ADVANCED COMMUNICATIONS & SENSING
V1.23 © 2009 Semtech Corp. www.semtech.com
1
SX8724
ZoomingADC™ for Pressure and Temperature Sensing
Description
The SX8724 is a data acquisition system based on
Semtech’s low power ZoomingADC™ technology. It
directly connects most types of miniature sensors
with a general purpose microcontroller.
With 3 differential inputs, it can adapt to multiple
sensor systems. Its digital outputs are used to bias
or reset the sensing elements.
Applications
• Industrial pressure sensing
• Industrial temperature sensing
• Barometer
• Compass
Features
• Up to 16-bit differential data acquisition
• Programmable gain: (1/12 to 1000)
• Sensor offset compensation up to 15 times
full scale of input signal
• 3 differential or 6 single-ended signal inputs
• Programmable Resolution versus Speed
versus Supply current
• 4 digital outputs to bias Sensors
• Internal or external voltage reference
• Internal time base
• Low-power (250 uA for 16b @ 500 S/s)
• 2-wire interface
Ordering Information
Device Package Reel quantity
SX8724E082TRT
SX8724E082TDT
MLPQ-16 4x4
MLPQ-16 4x4
3000
1000
1) Available in tape and reel only
2) Lead free, WEEE and RoHS compliant.
Functional Block Diagram
SIGNAL MUX
REF MUX
ADVANCED COMMUNICATIONS & SENSING
V1.23 © 2009 Semtech Corp. www.semtech.com
2
SX8724
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