TSL2580, TSL2581
LIGHT-TO-DIGITAL CONVERTER
TAOS098 − MARCH 2010
PRINCIPLES OF OPERATION
Analog-to-Digital Converter
The TSL258x 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 TSL258x 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
Management Bus (SMBus) versions 1.1 and 2.0, and I
2
C bus Fast-Mode. The TSL258x offers three slave
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
GND
Float
VDD
SLAVE ADDRESS
0101001
0111001
1001001
SMB ALERT ADDRESS
0001100
0001100
0001100
NOTE: The Slave and SMB Alert Addresses are 7 bits. Please note the SMBus and I
2
C protocols on pages 10 through 12. A read/write bit should
be appended to the slave address by the master device to properly communicate with the TSL258x device.
SMBus and I
2
C Protocols
Each
Send
and
Write
protocol is, essentially, a series of bytes. A byte sent to the TSL258x 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 TSL258x responds to any Receive Byte requests with the contents of the register
specified by the stored register select address.
The TSL2580 implements the following protocols of the SMB 2.0 specification:
D
D
D
D
D
D
D
Send Byte Protocol
Receive Byte Protocol
Write Byte Protocol
Write Word Protocol
Read Word Protocol
Block Write Protocol
Block Read Protocol
The TSL2581 implements the following protocols of the Philips Semiconductor I
2
C specification:
D
I
2
C Write Protocol
D
I
2
C Read (Combined Format) Protocol
Copyright
E
2010, TAOS Inc.
r
r
The
LUMENOLOGY
r
Company
8
www.taosinc.com
TAOS [ TEXAS ADVANCED OPTOELECTRONIC SOLUTIONS ]
