2.3.3 DRV2605
The DRV2605 device is designed to provide extremely-flexible haptic control of ERM and LRA actuators over
a shared I 2C-compatible bus. This control relieves the host processor from ever generating pulse-width
modulated (PWM) drive signals, saving both costly timer interrupts and hardware pins. The DRV2605 device
provides an extensive integrated library over 100 licensed effects from Immersion for ERM and LRA which
eliminates the need to design haptics waveforms. The DRV2605 device offers a licensed version of the
TouchSense 2200 software from Immersion, which includes the 2200 Effects Library, and 2200 audio-to-vibe
features. Additionally, the real-time playback mode allows the host processor to bypass the library playback
engine and play waveforms directly from the host through I2C. The DRV2605 device also contains a smart-loop
architecture, which allows effortless auto resonant drive for LRA as well as feedback-optimized ERM drive. This
feedback provides automatic overdrive and braking, which creates a simplified input waveform paradigm as well
as reliable motor control and consistent motor performance. This feature is utilized to control an LRA in this
reference design.
2.3.4 TLV75518
The TLV755P is an ultra-small, low quiescent current, low-dropout regulator (LDO) that sources 500 mA with
good line and load transient performance. The TLV755P is optimized for a wide variety of applications by
supporting an input voltage range from 1.45 V to 5.5 V. To minimize cost and solution size, the device is offered
in fixed output voltages ranging from 0.6 V to 5 V to support the lower core voltages of modern microcontrollers
(MCUs). Additionally, the TLV755P has a low IQ with enable functionality to minimize standby power. This
device features an internal soft-start to lower inrush current, thus providing a controlled voltage to the load and
minimizing the input voltage drop during start up. When shutdown, the device actively pulls down the output to
quickly discharge the outputs and ensure a known start-up state.
This reference design uses the 1.8 V output option of this device to supply power to the LDC3114 devices and
level shifters.
2.3.5 TCA9534
The TCA9534 is a 16-pin device that provides 8 bits of general purpose parallel input and output (I/O) expansion
for the two-line bidirectional I 2C bus (or SMBus) protocol. The device can operate with a power supply voltage
ranging from 1.65 V to 5.5 V, which allows for use with a wide range of devices. The device supports both
100-kHz (Standard-mode) and 400-kHz (Fast-mode) clock frequencies. I/O expanders such as the TCA9534
provide a simple solution when additional I/Os are needed for switches, sensors, push-buttons, LEDs, fans, and
other similar devices. In this reference design, multiple of these devices are used to control the LEDs on the
board.
2.3.6 PCA9543
The PCA9543A is a dual bidirectional translating switch controlled by the I2C bus. The SCL/SDA upstream pair
fans out to two downstream pairs, or channels. Either individual SCn/SDn channel or both channels can be
selected, determined by the contents of the programmable control register. Two interrupt inputs (INT1– INT0),
one for each of the downstream pairs, are provided. One interrupt output (INT) acts as an AND of the two
interrupt inputs. An active-low reset (RESET) input allows the PCA9543A to recover from a situation where one
of the downstream I2C buses is stuck in a low state. Pulling RESET low resets the I2C state machine and
causes both of the channels to be deselected, as does the internal power-on reset function. This device is used
in this reference design to allow communication to both LDC3114-Q1 devices since they share the same I2C
address.
2.3.7 Sensor Control Board
The sensor control board (SCB) is the MCU board that controls the reference design using an MSP432. This
board handles the firmware and USB interface for the design. The SCB can easily be detached and used with
different EVMs that are supported by it. For more information on the SCB, please visit the
Board (SCB) for Evaluation Modules
System Overview
Inductive Touch and Magnetic Dial Contactless User Interface Reference
Design
9
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