DRV2605L Datasheet, PDF (26/69 Pages) Texas Instruments – DRV2605L 2 to 5.2 V Haptic Driver for LRA and ERM With Effect Library and Smart-Loop Architecture

DRV2605L
SLOS854C – MAY 2014 – REVISED SEPTEMBER 2014
www.ti.com
Programming (continued)
8.5.4 Programming for Open-Loop Operation
The DRV2605L device can be used in open-loop mode and closed-loop mode. If open-loop operation is desired,
the first step is to determine which actuator type is to use, either ERM or LRA.
8.5.4.1 Programming for ERM Open-Loop Operation
To configure the DRV2605L device in ERM open-loop operation, the ERM must be selected by writing the
N_ERM_LRA bit to 0 (in register 0x1A), and the ERM_OPEN_LOOP bit to 1 in register 0x1D.
8.5.4.2 Programming for LRA Open-Loop Operation
To configure the DRV2605L device in LRA open-loop operation, the LRA must be selected by writing the
N_ERM_LRA bit to 1 in register 0x1A, and the LRA_OPEN_LOOP bit to 1 in register 0x1D. If PWM interface is
used, the open-loop frequency is given by the PWM frequency divided by 128. If PWM interface is not used, the
open-loop frequency is given by the OL_LRA_PERIOD[6:0] bit in register 0x20.
8.5.5 Programming for Closed-Loop Operation
For closed-loop operation, the device must be calibrated according to the actuator selection. When calibrated
accordingly, the user only needs to provide the desired waveform. The DRV2605L device automatically adjusts
the level and, for the LRA, automatically adjusts the driving frequency.
8.5.6 Auto Calibration Procedure
The calibration engine requires a number of bits as inputs before it can be executed (see Figure 25). 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 25 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 25. Calibration-Engine Functional Diagram
Variation occurs between different actuators even if the actuators are of the same model. To ensure optimal
results, TI recommends that the calibration routine be run at least once for each actuator. The OTP feature of the
DRV2605L device can store the calibration values. Because of these stored values, the calibration procedure
does not have run every time. Having a single set of calibration register values that can be loaded during the
system initialization is possible.
26
Submit Documentation Feedback
Product Folder Links: DRV2605L
Copyright © 2014, Texas Instruments Incorporated