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Tone Control Evaluation Module
User's Guide
January 1999
Mixed-Signal Products
SLOU031
IMPORTANT NOTICE Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability. TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with TI's standard warranty. Testing and other quality control techniques are utilized to the extent TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed, except those mandated by government requirements. CERTAIN APPLICATIONS USING SEMICONDUCTOR PRODUCTS MAY INVOLVE POTENTIAL RISKS OF DEATH, PERSONAL INJURY, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE ("CRITICAL APPLICATIONS"). TI SEMICONDUCTOR PRODUCTS ARE NOT DESIGNED, AUTHORIZED, OR WARRANTED TO BE SUITABLE FOR USE IN LIFE-SUPPORT DEVICES OR SYSTEMS OR OTHER CRITICAL APPLICATIONS. INCLUSION OF TI PRODUCTS IN SUCH APPLICATIONS IS UNDERSTOOD TO BE FULLY AT THE CUSTOMER'S RISK. In order to minimize risks associated with the customer's applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other intellectual property right of TI covering or relating to any combination, machine, or process in which such semiconductor products or services might be or are used. TI's publication of information regarding any third party's products or services does not constitute TI's approval, warranty or endorsement thereof.
Copyright (c) 1998, Texas Instruments Incorporated
Preface
Related Documentation From Texas Instruments
J J
TI Plug-N-Play Audio Amplifier Evaluation Platform (literature number SLOU011) provides detailed information on the evaluation platform and its use with TI audio evaluation modules. TLC2274 Advanced LinCMOS RAIL-TO-RAIL OPERATIONAL AMPLIFIERS (literature number SLOS190) This is the data sheet for the TLC2274 Quad operational amplifier integrated circuit used in the Tone Control EVM. TLV2231 Advanced LinCMOS RAIL-TO-RAIL LOW-POWER SINGLE OPERATIONAL AMPLIFIER (literature number SLOS158) This is the data sheet for the TLV2231 operational amplifier integrated circuit used in the Tone Control EVM.
J
FCC Warning
This equipment is intended for use in a laboratory test environment only. It generates, uses, and can radiate radio frequency energy and has not been tested for compliance with the limits of computing devices pursuant to subpart J of part 15 of FCC rules, which are designed to provide reasonable protection against radio frequency interference. Operation of this equipment in other environments may cause interference with radio communications, in which case the user at his own expense will be required to take whatever measures may be required to correct this interference.
Trademarks
TI is a trademark of Texas Instruments Incorporated.
Chapter Title--Attribute Reference
iii
iv
Running Title--Attribute Reference
Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 Feature Highlights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3 Tone Control EVM Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Quick Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1 Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 Quick Start List for Platform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 Quick Start List for Stand-Alone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 1-2 1-3 1-4 2-1 2-2 2-3 2-4
2
3
Details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 3.1 Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2 3.2 The Tone Control Evaluation Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3 3.2.1 Tone Control EVM Circuit Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5 3.2.2 Tone Control EVM Frequency Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6 3.3 Using The Tone Control EVM With the Plug-N-Play Evaluation Platform . . . . . . . . . . . 3-7 3.3.1 Installing and Removing EVM Boards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7 3.3.2 Signal Routing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-8 3.3.3 Mute/Mode/Etc. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9 3.3.4 Power Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-10 3.3.5 Inputs and Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-10 3.4 Using The Tone Control EVM Stand-Alone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-11 3.5 Tone Control Evaluation Module Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12
Chapter Title--Attribute Reference
v
Running Title--Attribute Reference
Figures
1-1 2-1 2-2 3-1 3-2 3-3 3-4 3-5 3-6 3-7 3-8 The Tone Control Evaluation Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3 Quick Start Platform Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 Quick Start Module Map -- Stand-Alone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4 The TI Plug-N-Play Audio Amplifier Evaluation Platform . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2 Tone Control EVM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3 Tone Control EVM Schematic Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4 Tone Control Evaluation Module Frequency Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5 Tone Control EVM Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5 Bass and Treble Tone Control Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6 Platform Signal Routing and Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-8 Tone Control EVM Stand-Alone Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-11
Tables
3-1 Tone Control EVM Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12
vi
Chapter 1
Introduction
This chapter provides an overview of the Texas Instruments (TITM) Tone Control Evaluation Module (SLOP109). It includes a list of EVM features, a brief description of the module illustrated with a pictorial diagram, and a list of EVM specifications.
