TS4851 View Datasheet(PDF) - STMicroelectronics

Part Name

Description

Manufacturer

TS4851

Mono 1W Speaker and Stereo 160mW Headset BTL Drivers with Digital Volume Control

STMicroelectronics 

Application Information

TS4851

and the maximum value is obtained when:

∂----P----d----i--s---s---- = 0

∂POUT

and its value is:

Pdiss max

=

2 Vcc2

π2RL

(W)

Note: This maximum value is depends only on power supply voltage and load values.

The efficiency is the ratio between the output power and the power supply:

η = -----P-----O----U---T------ = ---π---V-----P---E----A---K--

Psupply 4VCC

The maximum theoretical value is reached when Vpeak = Vcc, so:

π---- = 78.5%

4

The TS4851 has three independent power amplifiers. Each amplifier produces heat due to its power

dissipation. Therefore, the maximum die temperature is the sum of each amplifier’s maximum power

dissipation. It is calculated as follows:

l Pdiss speaker = Power dissipation due to the speaker power amplifier.

l Pdiss head = Power dissipation due to the Headphone power amplifier

l Total Pdiss = Pdiss speaker + Pdiss head1 + Pdiss head2 (W)

In most cases, Pdiss head1 = Pdiss head2, giving:

Total Pdiss = Pdiss speaker + 2Pdiss head (W)

2

TotalP diss =

2 VCC

⎡

⎢

π ⎢⎣

POUT SPEAKER

R L SPEAKER

+2

POUT HEAD

⎤

⎥

RL HEAD ⎥⎦

[ ] − POUT SPEAKER + 2 POUT HEAD

(W )

The following graph (Figure 60) shows an example of the previous formula, with Vcc set to +5V,

Rload speaker set to 8Ω and Rload headphone set to 16Ω.

Figure 60: Example of total power dissipation vs. speaker and headphone output power

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