SLOS700C January   2011  – April 2016 TPA6139A2

UNLESS OTHERWISE NOTED, this document contains PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Programmable Gain Settings
    7. 7.7 Typical Characteristics, Line Driver
  8. 8 Parameter Measurement Information
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 DirectPath Headphone Driver
    4. 9.4 Device Functional Modes
      1. 9.4.1 Internal Undervoltage Detection
      2. 9.4.2 Pop-Free Power Up
  10. 10Application and Implementation
    1. 10.1 Application Information
      1. 10.1.1 Capacitive Load
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. 10.2.2.1 Component Selection
          1. 10.2.2.1.1 Charge Pump
          2. 10.2.2.1.2 Decoupling Capacitors
          3. 10.2.2.1.3 Gain Setting
          4. 10.2.2.1.4 Input-Blocking Capacitors
      3. 10.2.3 Application Curves
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Device Support
    2. 13.2 Documentation Support
    3. 13.3 Community Resources
    4. 13.4 Trademarks
    5. 13.5 Electrostatic Discharge Caution
    6. 13.6 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

10 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.

10.1 Application Information

The TPA6139A2 device starts its operation by asserting the MUTE pin to logic 1. The device enters in mute mode when pulling the MUTE pin low. The charge pump generates a negative supply voltage. The charge pump flying capacitor connected between CP and CN transfers charge to generate the negative supply voltage. The output voltages are capable of positive and negative voltage swings and are centered close to 0 V, eliminating the need for output capacitors. Input coupling capacitors block any DC bias from the audio source and ensure maximum dynamic range.

This typical connection diagram highlights the required external components and system level connections for proper operation of the device in popular use case. Any design variation can be supported by TI through schematic and layout reviews. Visit https://e2e.ti.com for design assistance and join the audio amplifier discussion forum for additional information.

10.1.1 Capacitive Load

The TPA6139A2 has the ability to drive a high capacitive load up to 220 pF directly. Higher capacitive loads can be accepted by adding a series resistor of 47 Ω or larger for the line driver output.

10.2 Typical Application

TPA6139A2 app_cir_los700.gif Figure 11. Single-Ended Input and Output, Gain Set to –1.5x

10.2.1 Design Requirements

Table 1 lists the design parameters of this example.

Table 1. Design Parameters

DESIGN PARAMETER EXAMPLE VALUE
Input voltage supply range 3 V to 3.6 V
Current 130 mA
Load impedance 32 Ω

10.2.2 Detailed Design Procedure

10.2.2.1 Component Selection

10.2.2.1.1 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 1 μF is typical. Capacitor values that are smaller than 1 μF cannot be recommended as it limits the negative voltage swing in low impedance loads.

10.2.2.1.2 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 1 μF, 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.

10.2.2.1.3 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 2 lists the gain settings. The default gain with the gain-set pin left open is –2x.

Table 2. Gain Settings

Gain_set RESISTOR GAIN GAIN (dB) INPUT RESISTANCE
No connect –2x 6 37k
82k0 –1x 0 55k
49k2 –1.5x 3.5 44k
35k1 –2.3x 7.2 33k
27k3 –2.5x 8 31k
20k5 –3x 9.5 28k
15k4 –3.5x 10.9 24k
11k5 –4x 12 22k
9k09 –5x 14 18k
7k50 –5.6x 15 17k
6k19 –6.4x 16.1 15k
5k11 –8.3x 18.4 12k
3k90 –10x 20 10k

10.2.2.1.4 Input-Blocking Capacitors

DC input-blocking capacitors are required to be added in series with the audio signal into the input pins of the TPA6139A2. These capacitors block the DC portion of the audio source and allow the TPA6139A2 inputs to be properly biased to provide maximum performance. The input blocking capacitors also limit the DC gain to 1, limiting the DC-offset voltage at the output.

These capacitors form a high-pass filter with the input resistor, RIN. The cutoff frequency is calculated using Equation 1. For this calculation, the capacitance used is the input-blocking capacitor and the resistance is the input resistor chosen from Table 2. Then the frequency or capacitance can be determined when one of the two values is given, as shown in Equation 1.

Equation 1. TPA6139A2 eq-1_SLOS700.gif

For a fixed cutoff frequency of 2 Hz, the size of the input capacitance is shown Table 3 with the capacitors rounded up to the nearest E6 values. For 20-Hz cutoff, simply divide the capacitor values with 10; for example, for 1x gain, 150 nF is needed.

Table 3. Input Capacitor for Different Gain and Cutoff

Gain_set
RESISTOR		 GAIN Gain
(dB)		 INPUT
RESISTANCE		 2-Hz
CUTOFF
249k –2x 6 37k 2.2 µF
82k0 –1x 0 55k 1.5 µF
49k2 –1.5x 3.5 44k 2.2 µF
35k1 –2.3x 7.2 33k 3.3 µF
27k3 –2.5x 8 31k 3.3 µF
20k5 –3x 9.5 28k 3.3 µF
15k4 –3.5x 10.9 24k 3.3 µF
11k5 –4x 12 22k 4.7 µF
9k09 –5x 14 18k 4.7 µF
7k50 –5.6x 15 17k 4.7 µF
6k19 –6.4x 16.1 15k 6.8 µF
5k11 –8.3x 18.4 12k 6.8 µF
3k90 –10x 20 10k 10 µF

10.2.3 Application Curves

The characteristics of this design are shown in Typical Characteristics, Line Driver.

Table 4. Table of Graphs

FIGURE
THD+N vs Output Voltage Figure 2
Total Harmonic Distortion vs Frequency Figure 6
Mute to Un-Mute Figure 7
Un-Mute to mute Figure 8