sx8675iwltrt Semtech Corporation, sx8675iwltrt Datasheet - Page 18

• Manufacturer Part Number: sx8675iwltrt
• Description: Haptics Enabled Multitouch 4/5-wire Resistive Touchscreen Controller With Proximity Sensing
• Manufacturer: Semtech Corporation

ADVANCED COMMUNICATIONS & SENSING
The two contacts create touch resistances Rt1 and Rt2 between the two layers of the touchscreen.
The SX8674/75/76 perform on-chip specific multitouch measurements which the host retrieves and processes
with a specific software enabling the detection of the gestures described in § 13.3.
For optimum gesture detection, RmSelX and RmSelY parameters should be set according to table below.
4.6
The chip offers 4 types of data processing which allows the user to make trade-offs between data throughput,
power consumption and noise rejection.
The parameter FILT is used to select the filter order Nfilt. The noise rejection will be improved with a high order
to the detriment of power consumption. Each channel can be sampled up to 7 times and then processed to get a
single consolidated coordinate.
Rev 1 – 25
Digital Processing
th
July 2011
Figure 18 – Digital Processing Block Diagram
X/Y Panel Resistance ( )
Figure 17 – Dual-touch Simplified Model
Table 5 – RmSelX/Y Selection Table
9376-18780
1876-4375
4376-9375
939-1875
100-187
188-312
313-938
>18780
Rxtot
Rytot
c
n
Resistive Touchscreen Controller with Proximity Sensing
N
=
=
1
R1
R4
18
∑
N
i
+
+
0
1
R2
R5
s
n
+
+
i
R3
R6
SX8674/SX8675/SX8676
RmSelX/Y
000
001
010
011
100
101
110
111
Haptics Enabled Multitouch 4/5-Wire
www.semtech.com