AT42QT1012_10 ATMEL [ATMEL Corporation], AT42QT1012_10 Datasheet - Page 13

• Manufacturer Part Number: AT42QT1012_10
• Description: One-channel Toggle-mode Touch Sensor IC with Power Management Functions
• Manufacturer: ATMEL [ATMEL Corporation]

3.11.4
9543D–AT42–08/10
Configuring the User-programmed Auto-off Delay
Figure 3-7.
The QT1012 can be configured to give auto-off delays ranging from minutes to hours by means
of a simple RC network and the delay multiplier input.
With the delay multiplier set at x1 the auto-off delay is calculated as follows:
Delay value = integer value of
And Rt x Ct =
Note:
To ensure correct operation it is recommended that the value of
Values outside this range may be interpreted as the hard wired options TIME linked to OUT and
TIME linked to “off” respectively, causing the QT1012 to use the relevant predefined auto-off
delays.
Table 3-5.
K values (19 and 22) are obtained from
Note:
Output Type
Active high
Active low
Rt is in k, Ct is in nF, Delay is in seconds. K values are obtained from
page
Rt is in k, Ct is in nF.
14.
Programmable Delay
Programmable Auto-off Delay (Example)
Vm = Vss (delay multiplier = 1), Vdd = 3.5V
Delay K
-------------------------- -
Auto Off Delay (Seconds)
(Rt x Ct x 15) / 19
(Rt x Ct x 15) / 22
15

ELECTRODE
SENSE
Vm
RS
CS
Rm
Rt Ct
------------------ -
4
3
SNS
SNSK
K

x 15 seconds
VDD
VDD
VSS
Figure 3-8 on page
5
2
TIME
OUT
1
6
Ct
Rt
14.
Rop
Rt Ct
------------------ -

K
AT42QT1012
is between 4 and 240.
Figure 3-8 on
13