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The TPA721 MSOP Audio Power Amplifier Evaluation Module

3-5

Details

The TPA721 amplifier IC, like most other amplifiers, exhibits its best distortion
and noise performance at lower gain levels (see the TPA721 data sheet). Even
so, the TPA721 at its highest gain setting has significantly less distortion than
most low-cost speakers.

Gain versus total harmonic distortion (THD) should be considered in each
application. Both the module input signal level and the TPA721 MSOP module
gain should be adjusted to obtain the lowest overall distortion level for a
particular overall gain. A quick rule of thumb (everything else being equal): the
module input signal level should be as high as possible without clipping or
overloading the TPA721 input, and the TPA721 gain should be kept as low as
possible.

3.2.4

Shutdown

When the shutdown terminal of the TPA721 amplifier IC is taken high, the IC
ceases operation and enters a low-power state. This is accomplished by
applying a control signal to the module shutdown pin (S1) or by pressing the
shutdown switch on the module. When the control signal goes low or is
removed (or the switch is released), amplifier operation resumes.

The plug-n-play platform can generate the shutdown (mute) signal for the
module either when a plug is inserted into the platform headphone output jack
or when the plug is removed, as selected by a platform jumper (JP8).

3.2.5

Internal Depop Circuitry

Internal depop circuitry reduces or eliminates the various turn-on transients
that might appear at the output during the transition from power off or shutdown
mode to normal operation. These output transients are often heard as a pop
from the speaker and occur when the two amplifiers in the IC turn on or off at
different rates, causing a voltage spike to appear across the output. The depop
circuitry adds a delay with an RC network at the amplifier IC bypass pin to help
ensure that the amplifiers turn on and off at the same rate, thus eliminating the
pop. For best results, bypass capacitor C1 should have a value between
0.1 

µ

F and 2.2 

µ

F. A 1 

µ

F unit was selected for the EVM.

Summary of Contents for TPA721

Page 1: ...2001 Mixed Signal Products TPA721 MSOP Audio Power Amplifier Evaluation Module User s Guide SLOU033A...

Page 2: ...esign 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 rel...

Page 3: ...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 de...

Page 4: ...iv...

Page 5: ...Amplifier Evaluation Module 3 3 3 2 1 TPA721 Audio Amplifier IC 3 4 3 2 2 BTL Operation 3 4 3 2 3 Module Gain 3 4 3 2 4 Shutdown 3 5 3 2 5 Internal Depop Circuitry 3 5 3 3 Using The TPA721 MSOP EVM Wi...

Page 6: ...3 3 3 3 TPA721 MSOP EVM Schematic Diagram 3 3 3 4 TPA721 Audio Amplifier IC 3 4 3 5 Platform Signal Routing and Outputs 3 7 3 6 Mute Mode and Polarity Control 3 8 3 7 Typical Headphone Plug 3 10 3 8 T...

Page 7: ...21 MSOP audio amplifier evaluation module SLOP215 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 Page...

Page 8: ...signed to simply plug into the platform automatically making all signal control and power connections J Platform provides flexible power options J Jumpers on the platform select power and module contr...

Page 9: ...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 pair of TP...

Page 10: ...1 4 Introduction...

Page 11: ...directly into existing circuits or equipment The platform switch and jumper settings shown in Table 2 1 are typical for the TPA721 MSOP EVM They will cause the TPA721 amplifier IC on the EVM to shut...

Page 12: ...or both may result Figure 2 1 Quick Start Platform Map Signal Conditioning CAUTION Do not insert or remove EVM boards with power applied ICC JP4 F1 VR1 R1 JP3 JP2 JP1 AC DC J2 VCC J1 D1 D2 D3 D4 J2 J...

Page 13: ...X Don t care 2 Set S2 to ON when signal conditioning board is installed in U1 set S2 to OFF when no signal conditioning board is installed Power supply 6 Select and connect the power supply a Connect...

Page 14: ...M C6 C5 S1 R1 R2 C2 C1 R3 R4 C3 Due to the very small size of the MSOP IC package the standard part number TPA721 is replaced with the code TIABC Power supply 1 Ensure that all external power sources...

Page 15: ...n and a parts list for the TPA721 MSOP evaluation module Topic Page 3 1 Precautions 3 2 3 2 The TPA721 MSOP Audio Power Amplifier Evaluation Module 3 3 3 3 Using The TPA721 MSOP EVM With The Plug N Pl...

Page 16: ...or both may result Figure 3 1 The TI Plug N Play Audio Amplifier Evaluation Platform Signal Conditioning CAUTION Do not insert or remove EVM boards with power applied ICC JP4 F1 VR1 R1 JP3 JP2 JP1 AC...

Page 17: ...tput 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 b...

Page 18: ...ied load BTL configuration for increased power BTL operation provides many benefits including quadruple the output power of single ended operation and no need for bulky output coupling capacitors For...

Page 19: ...lished by applying a control signal to the module shutdown pin S1 or by pressing the shutdown switch on the module When the control signal goes low or is removed or the switch is released amplifier op...

Page 20: ...ly 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...

Page 21: ...with a shutdown mute control input pin When this input is tied to VDD the TPA721 amplifier IC on the module shuts down and assumes a low power mode When the EVM control input is tied to GND or allowed...

Page 22: ...er JP6 to MUTE J To not affect the TPA721 amplifier when a plug is inserted into the headphone jack jumper JP6 to Mode or leave JP6 unjumpered 3 3 3 3 Mute Mode Polarity Select JP8 A second 3 pin jump...

Page 23: ...n be used to supply VDD voltage to the platform and the TPA721 MSOP evaluation modules installed on it The platform is equipped with overvoltage and reverse polarity supply voltage input protection in...

Page 24: ...nal 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 a...

Page 25: ...t to overcome the pulldown resistors on the modules 20 k 20 k for two EVMs 3 4 1 TPA721 MSOP EVM Connected for BTL Output Figure 3 8 TPA721 MSOP EVM Connected for Stereo BTL Output Audio Input Left Ex...

Page 26: ...603 0 R1 R4 Resistor 20 k 1 16 W 5 0603 2 Panasonic ERJ 3GSYJ203 Digi Key P20KGCT ND R5 Resistor 39 k 1 16 W 5 0603 1 Panasonic ERJ 3GSYJ393 Digi Key P39KGCT ND R2 Resistor 0 1 16 W 0603 1 Panasonic E...

Page 27: ...Mouser Electronics Authorized Distributor Click to View Pricing Inventory Delivery Lifecycle Information Texas Instruments TPA721MSOPEVM...

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