Document
EM MICROELECTRONIC - MARIN SA
EM6420
Ultra Low Power Capacitive Touch Sensor Interface IC
Description
The EM6420 is an ultra low power Touch Sensor Interface IC able to scan sequentially up to 16 capacitive sensors. The device parameters (number of used sensors, sensors scan frequency, sensors sensitivity level, IRQ condition) are configurable either from a host microcontroller through a communication port or through configuration inputs.
Recognised touch inputs will be signaled with an active edge at the IRQ pad and data are ready to be read through the communicaion port by the host MCU. Conditions for the IRQ to get active are configurable : at the end of every scan, at the end of a scan if at least one sensor is active or at the end of a scan if the sensors state has changed.
The EM6420 can also detect the most active sensor in applications where sensors are tightly spaced. It compares relative levels among sensors and selects the sensor with the largest signal strength.
To increase the number of sensors >16, use several EM6420 in parallel.
Depending on the selected supply voltage range, 3 or 4 decoupling capacitors are required for the entire functionality of the EM6420 from -40 to + 85°C.
Features
• Up to 16 analogue sensor inputs • User selectable communication interfaces : 4-wire SPI,
I2C, 4-bit parallel interface and 8-bit direct output • User-selectable active edge IRQ output signal • Active high enable input • No software development and tuning required • Development tools and documentations available • Complete touch module available: IC + electrodes
design on various non-conductive substrates
Electrical Characteristics
• Supply voltage • Power consumption
Low Power Mode
• Ultra Low Power Mode
• Nominal sensor capacitance
1.2 V to 2.0 V or 2.2 to 3.6 V
8.0 µA @ 3.0 V (14.5 µA @1.5 V) for 16 sensors scanned at 8 Hz 2.0 µA @ 3.0 V (5.0 µA @1.5 V) for 16 sensors scanned at 8 Hz
3 to 31 pF
• Sensors frequency
scan
1 Hz to 128 Hz *frequency depending on number of sensors
• COM clock frequency up to 400 kHz
Availability • Naked die • SMT package MLF32-36-40
Design Considerations The EM6420 is well suited for battery and mains powered applications where the following features are important : • Tamper proof applications • Nice and clean designs • Touch function to avoid buttons and keys • Slider functions • Hygienic issues, cleaning aspects • Waterproof designs Applications • Mobile phones, cordless phones • PDA, keyboards • White & brown goods • Toys • Lighting - Sliders for dimming
Copyright 2012, EM Microelectronic-Marin SA
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6420-DS.doc, Version 4.0 , 4-Jun-12
www.emmicroelectronic.com
EM6420
TABLE OF CONTENTS
1. PRELIMINARIES ...............................................................................................................................................4 1.1 Reference.................................................................................................................................................................4 1.2 Conventions .............................................................................................................................................................4
2. GENERAL DESCRIPTION ................................................................................................................................5
3. FEATURES ........................................................................................................................................................6 3.1 Key elements............................................................................................................................................................6 3.2 Power Supply ...........................................................................................................................................................6 3.3 Interfaces .................................................................................................................................................................6 3.4 Development Tools ..................................................................................................................................................6 3.5 Touch modules based on EM6420 IC ......................................................................................................................6
4. BLOCK DIAGRAM.............................................................................................................................................7
5. PAD DESCRIPTION ..........................................................................................................................................7
6. ELECTRICAL SPECIFICATIONS .....................................................................................................................9 6.1 Absolute Maximum Ratings..............................................................................