AT42QT2161-MMU Atmel, AT42QT2161-MMU Datasheet - Page 31

• Manufacturer Part Number: AT42QT2161-MMU
• Description: IC TOUCH SENSOR 16KEY QFN M-MOD
• Manufacturer: Atmel
• Type: Capacitiver

Specifications of AT42QT2161-MMU

• Touch Panel Interface: 8, 2-Wire
• Number Of Inputs/keys: 16 Key, Slider
• Resolution (bits): 10 b
• Data Interface: I²C, Serial
• Voltage Reference: Internal
• Voltage - Supply: 1.8 V ~ 5.5 V
• Current - Supply: 1.14mA
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-VFQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

6.16
9614A–AT42–08/10
Address 19: Drift Hold Time/Awake Timeout
Table 6-16.
The Negative Recal Delay timer monitors such detections; if a detection event exceeds the
timer's setting, the key will be automatically recalibrated. After a recalibration has taken place,
the affected key will once again function normally even if it is still being contacted by the foreign
object. This feature is set globally.
NRD can be disabled by setting it to zero (infinite timeout) in which case the key will never
autorecalibrate during a continuous detection (but the host could still command it).
NRD is set globally, which can range in value from 1 – 255. NRD above 0 is expressed in 0.16s
increments.
Default: 255 (40.8s)
The DHT/AWAKE value is used for Drift Hold Time and Awake Timeout parameters.
Drift Hold Time (DHT)
This is used to restrict drift on all keys while one or more keys are activated. DHT defines the
length of time the drift is halted after a key detection.
This feature is particularly useful in cases of high-density keypads where touching a key or
hovering a finger over the keypad would cause untouched keys to drift, and therefore create a
sensitivity shift, and ultimately inhibit any touch detection.
Awake Timeout (AWAKE)
After each matrix scan, the part will automatically go to sleep whenever possible to conserve
power, unless there has been a key state change. The AWAKE timeout feature determines how
long the device will remain in the minimum LP mode from the last key state change.
Subsequent key state changes reinitialize the AWAKE interval. Once the part has been
awakened by a change, the key response time will be fast for as long as the keyboard remains in
use. Once key activity lapses for a period longer than the AWAKE timeout, the part will return to
the assigned LP mode.
DHT/AWAKE can be configured to a value of between 0.32s and 40.8s, in increments of 0.16s.
Values of 0 and 1 are invalid and should not be used.
Note: It is recommended having a DHT/AWAKE of at least two seconds to prevent unintended
key sensitivity drifts and the slider being unresponsive in longer LP modes.
DHT/AWAKE Default: 25 (4s)
Address
19
Drift Hold Time/Awake Timeout
b7
b6
b5
b4
DHT/AWAKE
b3
b2
AT42QT2161
b1
b0
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