TS4956 datasheet(39/51 Pages) STMICROELECTRONICS

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TS4956

Application information

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

The maximum theoretical value is reached when VPEAK = VCC/2, so

The TS4956 has in modes 3 and 4 two active output 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:

Pdiss 1 = power dissipation due to the first power amplifier.

Pdiss 2 = power dissipation due to the second power amplifier.

Total Pdiss =Pdiss 1 +Pdiss 2 (W)

In most cases,

Pdiss 1 =Pdiss 2, giving:

4.3.3

BTL output configuration (modes 1, 2, 7):

The average current delivered by the supply voltage is:

Figure 128. Current delivered by supply voltage in the BTL output configuration

The power delivered by supply voltage is:

Then, the power dissipation by each amplifier is

out

su pply

-------------------

πV

PEAK

---------------------

---

39.25%

TotalP

diss

diss1

TotalP

diss

42VCC

π R

---------------------- P

out

ou t W

()

–

Icc

AVG

---

PEAK

-----------------

()

sin

∫

PEAK

πR

---------------------A

()

sup ply

CCICC

AV G

()

diss

22 VCC

π R

---------------------- P

ou t

out W

()

–

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