Datasheet

8
AT42QT1040 [DATASHEET]
9524D–AT42–05/2013
See under Figure 1.3 on page 4 for suggested regulator manufacturers.
It is assumed that a larger bypass capacitor (for example, 1 µF) is somewhere else in the power circuit; for example,
near the regulator.
To assist with transient regulator stability problems, the QT1040 waits 500 µs any time it wakes up from a sleep state
(that is, in Sleep mode) before acquiring, to allow Vdd to fully stabilize.
3.6 VQFN Package Restrictions
The central pad on the underside of the VQFN chip should be connected to ground. Do not run any tracks
underneath the body of the chip, only ground. Figure 3-1 shows an example of good/bad tracking.
Figure 3-1. Examples of Good and Bad Tracking
Caution: A regulator IC shared with other logic can result in erratic operation and is
not advised.
A single ceramic 0.1 µF bypass capacitor, with short traces, should be placed very
close to the power pins of the IC. Failure to do so can result in device oscillation, high
current consumption, erratic operation, and so on.
Example of GOOD tracking Example of BAD tracking