tfa9815t NXP Semiconductors, tfa9815t Datasheet - Page 16

• Manufacturer Part Number: tfa9815t
• Description: Stereo Full-bridge Audio Ampli?er 2 X 17 W
• Manufacturer: NXP Semiconductors

NXP Semiconductors
TFA9815_1
Preliminary data sheet
13.2 Output current limiting
13.3 Speaker configuration and impedance
The maximum peak output current is limited by the level of the overcurrent protection
threshold. During normal operation the output current should not exceed this threshold
level of 3 A otherwise the OCP will be triggered and the device will stop switching for 5 s.
The peak output current in BTL can be estimated using the following equation:
Where:
For a flat-frequency response (second-order Butterworth filter) it is necessary to change
the low-pass filter components LLC and CLC according to the speaker configuration and
impedance.
I
O
Fig 6.
•
•
•
•
max
V
R
R
R
P
L
DSon
S
(W)
= supply voltage [V]
= load impedance [ ]
P
= series resistance output inductor [ ]
o
----------------------------------------------------- -
R
40
30
20
10
THD+N = 10 %
f = 1 kHz
(1) R
(2) R
(3) R
BTL output power as function of supply voltage: THD = 10 %
0
L
= on resistance power switch [ ]
8
+
Table 13
L
L
L
2
= 4
= 6
= 8
1
2
3
V
R
P
DSon
Rev. 01 — 16 December 2008
shows the practical required values:
10
+
R
S
3 A
12
14
16
Audio amplifier 2 x 17 W
18
V
010aaa450
P
© NXP B.V. 2008. All rights reserved.
TFA9815
(V)
20
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