®
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semiconductor solutions
LDS6028
PureTouch™ Capacitance Touch IC with
Integrated Keypad LED Drivers
The LDS6028 PureTouch™ controller empowers system designers to create streamlined, attractive and reliable
product designs with capacitive touch controls. Integrated LED drivers allow visual feedback to be implemented
when a touch occurs, without the need for host intervention.
Description
The LDS6028 is a programmable capacitance-to-digital converter (CDC) designed for use with capacitive
sensor arrays implementing touch-based input controls including sliders, scroll wheels, and buttons.
Featuring 15 sensor inputs, 8 of which are dual-purpose I/Os configurable as either capacitive sensor
inputs or keypad LED drivers, the LDS6028 provides the flexibility to implement multiple touch inputs
with integrated lighting effects using a single controller.
When configured for capacitive sensing, the I/Os are directed through an integrated switch matrix to a
500 kHz sigma-delta CDC which senses changes in the external sensor array. When a sufficiently large
change in capacitance occurs, a sensor activation is registered and the host processor is notified. LED
lighting effects are automatically initiated by a touch event with no processor intervention required.
On-chip calibration logic continuously monitors the environment and automatically adjusts on-and-off
threshold levels to prevent false sensor activation. The LDS6028 is offered with both SPI-compatible
and I2C-compatible interfaces (active interface selected by I/F select pin) and features a general-purpose
input/output (GPIO) and interrupt output for additional communication with the host processor.
VDD1
RESETB
TEST
VDDIO
I/F SEL
SHIELD
LED0-
LED7
VSS2
VDD2
C1
C0
C6
C7/LED0
C14/LED7
VSS1
Switch
Matrix
Serial Interface and
Control Logic Interrupt and GPIO Logic
500 kHz
Excitation
Source
Calibration
RAM
Control and
Data Registers
LDS6028
Power-On
Reset Logic
Calibration
Engine
Sigma-Delta
CDC
INTBGPIOCSB/
A0
SCLK/
SCL
SDI/
A1
SD0/
SDA
LED Driver
Current Sources
Figure 1. LDS6028 block diagram
1
IDT® LDS6028 PURETOUCH™ CAPACITANCE TOUCH IC
LDS6028 Features
Versatile, accurate capacitance-
to-digital converter (CDC)
• 500kHzsigma-deltaCDC
• 15capacitancesensorinputchannels
• 2msupdaterateperactivesensor
Integrated keypad LED drivers
• C7-C14sensorinputscongurable
as keypad LED drivers
• 7.75mAmaximumdrivingcurrent
(up to 62 mA available by connecting
multiple outputs to a single LED)
• Flexibledimmingcontrol
• Processor-freesynchronizationwith
touch events
Integrated, automatic
calibration algorithms
• Environmentalcompensation
• On-chipRAMtostorecalibrationdata
Integrated touch preference modes
• StrongestSingleTouch
• StrongestTwoTouches
• Unrestricted(All)Touches
Ultra-low touch sensor
power consumption*
• Operatingmode(typical):
<150 uW (VDD1=1.8V)
• Shutdownmode(typical):
<1 uW (VDD1=1.8V)
* Excludes LED driver current and I/F and voltage
dependent VDDIO current
®
© 2009 Integrated Device Technology, Inc. All rights reserved. Product specifications subject to change without notice. IDT and the IDT logo are registered trademarks of Integrated Device
Technology, Inc. All other brands, product names and marks are or may be trademarks or registered trademarks used to identify products or services of their respective owners.
Printed in USA 08-09/MG/BWD/PDF_r7_v1 FLYR-LDS6028-089
Discover what IDT know-how can do for you.
www.IDT.com/go/touch
Integrated keypad LED drivers
The LDS6028 features integrated keypad LED drivers enabling the implementation of visual feedback for
touch-based controls and fun lighting effects. The keypad LEDs may be powered either from Vbattery
directly or from a regulated voltage supply. On/off transition times are programmed globally for all LEDs
and maximum current may be programmed for each LED individually. LEDs may be either manually
controlled or synchronized to automatically trigger when a touch event occurs.
Ideal solution for portable applications
The LDS6028 is optimized for minimal power consumption, with touch sensor circuits operating from
a 1.8V supply voltage. In full power mode, sensor conversion and calibration occur continuously,
minimizing the time between touch event and touch detection. With its ultra-low touch sensor power
consumption of <150 uW (typical), the LDS6028 may be operated continuously in full power mode,
eliminating the need for introduced latencies that can cause noticeable delays and degrade the
user experience.
The total solution footprint is also optimized for portable applications, with the functionality of multiple
components consolidated into a single device. With integrated keypad LED driver functionality, the
LDS6028 is a flexible solution combining the functionality of two discrete ICs into a compact 5mm x 5mm
TQFNpackagewith0.75mmpackagethickness.
VDD1 (1.65V~1.95V)
C1
C1=C2: > 1uF
VDDIO
I/F SEC
SHIELD
LDS6028 Host Processor
with SPI
CSB
SCLK
SDI
SDO
VDD
VSS
SSB
SCLK
MOSI
RESETB RESETB
MISO
INTB INTB
GPIO
C12/LED5
C11/LED4
C6
C7/LED0
C8/LED1
C9/LED2
C10/LED3
C5
floating
floating
C14/LED7
C13/LED6
floating
floating
floating
floating
floating
TEST0-1
floating
VSS1
VSS2
VDD1
VDD2
VDD2 (3.0V~5.5V)
C2
VDDIO (1.65V~3.6V)
SENSOR
PCB
C0
C1
C2
C3
C4
LED0-LED3
Figure 2. LDS6028 application diagram
Flexible interface options
• SPI-compatibleserialI/F
• I2C-compatible serial I/F
• SeparateVDDIO level for serial interface
• GPIOandInterruptOutput
Small footprint package
• 40pin5mmx5mmQFN,
0.8mm max height
Power supply range
• Touchsupply(VDD1):1.65V-1.95V
• LEDsupply(VDD2):3.0V-5.5V
• VDDIO=1.65V-3.6V
Applications
• Mobilehandsetsandsmartphones
• Personalmusicandmediaplayers
(MP3/MP4)
• Gamingdevices
• Remotecontrols
• Television,audio/video
• Set-topboxes
• Multi-functionprinters
• Enterprisetelephony