Topic
1.1 1.2 1.3
Page
Feature Highlights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3 Tone Control EVM Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
Introduction
1-1
Feature Highlights
1.1 Feature Highlights
The TI Tone Control Evaluation Module and the TI Plug-N-Play Audio Amplifier Evaluation Platform include the following features:
-
Tone Control Evaluation Module
J J J J J J J J J J J J J J J J J J
Individual slide pots for left and right channel volume control Individual slide pots for bass and treble -- the bass control adjusts both channels simultaneously and the treble control adjusts both channels simultaneously 20-dB cut and 15-dB boost for both bass and treble 3.3-V and 5-V operation
-
Quick and Easy Configuration with The TI Plug-N-Play Audio Amplifier Evaluation Platform Evaluation module is designed to simply plug into the platform, automatically making all signal, control, and power connections Platform provides flexible power options Jumpers on the platform select power and module control options Switches on the platform route signals Platform provides quick and easy audio input and output connections
-
Platform Power Options External 5-V - 15-V DC VCC supply inputs External regulated VDD supply input Socket for onboard 5-V/3.3-V VDD voltage regulator EVM Onboard overvoltage and reverse polarity power protection
-
Platform Audio Input and Output Connections Left and right RCA phono jack inputs Miniature stereo phone jack input Left and right RCA phono jack outputs Left and right compression speaker terminal outputs Miniature stereo headphone jack output
1-2
Introduction
Description
1.2 Description
The Tone Control Evaluation Module is a complete audio volume level and base and treble control board that is designed primarily for use with the TI Plug-N-Play Audio Amplifier Evaluation Platform. It consists of separate slide pots for the right- and left-channel volume control, a slide pot for controlling the bass response of both channels, a slide pot for adjusting the treble response of both channels, a single-channel operational amplifier IC, a quad operational amplifier IC, and a small number of passive components mounted on a circuit board that measures approximately 2 1/4 inches by 1 3/4 inches (Figure 1-1).
Figure 1-1. The Tone Control Evaluation Module
R18 Treble Max R10 Bass R11 C12 C10 R17 R15 C9 R16 R3 GND U1 C5 J4 U2 C6 R12 C8 C13 C7 R9 R14 C11 C3 Vdd + C14 R13
J3
Single in-line header pins extend from the underside of the module circuit board to allow the EVM to be plugged into the TI Plug-N-Play Audio Amplifier Evaluation Platform, or to be wired directly into existing circuits and equipment when used stand-alone. The platform, with room for a single tone control evaluation module, is a convenient vehicle for evaluating TI's audio power amplifier and related evaluation modules. The EVMs simply plug into the platform, which automatically provides power to the modules, interconnects them correctly, and connects them to a versatile array of standard audio input and output jacks and connectors. Easy-to-use configuration controls allow the platform and EVMs to quickly model many possible end-equipment configurations. There is nothing to build, nothing to solder, and nothing but the speakers included with the platform to hook up.
J1 + 1998 SLOP109 Rev. B C1 R In J2 + R1 RT Vol LT Vol L In R7 C2 R2
+ R19 R Out J5 + L Out R20
C4
R4
R8 C15 R5 R6
C16
Max
Tone Control Board
Introduction
1-3
Tone Control EVM Specifications
1.3 Tone Control EVM Specifications
Supply voltage range, VDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 V to 5.5 V Supply current, IDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.85 mA max Audio input voltage, VI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Vpp max Audio output voltage, VO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Vpp max
1-4
Introduction
Chapter 2
Quick Start
Follow the steps in this chapter to quickly prepare the Tone Control EVM for use. Using the Tone Control EVM with the TI Plug-N-Play Audio Amplifier Evaluation Platform is a quick and easy way to connect power, signal, and control inputs, and signal outputs to the EVM using standard connectors. However, the Tone Control EVM can be used stand-alone by making connections directly to the module pins, and can be wired into existing circuits or equipment.
