SLOS825E December 2012 – April 2018 DRV2605
In closed-loop bidirectional mode, the DRV2605 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 DRV2605 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.
Closed-loop bidirectional mode is compatible with all DRV2605 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.