Document
WIRELESS & SENSING
SX9500
Ultra Low Power, Four Channels Capacitive Proximity/Button Solution
GENERAL DESCRIPTION
The SX9500 is a low-cost, very low power 4-channel capacitive controller that can operate either as a proximity or button sensor. The SX9500 includes sophisticated on-chip auto-calibration circuitry to regularly perform sensitivity adjustments, maintaining peak performance over a wide variation of temperature, humidity and noise environments, providing simplified product development and enhanced performance.
The SX9500 operates directly from an input supply voltage of 2.7 to 5.5V, and includes a separate I2C serial bus supply input to enable communication with 1.8 – 5.5V hosts. The I2C serial communication bus reports proximity or touch detection and is used to facilitate parameter settings adjustment. Upon a proximity detection, the NIRQ output asserts, enabling the user to either determine the relative proximity distance, or simply obtain an indication of detection.
A dedicated transmit enable (TXEN) pin is available to synchronize capacitive measurements for applications that require synchronous detection, enabling very low supply current and high noise immunity by only measuring proximity when requested.
KEY PRODUCT FEATURES
2.7 – 5.5V Input Supply Voltage
Capacitive Sensor Inputs
Down to 0.08 fF Capacitance Resolution
Stable Proximity & Touch Sensing With Temperature
Capacitance Offset Compensation to 30pF
Active Sensor Guarding
Automatic Calibration
Ultra Low Power Consumption:
Active Mode: Doze Mode: Sleep Mode:
170 uA 18 uA 2.5 uA
400KHz I2C Serial Interface
Four programmable I2C Sub-Addresses
Input Levels Compatible with 1.8V Host Processors
Open Drain NIRQ Interrupt pin
Three (3) Reset Sources: POR, NRST pin, Soft Reset
-40°C to +85°C Operation
Compact Size: 3 x 3mm Thin QFN package
Pb & Halogen Free, RoHS/WEEE compliant
APPLICATIONS
• Notebooks • Tablets • Mobile Appliances
ORDERING INFORMATION
Part Number SX9500IULTRT 1
SX9500EVKA 1 3000 Units/reel
Package QFN-20 Eval. Kit
Marking ZND8
TYPICAL APPLICATION CIRCUIT
Revision 4 February 4, 2014
© 2014 Semtech Corporation 1
www.semtech.com
WIRELESS & SENSING
SX9500
Ultra Low Power, Four Channels Capacitive Proximity/Button Solution
Table of Contents
GENERAL DESCRIPTION........................................................................................................................ 1
KEY PRODUCT FEATURES..................................................................................................................... 1
APPLICATIONS....................................................................................................................................... 1
ORDERING INFORMATION...................................................................................................................... 1
TYPICAL APPLICATION CIRCUIT ............................................................................................................ 1
1 GENERAL DESCRIPTION............................................................................................................... 4
1.1 Pin Diagram
4
1.2 Marking Information
4
1.3 Pin Description
5
1.4 Acronyms
5
2 ELECTRICAL CHARACTERISTICS ................................................................................................. 6
2.1 Absolute Maximum Ratings
6
2.2 Operating Conditions
6
2.3 Thermal Characteristics
6
2.4 Electrical Specifications
7
3 PROXIMITY SENSING INTERFACE ................................................................................................. 9
3.1 Introduction
9
3.2 Scan Period
9
3.3 Analog Front-End (AFE) 3.3.1 Capacitive Sensing Basics 3.3.2 AFE Block Diagram 3.3.3 Capacitance-to-Voltage Conversion (C-to-V) 3.3.4 Shield Control 3.3.5 Offset Compensation 3.3.6 Analog-to-Digital Conversion (ADC)
10 10 12 12 12 12 13
3.4 Digital Processing 3.4.1 Overview 3.4.2 PROXRAW Update 3.4.3 PROXUSEFUL Update 3.4.4 PROXAVG Update 3.4.5 PROXDIFF Update 3.4.6 PROXSTAT Update
13 13 15 15 16 18 18
3.5 Host Operation
19
3.6 Operational Modes 3.6.1 Active 3.6.2 Doze 3.6.3 Sleep 3.6.4 TXEN Pin
20 20 20 20 20
4 I2C INTERFACE ........................................................................................................................... 21
4.1 Introduction
21
4.2 I2C Write
21
4.3 I2C Read
21
5 RESET......................................................................................................................................... 23
5.1 Power-up
23
5.2 NRST Pin
23
5.3 Software Reset
24
6 INTERRUPT ................................................................................................................................. 25
Revision 4 February 4, 2014
© 2014 Semtech Corporation 2
www.semtech.com
WIRELESS & SENSING
SX9500
Ultra Low Power, Four Channels Capacitive Proximity/Button Solution
6.1 Power-up
25
6.2 Assertion and Clearing
25
7 PINS DESCRIPTION ...........