Topic
2.1 2.2 2.3
Page
Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 Quick Start List for Platform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3 Quick Start List for Stand-Alone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
Quick Start
2-1
Precautions
2.1 Precautions
Power Supply Input Polarity and Maximum Voltage Always ensure that the polarity and voltage of the external power connected to VCC power input connector J1, J2, and/or VDD power input connector J6 are correct. Overvoltage or reverse-polarity power applied to these terminals can open onboard soldered-in fuses and cause other damage to the platform, installed evaluation modules, and/or the power source.
Inserting or Removing EVM Boards Do not insert or remove EVM boards with power applied -- damage to the EVM board, the platform, or both may result.
Figure 2-1. Quick Start Platform Map
6b
JP3 Batt JP2 AC/DC JP1 (J2) VCC(J1) DC SOURCE F1 VR1 C1+
1
Off
11
On ICC
6b
6b
VR2
JP4 Pwr S1
J1
VCC In +
SUPPLY
POWER
6a
F2
U6
6b
Power Input
DC Power In/Out
B1
D4 J2 AC/DC In Right In Stereo In Left In
+ VDD In/Out
J6
D3
D2
D1 R2 IDD JP5
J7 Right J8 Out
LED2 VDD
R1
J3
Signal Conditioning
LED1 VCC
Audio Power Amps U3
+ Right - Out
9
J4 U1
Off S2
10
Audio Input J5
U2
Speaker Output
On Conditioning
Mode Spk(U2-U4) C3 C2 JP8
- Left Out
U4
****CAUTION**** Do not insert or remove EVM boards with power applied
U5
Mute Polarity Lo Hi
JP6
+
JP7 HP(U5) U2-U4
J9
Left Out
TEXAS INSTRUMENTS 1997 2
U5
Stereo
Plug-N-Play Audio Amplifier Evaluation Platform SLOP097 Rev. C.1 3
Headphone Output J10
HP Out
+ S3 HP Source
TP1
GND
R3 R4
+
10
R5
2-2
Quick Start
Quick Start List for Platform
2.2 Quick Start List for Platform
Follow these steps when using the Tone Control EVM with the TI Plug-N-Play Audio Amplifier Evaluation Platform (see the platform user's guide, SLOU011, for additional details). Numbered callouts for selected steps are shown in Figure 2-1, and details appear in Chapter 3.
-
Platform preparations
1) Ensure that all external power sources are set to OFF and that the platform power switch S1 is set to OFF. 2) Install the tone control module in the Signal Conditioning platform socket U1, taking care to align the module pins correctly. 3) Set switch S2 to ON to select signal conditioning by the Tone Control EVM. 4) Install power amplifiers and/or a headphone amplifier module in the appropriate platform sockets (see the amplifier module User's Guide for details). 5) Set platform jumpers and switches in accordance with the user's guide for each amplifier module installed on the platform.
-
Power supply
6) Select and connect the power supply (ensure power supply is set to OFF ): a) Connect an external regulated power supply set to 5 V to platform VDD power input connector J6 taking care to observe marked polarity, or b) Install a voltage regulator EVM (SLVP097 or equiv.) in platform socket U6. Connect a 7 V - 12 V power source to a platform VCC power input J1 or J2 and jumper the appropriate power input (see platform user's guide).
-
Inputs and outputs
7) Ensure that the audio signal source level is set to minimum. 8) Set the EVM right and left volume slide pots to minimum. 9) Connect the audio source to left and right RCA phono jacks J3 and J5 or stereo miniature phone jack J4. 10) Connect 3- - 8- speakers to left and right RCA jacks J7 and J9 or to stripped wire speaker connectors J8, or plug headphones into J10.
-
Power Up
11) Verify correct voltage and input polarity and set the external power supply to ON. If VCC and an onboard regulator EVM are used to provide VDD, set platform power switch S1 to ON. Platform LED2 should light indicating the presence of VDD, and the evaluation modules installed on the platform should begin operation. 12) Adjust the signal source and Tone Control EVM audio levels as needed.
Quick Start
2-3
Quick Start List for Stand-Alone
2.3 Quick Start List for Stand-Alone
Follow these steps to use the Tone Control EVM stand-alone or when connecting it into existing circuits or equipment. Connections to the tone control module header pins can be made via individual sockets, wirewrapping, or soldering to the pins, either on the top or the bottom of the module circuit board. The Tone Control EVM is shown in Figure 2-2 and details appear in Chapter 3.
