Texas Instruments DRV2605EVM-CT ERM/LRA Haptic Driver Evaluation DRV2605EVM-CT DRV2605EVM-CT Datenbogen
Produktcode
DRV2605EVM-CT
Input
Steady-State
Output Magnitude
ODClamp[7:0]
0 V
Open Loop
ERM_OpenLoop = 1 OR LRA_OpenLoop = 1
RTP (8-bit) DataFormat
_RTP = 0
PWM
Input Interface
0%
50%
100%
RTP (8-bit) DataFormat
_RTP = 1
0x00
0x7F
0xFF
0x81
0x00
0x7F
-ODClamp[7:0]
SLOS825B – DECEMBER 2012 – REVISED JANUARY 2014
MODES OF OPERATION
The DRV2605 smart loop architecture has three modes of operation. Each of these modes can be used to drive
either ERM or LRA devices.
either ERM or LRA devices.
1. Open Loop Mode
2. Closed Loop Mode (Uni-Directional)
3. Closed Loop Mode (Bi-Directional)
Each mode has its own advantages and disadvantages. The DRV2605 brings a new, cutting-edge actuator
control with closed loop operation around the back-EMF for automatic overdrive and braking; however, some
existing haptic libraries already include overdrive and braking that is embedded in the waveform data. Open loop
mode is used to preserve compatibility with such systems.
control with closed loop operation around the back-EMF for automatic overdrive and braking; however, some
existing haptic libraries already include overdrive and braking that is 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 DRV2605 interface is translated to the output drive
signal.
signal.
Open Loop Mode
In open loop mode, the reference level for full-scale drive is set by the ODClamp[7:0] value. A mid-scale input
value gives no drive signal, and less than mid-scale give a negative drive value. For ERM, a negative drive value
results in counter-rotation, or braking. For LRA, this translates to a 180 degree phase shift in commutation.
In open loop mode, the reference level for full-scale drive is set by the ODClamp[7:0] value. A mid-scale input
value gives no drive signal, and less than mid-scale give a negative drive value. For ERM, a negative drive value
results in counter-rotation, or braking. For LRA, this translates to a 180 degree phase shift in commutation.
The RTP mode has 8 bits of resolution over the I2C bus. The RTP data can be in either signed (2’s complement)
or unsigned format as defined by DataFormat_RTP.
or unsigned format as defined by DataFormat_RTP.
Restrictions: Open loop operation for LRA is only valid with the PWM interface. See “Open Loop Operation for
LRA” for details. All input interfaces shown will work with ERM.
LRA” for details. All input interfaces shown will work with ERM.
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