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C(DCINPUT-BLOCKING)
1
2
CIN =
(3)
fc
IN +
1
2p R
IN CIN
C
IN +
1
2p fc
IN RIN
or
(4)
Charge Pump Flying Capacitor and CPVSS Capacitor
Decoupling Capacitors
Layout Recommendations
Exposed Pad On TPA6130A2RTJ Package Option
GND Connections
I
2C CONTROL INTERFACE DETAILS
Addressing the TPA6130A2
SLOS488B – NOVEMBER 2006 – REVISED FEBRUARY 2008
CIN is a theoretical capacitor used for mathematical calculations only. Its value is the series combination of the dc
input-blocking capacitors, C(DCINPUT-BLOCKING). Use Equation 3 to determine the value of C(DCINPUT-BLOCKING). For example, if CIN is equal to 0.22 F, then C(DCINPUT-BLOCKING) is equal to about 0.47 F.
The two C(DCINPUT-BLOCKING) capacitors form a high-pass filter with the input impedance of the TPA6130A2. Use
Equation 3 to calculate CIN, then calculate the cutoff frequency using CIN and the differential input impedance of the TPA6130A2, RIN, using Equation 4. Note that the differential input impedance changes with gain. See Figure 33 for input impedance values. The frequency and/or capacitance can be determined when one of the two
values are given.
If a high pass filter with a -3 dB point of no more than 20 Hz is desired over all gain settings, the minimum
impedance would be used in the above equation.
Figure 33 shows this to be 37 k
. The capacitor value by the
above equation would be 0.215
F. However, this is C
IN, and the desired value is for C(DCINPUT-BLOCKING).
Multiplying CIN by 2 yields 0.43 F, which is close to the standard capacitor value of 0.47 F. Place 0.47 F
capacitors at each input terminal of the TPA6130A2 to complete the filter.
The charge pump flying capacitor serves to transfer charge during the generation of the negative supply voltage.
The CPVSS capacitor must be at least equal to the flying capacitor in order to allow maximum charge transfer.
Low ESR capacitors are an ideal selection, and a value of 1 F is typical.
The TPA6130A2 is a DirectPath headphone amplifier that requires adequate power supply decoupling to
ensure that the noise and total harmonic distortion (THD) are low. Use good low equivalent-series-resistance
(ESR) ceramic capacitors, typically 1.0 F. Find the smallest package possible, and place as close as possible to
the device VDD lead. Placing the decoupling capacitors close to the TPA6130A2 is important for the performance
of the amplifier. Use a 10
F or greater capacitor near the TPA6130A2 to filter lower frequency noise signals.
The high PSRR of the TPA6130A2 will make the 10
F capacitor unnecessary in most applications.
Solder the exposed metal pad on the TPA6130A2RTJ QFN package to the a pad on the PCB. The pad on the
PCB may be grounded or may be allowed to float (not be connected to ground or power). If the pad is grounded,
it must be connected to the same ground as the GND pins (3, 9, 10, 13, and 19). See the layout and mechanical
drawings at the end of the datasheet for proper sizing. Soldering the thermal pad improves mechanical reliability,
improves grounding of the device, and enhances thermal conductivity of the package.
The GND pin for charge pump should be decoupled to the charge pump VDD pin, and the GND pin adjacent to
the Analog VDD pin should be separately decoupled to each other.
The device operates only as a slave device whose address is 1100000 binary.
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