AN10436 PHILIPS [NXP Semiconductors], AN10436 Datasheet - Page 23

• Manufacturer Part Number: AN10436
• Description: TDA8932B/33(B) Class-D audio amplifier
• Manufacturer: PHILIPS [NXP Semiconductors]

NXP Semiconductors
AN10436_1
Application note
3.2 Peak output current estimation
3.3 Control circuit
The most important benefit of cycle-by-cycle current limiting is the loss of audio holes
without requiring a lot of head room towards the maximum peak output current of the
TDA8932B/33(B). The peak output current is limited internally above:
During normal operation, the output current should not exceed the threshold level of
I
cause distortion. The peak output current in either SE or BTL can be estimated through
the use of these equations:
Where:
Example TDA8932B (I
A 4 Ω speaker in the SE configuration can be used until a supply voltage of 33 V (approx.)
without running into current limiting.
A 4 Ω speaker in the BTL configuration can be used until a supply voltage of
17.5 V (approx.) without running into current limiting.
The recommended POWERUP circuit is a resistor divider between the supply voltage and
CGND of the amplifier. Optionally a transistor can be used to enter SLEEP mode to
reduce the power consumption in e.g., system idle mode.
SE: I
BTL: I
O(ocp)
•
•
V
R
R
R
R
P
L
DSon
s
ESR
4 A minimum for the TDA8932B.
2 A minimum for the TDA8933(B).
O peak
= series resistance output inductor (Ω)
= load impedance (Ω)
= supply voltage (V) (V
= 4 A minimum (TDA8932B) or I
(
O peak
= equivalent series resistance of SE capacitance (Ω)
(
= on-resistance power switch (Ω)
)
≤
)
≤
--------------------------------------------------------- -
R
L
--------------------------------------------------- -
R
+
L
+
R
DSon
2
Rev. 01 — 12 December 2007
0.5 V
⋅
O(ocp)
(
V
R
⋅
+
DSon
p
R
P
s
DDP
= 4 A minimum):
+
+
R
-V
R
ESR
s
SSP
)
)
O(ocp)
= 2 A minimum (TDA8933(B)) because it will
TDA8932B/33(B) Class-D audio amplifier
AN10436
© NXP B.V. 2007. All rights reserved.
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