Figure 2-2. Quick Start Module Map -- Stand-Alone
R18 Treble Max R10 Bass R11 C12 C10 R17 R15 C9 R16 R3 GND U1 C5 J4 U2 C6 R12 C8 C13 C7 R9 R14 C11 C3 Vdd +
C14 R13
J3
-
1) Ensure that all external power sources are set to OFF. 2) Connect an external regulated power supply set to 5 V to the module VDD and GND pins taking care to observe marked polarity.
-
3) Ensure that audio signal source level adjustments are set to minimum. 4) Set the Tone Control EVM volume slide pots to minimum. 5) Connect the audio source to the module R IN and L IN pins, taking care to observe marked polarity. Power Up 6) Verify correct voltage and input polarity and set the external power supply to ON. The EVM should begin operation. 7) Adjust the signal source and Tone Control EVM audio levels as needed.
J1 + 1998 SLOP109 Rev. B C1 R In J2 + R1 RT Vol LT Vol L In R7
+ R19 R Out J5 + L Out R20
C4
R4
R8 C15 R5 R6
C16
Max
Power supply
Inputs and outputs
C2
R2
Tone Control Board
-
2-4
Quick Start
Chapter 3
Details
This chapter provides details on the Tone Control EVM, the steps in the QuickStart List, additional application information, and a parts list for the Tone Control evaluation module.
Topic
3.1 3.2 3.3 3.4 3.5
Page
Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2 The Tone Control Evaluation Module . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3 Using the Tone Control EVM With the Plug-N-Play Evaluation Platform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7 Using The Tone Control EVM Stand-Alone . . . . . . . . . . . . . . . . . . . . . 3-11 Tone Control Evaluation Module Parts List . . . . . . . . . . . . . . . . . . . . 3-12
Details
3-1
Precautions
3.1 Precautions
Power Supply Input Polarity and Maximum Voltage Always ensure that the polarity and voltage of the external power connected to VCC power input connector J1, J2, and/or VDD power input connector J6 are correct. Overvoltage or reverse-polarity power applied to these terminals can open onboard soldered-in fuses and cause other damage to the platform, installed evaluation modules, and/or the power source.
Inserting or Removing EVM Boards Do not insert or remove EVM boards with power applied -- damage to the EVM board, the platform, or both may result.
Figure 3-1. The TI Plug-N-Play Audio Amplifier Evaluation Platform
Off On JP3 Batt JP2 AC/DC JP1 (J2) VCC(J1) DC SOURCE F1 VR1 C1+ ICC VR2 JP4 Pwr S1
J1
VCC In +
SUPPLY
POWER
F2
U6
Power Input
DC Power In/Out
B1
D4 J2 AC/DC In Right In Stereo In Left In
+ VDD In/Out
J6
D3
D2
D1 R2 IDD JP5
J7 Right J8 Out
LED2 VDD
R1
J3 J4
Signal Conditioning
LED1 VCC
Audio Power Amps U3
+ Right - Out
Off S2
U1
Audio Input J5
U2
Speaker Output
On Conditioning
Mode Spk(U2-U4) C3 C2 JP8
- Left Out
U4
****CAUTION**** Do not insert or remove EVM boards with power applied
U5
Mute Polarity Lo Hi
JP6
+
JP7 HP(U5) U2-U4
J9
Left Out
TEXAS INSTRUMENTS 1997
U5
Stereo
Plug-N-Play Audio Amplifier Evaluation Platform SLOP097 Rev. C.1
Headphone Output J10
HP Out R5
+ S3 HP Source
TP1
GND
R3 R4
+
3-2
Details
The Tone Control Evaluation Module
3.2 The Tone Control Evaluation Module
The Tone Control Evaluation Module provides a convenient way to control the audio volume and the tonal response of audio amplifier EVMs plugged into the TI Plug-N-Play Audio Amplifier Evaluation Platform. Tone controls allow the frequency response of the audio system to be adjusted to compensate for the response of speakers and their enclosures, or to simply provide a more pleasing sound. A pair of slide pots adjusts the volume of each channel independently, while a single slide pot adjusts the bass response of both channels simultaneously and another slide pot adjusts the treble response of both channels. The module provides a gain of 2 at the maximum volume setting when both tone controls are at their midpoints (flat). Although the Tone Control EVM is designed to be used with the TI Plug-N-Play Audio Amplifier Evaluation Platform (Figure 3 -1), it can be wired directly into circuits or equipment. The module has single in-line header connector pins mounted to the underside of the board. These pins allow the module to be plugged into the TI platform, which automatically makes all the signal input and output, power, and control connections to the module. The module connection pins are on 0.1-inch centers to allow easy use with standard perf board and plug board-based prototyping systems. Or, the EVM can be wired directly into existing circuits and equipment when used stand-alone. The module appears in Figure 3-2 and its schematic is shown in Figure 3 - 3.
