10

AT42QT1040 [DATASHEET]

9524D–AT42–05/2013

Figure 4-1.

~500 ns Pulse On OUT2 Pin

4.3

Speed Selection

Speed selection is determined by a 1 M

 resistor (RFS resistor) connected between SNSK1 and either Vdd (Fast

Mode) or Vss (Slow Mode).

In Fast Mode, the device sleeps for 16 ms between burst acquisitions. In Slow Mode, the device sleeps for 64 ms

between acquisitions. Hence, Slow Mode conserves more power but results in slightly less responsiveness.

Note:

The RFS resistor should always be connected to either Vdd or Vss and not changed during operation of the

device. Changing the RFS option will affect the sensitivity of the particular key. Always check that the

sensitivity is suitable after a change. Retune Cs1 if necessary.

4.4

Moisture Tolerance

The presence of water (condensation, sweat, spilt water, and so on) on a sensor can alter the signal values

measured and thereby affect the performance of any capacitive device. The moisture tolerance of QTouch devices

can be improved by designing the hardware and fine-tuning the firmware following the recommendations in the

Pulse on OUT2

SNS0K

OUT2

SNS0K

OUT2

~20 ms

Power-on/

Reset

Table 4-2.

RFS Resistor

RFS Connected To



Mode

Vdd

Fast mode

Vss

Slow mode