AT42QT1070-SSU Atmel, AT42QT1070-SSU Datasheet - Page 57

• Manufacturer Part Number: AT42QT1070-SSU
• Description: IC TOUCH SENSOR 7KEY 14-SOIC
• Manufacturer: Atmel
• Type: Capacitiver

Specifications of AT42QT1070-SSU

• Number Of Inputs/keys: 7 Key (Comms), 5 Key (Standalone)
• Data Interface: I²C
• Voltage Reference: Internal
• Voltage - Supply: 1.8 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 14-SOIC (0.154", 3.90mm Width)
• Supply Voltage: 1.8 V to 5.5 V
• Dimensions: 3 mm L x 3 mm W x 0.8 mm H
• Temperature Range: - 40 C to + 85 C
• Termination Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Supply: -
• Resolution (bits): -
• Touch Panel Interface: -
• Data Rate/sampling Rate (sps, Bps): -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Touch Sensors Design Guide
To design the slider:
1. Decide on the length of your slider (L).
2. Apply the rules in
Equation 6-8. Calculation for X
3. Check that the width (W) of each key in the slider is between 6 and 8 mm:
4. Determine where the gaps between the keys occur by calculating the number of X fingers in each
X
If W is < 6 mm, then consider doing one of the following:
– Break the slider into fewer keys
– Make the slider a little longer
If W is > 8 mm, then consider doing one of the following:
– Break the slider into more keys (if the controller supports more keys)
– Make slider a little shorter
– Use a resistively interpolated design to artificially break the slider into smaller pieces (see
key.
For the inner keys this is equal to (X
the end keys, because the X fingers at the end of the slider are merged into the borders. For
example, in
Note that the outer two keys, of course, have slightly more X to Y coupling because they do not have
a shared Y finger at the ends; this is normal.
fingers
Section 6.4.2 “One-Layer Medium/Large Slider Or Wheel” on page
and X
Figure 6-1 on page 6-2
X

X

X
Where:

W = ((X
border
nominalfingers
fingers
border
number; that is, round down to the nearest integer. For example,

...
Section 4.2.2 “X and Y Electrodes” on page 4-2
for the whole slider (see

= ( L - X
= ((
fingers
is the FLOOR operator, defined as the largest integer not greater than the

(X
=
+ 2) / keys) x (1.5T + Y
nominalfingers
fingers

(L - 3T - Y
fingers
x (1.5T + Y
and X
the number of X fingers in the four keys is: 4, 5, 5, 4.
fingers
+ 2) / keys
width
border
+ 2) / keys. However, there is one less X finger in each of
) / (1.5T + Y
Figure 6-1
width
For a Slider
) - T - Y
width

Mutual-capacitance One-dimensional Sensors
) x keys) + 2
) - Y
for definitions).
width
width
width
)

) / 2

and use
6-10)
Equation 6-8

6.6

10620D–AT42–04/09
is 6.
to calculate
6-3