DRV2605L Datasheet, PDF (21/69 Pages) Texas Instruments – DRV2605L 2 to 5.2 V Haptic Driver for LRA and ERM With Effect Library and Smart-Loop Architecture

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DRV2605L
SLOS854C – MAY 2014 – REVISED SEPTEMBER 2014
8.4.3 Operation of the GO Bit
The GO bit is the primary way to assert the GO signal, which fires processes in the DRV2605L device. The
primary purpose of the GO bit is to fire the playback of the waveform identifiers in the waveform sequencer
(registers 0x04 to 0x0B). However, The GO bit can also fire the calibration or diagnostics processes.
When using the GO bit to play waveforms in internal trigger mode, the GO bit is asserted by writing 0x01 to
register 0x0C. In this case, the GO bit can be thought of as a software trigger for haptic waveforms. The GO bit
remains high until the playback of the haptic waveform sequence is complete. Clearing the GO bit during
waveform playback cancels the waveform sequence. The GO bit can also be asserted by the external trigger
when in external trigger mode. The GO bit in register 0x0C mirrors the state of the external trigger.
Setting RTP mode , PWM mode, or audio-to-vibe mode also sets the GO bit. However, setting the GO bit in this
way has no impact on the GO bit located in register 0x0C.
MODE[2:0] = 1 (External trigger ² edge)
Also accessible
2
(R/W) through I C
MODE[2:0] = 2 (External trigger ² level)
GO Bit
IN/TRIG (Trigger)
GO Bit
MODE[2:0] = 3 (PWM and analog input)
MODE[2:0] = 4 (Audio-to-haptics)
GO Signal
MODE[2:0] = 5 (RTP mode)
Figure 19. GO-Signal Logic
8.4.4 Operation During Exceptional Conditions
This section lists different exceptional conditions and the ways that the DRV2605L device operates during these
conditions. This section also describes how the device goes into and out of these states.
8.4.4.1 Operation With No Actuator Attached
In LRA closed-loop mode, if a waveform is played without an actuator connected to the OUT+ and OUT– pins,
the output pins toggle. However, the toggling frequency is not predictable. In LRA open-loop mode, the output
pins toggle at the specified open-loop frequency.
8.4.4.2 Operation With a Non-Moving Actuator Attached
The model of a non-moving actuator can be simplified as a resistor. If a resistor (with similar loading as an LRA,
such as 25 Ω) is connected across the OUT+ and OUT– pins, and the DRV2605L device is in LRA closed-loop
mode, the output pins toggle at a default frequency calculated with Equation 1. In LRA open-loop mode the
output pins toggle at the specified open-loop frequency.
8.4.4.3 Operation With a Short at REG Pin
If the REG pin is shorted to GND, the device automatically shuts down and an overcurrent-protection circuit is
enabled and clamps the maximum current supplied by the regulator. When the short is removed, the device
starts in the default condition.
8.4.4.4 Operation With a Short at OUT+, OUT–, or Both
If any of the output pins (OUT+ or OUT–) is shorted to V_DD, GND, or to each other while the device is playing a
waveform, the OC_DETECT bit is asserted and remains asserted until the short is removed. A current-protection
circuit automatically enables to shutdown the current through the short.
If the driver is playing a waveform the DRV2605L device checks for shorts in the output through either a haptic-
playback, auto-calibration, or diagnostics process. If the short occurs when the device is idle, the short is not
detected until the device attempts to run a waveform.
Copyright © 2014, Texas Instruments Incorporated
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