DRV2624 Datasheet, PDF (28/79 Pages) Texas Instruments – DRV2624 Ultra Low Power Closed-Loop LRA/ERM Haptic Driver with Internal Memory

DRV2624
SLOS893A – DECEMBER 2015 – REVISED DECEMBER 2015
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Programming (continued)
The calibration engine requires a number of parameters as inputs before the calibration can be executed. When
the inputs are configured, the calibration routine can be executed. After calibration execution occurs, the output
parameters are written over the specified register locations. Figure 28 shows all of the required inputs and
generated outputs. To ensure proper auto-resonance operation, the LRA actuator type requires more input
parameters than the ERM. The LRA parameters are ignored when the device is in ERM mode.
Inputs
Outputs
ERM_LRA
FB_BRAKE_FACTOR[2:0]
BEMF_GAIN[1:0]
LOOP_GAIN[1:0]
RATED_VOLTAGE[7:0]
OD_CLAMP[7:0]
A_CAL_COMP[7:0]
AUTO_CAL_TIME[1:0]
Auto-calibration engine
DRIVE_TIME[4:0]
SAMPLE_TIME[1:0]
A_CAL_BEMF[7:0]
BLANKING_TIME[3:0]
LRA
only
IDISS_TIME[3:0]
DIAG_RESULT
ZC_DET_TIME[1:0]
Figure 28. Calibration-Engine Functional Diagram
For proper calibration results, the calibration waveform must be executed long enough to achieve a steady
acceleration. Therefore, the DRV2624 device has a configurable amount of time for the calibration waveform,
which can be selected by the AUTO_CAL_TIME[1:0] parameter. Additionally, the option to control the calibration
time by using a trigger is provided to accommodate for the cases that require longer times than those allowed by
the AUTO_CAL_TIME parameter. Under the triggered control option, the calibration will start executing after the
initial trigger, and then will stop execution once a stop trigger is received. At that point the output values of the
calibration will be populated. Note that a minimum duration is required for the calibration to work properly.
Table 2. Calibration Routine Behavior Under Different AUTO_CAL_TIME Selections
AUTO_CAL_TIME[1:0]
0
1
2
ACTION
250 ms calibration waveform
500 ms calibration waveform
1 s calibration waveform
COMMENTS
Can be triggered either using the GO bit or externally.
To use the external trigger, the TRIG_PIN_FUNC
3
Trigger controlled
parameter must be configured appropriately.
In this case the minimum duration should be 1 s,
otherwise the result of the calibration can be
corrupted.
28
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