Figure 3-2. Tone Control EVM
R18 Treble Max R10 Bass R11 C12 C10 R17 R15 C9 R16 R3 GND U1 C5 J4 U2 C6 R12 C8 C13 C7 R9 R14 C11 C3 Vdd + C14 R13
J3
J1 + 1998 SLOP109 Rev. B C1 R In J2 + R1 RT Vol L In R7 C2 R2 LT Vol
+ R19 R Out J5 + L Out R20
C4
R4
R8 C15 R5 R6
C16
Max
Tone Control Board
Details
3-3
The Tone Control Evaluation Module
Figure 3-3. Tone Control EVM Schematic Diagram
VDD VDD R3 20 k C3 10 F + 3_ 5 4 1+ R4 20 k GND C4 2.2 F 2 U1 mid C5 0.1 F U1 = TLC2274 Quad Op-Amp U2 = TLV2231 Single Op-Amp
R19 10 k C1 2.2 F R In R5 10 k R1 50 k AT mid Vol R7 20 k 6_ 5+ U2:A 7 4 C6 0.1 F VDD R12 10 k C2 2.2 F R2 50 k AT mid L In R6 10 k Vol R8 20 k 6_ 7 5+ U2:B R13 10 k R10B 100 k R11 10 k R10A 100 k
C7 0.033 F R14 10 k R16 3.3 k
C11 3300 pF R18A 100 k C12 3300 pF
C9 0.033 F
9_ 8 10 + 11 U2:D
C15 1.0 F
Bass
Treble
R19 100 k
R Out
mid
mid
C8 0.033 F R15 10 k R17 2.2 k C10 0.033 F
C13 3300 pF R18B 100 k C14 3300 pF 9_ 8 10 + U2:C mid R20 100 k L Out
C16 1.0 F
mid
The Tone Control EVM is a variation of the classic and very popular Baxandall negative feedback tone control. This circuit allows a range of adjustment from cut, through flat, to boost in bass response with a single potentiometer. Another potentiometer provides the same range of adjustment for the treble response. The component values indicated in the schematic provide the response curve shown in Figure 3-4. Each of the tone adjusting potentiometers is a dual unit, allowing the simultaneous adjustment of both channels with a single control. A separate volume control for each channel allows the adjustment of balance between the channels as well as volume. A single TLC2274 quad rail-to-rail operational amplifier IC contains all the amplifiers required for both channels. A TLV2231 operational amplifier IC is connected to provide a midpoint voltage (and signal ground) for proper operation of the TLC2274.
3-4
Details
The Tone Control Evaluation Module
Figure 3-4. Tone Control Evaluation Module Frequency Response
20 Full Boost 15 Output Level - dB 10 5 Flat 0 -5
-10 -15 Full Cut -20 15 100 1K f - Frequency - Hz 10K 20K
3.2.1
Tone Control EVM Circuit Description
Each of the two separate channels on the Tone Control EVM is basically an active filter built around an IC operational amplifier. An active filter design was chosen over a passive filter circuit because active filters have the frequency-response adjusting components located in the feedback loop of the filter amplifiers, providing much lower THD, little or no insertion loss, and a symmetrical response about the axis in both boost and cut, compared with most passive designs. Each channel also includes an input buffer amplifier to provide some gain, isolation from source impedance variations, signal inversion, and a low-impedance drive for the filter circuit. A block diagram of the right channel of the Tone Control EVM is shown in Figure 3-5. The left channel is identical.
