Datasheet

I
I C
1
C =
(2 R f )p ´ ´
C
I I
1
f =
(2 R C )p ´ ´
TPA2028D1
www.ti.com SLOS660B –JANUARY 2010–REVISED SEPTEMBER 2012
DECOUPLING CAPACITOR C
S
)
The TPA2028D1 is a high-performance Class-D audio amplifier that requires adequate power supply decoupling
to ensure the efficiency is high and total harmonic distortion (THD) is low. For higher frequency transients,
spikes, or digital hash on the line, a good low equivalent-series-resistance (ESR) 1-μF ceramic capacitor
(typically) placed as close as possible to the device PVDD lead works best. Placing this decoupling capacitor
close to the TPA2028D1 is important for the efficiency of the Class-D amplifier, because any resistance or
inductance in the trace between the device and the capacitor can cause a loss in efficiency. For filtering lower-
frequency noise signals, a 4.7 μF or greater capacitor placed near the audio power amplifier would also help, but
it is not required in most applications because of the high PSRR of this device.
INPUT CAPACITORS C
I
)
TPA2028D1 requires input capacitors to ensure low output offset and low pop.
The input capacitors and input resistors form a high-pass filter with the corner frequency, f
C
, determined in
Equation 5.
(5)
The value of the input capacitor is important to consider as it directly affects the bass (low frequency)
performance of the circuit. Speakers in wireless phones cannot usually respond well to low frequencies, so the
corner frequency can be set to block low frequencies in this application. Not using input capacitors can increase
output offset. Equation 6 is used to solve for the input coupling capacitance. If the corner frequency is within the
audio band, the capacitors should have a tolerance of ±10% or better, because any mismatch in capacitance
causes an impedance mismatch at the corner frequency and below.
(6)
PACKAGE INFORMATION
Package Dimensions
The package dimensions for this YZF package are shown in the table below. See the package drawing at the
end of this data sheet for more details.
Table 5. YZF Package Dimensions
PACKAGED DEVICES D E
Min = 1594μm Min = 1594μm
TPA2028D1YZF
Max = 1654μm Max = 1654μm
BOARD LAYOUT
In making the pad size for the WCSP balls, it is recommended that the layout use non solder mask defined
(NSMD) land. With this method, the solder mask opening is made larger than the desired land area, and the
opening size is defined by the copper pad width. Figure 45 and Table 6 shows the appropriate diameters for a
WCSP layout. The TPA2028D1 evaluation module (EVM) layout is shown in the next section as a layout
example.
Copyright © 2010–2012, Texas Instruments Incorporated 29
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