SLOS490C July   2006  – November 2015

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 Operating Characteristics
    7. 7.7 Dissipation Ratings
    8. 7.8 Typical Characteristics
  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 Fully Differential Amplifiers
        1. 9.3.1.1 Advantages of Fully Differential Amplifiers
      2. 9.3.2 Fully Differential Amplifier Efficiency and Thermal Information
      3. 9.3.3 Differential Output Versus Single-Ended Output
    4. 9.4 Device Functional Modes
      1. 9.4.1 Summing Input Signals With The TPA6205A1
        1. 9.4.1.1 Summing Two Differential Input Signals
        2. 9.4.1.2 Summing a Differential Input Signal and a Single-Ended Input Signal
        3. 9.4.1.3 Summing Two Single-Ended Input Signals
      2. 9.4.2 Shutdown Mode
  10. 10Application and Implementation
    1. 10.1 Application Information
    2. 10.2 Typical Applications
      1. 10.2.1 TPA6205A1 With Differential Input
        1. 10.2.1.1 Design Requirements
        2. 10.2.1.2 Detailed Design Procedure
          1. 10.2.1.2.1 Selecting Components
            1. 10.2.1.2.1.1 Resistors (RF and RI)
            2. 10.2.1.2.1.2 Bypass Capacitor (CBYPASS) and Start-Up Time
            3. 10.2.1.2.1.3 Input Capacitor (CI)
            4. 10.2.1.2.1.4 Decoupling Capacitor (CS)
          2. 10.2.1.2.2 Using Low-ESR Capacitors
        3. 10.2.1.3 Application Curves
      2. 10.2.2 TPA6205A1 With Differential Input and Input Capacitors
        1. 10.2.2.1 Design Requirements
        2. 10.2.2.2 Detailed Design Procedure
        3. 10.2.2.3 Application Curves
      3. 10.2.3 TPA6205A1 With Single-Ended Input
        1. 10.2.3.1 Design Requirements
        2. 10.2.3.2 Detailed Design Procedure
        3. 10.2.3.3 Application Curves
  11. 11Power Supply Recommendations
    1. 11.1 Power Supply Decoupling Capacitors
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Community Resources
    2. 13.2 Trademarks
    3. 13.3 Electrostatic Discharge Caution
    4. 13.4 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

These typical connection diagrams highlight the required external components and system level connections for proper operation of the device in several popular cases. Each of these configurations can be realized using the Evaluation Modules (EVMs) for the device. These flexible modules allow full evaluation of the device in the most common modes of operation. Any design variation can be supported by TI through schematic and layout reviews. Visit http://e2e.ti.com for design assistance and join the audio amplifier discussion forum for additional information.

10.2 Typical Applications

Figure 32 through Figure 31 show application schematics for differential and single-ended inputs.

10.2.1 TPA6205A1 With Differential Input

The TPA6205A1 can be used with differential input without input capacitors. This section describes the design considerations for this application.

SLOS490TPA6205A1 app_schem_01_typical_diff_inp_slos490.gif Figure 32. Typical Differential Input Application Schematic

10.2.1.1 Design Requirements

Table 3 lists the design parameters of the device.

Table 3. Design Parameters

PARAMETER EXAMPLE VALUE
Power Supply 5 V
Shutdown Input High > 2 V
Low < 0.8 V
Speaker 8 Ω

10.2.1.2 Detailed Design Procedure

10.2.1.2.1 Selecting Components

Typical values are shown in Table 4.

Table 4. Typical Component Values

COMPONENT VALUE
RI 10 kΩ
RF 10 kΩ
C(BYPASS)(1) 0.22 µF
CS 1 µF
CI 0.22 µF
(1) C(BYPASS) is optional

10.2.1.2.1.1 Resistors (RF and RI)

The input (RI) and feedback resistors (RF) set the gain of the amplifier according to Equation 23.

Equation 23. SLOS490TPA6205A1 eq_01_slos490.gif

RF and RI should range from 1 kΩ to 100 kΩ. Most graphs were taken with RF = RI = 20 kΩ.

Resistor matching is very important in fully differential amplifiers. The balance of the output on the reference voltage depends on matched ratios of the resistors. CMRR, PSRR, and the cancellation of the second harmonic distortion diminishes if resistor mismatch occurs. Therefore, it is recommended to use 1% tolerance resistors or better to keep the performance optimized.

