sx8675iwltrt Semtech Corporation, sx8675iwltrt Datasheet - Page 37

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

ADVANCED COMMUNICATIONS & SENSING
6
6.1
Haptics technology is commonly used in systems which include a touchscreen interface. Its purpose is to provide
tactile feedback to the user to acknowledge a touch event hence improving greatly the robustness of the system
and user comfort and perception.
The on-chip haptics interface is designed to drive two common actuator types: Eccentric Rotating Mass (ERM)
and Linear Resonant Actuator (LRA). This is performed without any external component due to fully embedded
analog processing and with very limited host interaction due to the embedded digital processing block.
The host configures drive parameters from the I2C port according to the particular haptics load to be used. The
haptics drive level is then controlled in real time by either of two methods: by a dedicated digital pin, MIN, which
accepts a pulse-width-modulated (PWM) digital signal; or by writing the desired output level directly to a register
via the I2C interface.
This digital information is filtered to prevent fast transitions and hence high current spikes (HAPTBW), converted
into the analog domain by an 8-bit DAC, and finally amplified (HAPTGAIN) to provide a differential signal
between MOUTP and MOUTN pins which can be directly connected to the motor thanks to their high drive
current capability.
For better isolation from the rest of the chip, the haptics interface analog block has its own power supply pins
MVDD and MGND.
The haptics interface is enabled when HAPTTYPEEN != 0.
6.2
6.2.1
An ERM is a DC motor with an off-balance load to create a vibration. Speed and direction are controlled by the
applied voltage. The ERM load is selected when HAPTTYPEEN = 10.
Rev 1 – 25
H
Introduction
ERM Load
APTICS
Introduction
th
July 2011
I
NTERFACE
(SX8674/75)
Figure 48 – Haptics Interface Overview
Resistive Touchscreen Controller with Proximity Sensing
37
SX8674/SX8675/SX8676
Haptics Enabled Multitouch 4/5-Wire
www.semtech.com