TSL2562, TSL2563

LOW-VOLTAGE

LIGHT-TO-DIGITAL CONVERTER

TAOS066J − MAY 2007

9

The LUMENOLOGY r Company

r

r

Copyright E 2007, TAOS Inc.

www.taosinc.com

PRINCIPLES OF OPERATION

Analog-to-Digital Converter

The TSL256x contains two integrating analog-to-digital converters (ADC) that integrate the currents from the

channel 0 and channel 1 photodiodes. Integration of both channels occurs simultaneously, and 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 invalid data is not read during the transfer. After

the transfer, the device automatically begins the next integration cycle.

Digital Interface

Interface and control of the TSL256x is accomplished through a two-wire serial interface to a set of registers

that provide access to device control functions and output data. The serial interface is compatible with System

addresses that are selectable via an external pin (ADDR SEL). The slave address options are shown in Table 1.

Table 1. Slave Address Selection

ADDR SEL TERMINAL LEVEL

SLAVE ADDRESS

SMB ALERT ADDRESS

GND

0101001

0001100

Float

0111001

0001100

VDD

1001001

0001100

be appended to the slave address by the master device to properly communicate with the TSL256X device.

Each Send and Write protocol is, essentially, a series of bytes. A byte sent to the TSL256x with the most

significant bit (MSB) equal to 1 will be interpreted as a COMMAND byte. The lower four bits of the COMMAND

byte form the register select address (see Table 2), which is used to select the destination for the subsequent

byte(s) received. The TSL256x responds to any Receive Byte requests with the contents of the register

specified by the stored register select address.

The TSL256X implements the following protocols of the SMB 2.0 specification: