Datasheet
DRV2605
www.ti.com
SLOS825C –DECEMBER 2012–REVISED SEPTEMBER 2014
7.6.20 Feedback Control (Address: 0x1A)
Figure 47. Feedback Control Register
7 6 5 4 3 2 1 0
N_ERM_LRA FB_BRAKE_FACTOR[2:0] LOOP_GAIN[1:0] BEMF_GAIN[1:0]
R/W-0 R/W-0 R/W-1 R/W-1 R/W-0 R/W-1 R/W-1 R/W-0
Table 23. Feedback Control Register Field Descriptions
BIT FIELD TYPE DEFAULT DESCRIPTION
7 N_ERM_LRA R/W 0
This bit sets the DRV2605 device in ERM or LRA mode. This bit should be set
prior to running auto calibration.
0: ERM Mode
1: LRA Mode
6-4 FB_BRAKE_FACTOR[2:0] R/W 3
This bit selects the feedback gain ratio between braking gain and driving gain.
In general, adding additional feedback gain while braking is desirable so that the
actuator brakes as quickly as possible. Large ratios provide less-stable
operation than lower ones. The advanced user can select to optimize this
register. Otherwise, the default value should provide good performance for most
actuators. This value should be set prior to running auto calibration.
0: 1x
1: 2x
2: 3x
3: 4x
4: 6x
5: 8x
6: 16x
7: Braking disabled
3-2 LOOP_GAIN[1:0] R/W 1
This bit selects a loop gain for the feedback control. The LOOP_GAIN[1:0] bit
sets how fast the loop attempts to make the back-EMF (and thus motor velocity)
match the input signal level. Higher loop-gain (faster settling) options provide
less-stable operation than lower loop gain (slower settling). The advanced user
can select to optimize this register. Otherwise, the default value should provide
good performance for most actuators. This value should be set prior to running
auto calibration.
0: Low
1: Medium (default)
2: High
3: Very High
1-0 BEMF_GAIN[1:0] R/W 2
This bit sets the analog gain of the back-EMF amplifier. This value is interpreted
differently between ERM mode and LRA mode. Auto calibration automatically
populates the BEMF_GAIN bit with the most appropriate value for the actuator.
ERM Mode
0: 0.33x
1: 1.0x
2: 1.8x (default)
3: 4.0x
LRA Mode
0: 5x
1: 10x
2: 20x (default)
3: 30x
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