TS4994 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
TS4994
STMicroelectronics
'TS4994' PDF : 31 Pages View PDF
TS4994
Application Information
4.6 Power dissipation and efficiency
Assumptions:
l Load voltage and current are sinusoidal (Vout and Iout)
l Supply voltage is a pure DC source (Vcc)
Regarding the load we have:
Vout = VPEAK sinω t (V)
and
Iout
=
-V----o---u---t--
RL
(A)
and
Pout
=
-V----P---E----A---K----2---
2RL
(W)
Therefore, the average current delivered by the supply voltage is:
I CC AVG =
2 V-----P----E---A---K---- (A)
πRL
The power delivered by the supply voltage is:
Psupply = Vcc IccAVG (W)
Then, the power dissipated by each amplifier is
Pdiss = Psupply - Pout (W)
Pdiss
=
2---------2---V-----C----C--
π RL
Pout–Pout
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 only dependent 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
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