Features
•
maXTouch
™
Touchscreen
– True 12-bit multi-touch with independent XY tracking for up to 10 concurrent
touches in real time with touch size reporting
– Up to 4.3 inch diagonal screen size supported with 10 mm “pinch” separation
– Up to 10.1 inch support with correspondingly wider “pinch”
Number of Channels
– Up to 224 (subject to other configuration limitations)
– Electrode grid configurations up to 20 X by 10 Y lines supported (subject to 30
total pins and a maximum of 14 Y lines)
maXTouch Touch Key Support
– Up to 32 channels can be allocated as fixed keys (subject to other configurations)
Zero Additional Part Count
– 16 X by 14 Y matrix (224 channels) implementable with power bypass capacitors only
Signal Processing
– Advanced digital filtering using both hardware engine and firmware
– Self-calibration
– Auto drift compensation
– Adjacent Key Suppression
®
(AKS
™
) technology
– Grip and face suppression
– Reports one-touch and two-touch gestures
– Down-scaling and clipping support to match LCD resolution
– Ultra-fast start-up and calibration for best user experience
– Supports axis flipping and axis switch-over for portrait and landscape modes
Scan Speed
– Maximum single touch >250Hz, subject to configuration
– Configurable to allow power/speed optimization
– Programmable timeout for automatic transition from active to idle states
Response Times
– Initial latency <10 ms for first touch from idle, subject to configuration
Sensors
– Works with PET or glass sensors
– Works with all proprietary sensor patterns recommended by Atmel
®
– Works with passive stylus
Panel Thickness
– Glass up to 3 mm, screen size dependent
– Plastic up to 1.5 mm, screen size dependent
Interface
– I
2
C-compatible slave mode 400 kHz
Dual-rail Power
– Interface 1.8V to 3.3V nominal, analog 2.7V to 3.3V nominal
Power Consumption
– Idle 80Hz: <1.8 mW, subject to configuration
– One Touch Active 80Hz: 3.9 mW, subject to configuration
– Sleep: 4.5
µW
Package
– 49-ball UFBGA 5 x 5 x 0.6 mm, 0.65 ball pitch
– 49-ball VFBGA 5 x 5 x 1 mm, 0.65 ball pitch
•
•
•
•
maXTouch
™
224-channel
Touchscreen
Sensor IC
mXT224
(AT42QT602240)
Summary
•
•
•
•
•
•
•
Note: This is a summary document.
A complete document is available
under NDA. For more information
contact www.atmel.com/touchscreen.
•
9530AS–AT42–09/09
mXT224
2. Overview of the mXT224
2.1
Introduction
The mXT224 (AT42QT602240) uses a unique charge-transfer acquisition engine to implement
the QMatrix
™
capacitive sensing method patented by Atmel
®
. This allows the measurement of
up to 224 mutual capacitance nodes in under 1 ms. Coupled with a state-of-the-art XMEGA
™
CPU, the entire touchscreen sensing solution can measure, classify and track a single finger
touch every 4 ms if required.
The acquisition engine uses an optimal measurement approach to ensure almost complete
immunity from parasitic capacitance on the receiver inputs (Y lines). The engine includes
sufficient dynamic range to cope with touchscreen mutual capacitances spanning 0.5 pF to 5 pF,
allowing great flexibility for use with Atmel’s proprietary ITO pattern designs. One and two layer
ITO sensors are possible using glass or PET substrates.
The main AVR
®
XMEGA CPU has, under its control, two powerful, yet low power,
microsequencer coprocessors. These combine to allow the signal acquisition, preprocessing,
postprocessing and housekeeping to be partitioned in an efficient and flexible way. This gives
ample scope for to sensing algorithms, touch tracking or advanced shape-based filtering. An
in-circuit reflash can be performed over the chip’s hardware-driven two-wire interface
(I
2
C-compatible).
Overall, the mXT224 represents a step improvement over competing technologies, providing a
near optimal mix of low power, small size and low part count, while offering unrivalled true
multitouch performance.
5
9530AS–AT42–09/09
Test/Measurement
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