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AT42QT1010 [DATASHEET]

9542I–AT42–05/2013

3.

Operation Specifics

3.1

Run Modes

3.1.1

Introduction

The QT1011 has three running modes which depend on the state of the SYNC pin (high or low).

3.1.2

Fast Mode

The QT1011 runs in Fast mode if the SYNC pin is permanently high. In this mode the QT1011 runs at maximum

speed at the expense of increased current consumption. Fast mode is useful when speed of response is the prime

design requirement. The delay between bursts in Fast mode is approximately 1 ms, as shown in Figure 3-1.

Figure 3-1.

Fast Mode Bursts (SYNC Held High)

3.1.3

Low Power Mode

The QT1011 runs in Low Power (LP) mode if the SYNC pin is held low. In this mode it sleeps for approximately

80 ms at the end of each burst, saving power but slowing response. On detecting a possible key touch, it temporarily

switches to Fast mode until either the key touch is confirmed or found to be spurious (via the detect integration

process). It then returns to LP mode after the key touch is resolved, as shown in Figure 3-2.

Figure 3-2.

Low Power Mode (SYNC Held Low)

SNSK

SYNC

~1 ms

sleep

sleep

SYNC

SNSK

sleep

fast detect

integrator

OUT

~80 ms