User’s Guide May 2004 HPA Audio Power SLOU169
IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete.
EVM IMPORTANT NOTICE Texas Instruments (TI) provides the enclosed product(s) under the following conditions: This evaluation kit being sold by TI is intended for use for ENGINEERING DEVELOPMENT OR EVALUATION PURPOSES ONLY and is not considered by TI to be fit for commercial use.
EVM WARNINGS AND RESTRICTIONS It is important to operate this EVM within the supply voltage range of ±5 V to ±15 V. Exceeding the specified supply range may cause unexpected operation and/or irreversible damage to the EVM. If there are questions concerning the supply range, please contact a TI field representative prior to connecting the input power. Applying loads outside of the specified output range may result in unintended operation and/or possible permanent damage to the EVM.
How to Use This Manual Preface About This Manual This users guide describes the characteristics, operation, and use of the TPA6120A2 evaluation module (EVM). This users guide includes EVM description, performance specifications, board layout, bill of materials (BOM), and schematic diagram.
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Contents 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 1.1 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 1.2 Performance Specification Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 2 Getting Started . . . . . . . . . . . . . . . . . . . . . .
Contents 2−1 4−1 4−2 4−3 Top Layer With Numbered Callouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3 Top Layer of the TPA6120A2 EVM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2 Bottom Layer of the TPA6120A2 EVM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3 TPA6120A2 EVM Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 1 The TPA6120A2 is a high-fidelity audio amplifier. The amplifier can operate from a split power supply, and is designed for low noise, high dynamic range performance. Topic Page 1.1 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 1.2 Performance Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Description 1.1 Description The TPA6120A2 EVM is designed to operate specifically with a split power supply, and is configured such that both left and right channels have a noninverting gain of 2 V/V. The output signal is routed into RCA jacks J1 and J2, as well as the 1/4 inch headphone jack, J10. The EVM is approximately 3 inches x 3 inches square, and comes complete with standoffs. 1.2 Performance Specifications Table 1−1.
Chapter 2 Follow these steps to use the TPA6120A2 EVM in its original configuration. No soldering is necessary. Connection to the TPA6120A2 EVM can be made with banana plugs, RCA jacks, and a 1/4 inch headphone jack. See Figure 2−1 for an illustration of the top layer. Topic Page 2.1 Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 2.2 Inputs and Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Supply 2.1 Power Supply 1) Make sure all external power supplies are turned off. 2) Connect an external power supply with the positive voltage set between 5 V and 15 V to the terminal marked +12 V (J8) on the EVM. 3) Connect the negative voltage to the terminal marked −12 V (J9), making sure the negative voltage is set to the same magnitude as that of the positive (i.e., ±5 V, ±12 V, ±15 V). 4) Connect the ground of the external supply to the terminal marked GND (J7) on the EVM. 2.
Power Up Figure 2−1. Top Layer With Numbered Callouts (From paragraphs 2.1 through 2.
Power Up (This page has been left blank intentionally.
Chapter 3 The TPA6120A2 EVM comes in a noninverting configuration with a gain of 2 V/V. However, the EVM is designed to be flexible, and can be converted to operate in inverting and differential configurations. The TPA6120A2 EVM can also be operated in a single power supply configuration. Topic Page 3.1 Inverting Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2 3.2 Differential Configuration . . . . . . . . . . . . . . . . . . . . . .
Inverting Configuration 3.1 Inverting Configuration The TPA6120A2 EVM can be converted to operate in an inverting gain configuration. To do this, it is necessary to remove resistors R11 and R12, then connect the audio source to RCA jacks LIN− (J3) and RIN− (J4) instead of LIN+ (J5) and RIN+ (J6). With the feedback and input resistors already in place on the EVM, the gain is set to −1 V/V (RF/RI). 3.
Chapter 4 The TPA6120A2 EVM layout was carefully planned to minimize the capacitance and inductance detected by the output and input pins of the amplifier. Test points are available, but intentionally left unpopulated to keep signal interference as low as possible. This chapter includes the EVM layout, the TPA6120A2 EVM component selection, schematic, and bill of materials. Topic Page 4.1 TPA6120A2 EVM Top Layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TPA6120A2 EVM Top Layer 4.1 TPA6120A2 EVM Top Layer Figure 4−1 shows the top layer of the TPA6120A2 EVM. The RCA jacks at the inputs are configured to short to ground when no plug is inserted. The noninverting configuration of the EVM requires that RIN− and LIN− be at ground. Rather than have the signal go through the long signal trace to get to the input jacks, 0-Ω resistors R11 and R12 are used to provide a connection to ground much closer to the device. A star point for ground should be chosen.
TPA6120A2 EVM Bottom Layer 4.2 TPA6120A2 EVM Bottom Layer Figure 4−2 shows the bottom layer of the TPA6120A2 EVM. Note that the copper has been removed from around the capacitive sensitive nodes. It is important to remember that the thermal pad on the underside of the IC must be properly soldered to the board at all times. Figure 4−2.
Component Selection 4.3 Component Selection The TPA6120A2 is a high-fidelity audio amplifier. The composition of components is important when dealing with high fidelity. The best practice is to operate the device with a split power supply. This eliminates the need for capacitors in the signal path, which can introduce distortion. Capacitors can also fail after a certain period of time. The failure mode of many capacitors is to essentially turn into a short.
Schematic The TPA6120A2 EVM uses 4.02-kΩ resistors to tie the positive terminals to ground. This value is a good compromise between the device’s effect on the performance of the audio source and the output offset voltage. When the source is removed or is off (or high impedance), the maximum output offset value possible with a 4.02-kΩ resistor is about 85 mV. The loading effect on the audio source is minimal since for most sources, a 4.02-kΩ load is seen as high impedance. Going from 4.
Bill of Materials 4.6 Bill of Materials Table 4−1. TPA6120A2 EVM Bill of Materials Manufacturer Component Qty Value Size Name Number Distributor Name Number C5, C6 2 10 µF, 50V, +80/−20%, F 1210 Panasonic ECJ−4YF1H106Z Digi−Key PCC2308TR−ND C1, C2, C3, C4 4 0.1 µF, 50V, ±10%, X7R 0805 Panasonic ECJ−2YB1H104K Digi−Key PCC1840TR−ND C7, C8 2 100 µF, Aluminum Electrolytic, 63V, ±20% 10 mm x 12.