Figure 3-5. Tone Control EVM Block Diagram
C1 In R1 (Log) U2:A 2x Feedback Network U2:D Out
Mid
Buffer Amplifier
Tone Control
Filter Amplifier
The input buffer amplifier provides a gain of approximately 2 (RF/RIN) with the resistor values installed on the module. Input capacitor C1 blocks DC and sets the overall low-frequency rolloff of the EVM at approximately 16 Hz with the installed value of 2.2 F. Volume control R1 has an audio taper to provide a perceived response in volume that is proportional to the physical position of the slider and gives an adjustment range at the output of the buffer amplifier of from 0 V to approximately 2 x the audio signal input voltage.
Details
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The Tone Control Evaluation Module
The tone adjusting action in each channel of the Tone Control EVM is provided by an equalized amplifier (or active filter) created by placing a frequencydependent negative feedback network around an operational amplifier. Almost any overall gain-versus-frequency characteristic can be defined by the design of the feedback network. The EVM provides the familiar Hi-Fi tone control, in which the low audio frequencies can be boosted or cut approximately 20 dB with the bass control and the high audio frequencies can be boosted or cut approximately 20 dB with the treble control. Middle frequencies are not affected by the tone controls. An overall flat response (no boost or cut at frequency extremes) is obtained when the tone controls are at their mid-point position.
3.2.2
Tone Control EVM Frequency Response
The overall Tone Control EVM frequency response can be shifted up or down by changing the values of capacitors C7, C9, C11, and C12 in the tone adjusting networks on the module. Care must be taken, however, because the surface-mount solder pads on the board are somewhat fragile and will not survive a large number of soldering/desoldering operations. To shift the EVM frequency response downward, for example, increase the values of the capacitors in the tone adjusting networks. Doubling the values of C7, C9, C11, and C12 shifts the break frequency downward a full octave (Case B, Figure 3-6). Conversly, halving the values of C7, C9, C11, and C12 shifts the break frequency upward a full octave. Note that to keep the boost and cut break frequencies the same, the value of C7 must equal that of C9, and the value of C11 must equal that of C12. In addition, although the bass and treble break frequencies can be adjusted separately if desired, to maintain the overall shape and symmetry of the response, all four capacitors must be increased or decreased by the same factor.
Figure 3-6. Bass and Treble Tone Control Response
20 15 10 Output Level - dB 5 0 -5 Case B Case A Case A: C7, C9 = 0.033 F C11, C12 = 3300 pF
-10 -15 -20 15 100 Case B: C7, C9 = 0.068 F C11, C12 = 6800 pF 1K f - Frequency - Hz 10K 20K
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Details
Using The Tone Control EVM With the Plug-N-Play Evaluation Platform
3.3 Using The Tone Control EVM With the Plug-N-Play Evaluation Platform
The Tone Control Evaluation Module was designed to be used with the TI Plug-N-Play Audio Amplifier Evaluation Platform. It simply plugs into socket U1. The following paragraphs provide additional details for using the Tone Control EVM with the platform.
3.3.1
Installing and Removing EVM Boards
TI Plug-N-Play evaluation modules use single-in-line header pins installed on the underside of the module circuit board to plug into sockets on the platform. The EVM pins and the platform sockets are keyed such that only the correct type of EVM can be installed in a particular socket, and then only with the proper orientation. Evaluation modules are easily removed from the platform by simply prying them up and lifting them out of their sockets. Care must be taken, however, to prevent bending the pins.
3.3.1.1
EVM Insertion
1) Remove all power from the evaluation platform. 2) Locate the appropriate socket on the platform. 3) Orient the module correctly. 4) Carefully align the pins of the module with the socket pin receptacles. 5) Gently press the module into place. 6) Check to be sure that all pins are seated properly and that none are bent over.
3.3.1.2
EVM Removal
1) Remove all power from the evaluation platform. 2) Using an appropriate tool as a lever, gently pry up one side of the module a small amount. 3) Change to the opposite side of the module and use the tool to pry that side up a small amount. 4) Alternate between sides, prying the module up a little more each time to avoid bending the pins, until it comes loose from the socket. 5) Lift the EVM off of the platform.
