AN10436 PHILIPS [NXP Semiconductors], AN10436 Datasheet - Page 15

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

NXP Semiconductors
AN10436_1
Application note
2.6.4 UnderVoltage Protection (UVP)
2.6.5 OverVoltage Protection (OVP)
2.6.6 UnBalance Protection (UBP)
High threshold level:
Where:
The TDA8932B/33(B) will recover when the output voltage at OUT1 and OUT2 is within
(21/32) V
The TDA8932B/33(B) requires a minimum supply voltage for proper operation. When the
supply voltage drops below the UVP threshold level of 9.5 V (typical V
power stage becomes floating and the DIAG is set low for at least 50 ms.
An OVP is incorporated because an SE Class-D amplifier is able to increase the supply
voltage when it is driven at low audio frequencies. This phenomenon is better known as
"supply pumping" (see also
the absolute maximum supply voltage rating of the TDA8932B/33(B). This is a protection
against self-destruction. The OVP threshold level is an internal fixed level at 38.5 V
(typical V
floating and the DIAG is set low for at least 50 ms.
Remark: The OVP will neither prevent nor limit an overvoltage caused by the power
supply.
The UBP senses the supply voltage unbalance between the analog supply voltages V
and V
unbalance exceeds a certain level to avoid improper biasing resulting in e.g. pop. The
DIAG is set low and remains low for at least 50 ms.
The supply voltage where the UBP becomes active with an asymmetrical supply can be
estimated as follows:
Low threshold level:
High threshold level:
Where:
V
V
V
O wp
P ubp
P ubp
V
V
V
V
(
(
(
O(wp)
DDA
P(ubp)
SSA
SSA
)h
)l
)h
(V).
= analog supply voltage (V).
=
= window protection output voltage (low or high). Referenced to V
=
=
DDA
DDA
= unbalance protection supply voltage (low and high). V
with respect to the HVPREF voltage at pin 11. The UBP is triggered when the
21
----- - V
32
8
-- - V
5
8
-- - V
3
⋅
− V
⋅
> V
⋅
HVPREF
HVPREF
DDA
SSA
o
> (11/32) V
). Beyond this OVP threshold level the power stage will become
Rev. 01 — 12 December 2007
Section
DDA
.
4.3). The OVP prevents that supply pumping exceeds
TDA8932B/33(B) Class-D audio amplifier
DDA
(pin 8) referenced to
DDA
AN10436
© NXP B.V. 2007. All rights reserved.
− V
SSA
SSA
(V).
), the
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DDA
(4)
(5)
(6)