TPA6139A2 Datasheet, PDF (10/22 Pages) Texas Instruments – DirectPath™ 25-mW Headphone Amplifier With Programmable-Fixed Gain

TPA6139A2
SLOS700B – JANUARY 2011 – REVISED JUNE 2012
COMPONENT SELECTION
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Charge Pump
The charge pump flying capacitor serves to transfer charge during the generation of the negative supply voltage.
The VSS capacitor must be at least equal to the charge pump capacitor in order to allow maximum charge
transfer. Low ESR capacitors are an ideal selection, and a value of 1μF is typical. Capacitor values that are
smaller than 1μF cannot be recommended as it limits the negative voltage swing in low impedance loads.
Decoupling Capacitors
The TPA6139A2 is a DirectPath™ amplifier that requires adequate power supply decoupling to ensure that the
noise and total harmonic distortion (THD) are low. A good low equivalent-series-resistance (ESR) ceramic
capacitor, typically 1μF, placed as close as possible to the device VDD leads works best. Placing this decoupling
capacitor close to the TPA6139A2 is important for the performance of the amplifier. For filtering lower frequency
noise signals, a 10-μF or greater capacitor placed near the audio power amplifier also helps, but it is not required
in most applications because of the high PSRR of this device.
Gain-Setting
The gain setting is programmed with the GAIN pin individually for line driver and headphone section. Gain setting
is latched when the MUTE pin is set high. Table 1 lists the gain settings. The default gain with the gain-set pin
left open is –2x.
Gain_set RESISTOR
No connect
82k0
49k2
35k1
27k3
20k5
15k4
11k5
9k09
7k50
6k19
5k11
3k90
Table 1. Gain Settings
GAIN
–2.0x
–1.0x
–1.5x
–2.3x
–2.5x
–3.0x
–3.5x
–4.0x
–5.0x
–5.6x
–6.4x
–8.3x
–10x
GAIN (dB)
6.0
0.0
3.5
7.2
8.0
9.5
10.9
12.0
14.0
15.0
16.1
18.4
20.0
INPUT RESISTANCE
37k
55k
44k
33k
31k
28k
24k
22k
18k
17k
15k
12k
10k
Internal Under Voltage Detection
The TPA6139A2 contains an internal precision band gap reference voltage and a comparator used to monitor the
supply voltage, VDD. The internal VDD monitor is set at 2.8V with 200mV hysteresis.
1.25 V
Bandgap
VDD 10
AMP Enable
Comparator
Internal VDD
10
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