DRV2605L Datasheet, PDF (28/69 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
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Programming (continued)
8.5.8 Waveform Playback Programming
8.5.8.1 Data Formats for Waveform Playback
The DRV2605L smart-loop architecture has three modes of operation. Each of these modes can drive either
ERM or LRA devices.
1. Open-loop mode
2. Closed-loop mode (unidirectional)
3. Closed-loop mode (bidirectional)
Each mode has different advantages and disadvantages. The DRV2605L device brings new cutting-edge
actuator control with closed-loop operation around the back-EMF for automatic overdrive and braking. However,
some existing haptic implementations already include overdrive and braking that are embedded in the waveform
data. Open-loop mode is used to preserve compatibility with such systems.
The following sections show how the input data for each DRV2605L interface is translated to the output drive
signal.
8.5.8.1.1 Open-Loop Mode
In open-loop mode, the reference level for full-scale drive is set by the OD_CLAMP[7:0] bit in Register 0x17. A
mid-scale input value gives no drive signal, and a less-than mid-scale gives a negative drive value. For an ERM,
a negative drive value results in counter-rotation, or braking. For an LRA, a negative drive value results in a 180-
degree phase shift in commutation.
The RTP mode has 8 bits of resolution over the I²C bus. The RTP data can either be in a signed (2s
complement) or unsigned format as defined by the DATA_FORMAT_RTP bit.
Steady-State
Output Magnitude
Open Loop
ERM_OPEN_LOOP = 1 OR LRA_OPEN_LOOP = 1
OD_CLAMP[7:0]
0V
-OD_CLAMP[7:0]
Input Interface
PWM
0%
RTP (8-bit) DATA_FORMAT_RTP = 0 0x81
RTP (8-bit) DATA_FORMAT_RTP = 1 0x00
Figure 26.
50%
0x00
0x7F
Input
100%
0x7F
0xFF
28
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