10.2.1.2.1.2 Bypass Capacitor (CBYPASS) and Start-Up Time

The internal voltage divider at the BYPASS pin of this device sets a mid-supply voltage for internal references and sets the output common mode voltage to VDD/2. Adding a capacitor to this pin filters any noise into this pin and increases the kSVR. C(BYPASS)also determines the rise time of VO+ and VO– when the device is taken out of shutdown. The larger the capacitor, the slower the rise time. Although the output rise time depends on the bypass capacitor value, the device passes audio 4 μs after taken out of shutdown and the gain is slowly ramped up based on C(BYPASS).

To minimize pops and clicks, design the circuit so the impedance (resistance and capacitance) detected by both inputs, IN+ and IN–, is equal.

10.2.1.2.1.3 Input Capacitor (CI)

The TPA6205A1 does not require input coupling capacitors if using a differential input source that is biased from 0.5 V to VDD – 0.8 V. Use 1% tolerance or better gain-setting resistors if not using input coupling capacitors.

In the single-ended input application an input capacitor, CI, is required to allow the amplifier to bias the input signal to the proper DC level. In this case, CI and RI form a high-pass filter with the corner frequency determined in Equation 24.

Equation 24. SLOS490TPA6205A1 eq_02_slos490.gif
SLOS490TPA6205A1 sc_01_inp_capacitor_slos490.gif Figure 33. CI and RI High-Pass Filter Cutoff Frequency

The value of CI is important to consider as it directly affects the bass (low frequency) performance of the circuit. Consider the example where RI is 10 kΩ and the specification calls for a flat bass response down to 100 Hz. Equation 24 is reconfigured as Equation 25.

Equation 25. SLOS490TPA6205A1 eq_03_slos490.gif

In this example, CI is 0.16 μF, so one would likely choose a value in the range of 0.22 μF to 0.47 μF. A further consideration for this capacitor is the leakage path from the input source through the input network

(RI , CI) and the feedback resistor (RF ) to the load. This leakage current creates a DC offset voltage at the input to the amplifier that reduces useful headroom, especially in high gain applications. For this reason, a ceramic capacitor is the best choice. When polarized capacitors are used, the positive side of the capacitor should face the amplifier input in most applications, as the dc level there is held at VDD/2, which is likely higher than the source dc level. It is important to confirm the capacitor polarity in the application.

10.2.1.2.1.4 Decoupling Capacitor (CS)

The TPA6205A1 is a high-performance CMOS audio amplifier that requires adequate power supply decoupling to ensure the output total harmonic distortion (THD) is as low as possible. Power supply decoupling also prevents oscillations for long lead lengths between the amplifier and the speaker. For higher frequency transients, spikes, or digital hash on the line, a good low equivalent-series-resistance (ESR) ceramic capacitor, typically 0.1 μF to 1 μF, placed as close as possible to the device VDD lead works best. For filtering lower frequency noise signals, a 10-μF or greater capacitor placed near the audio power amplifier also helps, but is not required in most applications because of the high PSRR of this device.

10.2.1.2.2 Using Low-ESR Capacitors

Low-ESR capacitors are recommended throughout this applications section. A real (as opposed to ideal) capacitor can be modeled simply as a resistor in series with an ideal capacitor. The voltage drop across this resistor minimizes the beneficial effects of the capacitor in the circuit. The lower the equivalent value of this resistance the more the real capacitor behaves like an ideal capacitor.

10.2.1.3 Application Curves

SLOS490TPA6205A1 tc_01_op_vs_sv_slos490.gif
Figure 34. Output Power vs Supply Voltage
SLOS490TPA6205A1 tc_25_sc_vs_sv_slos490.gif
Figure 35. Supply Current vs Supply Voltage

10.2.2 TPA6205A1 With Differential Input and Input Capacitors

The TPA6205A1 supports differential input operation with input capacitors. This section describes the design considerations for this application.

SLOS490TPA6205A1 app_schem_02_diff_inp_opt_w_inp_cpctrs_slos490.gif Figure 36. Differential Input Application Schematic Optimized With Input Capacitors

10.2.2.1 Design Requirements

Refer to the Design Requirements.

10.2.2.2 Detailed Design Procedure

Refer to the Detailed Design Procedure.

10.2.2.3 Application Curves

Refer to the Application Curves.

10.2.3 TPA6205A1 With Single-Ended Input

The TPA6205A1 can be used with single-ended inputs, using Input capacitors. This section describes the design considerations for this application.

SLOS490TPA6205A1 app_schem_03_sngl_end_inp_slos490.gif Figure 37. Single-Ended Input Application Schematic

10.2.3.1 Design Requirements

Refer to the Design Requirements.

10.2.3.2 Detailed Design Procedure

Refer to the Detailed Design Procedure.

10.2.3.3 Application Curves

Refer to the Application Curves.