TSL2580, TSL2581
LIGHT-TO-DIGITAL CONVERTER
TAOS098 − MARCH 2010
Functional Block Diagram
Channel 0
Visible and IR
Integrating
A/D Converter
V
DD
= 2.7 V to 3.6 V
Channel 1
IR Only
ADDR SEL
Address Select
Command
Register
ADC
Register
Interrupt
INT
SCL
Two-Wire Serial Interface
SDA
Detailed Description
The TSL2580 and TSL2581 are second-generation ambient light sensor devices. Each contains two integrating
analog-to-digital converters (ADC) that integrate currents from two photodiodes. Integration of both channels
occurs simultaneously. Upon completion of the conversion cycle, the conversion result is transferred to the
Channel 0 and Channel 1 data registers, respectively. The transfers are double-buffered to ensure that the
integrity of the data is maintained. After the transfer, the device automatically begins the next integration cycle.
Communication to the device is accomplished through a standard, two-wire SMBus or I
2
C serial bus.
Consequently, the TSL258x device can be easily connected to a microcontroller or embedded controller. No
external circuitry is required for signal conditioning, thereby saving PCB real estate as well. Since the output
of the TSL258x device is digital, the output is effectively immune to noise when compared to an analog signal.
The TSL258x devices also support an interrupt feature that simplifies and improves system efficiency by
eliminating the need to poll a sensor for a light intensity value. The primary purpose of the interrupt function is
to detect a meaningful change in light intensity. The concept of a
meaningful change
can be defined by the user
both in terms of light intensity and time, or persistence, of that change in intensity. The TSL258x devices have
the ability to define a threshold above and below the current light level. An interrupt is generated when the value
of a conversion exceeds either of these limits.
Copyright
E
2010, TAOS Inc.
r
r
The
LUMENOLOGY
r
Company
2
www.taosinc.com
TAOS [ TEXAS ADVANCED OPTOELECTRONIC SOLUTIONS ]
