TS4890 datasheet(35/46 Pages) STMICROELECTRONICS

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TS4890

Application information

The maximum theoretical value is reached when Vpeak = Vcc, so

5.5

Decoupling of the circuit

Two capacitors are needed to bypass properly the TS4890. A power supply bypass

capacitor Cs and a bias voltage bypass capacitor Cb.

Cs has especially an influence on the THD+N in high frequency (above 7kHz) and indirectly

on the power supply disturbances.

With 100 µF, you can expect similar THD+N performance like shown in the datasheet.

If Cs is lower than 100 µF, in high frequency THD+N increases and disturbances on the

power supply rail are less filtered.

To the contrary, if Cs is higher than 100ìF, those disturbances on the power supply rail are

more filtered.

Cb has an influence on THD+N in lower frequency, but its function is critical on the final

result of PSRR with input grounded in lower frequency.

If Cb is lower than 1 µF, THD+N increases in lower frequency (see THD+N vs frequency

curves) and the PSRR worsens up.

If Cb is higher than 1 µF, the benefit on THD+N in lower frequency is small but the benefit on

PSRR is substantial (see PSRR vs. Cb curves).

Note that Cin has a non-negligible effect on PSRR in lower frequency. Lower is its value,

higher is the PSRR.

5.6

Pop and click performance

In order to have the best performances with the pop and click circuitry, the formula below

must be followed:

with

OUT

Psupply

-----------------------

πV

PEAK

4Vcc

---------------------

---

78.5percentage

≤

feed

() C

()

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