DRV2624 Datasheet, PDF (66/79 Pages) Texas Instruments – DRV2624 Ultra Low Power Closed-Loop LRA/ERM Haptic Driver with Internal Memory

DRV2624
SLOS893A – DECEMBER 2015 – REVISED DECEMBER 2015
www.ti.com
9.2.2.3 Interface Selection
The DRV2624 device was designed with a default configuration that supports a wide variety of LRA actuators. If
an actuator compatible with the default of the device is selected, then the SimpleDrive can be used without the
use of I²C interface. For this case, the user has 3 options available: controlling the NRST and TRIG/INTZ pin
independently (4 pin interface: VDD, GND, NRST, TRIG/INTZ), shorting NRST with TRIG/INTZ pin and
controlling them with a single GPIO (3 pin interface: VDD, GND, TRIG), or shorting NRST, TRIG/INTZ and VDD
together (2 pin interface: VDD, GND). Note that for the 2-pin interface, the VDD signal must ramp faster than the
startup time (about 500 µs) otherwise a UVLO condition will be detected which will prevent the device from
playing the desired waveform
The I²C interface is required to configure the device. The device can be used fully with this interface with either
RTP or internal memory. The advantage of using this interface is that no additional GPIO (for the TRIG/INTZ pin)
is required for firing effects. Therefore the TRIG/INTZ pin can be connected to GND. Using the external trigger
pin has the advantage that no I²C transaction is required to fire the pre-loaded effect, which is a good choice for
interfacing with a button.
9.2.2.4 Power Supply Selection
The DRV2624 device supports a wide range of voltages in the input. Ensuring that the battery voltage is high
enough to support the desired vibration strength with the selected actuator is an important design consideration.
The typical application uses Li-ion or Li-polymer batteries which provide enough voltage headroom to drive most
common actuators.
If very strong vibrations are desired, a boost converter can be placed between the power supply and the V_DD pin
to provide a constant voltage with a healthy headroom (5-V rails are common in some systems) which is
particularly true if 2 AA batteries in series are being used to power the system.
9.2.3 Application Curves
TRIG/INTZ
Acceleration
[OUT+] − [OUT−] (Filtered)
TRIG/INTZ
Acceleration
[OUT+] − [OUT−] (Filtered)
0
100m
200m
300m
400m
Time (s)
Figure 102. LRA SimpleDrive
0
40m
80m
120m
160m
200m
Time (s)
Figure 103. ERM Open-Loop Drive with Automatic Brake
9.3 Initialization Set Up
9.3.1 Initialization Procedure
1. After power-up, wait at least 1 ms before the DRV2624 device accepts I²C commands.
2. Assert the NRST pin (logic high). The NRST pin can be asserted any time during or after the ?? µs wait
period.
3. Write the MODE parameter (address 0x01) to value 0x00 to remove the device from standby mode.
4. Run auto-calibration to configure the DRV2624 device for the desired actuator. Alternatively, rewrite the
results from a previous calibration.
5. If using the embedded RAM memory, populate the RAM with waveforms at this time.
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