SX8658IWLTRT Semtech, SX8658IWLTRT Datasheet - Page 12

• Manufacturer Part Number: SX8658IWLTRT
• Description: 58T7572
• Manufacturer: Semtech

Specifications of SX8658IWLTRT

• Controller Type: Resistive Touch Screen
• Ic Interface Type: I2C, Serial
• Supply Voltage Range: 2.3V To 3.6V
• Operating Temperature Range: -40°C To +85°C
• Resolution (bits): 12bit

SX8657/SX8658
Haptics Enabled 4/5-Wire
Resistive Touchscreen Controller with Proximity Sensing
ADVANCED COMMUNICATIONS & SENSING
4
T
I
OUCHSCREEN
NTERFACE
4.1
Introduction
The purpose of the touchscreen interface is to measure and extract touch information like coordinates and
pressure. This is done in two steps, first an ADC measures the analog signal coming from the screen, and then
digital processing is performed to consolidate the data.
As illustrated below the chip’s touchscreen interface is compatible with both 4-wire and 5-wire touchscreens.
Touchscreen type is defined by parameter TSTYPE.
Figure 7 – Touchscreen Interface Overview
A 4-wire resistive touch screen consists in two (resistive) conductive sheets separated by an insulator when not
pressed. Each sheet is connected through 2 electrodes at the border of the sheet. When a pressure is applied
on the top sheet, a connection with the lower sheet is established.
Figure 8 – 4-wire Touchscreen
A 5-wire resistive touch screen consists in two (resistive) conductive sheets separated by an insulator when not
pressed. 4 electrodes are connected on the 4 corners of the bottom conductive sheet. They are referred as Top
Left (TL), Top Right (TR), Bottom Left (BL) and Bottom Right (BR).
The fifth wire (WIPER) is used for sensing the top sheet voltage. When a pressure is applied on the top sheet, a
connection with the lower sheet is established.
th
Rev 1 – 25
July 2011
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