Datasheet

R13

3.3 kW

0 W

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

IN-

PWM+

IN+

R21

6.5 kW

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General Operation

3.5.1.4 Second-Order Filter, Single-Ended

Second-order filters take longer to settle than first-order filters. With differential inputs, the inverting and

noninverting inputs settle at the same time. With a single-ended input, they do not. This characteristic is

seen in the waveforms (refer to Figure 12 and Figure 13).

Figure 12. Second-Order, Single-Ended Filter Figure 13. Second-Order, Differential Filter

To avoid this issue, a dummy filter may be connected to the unused input; the filter input should then be

tied to the DRV8662 enable (EN) signal through a resistor divider, as seen in Figure 14. When the

DRV8662 is enabled, the enable (EN) signal charges this dummy filter.

Figure 14. Single-Ended Input with Dummy Filter

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

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