DRV2605L-Q1 Datasheet, PDF (29/67 Pages) Texas Instruments – Automotive Haptic Driver for LRA and ERM

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DRV2605L-Q1
SLOS874A – OCTOBER 2015 – REVISED OCTOBER 2015
Programming (continued)
7.5.7.1.3 Closed-Loop Mode, Bidirectional
In closed-loop bidirectional mode, the DRV2605L-Q1 device provides automatic overdrive and braking for both
ERM and LRA devices. Closed-loop bidirectional mode preserves compatibility with data created in open-loop
signaling by maintaining zero drive-strength at the mid-scale value. When input values less than the mid-scale
value are given, the DRV2605L-Q1 device interprets them as the same as the mid-scale with zero drive.
The reference level for steady-state full-scale drive is set by the RATED_VOLTAGE[7:0] bit (when auto
calibration is performed). The output voltage can momentarily exceed the rated voltage for automatic overdrive
and braking, but does not exceed the OD_CLAMP[7:0] voltage. Braking occurs automatically based on the input
signal when the back-EMF feedback determines that braking is necessary. Although the Closed-Loop mode
preserves compatibility with existing device data formats, it provides closed loop benefits and is the default
configuration at power up.
The RTP mode has 8 bits of resolution over the I²C bus. The RTP data can either be in signed (2s complement)
or unsigned format as defined by the DATA_FORMAT_RTP bit.
Steady-State
Output Magnitude _{Closed Loop, BIDIR_INPUT = 1}
RATED_VOLTAGE[7:0]
½ RATED_VOLTAGE[7:0]
Full Braking
Input Interface
PWM
0%
RTP (8-bit) DATA_FORMAT_RTP = 0 _0x81
RTP (8-bit) DATA_FORMAT_RTP = 1 0x00
Figure 27.
50%
0x00
0x7F
75%
0x3F
0xBF
Input
100%
0x7F
0xFF
NOTE
Closed-loop bidirectional mode is compatible with all DRV2605L-Q1 interfaces except for
TS2200 Library A (with fixed overdrive programming). Library A should only be used in
open-loop mode. Libraries B through F (no overdrive) can take advantage of the automatic
overdrive and braking of closed-loop bidirectional mode.
Copyright © 2015, Texas Instruments Incorporated
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