MAX13330_09 Datasheet, PDF(12/15 Page) Maxim Integrated Products – Automotive DirectDrive Headphone Amplifiers with Output Protection and Diagnostics

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MAX13330_09 Datasheet, PDF (12/15 Pages) Maxim Integrated Products – Automotive DirectDrive Headphone Amplifiers with Output Protection and Diagnostics

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Automotive DirectDrive Headphone Amplifiers

with Output Protection and Diagnostics

Flying Capacitor (C1)

The value of the flying capacitor (C1) affects the charge

pumpâs load regulation and output resistance. A C1

value that is too small degrades the deviceâs ability to

provide sufficient current drive, which leads to a loss of

output voltage. Increasing the value of C1 improves

load regulation and reduces the charge-pump output

resistance to an extent. See the Output Power vs.

Load Resistance graph in the Typical Operating

Characteristics. Above 1ÂµF, the on-resistance of the

switches and the ESR of C1 and C2 dominate.

Holding Capacitor (C2)

The hold capacitor value and ESR directly affect the

ripple at CPVSS. Increasing the value of C2 reduces

output ripple. Likewise, decreasing the ESR of C2

reduces both ripple and output resistance. Lower

capacitance values can be used in systems with low

maximum output power levels. See the Output Power

vs. Load Resistance graph in the Typical Operating

Characteristics.

Power-Supply Bypass Capacitor (C3)

The power-supply bypass capacitor (C3) lowers the

output impedance of the power supply and reduces the

impact of the MAX13330/MAX13331 charge-pump

switching transients. Bypass CPVDD with C3, the same

value as C1, and place it physically close to the CPVDD

and PGND pins.

Layout and Grounding

Proper layout and grounding are essential for optimum

performance. Connect CPVDD and VDD together at the

device. Connect CPVSS and VSS together at the

device. Bypassing of both supplies is accomplished by

charge-pump capacitors C2 and C3 (see the Typical

Application Circuits). Place capacitors C2 and C3 as

close to the device as possible and bypass them to the

PGND plane. Keep PGND and all traces that carry

switching transients as short as possible to minimize

EMI. Route them away from SGND, the audio signal

path, and the external feedback components

(MAX13331). Connect the PGND plane and the SGND

plane together at a single point on the PCB. Refer to

the MAX13330/MAX13331 Evaluation Kit for layout

guidelines.

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