SA58670_1

© NXP B.V. 2008. All rights reserved.

Product data sheet

Rev. 01 — 4 January 2008

16 of 25

NXP Semiconductors

SA58670

2.1 W/channel stereo class-D audio amplifier

11. Application information

11.1 Power supply decoupling considerations

The SA58670 is a stereo class-D audio amplifier that requires proper supply voltage

decoupling to ensure the rated performance for THD+N and power efficiency. To decouple

high frequency transients, supply voltage spikes and digital noise on the supply voltage

bus line, a low Equivalent Series Resistance (ESR) capacitor of typically 1

µF is placed as

close as possible to the PVDD pins of the SA58670. It is important to place the decoupling

capacitor at the supply voltage pins of the SA58670 because any resistance or inductance

in the PCB trace between the SA58670 and the capacitor can cause a loss in efficiency.

Additional decoupling using a larger capacitor, 4.7

µF or greater, may be done on the

supply voltage connection on the PCB to filter low frequency signals. Usually this is not

required due to high PSRR of the SA58670.

11.2 Input capacitor selection

The SA58670 does not require input coupling capacitors when used with a differential

required or if it is driven using a single-ended source, input coupling capacitors are

required.

The 3 dB cut-off frequency created by the input coupling capacitor and the input resistors

(see Table 6) is calculated by Equation 1:

(1)

Fig 16. SA58670 application schematic

001aah515

SA58670

OUTRP

OUTRN

10

µF

1 nF

1 nF

FB

FB

1 nF

1 nF

OUTLP

OUTLN

G1

PVDD

PGND

1

µF

10

µF

1

µF

SDL

SDR

AVDD

10

µF

1

µF

PGND

PVDD

G0

INLP

1

µF

INLN

1

µF

differential inputs

left channel

INRN

1

µF

INRP

1

µF

differential inputs

right channel

AGND

FB

FB

f

3dB

–

1

2

π R

i

×

C

i

×

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=