOGY

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www.taosinc.com

Functional Block Diagram

CH0

SDA

INT

SCL

LDR

Wait Control

Prox

ADC

Prox Control

Prox

Data

Prox LED

Current Driver

Prox

Integration

CH1

Upper Limit

Lower Limit

Interrupt

GND

Detailed Description

Proximity detection requires only a single external LED. This external LED is driven by an internal LED current driver,

which pulses the LED with current for approximately 7 microseconds. The number of pulses, from 1 to 255, and the

current level, from 1.9 mA to 120 mA, can be programmed and together provide a 16,000:1 contiguous dynamic

range. Because the driver is a constant current sink, no external current limiting resistor is required to protect the LED.

In addition to the internal LED current driver, the TSL2672 proximity detector provides on-chip photodiodes, oscillator,

proximity detection solution.

Each device has two photodiodes; a channel 0 photodiode (CH0), which is responsive to both visible and infrared

light, and a channel 1 photodiode (CH1), which is primarily responsive to only infrared light. The user selects the

appropriate diode for their application.

The integrating amplifier and ADC converts the selected photodiode current into a digital value providing up to 16

bits of resolution. Upon completion of a proximity conversion cycle, the result is transferred to the proximity data

registers where it is available to be read.

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

noise-immune when compared to an analog interface.

The device provides a separate pin for level-style interrupts to simplify and improve system efficiency by eliminating

the need to poll for proximity data. When interrupts are enabled, an interrupt is generated when the proximity data

either exceeds an upper threshold or is less than a lower threshold. Once generated, the interrupt remains asserted

until cleared by the controlling firmware. In addition, a programmable interrupt persistence filter allows the user to

determine the number of consecutive out-of-range measurements necessary to trigger an interrupt.