SA58670 NXP Semiconductors, SA58670 Datasheet - Page 16

• Manufacturer Part Number: SA58670
• Manufacturer: NXP Semiconductors

NXP Semiconductors
11. Application information
SA58670_3
Product data sheet
11.1 Power supply decoupling considerations
11.2 Input capacitor selection
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 F 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 F 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.
The SA58670 does not require input coupling capacitors when used with a differential
audio source that is biased from 0.5 V to V
be biased within the common-mode input voltage (V
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
f
Fig 16. SA58670 application schematic
–
3dB
Table
=
V
----------------------------- -
2
DD
6) is calculated by
R
1
10 F
i
C
V
1 nF
1 nF
DD
i
FB
FB
1 F
Rev. 03 — 11 June 2009
1 F
G1
OUTLP
OUTLN
PVDD
PGND
differential inputs
INLP
left channel
Equation
INLN
SDL
1 F
SA58670
1:
AGND
2.1 W/channel stereo class-D audio amplifier
DD
SDR
1 F
differential inputs
0.8 V. In other words, the input signal must
right channel
INRN
AVDD
i(cm)
1 F
INRP
OUTRP
OUTRN
PGND
PVDD
) range. If high-pass filtering is
1 F
G0
10 F
FB
FB
V
DD
1 F
V
1 nF
1 nF
DD
SA58670
© NXP B.V. 2009. All rights reserved.
10 F
001aah515
V
DD
16 of 25
(1)