Details
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Using The Tone Control EVM With the Plug-N-Play Evaluation Platform
3.3.2
Signal Routing
Signal flow on the platform is controlled by two signal routing switches, as shown in Figure 3 -7.
Figure 3-7. Platform Signal Routing and Outputs
Off + R Audio Input L U1 Tone Control EVM S2 U2 -- U4 Power Amplifier EVM L On U5 Stereo Headphone Amplifier R S3 L L U5 GND U2 - U4 R + - J10 Headphone Output - + L + R R - - J7, J8, J9 Speaker Outputs
3.3.2.1
Signal Conditioning
The Tone Control EVM plugs into the Signal Conditioning socket (U1) on the platform. The audio signal from the platform input jacks can be applied to the signal conditioning socket (U1) or can bypass socket U1 as determined by conditioning switch S2. Switch S2 selects the tone control signal conditioning or bypasses it
3.3.2.2
Headphone Output Jack
Switch S3 is the source select for the stereo headphone output jack, J10. The headphone jack is capacitively coupled (via 470 F electrolytics) and can output either the signal from the headphone amplifier in socket U5, or the signal from the power amplifier installed in sockets U2 - U4, as determined by the setting of headphone source select switch S3. When S3 is set to the power amplifier position (U2 - U4), the headphone jack is connected to the power amplifier OUT+ output lines. When a plug is inserted into the jack, signals output through J10 are returned to platform ground, requiring single-ended power amplifier operation. A switch inside the headphone jack produces a control signal that can be routed to the power amplifier socket to shut down the power amplifier EVM or switch it to single-ended output mode when a plug is inserted. See the User's Guide for the power amplifier and/or the headphone amplifier installed on the platform for information on the correct setting of switch S3.
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Details
Using The Tone Control EVM With the Plug-N-Play Evaluation Platform
3.3.3
Mute/Mode/Etc.
Some power amplifier EVMs have a mute or mode control input pin. This allows the power amplifier to enter the mute state for decreased power consumption or to switch output modes in response to a control signal applied to this pin. In typical applications, as often found in notebook computers, portable audio products, and such, the internal speakers mute when headphones are plugged into the headphone jack, or internal speakers mute when external speakers are connected. In applications using separate speaker and headphone amplifiers, the power amplifier can be shut down (muted) to conserve power when the headphone amplifier is in use. Output mode switching allows some power amplifier EVMs to operate in the bridge-tied load (BTL) output mode for increased power to internal speakers and then switch to single-ended mode to drive headphones when a plug is inserted into the headphone jack, eliminating the need for a separate headphone amplifier. The platform is equipped with mute/mode control signal select and polarity jumpers and a headphone source switch to provide the maximum flexibility in configuring the operation of the various power amplifier and headphone amplifier EVMs that might be installed on the platform. See the User's Guide for the power amplifier and/or the headphone amplifier installed on the platform for information on the correct settings of platform mute, mode, polarity jumpers, and the platform headphone source switch.
Details
3-9
Power Requirements
3.3.4
Power Requirements
The Tone Control Evaluation Module can operate from any voltage between approximately 3 V and 5.5 V. For best performance (highest output power with lowest distortion), the module should be operated at approximately 5 V unless there is a specific reason for operating it from a lower voltage. The TI Plug-N-Play Audio Amplifier Evaluation Platform with a voltage regulator EVM installed on it can provide a regulated VDD supply from a wide variety of unregulated VCC voltage inputs between approximately 5.5 V and 12 V, including an onboard 9 -V battery. Or, an external regulated power source can be used to supply VDD voltage to the platform and the tone control evaluation module installed on it. Although the Tone Control EVM draws a very small amount of current from the supply, power amplifiers installed on the platform can draw as much as approximately 2 A from the power supply during continuous full power output. Any power supply connected to the platform should be capable of providing adequate current to the power amplifier installed on the platform to avoid clipping of the output signal during peaks. Current consumption driving speakers at normal listening levels is typically 0.5 A or less. The platform is equipped with overvoltage and reverse-polarity supply voltage input protection in the form of fused crowbar circuits.
