DRV2624 Datasheet, PDF (57/79 Pages) Texas Instruments – DRV2624 Ultra Low Power Closed-Loop LRA/ERM Haptic Driver with Internal Memory

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BIT FIELD
4-0 DRIVE_TIME[4:0]
DRV2624
SLOS893A – DECEMBER 2015 – REVISED DECEMBER 2015
Table 41. Address: 0x27 (continued)
TYPE
R/W
DEFAULT DESCRIPTION
16
LRA Mode: Sets initial guess for LRA drive time in LRA mode. Drive time is automatically
adjusted for optimum drive on the fly; however, this register should be optimized for the
approximate LRA frequence. If it is set too low, it may affect the actuator startup time. If it is set
too high, it may cause instability. Optimum DriveTime (ms) ≈ 0.5 × LRA Period. If the LRA does
not exhibit a valid BEMF, then this parameter also sets the free-running frequency when LRA is
not attached or BEMF is not present.
ERM Mode: Sets the sample rate for the back-EMF detection. Lower drive times cause higher
peak-to-average ratios in the output signal, requiring more supply headroom. Higher drive times
cause the feedback to react at a slower rate.
0
LRA: 0.5 ms; ERM: 1 ms.
1
LRA: 0.6 ms; ERM: 1.2 ms.
2
LRA: 0.7 ms; ERM: 1.4 ms.
3
LRA: 0.8 ms; ERM: 1.6 ms.
4
LRA: 0.9 ms; ERM: 1.8 ms.
5
LRA: 1 ms; ERM: 2 ms.
6
LRA: 1.1 ms; ERM: 2.2 ms.
7
LRA: 1.2 ms; ERM: 2.4 ms.
8
LRA: 1.3 ms; ERM: 2.6 ms.
9
LRA: 1.4 ms; ERM: 2.8 ms.
10
LRA: 1.5 ms; ERM: 3 ms.
11
LRA: 1.6 ms; ERM: 3.2 ms.
12
LRA: 1.7 ms; ERM: 3.4 ms.
13
LRA: 1.8 ms; ERM: 3.6 ms.
14
LRA: 1.9 ms; ERM: 3.8 ms.
15
LRA: 2 ms; ERM: 4 ms.
16
LRA: 2.1 ms; ERM: 4.2 ms.
17
LRA: 2.2 ms; ERM: 4.4 ms.
18
LRA: 2.3 ms; ERM: 4.6 ms.
19
LRA: 2.4 ms; ERM: 4.8 ms.
20
LRA: 2.5 ms; ERM: 5 ms.
21
LRA: 2.6 ms; ERM: 5.2 ms.
22
LRA: 2.7 ms; ERM: 5.4 ms.
23
LRA: 2.8 ms; ERM: 5.6 ms.
24
LRA: 2.9 ms; ERM: 5.8 ms.
25
LRA: 3 ms; ERM: 6 ms.
26
LRA: 3.1 ms; ERM: 6.2 ms.
27
LRA: 3.2 ms; ERM: 6.4 ms.
28
LRA: 3.3 ms; ERM: 6.6 ms.
29
LRA: 3.4 ms; ERM: 6.8 ms.
30
LRA: 3.5 ms; ERM: 7 ms.
31
LRA: 3.6 ms; ERM: 7.2 ms.
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