Datasheet

R13
4.99 kW
R18
7.5 kW
C13
0.1 Fm
C4
0.1 Fm
PWM-
IN-
R14
4.99 kW
R17
7.5 kW
C14
0.1 Fm
C5
0.1 Fm
PWM+
IN+
www.ti.com General Operation
3.5.1.1 Filter Selection Criteria
Apply these criteria to select an input filter.
1. First-order RC filters, both single-ended and differential, are recommended for 20 kHz and higher data
sample rates. The first-order filters have adequate settling time and the fewest components.
2. Second-order filters are recommended for noiseless operation when using a lower data sample rate
where a sharper cutoff is necessary.
3. The attenuation at the PWM carrier frequency should be at least –40 dB for haptic applications.
3.5.1.2 First-Order Filter
For sample rates 20 kHz and greater, a first-order filter is recommended. The first-order filter is used in
both single-ended or differential configurations. Figure 8 shows a differential, first-order filter. The PWM
input filter is optimized for a 3.3-V differential PWM input signal (–11-dB attenuation); remove R17 and
R18 when applying a 1.8-V input signal.
Figure 8. First-Order Input Filter
The first-order filter in Figure 8 contains one pole with a slope of –20 dB. Figure 9 shows the frequency
response of the first-order filter.
Figure 9. First-Order Frequency Response
11
SLOU319A–August 2011–Revised December 2012 DRV8662 Piezo Haptics Driver Evaluation Module
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