ACS - Revision 4.2
October 2008
2008 Semtech Corp.
www.semtech.com
Page 2
Section
Page
Table of contents
ADVANCED COMMUNICATIONS & SENSING
DATASHEET
SX8722
High gain acquisition for sensor interface
1.
Specifications........................................................................................................................................................... 6
1.1.
Absolute Maximum Ratings ............................................................................................................................. 6
1.2.
Operating conditions ........................................................................................................................................ 6
1.3.
ZoomingADC Specifications ............................................................................................................................ 7
2.
Pin configuration and marking information ............................................................................................................ 10
2.1.
Pin configuration ............................................................................................................................................ 10
2.2.
Marking information ....................................................................................................................................... 10
3.
Pin Description....................................................................................................................................................... 11
4.
Timing Characteristics ........................................................................................................................................... 13
4.1.
I2C timing Waveforms.................................................................................................................................... 13
4.2.
Time specification without the 32.768 kHz Xtal ............................................................................................. 14
4.3.
Start-up time with the 32.768 kHz Xtal presence........................................................................................... 14
4.4.
Changing power mode by pin signal.............................................................................................................. 14
4.5.
Changing power mode by I2C command....................................................................................................... 15
5.
Circuit description .................................................................................................................................................. 16
5.1.
Detailed bloc diagram .................................................................................................................................... 16
5.2.
Functional description .................................................................................................................................... 16
5.3.
ZoomingADC ................................................................................................................................................. 19
6.
Access the SX8722 ............................................................................................................................................... 20
6.1.
Description ..................................................................................................................................................... 20
6.2.
SX8722 configuration..................................................................................................................................... 20
7.
I2C Commands...................................................................................................................................................... 20
8.
Serial communication ............................................................................................................................................ 21
8.1.
Write data direct............................................................................................................................................. 21
8.2.
Write data masked ......................................................................................................................................... 22
8.3.
Read data ...................................................................................................................................................... 22
8.4.
Other commands ........................................................................................................................................... 23
8.5.
Unknown commands ..................................................................................................................................... 23
8.6.
Reading data after a measurement. .............................................................................................................. 23
9.
Predefined settings ................................................................................................................................................ 24
9.1.
Introduction .................................................................................................................................................... 24
9.2.
Features covered by predefined settings....................................................................................................... 24
9.3.
Input multiplexers........................................................................................................................................... 25
9.3.1.
Overview ................................................................................................................................................. 25
9.3.2.
Input channel selection ........................................................................................................................... 25
9.3.3.
Reference channel selection................................................................................................................... 26
9.3.4.
Application example................................................................................................................................ 26
9.4.
Programmable gain amplifier settings............................................................................................................ 28
9.4.1.
Overview ................................................................................................................................................. 28
Not
Recommended
for
New
Designs