SA58672 Datasheet, PDF (14/27 Pages) NXP Semiconductors – 3.0 W mono class-D audio amplifier

NXP Semiconductors
SA58672
3.0 W mono class-D audio amplifier
For a required 3 dB cut-off frequency, Equation 3 is used to determine C_i:
C_i = -₂---_π-----_×-----_R---_i-¹--_×------_f---_–--₃---_d--_B-
(3)
The input signal may be DC-coupled, but not using input coupling capacitors may
increase the output offset voltage.
11.4 PCB layout considerations
The component location is very important for performance of the SA58672. Place all
external components very close to the device. Placing decoupling capacitors directly at
the power supply pins increases efficiency because the resistance and inductance in the
trace between the device power supply pins and the decoupling capacitor causes a loss in
power efficiency.
The trace width and routing are also very important for power output and noise
considerations.
For high current terminals (PVDD, PGND and audio output), the trace widths should be
maximized to ensure proper performance and output power. Use at least 500 µm wide
traces.
For the input pins (INP, INM), the traces must be symmetrical and run side-by-side to
maximize common-mode cancellation.
11.5 Evaluation demo board
The SA58672 evaluation demo board schematic is shown in Figure 14. An evaluation
demo board is available and it may be used for either differential or single-ended (SE)
input configuration. A component position on the PCB is provided to AC ground one of the
inputs using a 0 Ω chip resistor. When driving SE, the undriven input must be at the same
DC level as driven input. If the input is driven from an iPOD or MP3 player, the undriven
input is AC grounded; however, if driven from a CODEC, the undriven input is AC
decoupled to the same level as the CODEC output. Usually, a V_ref is provided on the
CODEC.
SA58672_4
Product data sheet
Rev. 04 — 8 June 2009
© NXP B.V. 2009. All rights reserved.
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