AT42QT1111-MU Atmel, AT42QT1111-MU Datasheet - Page 36

• Manufacturer Part Number: AT42QT1111-MU
• Description: IC TOUCH SENSOR 11KEY QFN
• Manufacturer: Atmel
• Series: QTouch™r
• Type: Capacitiver

Specifications of AT42QT1111-MU

• Touch Panel Interface: 10, 2-Wire
• Number Of Inputs/keys: 11 Key
• Data Interface: Serial, SPI™
• Voltage Reference: Internal
• Voltage - Supply: 3 V ~ 5.5 V
• Current - Supply: 12mA
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 32-VFQFN Exposed Pad
• Output Type: Logic
• Interface: SPI
• Input Type: Logic
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: AT42QT1111-MU; AT42QT1111-MUTR

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AT42QT1111-MU/AT42QT1111-AU
Table 7-16.
KEY_n_NTHR: the negative threshold for key n (where n is 0–10).
The negative threshold determines how much the signal must fall (compared to the reference)
before a key is considered to be “In Detect”. This level will generally need to be tuned
individually for each key. To disable an individual key, set the threshold for that key to 0.
KEY_n_NHYST: the negative hysteresis applied to key n detection threshold (where n is
0 – 10).
Negative Hysteresis operates as a “modifier” for the negative threshold in order to provide a
greater degree of control over the detection of a “Touch”. When a key signal is first detected as
being under the negative threshold, the threshold is reduced by a factor corresponding to the
selected negative hysteresis. This means that the key will not go in and out of detection when
the signal is on the borderline between drift-compensation or touch detection.
The settings for negative hysteresis are:
Default KEY_n_NTHR value:
Default KEY_n_NHYST value:
Address
25
26
27
28
29
00
01
10
11
Bit 7
No change to negative threshold
12.5% reduction in negative threshold
25% reduction in negative threshold
37.5% reduction in negative threshold
Negative Threshold/Negative Hysteresis (Continued)
Bit 6
Bit 5
KEY_10_NTHR
KEY_6_NTHR
KEY_7_NTHR
KEY_8_NTHR
KEY_9_NTHR
10 counts
2 (25 percent)
Bit 4
Bit 3
Bit 2
Bit 1
KEY_10_NHSYT
KEY_6_NHSYT
KEY_7_NHSYT
KEY_8_NHSYT
KEY_9_NHSYT
9571A–AT42–02/10
Bit 0