DRV2624 Datasheet, PDF (21/79 Pages) Texas Instruments – DRV2624 Ultra Low Power Closed-Loop LRA/ERM Haptic Driver with Internal Memory

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DRV2624
SLOS893A – DECEMBER 2015 – REVISED DECEMBER 2015
Device Functional Modes (continued)
8.4.5 Operation in STANDBY State
The DRV2624 is optimized for power preservation, therefore it will automatically go into standby when not in use.
In standby state, I²C communication is available and register content is preserved.
Stand-by state turns-off all non-essential blocks to preserve power, but features a fast turn on time that will
allows for low latency haptic playback from this mode.
If the host controller wants to force the DRV2624 device into standby, the host controller can do so by sending a
stop trigger, which can be done by writing a 0 to the GO bit, or, if using an external trigger, by following the
appropriate mechanism as described in Process Trigger.
The DRV2624 features an automatic braking option that will make the drive brake the actuator before going into
standby state. The automatic braking feature will be executed every time the device goes into standby state, with
the exception of a critical condition (such as over-current, thermal shutdown or UVLO). The automatic braking
feature can be enabled or disabled by using the AUTO_BRK_INTO_STBY bit.
8.4.6 Operation in ACTIVE State
The DRV2624 goes into active mode only when it must run a process (either waveform playback, calibration or
diagnostics).
When the device gets into active mode, the first thing done is to check for critical conditions (such as over-
current, thermal shutdown or UVLO). If a critical condition is present, the DRV2624 device sets the appropriate
flag (and fires an interrupt if configured to do so), and immediately goes into standby. If no critical condition is
present, the DRV2624 device runs the routine and when finished returns to the standby state.
If a critical condition happens during a routine execution, the routine is aborted immediately and the device sets
the appropriate flag (and fires an interrupt if configured to do so), and immediately goes into standby.
If a stop trigger is received while a routine is being executed, the routine will be stopped and the device will go
into standby state. If the automatic braking option is enabled (AUTO_BRK_INTO_STBY bit), then the DRV2624
device will brake the actuator before going into standby state.
8.4.7 Changing Modes of Operation
The DRV2624 device has 8 parameters that control different aspects of modes of operation, namely: LRA_ERM,
MODE[1:0], CONTROL_LOOP, TRIG_PIN_FUNC, AUTO_BRK_INTO_STBY, AUTO_BRK_OL, and
LRA_WAVE_SHAPE. If any of these parameters are changed in the middle of a process execution (waveform
playback, diagnostics or calibration), the DRV2624 will interpret the change as an abort and will go into standby.
LRA_ERM parameter selects the actuator type.
MODE[1:0] selects between the 4 available process that can be run, namely RTP and Waveform Sequencer for
waveform playback, diagnostics and calibration. The DRV2624 device will be in standby state until a trigger is
received. At that point the device will execute the process selected in the MODE[1:0] parameter. Once finished,
the DRV2624 device will return into standby state.
CONTROL_LOOP selects between open loop and closed loop.
TRIG_PIN_FUNC parameter selects the functionality of the TRIG/INTZ pin among the 3 possibilities: pulse
trigger, level trigger and interrupt.
AUTO_BRK_INTO_STBY parameter enables automatic braking when going into standby. The DRV2624 device
will monitor the back-EMF of the actuator before going into standby, and if the back-EMF is moving, the actuator
will brake and then go into standby. Note that for this function to be executed in open loop, the AUTO_BRK_OL
pin must be enabled.
AUTO_BRK_OL parameter enables automatic braking for open loop mode. If enabled, every time a waveform is
configured with a negative amplitude, the DRV2624 device will brake the actuator. This feature assumes that the
actuator has been calibrated and works under closed-loop conditions.
LRA_WAVE_SHAPE parameter (available for LRA only) allows for selecting the waveform shape to be used
when driving the LRA in open loop. In closed-loop this parameter will be ignored.
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