IQS550EV03 S Azoteq, IQS550EV03 S Datasheet - Page 8

• Manufacturer Part Number: IQS550EV03 S
• Description: Touch Sensor Development Tools Trackpad Demo for IQS550
• Manufacturer: Azoteq

Specifications of IQS550EV03 S

• Tool Is For Evaluation Of: IQS550
• Interface Type: I2C, SPI
• Operating Voltage: 1.65 V to 3.6 V
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C

3 ProxSense
The device contains a ProxSense
that uses patented technology to provide
detection of PROX and TOUCH, and calculate
X and Y touch and/or proximity coordinates. A
combination of hardware and software is used
to obtain a set of measurements used for
calculating the respective outputs.
An additional „Snap‟ output is now available
which adds further conventional button snap
functionality above the trackpad area.
The system can operate in a Normal- or Prox-
Mode charging configuration. In both of these
a low-power charging scheme can also be
implemented.
3.1 Individual Channels
On a trackpad type pattern (typically a
diamond shape layout), each intersection of
an Rx and Tx row/column forms a channel.
Each channel has a count value, Long-Term
Average, Proximity, Touch and Snap (if
enabled) status. The default on the IQS550
device is 15x10 thus giving 150 channels in
total.
Any channels not forming part of the trackpad
area (see Section 4.3) can be used as
separate sensors, and designed with any
projected sensor pattern (Rx + Tx) as required
by the design.
Each channel is limited in having a count
value < 20000. If the ATI setting or hardware
causes
conversion will be stopped, and a value of „0‟
will be read for that relevant count value.
3.2 Normal Mode Charging
The sensors are scanned one Tx transmitter
at a time, until all have completed, with all
enabled Rx‟s charging in each Tx „time-slot‟.
This then provides all the sample data for the
touch panel, which can be used to obtain
Long-term Average values, Prox and Touch
status,
information.
In a 15x10 system (15 Tx and 10 Rx), 15
conversion timeslots occur, with each timeslot
Copyright © Azoteq (Pty) Ltd
All Rights Reserved.
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IQS550 Trackpad Datasheet
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consisting of the acquisition of 10 receiver
channels.
Communication is only done once all these
timeslots are completed.
3.3 ProxMode Charging
An additional ProxMode charging scheme is
selectable, and aimed at providing long range
proximity detection, useful for implementing
low-power modes during periods of no user
activity.
configurable, and can function in either self- or
projected- capacitive mode. Standard sensor
electrode design for self or projected channels
must
sensing.
The system performs a ProxMode channel
acquisition (while waiting in a low-power state
for the conversion to complete).
complete, the data is processed, updating the
proximity status. A low duty cycle can then
also be selected, further reducing the total
current consumption.
sensitivity of the ProxSense
Mode charging before the user is within
operating distance of the sensors.
If a trackpad is implemented on which a
ProxMode
recommended to route the ProxMode Rx
channel around the perimeter of the trackpad
sensors (roughly 1mm from the sensors). The
channel is
capacitive sensing mode, and all the Tx‟s on
system will be fully operational in Normal
Revision 1.04
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Figure 3.1
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November 2012
Page 8 of 50
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