TDA8580J Datasheet, PDF (17/28 Pages) NXP Semiconductors – Multi-purpose power amplifier

Philips Semiconductors
Multi-purpose power amplifier
Preliminary specification
TDA8580J
For BTL application at V_p = 24 V, R_L = 8 Ω and P_o at
THD = 0.5% (see Fig.15), the Average Listening
Level (ALL) for music power without distortion yields:
P_o(ALL) = _{1----5-2--.-3-8---5--} = 1.45 W.
Table 2 P_d as a function of headroom (music signals) for
P_o = 2 × 23 W (THD = 0.5%).
HEADROOM
0 dB
12 dB
P_d
32 W
16 W
So for the average music listening level a total power
dissipation of 16 W can be used for calculating the
optimum heat sink thermal resistance.
Heatsink calculation
The measured thermal resistance of this package R_th(j-c) is
a maximum of 1.5 K/W. For a maximum ambient
temperature of 60^oC the required heatsink thermal
resistance can be calculated as shown in the following
example.
EXAMPLE
Measured or given values:
V_p = 24 V
R_L = 8 Ω (2 × BTL)
Measured worst case P_d (sine wave) = 32 W
T_j(max) = 150^oC
T_amb(max) = 60^oC
R_th(j-c) = 1.5 K/W
R_th(hs) = ^T----j--⁽--^m----^a---^x--⁾---^–---P--T--_d--^a--^m-----^b--⁽--^m----^a---^x---⁾ – R_{th(j – c)}
= ^{1----5---0--3---2–}-----6---0-- – 1.5 = 1.3 K/W
Table 3 Heatsink thermal resistance as a function of
headroom for P_o = 2 × 23 W (THD = 0.5%).
HEAD ROOM
0 dB
12 dB
P_d
32 W
16 W
R_th(hs)
1.3 K/W
4.12 K/W
2000 Apr 18
17