TA2021B Ver la hoja de datos (PDF) - Tripath Technology Inc.

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Fabricante

TA2021B

STEREO 25W (4Ω) CLASS-T™ DIGITAL AUDIO AMPLIFIER DRIVER USING DIGITAL POWER PROCESSING (DPP™) TECHNOLOGY

Tripath Technology Inc. 

Tripath Technology, Inc. - Technical Information

after the decoupling capacitors and use short returns to PGND1. These low side diodes, D1 and

D2, will prevent the outputs from going below ground. To be optimally effective they must have a

short and direct return path to its proper ground pin (PGND1) of the TA2021B. This can be

achieved with a ground plane or a trace. Additionally, each channel must use Schottky or Ultra

Fast Recovery diodes with short returns to VDD if the supply voltage exceeds 13.5V. These high

side diodes, D3 and D4, will prevent the outputs from going above VDD. To be optimally effective

they must have a short and direct return path to its proper VDD pin (VDD1) of the TA2021B. This

can be achieved with a ground plane or a trace.

The output inductors, L2 and L3, should be placed close to the TA2021B without compromising

the locations of the closely placed supply decoupling capacitors and output diodes. The purpose

of placing the output inductors close to the TA2021B output pins is to reduce the trace length of

the switching outputs. This will aid in reducing radiated emissions.

Please see the External Component Description section on page 6 for more details on the above-

mentioned components. The Application/ Test Circuit refers to the low side diodes as DO, The

high side diodes as DH, and both supply decoupling capacitors as CSW.

TA2021B Amplifier Gain

The gain of the TA2021B is set by the ratio of two external resistors, RI and RF, and is given by

the following formula:

VO

VI

=

−12

R

R

F

I

where VI is the input signal level and VO is the differential output signal level across the speaker.

Please note that OUTP1 and OUTP2 are 180° out of phase with their corresponding input

signals.

20 watts of RMS output power results from an 8.944 Vrms signal across a four-ohm speaker load.

If RF = RI, then 20 Watts will be achieved with 0.745 Vrms of input signal.

8.944 VRMS = (RL ∗ PO ) = (4Ω ∗ 20W )

Protection Circuits

The TA2021B is guarded against over-temperature and over-current conditions. When the

device goes into an over-temperature or over-current state, the FAULT pin goes to a logic HIGH

state indicating a fault condition. When this occurs, the amplifier is muted, all outputs are TRI-

STATED, and will float to 1/2 of VDD.

Over-temperature Protection

An over-temperature fault occurs if the junction temperature of the part exceeds approximately

155°C. The thermal hysteresis of the part is approximately 45°C, therefore the fault will

automatically clear when the junction temperature drops below 110°C.

Over-current Protection

An over-current fault occurs if more than approximately 7 amps of current flows from any of the

amplifier output pins. This can occur if the speaker wires are shorted together or if one side of

the speaker is shorted to ground. An over-current fault sets an internal latch that can only be

cleared if the MUTE pin is toggled or if the part is powered down. Alternately, if the MUTE pin is

9

TA2021B – 3.0/04.03

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