IQS550EV03 S Azoteq, IQS550EV03 S Datasheet - Page 14

• 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

4 Additional Features
4.1 Event Mode Communication
The device can be set up to bypass the
communication window when no activity is
sensed. This could be enabled if a master
does not want to be unnecessarily interrupted
during
communication will resume (RDY will indicate
available data) if a proximity, touch or snap is
sensed. It is recommended that the RDY be
placed on an interrupt-on-pin-change input on
the master.
As soon as the active output is no longer
sensed, one communication cycle will still be
available to be able to read that this event has
ended, and then the communication will again
cease until further interaction with the sensors
are observed.
Using the Event Mode will typically work as
follows:
The master sends a command to enable event
mode.
conversions
(communication) with the master, until a
proximity, touch or snap event occurs, which
is most likely the first time that the master will
be interested in the data. The master reads
data during the communication windows, until
the event is over, and then the communication
windows will again be bypassed.
If however the master would like to force
communication session, it must perform a
single byte read from the device at any time
(obviously without the need for RDY to go
HIGH, which it won‟t since communication is
skipped). The master will read one byte with a
value of 0xA3, and then the master gives an
I
communication session is successful.
when the next set of data is ready, a
temporary communication session will be
forced (and RDY will be set as usual to
indicate this). This will however not disable
Event Mode, and if this is required, it must be
disabled during this single temporary window.
The different events to trigger the Event Mode,
namely ProxMode Proximity, Proximity, Touch
Copyright © Azoteq (Pty) Ltd
All Rights Reserved.
2
C STOP. This shows that a request for a
every
The device then continually does
charging
without
cycle.
ProxSense
interaction
IQ Switch
Now
The
IQS550 Trackpad Datasheet
®
or Snap, can be configured. For example all
events except Touch can be disabled, and
then communication will only be available
when a touch output is detected.
4.2 RF Immunity
The IQS550 has immunity to high power RF
noise.
guidelines will be given to improve noise
immunity and the noise detection function is
explained.
4.2.1 Design Guidelines
To improve the RF immunity extra decoupling
capacitors are suggested on V
Place a 100pF in parallel with the 1uF ceramic
on V
decoupling capacitors should be placed as
close as possible to the V
PCB ground planes also improve noise
immunity.
4.2.2 RF detection
In cases of extreme RF interference, on-chip
RF detection is provided.
suitable RF antenna to the RF input pin, it
improves detection of RF noise. The RF noise
is identified on-chip, and suitable steps are
taken to block the corrupt samples from
influencing the output data.
designs this will not be necessary, since the
on-chip sensing has a good immunity to noise
interference.
4.3 Additional Non-Trackpad
If there is a requirement for standard projected
sensors that do no form part of the trackpad
area, then this can be configured.
trackpad sensors can be reduced by defining
the TrackpadRx and TrackpadTx parameters.
These define where the trackpad ends. Any
Rx/Tx channels remaining can be used as
standard capacitive sensing buttons/sensors,
and only proximity, touch and snap data is
processed on these channels, no XY data. An
example is shown in Figure 4.1.
trackpad area will be 8x7, and an additional 14
sensors are available outside of this area.
Clearly the following must be true:
Revision 1.04
Series
®
REG
Channels
. Place a 1uF ceramic on V
In
this
section
DD
and V
By connecting a
general
REG
In
REG
and V
November 2012
Page 14 of 50
Here the
pads.
standard
DD
design
DD
.
.
The
All