LM4752TS/NOPB National Semiconductor, LM4752TS/NOPB Datasheet - Page 17

• Manufacturer Part Number: LM4752TS/NOPB
• Description: IC AMP AUDIO PWR 11W AB TO263-7
• Manufacturer: National Semiconductor
• Type: Class ABr

Specifications of LM4752TS/NOPB

• Output Type: 2-Channel (Stereo)
• Max Output Power X Channels @ Load: 11W x 2 @ 4 Ohm
• Voltage - Supply: 9 V ~ 32 V
• Features: Thermal Shutdown Protection
• Mounting Type: Surface Mount
• Package / Case: D²Pak, TO-263 (7 leads + tab)
• Peak Reflow Compatible (260 C): Yes
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: *LM4752TS; *LM4752TS/NOPB; LM4752TS

2 • P
Conclusion: Choose a heatsink with θ
TO-263 Heatsink Design Examples
Example 1:
Given:
P
Calculating P
Calculating Heatsink Thermal Resistance:
Therefore the recommendation is to use 1.5 × 1.5 square inch
of single-sided copper clad.
Example 2:
Given:
P
Calculating P
θ
DMAX
DMAX
SA
θ
SA
DMAX
P
≤
DMAX
from P
from P
< 120°C / 3.7W − 2.0°C/W − 0.2°C/W = 30.2°C/W
[ (T
= 2 • [V
14.6W ] − 2°C/W − 0.2°C/W = 4.3°C/W
J
θ
= V
− T
SA
DMAX
DMAX
D
D
vs P
CC
vs P
A
< [(T
) / P
2
S
:
:
(Stereo Single-Ended Output)
T
T
R
V
θ
(Stereo Single-Ended Output)
T
T
R
V
θ
2
/ (
JC
O
JC
O
A
J
A
J
S
S
L
L
/ (2 •
=150°C
=150°C
DMAX
=30°C
=50°C
=4Ω
=12V
J
=4Ω
=12V
π
Graph:
Graph:
=2°C/W
=2°C/W
− T
P
2
P
R
DMAX
DMAX
] − θ
π
L
A
) = (12V)
14.6W
) / P
2
• R
≈
≈
JC
DMAX
L
3.7W
3.7W
) ] = (24V)
− θ
2
] − θ
CS
/
SA
π
= [ (150°C − 55°C) /
2
JC
≤
(4Ω)) = 3.65W
4.3°C/W.
− θ
2
/ (2 •
CS
π
2
• 4Ω) =
17
Calculating Heatsink Thermal Resistance:
Therefore the recommendation is to use 2.0 × 2.0 square inch
of single-sided copper clad.
Example 3:
Given:
Calculating P
Calculating Heatsink Thermal Resistance:
Therefore the recommendation is to use 2.0 × 2.0 square inch
of single-sided copper clad.
Layout and Ground Returns
Proper PC board layout is essential for good circuit perfor-
mance. When laying out a PC board for an audio power
amplifer, particular attention must be paid to the routing of the
output signal ground returns relative to the input signal and
bias capacitor grounds. To prevent any ground loops, the
ground returns for the output signals should be routed sepa-
rately and brought together at the supply ground. The input
signal grounds and the bias capacitor ground line should also
be routed separately. The 0.1 μF high frequency supply by-
pass capacitor should be placed as close as possible to the
IC.
P
DMAX
θ
θ
SA
SA
P
DMAX
< 100°C / 3.7W − 2.0°C/W − 0.2°C/W = 24.8°C/W
< 100°C / 3.7W − 2.0°C/W − 0.2°C/W = 24.8°C/W
= 4[V
= V
θ
θ
SA
DMAX
SA
CC
CC
2
< [(T
< [(T
2
/ (2
:
/ (
π
J
π
J
− T
− T
2
2
R
R
L
L
A
A
) = (12V)
(Bridged Output)
T
T
R
V
θ
)] = 4(12V)
) / P
) / P
JC
A
J
S
L
=150°C
=50°C
=8Ω
=12V
=2°C/W
DMAX
DMAX
2
] − θ
] − θ
/ (
2
π
/ (2
JC
JC
2
(4Ω)) = 3.65W
π
− θ
− θ
2
(8Ω)) = 3.65W
CS
CS
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