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Large gate resistors lead to slower MOSFET switching edges which require a larger break-before-make

(BBM) delay.

Break-Before-Make (BBM) Timing Control

The complementary half-bridge power MOSFETs require a deadtime between when one transistor is

turned off and the other is turned on (break-before-make) in order to minimize shoot through currents.

The TDA2075A has an analog input pin that controls the break-before-make timing of the output

defines the BBM setting by the following equation.

There is tradeoff involved in making this setting. As the delay is reduced, distortion levels improve but

shoot-through and power dissipation increase. All typical curves and performance information were done

circuit board layout, the value selected should be verified in the actual application circuit/board. It should

also be verified under maximum temperature and power conditions since shoot-through in the output

MOSFETs can increase under these conditions, possibly requiring a higher BBM setting than at room

temperature.

Recommended MOSFETs

The following devices are capable of achieving full performance, both in terms of distortion and efficiency,

for the specified load impedance and voltage range. Additional devices will be added as subsequent

characterization is completed.

Device Information – Recommended MOSFETs

Part Number

Manufacturer

Package

FQP13N10

Fairchild Semiconductor

100

12.8

12

0.142

TO220

FQP12P10

Fairchild Semiconductor

-100

-11.5

21

0.240

TO220

Output Filter Design

One advantage of Tripath amplifiers over PWM solutions is the ability to use higher-cutoff-frequency

filters. This means load-dependent peaking/droop in the 20kHz audio band potentially caused by the filter

can be made negligible. This is especially important for applications where the user may select a 6-Ohm

or 8-Ohm speaker. Furthermore, speakers are not purely resistive loads and the impedance they present

changes over frequency and from speaker model to speaker model.

Tripath recommends designing the filter as a 2nd order LC filter. Tripath has obtained good results with

The core material of the output filter inductor has an effect on the distortion levels produced by a

TDA2075A amplifier. Tripath recommends low-mu type-2 iron powder cores because of their low loss

TDA2075A for the specific core used.

Tripath also recommends that an RC damper be used after the LC low-pass filter. No-load operation of a

TDA2075A amplifier can create significant peaking in the LC filter, which produces strong resonant

currents that can overheat the output MOSFETs and/or other components. The RC dampens the