AT42QT1040-MMH Atmel, AT42QT1040-MMH Datasheet - Page 42

• Manufacturer Part Number: AT42QT1040-MMH
• Description: IC TOUCH SENSOR 4KEY 20-VQFN
• Manufacturer: Atmel
• Series: QTouch™r
• Type: Resistiver

Specifications of AT42QT1040-MMH

• Touch Panel Interface: 4, 2-Wire
• Number Of Inputs/keys: 4 Key
• Data Interface: I²C, Serial
• Data Rate/sampling Rate (sps, Bps): 200k
• Voltage Reference: Internal
• Voltage - Supply: 1.8 V ~ 5.5 V
• Current - Supply: 10mA
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 20-VQFN Exposed Pad, 20-HVQFN, 20-SQFN, 20-DHVQFN
• Output Type: Logic
• Input Type: Logic
• Supply Voltage: 1.8 V to 5.5 V
• Dimensions: 3 mm L x 3 mm W x 0.8 mm H
• Output Voltage: 0.7 V to 0.8 V
• Temperature Range: - 40 C to + 85 C
• Termination Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Interface: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: AT42QT1040-MMH; AT42QT1040-MMHTR

10620D–AT42–04/09
Mutual-capacitance Zero-dimensional Sensors
4.3
4.3.1
4.3.2
4-10
Non-Planar Construction
Introduction
Flooded-X Two-layer Method
It is often desirable to form electrodes on the inner surface of a panel that is not part of the main
capacitive touch circuit board. This technique can be used with a mutual-capacitance type sensor,
typically using a spring as part of the sensor (see
other methods are possible (see
little effect on the field distribution until a touch is made, at which point a percentage of the field is
deflected through the panel vertically.
The methods for interconnection are tightly coupled with the method of construction. The rules for the
interconnecting traces are identical to those already described in
page
traces is no longer near to touch.
The flooded-X two-layer method distributes the X and Y electrodes across two layers of a substrate. This
style has some great advantages in terms of sensitivity for small keys, and has some good intrinsic noise
rejecting capabilities. Another useful property is that because the X electrode completely shields the Y
electrode from behind, the sensor is not touch-sensitive from behind. The field behavior is similar to that
mentioned above.
Figure 4-10. Flooded-X Two-layer Method
4-7. However, some of the constraints can be relaxed because the substrate used to route the
2 mm
4 mm Minimum
Substrate
Section 4.3.2
Grid Infill, 4 mm
Where Possible
0.1 – 0.5 mm Wide,
Subject To RC
Time Constant
Front Panel
Y (Nearest
To Touch)
X Flood
and
Section 4.3.3 “Spring Method” on page
Section 4.3.4 on page
Substrate
Less Than 4 mm
Open Spaces
Section 4.2.4 “Interconnection” on
4-13). The overlying panel has
Touch Sensors Design Guide
t2,Er2
t1,Er1
4-12), although