ADVANCED COMMUNICATIONS & SENSING

V1.8 © 2009 Semtech Corp.

www.semtech.com

2

SX8725

ZoomingADC™ for Pressure and Temperature Sensing

Table of Contents

Description..............................................................................................................................................................1

Applications............................................................................................................................................................1

Features ..................................................................................................................................................................1

Ordering Information .............................................................................................................................................1

Functional Block Diagram.....................................................................................................................................1

Absolute Maximum Ratings ..................................................................................................................................4

Electrical Characteristics ......................................................................................................................................5

ZoomingADC Specifications.................................................................................................................................6

Timing Characteristics ..........................................................................................................................................8

2-WIRE Timing Waveforms ...................................................................................................................................8

Pin Configuration ...................................................................................................................................................9

Marking Information...............................................................................................................................................9

Pin Description .......................................................................................................................................................9

Circuit Description ...............................................................................................................................................10

General Description .............................................................................................................................................. 10

Block Diagram ....................................................................................................................................................... 10

VREF ..................................................................................................................................................................... 10

GPIO ..................................................................................................................................................................... 11

Charge Pump ........................................................................................................................................................ 12

RC Oscillator ......................................................................................................................................................... 13

2-WIRE.................................................................................................................................................................. 14

2-WIRE Communication Format ........................................................................................................................... 14

2-WIRE Address.................................................................................................................................................... 14

ZoomingADC ........................................................................................................................................................15

Features ................................................................................................................................................................ 15

Overview ............................................................................................................................................................... 15

ZADC Description.................................................................................................................................................. 15

Acquisition Chain................................................................................................................................................... 15

Registers ............................................................................................................................................................... 17

ZADC Detailed Functionality Description .............................................................................................................. 18

Continuous-Time vs. On-Request......................................................................................................................... 18

Input Multiplexers .................................................................................................................................................. 19

Programmable Gain Amplifiers ............................................................................................................................. 20

PGA & ADC Enabling............................................................................................................................................ 21

PGA1 ..................................................................................................................................................................... 21

PGA2 ..................................................................................................................................................................... 21

PGA3 ..................................................................................................................................................................... 21

ADC Characteristics .............................................................................................................................................. 22

Conversion Sequence ........................................................................................................................................... 22

Over-Sampling Frequency .................................................................................................................................... 22

Over-Sampling Ratio ............................................................................................................................................. 23

Elementary Conversions ....................................................................................................................................... 23

Resolution ............................................................................................................................................................. 24

Conversion Time and Throughput......................................................................................................................... 25

Output Code Format ............................................................................................................................................. 26

Power Saving Modes ............................................................................................................................................ 27

Registers Map ....................................................................................................................................................... 28

Registers Descriptions .......................................................................................................................................... 28

RC Register........................................................................................................................................................... 28

GPIO Registers ..................................................................................................................................................... 29

ZADC Registers .................................................................................................................................................... 30

Mode Register ....................................................................................................................................................... 31

Optional Operating Modes: External Voltage Reference Option .......................................................................... 32

Application Hints..................................................................................................................................................33

Recommended Operation Mode and Registers Settings...................................................................................... 33

Operation Mode..................................................................................................................................................... 33