Datasheet

R13

3.3 kW

R18

2.7 kW

C13

0.047 Fm

0.1 Fm

R14

3.3 kW

R17

2.7 kW

C14

0.047 Fm

0.1 Fm

PWM-

IN-

PWM+

IN+

General Operation

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3.5.1.3 Second-Order Filter, Differential

For data sample rates less than 20 kHz, a second-order filter is recommended. A differential input signal is

recommended for use with a second-order filter because of the longer settling time; however, if a single-

ended signal is used, see the Second-Order Filter, Single-Ended section. Figure 10 shows the differential,

second-order filter that is the default filter configuration for the EVM. The PWM input filter is optimized for

a 3.3-V differential PWM input signal (–1- dB attenuation); remove R17 and R18 when applying a 1.8-V

input signal.

Figure 10. Second-Order Input Filter

The second-order filter in Figure 10 contains two poles resulting in a slope of –40 dB. Figure 11 shows the

frequency response of the second-order filter.

Figure 11. Second-Order Filter Frequency Response

DRV8662 Piezo Haptics Driver Evaluation Module SLOU319A–August 2011–Revised December 2012

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