DA7280-Automotive

Wideband LRA/ERM Haptic Driver for Automotive

Applications

Datasheet

Revision 1.4

01-Mar-2022

CFR0011-120-00

41 of 79

© 2022 Renesas Electronics

● When setting the impedance in V2I_FACTOR_H and V2I_FACTOR_L via the formula in Section

5.6.2, use Zformula = 2*Zreal.

● When reading back from IMPEDANCE_H and IMPEDANCE_L, use an LSB of 0.03125 Ω.

5.7.13

Supply Monitoring, Reporting, and Automatic Output Limiting

DA7280-A monitors the level of the supply during playback and reports it via ADC_VDD_H and

ADC_VDD_L. The two should be concatenated and read using the following formula:

������������������ ������������������������������������ ������������������������������������������ = (������������������_������������������_������ × 128 + ������������������_������������������_������) × 0.1831 ������������

(13)

DA7280-A uses this information to prevent the device from clipping to supply by limiting the drive to a

value determined by the VDD_MARGIN register in 187.5 mV steps where 0x0 corresponds to no

margin, see Figure 22.

Output drive clipping to

VDD – VDD_MARGIN, not ABSMAX

Time [s]

VDD

ABSMAX

VDD - VDD_MARGIN

VDD_MARGIN

Figure 22: Automatic Output Limiting

The functionality is needed as DA7280-A regulates current and if supply clipping occurs, the

regulation stops and the BEMF information is lost. Furthermore, the VDD_MARGIN register allows

limiting of the power across the actuator for low supply values to prevent the battery from discharging

too fast.

5.7.14

BEMF Fault Limit

To detect malfunctioning actuators that have stopped moving due to a mechanical fault, DA7280-A

can be configured to trigger an actuator fault if the BEMF voltage level falls below a threshold for long

drive durations. The threshold for detection is set in BEMF_FAULT_LIM; a zero value of the register

disables the fault checking.

5.7.15

Increasing Impedance Detection Accuracy

To increase the accuracy of the impedance reading in IMPEDANCE_H and IMPEDANCE_L, the

register V2I_FACTOR_OFFSET_EN could be set to 0. This removes an algorithmic offset utilized by

the acceleration algorithm. Should V2I_FACTOR_OFFSET_EN be equal to 0, ACCELERATION_EN

is recommended to be set to 0.

5.7.16

Frequency Pause during Rapid Stop

To address low mechanical time constant LRAs (start/stop times less than 20 ms) and improve the

braking behavior, DA7280 has the option to pause frequency tracking during the execution of the

Rapid Stop algorithm by setting FRQ_PAUSE_ON_POLARITY_CHANGE to 1.