QT1081 Datasheet, PDF (10/20 Pages) Quantum Research Group – 8-KEY QTOUCH SENSOR IC

In many applications, it is desirable to sense touch at high
speed. Examples include scrolling ‘slider’ strips or ‘Off’
buttons. It is possible to place the device into a ‘Fast Detect’
mode that usually requires under 10ms to respond. This is
accomplished internally by setting the Detect Integrator to only
two counts, i.e. only two successive detections are required to
detect touch.
In LP mode, ‘Fast’ detection will not speed up the initial delay
(which could be up to 340ms nominal depending on the option
setting). However, once a key is detected the device is forced
back into normal speed mode. It will remain in this faster
mode until requested to return to LP mode.
When used in a ‘slider’ application, it is normally desirable to
run the keys without AKS.
In both normal and ‘Fast’ modes, the time required to process
a key release is the same. It takes six sequential
confirmations of nondetection to turn a key off.
Fast Detect mode can be enabled as shown in Tables 1.2 and
1.6.
2.10 Simplified Mode
A simplified operating mode which does not require the
majority of option resistors is available. This mode is set by
connecting a resistor labelled SMR between pins SNS6K and
SNS7 (see Figure 1.2).
In this mode there is only one option possible - AKS enable or
disable. When AKS is disabled, Fast Detect mode is enabled;
when AKS is enabled, Fast Detect mode is off.
AKS in this mode is Global only (i.e. operates across all
functioning keys).
The other option features are fixed as follows:
OUT_n, DETECT Pins: Push-pull, active high,
one-per-key outputs
SYNC/LP Function: LP mode, ~180ms response time
Max On-Duration: 60 seconds
See Tables 1.6 and 1.7.
2.11 Unused Keys
Unused keys should be disabled by removing the
corresponding Cs, Rs, and Rsns components and connecting
SNS pins as shown in the ‘Unused’ column of Table 1.1.
Unused keys are ignored and do not factor into the AKS
function (Section 2.7).
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QT1081_1R0.04_0307