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DA7280

LRA/ERM Haptic Driver with Multiple Input Triggers,

Integrated Waveform Memory and Wideband Support

Datasheet

Revision 3.0

30-Jul-2019

CFR0011-120-00

14 of 76

Functional Description

DA7280 is a haptic driver capable of driving both LRA and ERM actuators. The power-optimized

architecture and advanced closed-loop digital algorithms achieve a very high-fidelity haptic drive. It

features frequency control within an onboard Waveform Memory and three distinct GPI inputs, for

triggering up to six distinct sequences. This helps with emulating button pressing in many

applications including gaming, mobile, and wearable devices.

The device controls the level of drive across the load and senses the movement of the actuator. The

driven waveform is generated by a current regulated loop using a high-frequency PWM modulation.

The differential output drive features a switching regulator architecture with H-bridge differential drive

across the load at a frequency of 187.5 kHz. The drive level is based on the sequence from the data

source selected by I2C interface, input PWM signal, or Waveform Memory.

DA7280 is capable of closed-loop actuator monitoring while driving to enable calibration-free

playback, frequency tracking (LRA only), Active Acceleration, Rapid Stop, and actuator diagnostics.

Continuous resonant frequency tracking can be enabled while driving an LRA to track the mechanical

resonance of the actuator through closed-loop control. This maximizes electrical to mechanical

energy conversion efficiency for narrowband actuators and is especially useful in applications such

as operating system notifications and alarms.

Resonant frequency tracking can be disabled to operate DA7280 in open-loop wideband frequency

operation while driving LRAs with a wider bandwidth frequency response.

Active Acceleration and Rapid Stop features enable automated driving of both ERM and LRA loads

(when frequency tracking is enabled). This reduces the time to reach the target acceleration level

and the time for the actuator to come to a complete stop.

5.1

Features Description

Driving LRA and ERM Actuators

DA7280 can drive both ERMs and LRAs depending on the register configuration, see Section 5.6.2.

Automatic LRA Resonant Frequency Tracking

LRA resonant frequency shifts over time due to changing operating conditions, such as temperature

or position, and manufacturing spread. LRAs are high-Q systems; if driven at a fixed frequency, the

consequences are loss of electrical to mechanical energy conversion efficiency, weaker than nominal

actuator acceleration output, and significant part-to-part variation in the end-product haptic feel.

Figure 5 illustrates that if the drive frequency is fixed, for example at 200 Hz, frequency variation in

the resonant peak of only 10 Hz can result in a loss of 50 % of the output acceleration.

Frequency [Hz]

0.5

200

210

190

Typical Resonant Peak Variation

(part-to-part, across temperature, drive signal level, and manufacturing lots)

Resonant Peak

with Max Accel.

250

150

Figure 5: LRA Output Acceleration Swept in Frequency with Constant Power Input Signal

DA7280 Datasheet(PDF) 14 Page - Dialog Semiconductor

DA7280 Datasheet(HTML) 14 Page - Dialog Semiconductor

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