DRV2605L Datasheet, PDF (14/69 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
www.ti.com
Feature Description (continued)
8.3.3 Open-Loop Operation for LRA
In the event that open-loop operation is desired (such as for off-resonance driving) the DRV2605L device
includes an open-loop LRA drive mode that is available through the PWM input or through the digital interface.
When using the PWM input in open-loop mode, the DRV2605L device employs a fixed divider that observes the
PWM signal and commutates the output drive signal at the PWM frequency divided by 128. To accomplish LRA
drive, the host should drive the PWM frequency at 128 times the desired operating frequency.
When activated, the digital open-loop mode is available for pre-stored waveforms as well as for RTP mode. The
OL_LRA_PERIOD bit in register 0x20 programs the operating frequency, which is derived from the PWM output
frequency, ƒ_O(PWM). Use Equation 1 to calculate the driving frequency. This mode does not receive the benefits of
the smart-loop architecture.
8.3.4 Open-Loop Operation for ERM
The DRV2605L device offers ERM open-loop operation through the PWM input. The output voltage is based on
the duty cycle of the provided PWM signal, where the OD_CLAMP[7:0] bit in register 0x17 sets the full-scale
amplitude. For details see the Rated Voltage Programming section.
8.3.5 Flexible Front-End Interface
The DRV2605L device offers multiple ways to launch and control haptic effects. The MODE[2:0] bit in register
0x01 is used to select the interface mode.
8.3.5.1 PWM Interface
When the DRV2605L device is in PWM interface mode, it accepts PWM data at the IN/TRIG pin. The DRV2605L
device drives the actuator continuously in this mode until the user sets the device to standby mode or to enter
another interface mode. In this mode, the strength of vibration is determined by the duty cycle.
For the LRA, the DRV2605L device automatically tracks the resonance frequency unless the LRA_OPEN_LOOP
bit in register 0x1D is set. If the LRA_OPEN_LOOP bit is set, the LRA is driven according to the frequency of the
PWM input signal. Specifically, the driving frequency is the PWM frequency divided by 128.
8.3.5.2 Internal Memory Interface
The DRV2605L device has seven internal-ROM libraries designed by Immersion called TS2200. The first five
librariesand the last library are specifically tuned for six categories of ERMs operated in open-loop mode (see
Table 1). Library 6 is a closed-loop library tuned for LRAs. The library selection occurs through register 0x03 (see
the Library Selection (Address: 0x03) section).
ERM Library A
LIBRARY_SEL[2:0] = 1
ERM Library E
LIBRARY_SEL[2:0] = 5
LRA Library
LIBRARY_SEL[2:0] = 6
ERM Library F
LIBRARY_SEL[2:0] = 7
Figure 13. Library Selection
LIBRARY
A
B
C
D
Table 1. ERM Library Table
RATED VOLTAGE
1.3 V
3V
3V
3V
OVERDRIVE VOLTAGE
3V
3V
3V
3V
RISE TIME
40 ms to 60 ms
40 ms to 60 ms
60 ms to 80 ms
100 ms to 140 ms
BRAKE TIME
20 ms to 40 ms
5 ms to 15 ms
10 ms to 20 ms
15 ms to 25 ms
14
Submit Documentation Feedback
Product Folder Links: DRV2605L
Copyright © 2014, Texas Instruments Incorporated