DRV2603ERM Datasheet, PDF (12/28 Pages) Texas Instruments – DRV2603 ERM/LRA Haptic Driver Evaluation Kit

Measurement and Analysis
Actuator Selection Resistor Configurations
Actuator Type
ERM
LRA
External ERM
External LRA
(1) _{Does not matter}
R1
Open
Open
Open
Open
R2
Open
0Ω
Open
0Ω
R3
0Ω
Open
0Ω
Open
R34
Open
Open
X ⁽¹⁾
X ⁽¹⁾
www.ti.com
R35
Open
0Ω
X ⁽¹⁾
X ⁽¹⁾
4 Measurement and Analysis
4.1 Output Measurements
The DRV2603 uses PWM modulation to create the output signal for both ERM and LRA actuators. To
measure and observe the DRV2603 output waveform, connect an oscilloscope or other measurement
equipment to the filtered output test points, “OUT+” and “OUT-“.
OUT-
OUT
OUT+
470 pF
100 k
100k
470 pF
From DRV2603
Figure 12. Terminal Block and Test Points
The DRV2603 drives LRA and ERM actuators using a 20kHz PWM modulated waveform, but only the
frequencies around the LRA resonant frequency or the ERM DC drive voltage are relevant to the haptic
actuator vibration. The higher frequency switching content does not contribute to the vibration strength of
the actuator and can make it difficult to interpret the modulated output waveform on an oscilloscope. The
oscilloscope image on the left shows the DRV2603 unfiltered waveform and the image on the right shows
a filtered version used for observation and measurement.
Figure 13. DRV2603 Unfiltered Waveform
Figure 14. DRV2603 Filtered Waveform
To observe the modulated output waveform and ensure that the 20kHz switching waveform and
associated harmonics are not captured, use either a digital or analog, low pass filter when viewing the
output waveform. TI recommends using a 1st-order, low-pass filter with a cutoff between 1kHz and
3.5kHz.
Below are recommended output filters for use while measuring and characterizing the DRV2603. Certain
oscilloscopes have a built-in digital, low-pass filter, so no external components are required.
12
DRV2603 ERM/LRA Haptic Driver Evaluation Kit
SLOU340A – May 2012 – Revised May 2012
Copyright © 2012, Texas Instruments Incorporated
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