-
VDD voltage applied to platform screw terminals J6 MUST NOT exceed the absolute maximum rating for any EVM installed on the platform, or damage may result. In no case should VDD voltage of the incorrect polarity or in excess of 6.1 V be applied to screw terminals J6 of the platform, or the power protection circuit on the VDD line will trip. VCC voltage applied to the platform MUST NOT exceed the maximum voltage input specified for the voltage regulator module installed in socket U6 (12 V for the SLVP097), or damage to the voltage regulator module may result. In no case should VCC voltage applied to the platform exceed 15 V, or the overvoltage protection circuit on the VCC bus will trip.
3.3.5
Inputs and Outputs
The TI Plug-N-Play Audio Amplifier Evaluation Platform is equipped with several standard conectors for audio inputs and outputs.
3.3.5.1
Inputs
Audio signals enter the platform through either a pair of RCA phono jacks (J3 and J5) or a miniature (1/8) stereo phone jack (J4). The platform audio signal input jacks (J3, J4, and J5) are of the closed-circuit type, grounding the signal input lines when no plugs are inserted.
3.3.5.2
Outputs
Amplified audio output signals leave the platform through left and right RCA phono jacks (J7 and J9), left and right pairs of compression connectors for stripped speaker wires (J8), and optionally, through a miniature (1/8) stereo phone jack (J10), for headphones.
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Details
Using The Tone Control EVM Stand-Alone
3.4 Using The Tone Control EVM Stand-Alone
Using the Tone Control Evaluation Module stand-alone is much the same as using it with the platform. The same 5-V power supply requirement exists.
3.4.1
Tone Control EVM Connected for Stand-Alone Operation
Figure 3-8. Tone Control EVM Stand-Alone Operation
R18 Treble Max R10 Bass R11 C12 C10 R17 R15 C9 R16 R3 GND U1 C5 J4 U2 C6 R12 C8 C13 C7 R9 R14 C11 C3 Vdd + C14 R13
J3
5V Audio Output (Right)
Audio Input (Right)
J1 + 1998 SLOP109 Rev. B C1 R In R7
+ R19 R Out J5 + L Out
C4
R4
R8 C15 R5 R6
Audio Input (Left)
L In
J2 + R1 RT Vol Max C2 R2 LT Vol
Tone Control Board
C16 R20
Audio Output (Left)
Details
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Tone Control Evaluation Module Parts List
3.5 Tone Control Evaluation Module Parts List
Table 3-1. Tone Control EVM Parts List
Reference C1, C2, C4 C3 C15, C16 C7, C8, C9, C10 C5, C6 C11, C12, C13, C14 R10, R18 R1, R2 R5, R6, R9, R11, R12, R13, R14, R15 R3, R4, R7, R8 R16, R17 R19, R20 J1-J5 U1 U2 PCB Description Capacitor, ceramic, 2.2 F, 16 V, YV5 Capacitor, ceramic, 10 F, 16 V, YV5 Capacitor, ceramic, 1 F, 16 V, YV5 Capacitor, ceramic 0.033 F, 50 V, NPO Capacitor, ceramic, 0.1 F, 50 V, X7R Capacitor, ceramic 3300 pF, 50 V, NPO Dual potentiometer, 100 k, linear taper, slide control Potentiometer, 50 k, audio taper, slide control Resistor, CF, 10 k, 1/8 W, 5% 1206 Size 1206 1210 1206 1206 1206 1206 EVM Qty. 3 1 2 2 2 4 2 2 8 Source/ Part Number TDK C3216Y5V1C225Z TDK C3216Y5V1C106Z TDK C3216Y5V1C105Z Digi-Key Digi-Key PCC104BCT-ND Digi-Key CTS 448XC351109 CTS 448XC3503BAN
Resistor, CF, 20 k, 1/8 W, 5% Resistor, CF, 3.3 k, 1/8 W, 5% Resistor, CF, 10 k, 1/8 W, 5% Header, 2 position, 100-mil centers TLV2231IDBV IC operational amplifier TLC2274CD quad IC operational amplifier PCB, Tone Control EVM
1206 1206 1206
4 2 2 5 Digi-Key S1022-36ND TI TI TI SLOP109
SOT-23 SOIC
1 1 1
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Details

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