NXP Semiconductors TDA8932B - Manual (Page 10)

TDA8932B_4 © NXP B.V. 2008. All rights reserved.
Product data sheet Rev. 04 — 18 December 2008 10 of 48
NXP Semiconductors
TDA8932B
Class-D audio amplifier
• When the amplifier is completely shut down due to activation of the OCP because a
short-circuit to one of the supply lines is made, then during restart (after 100 ms) the
window protection will be activated. As a result the amplifier will not start until the
short-circuit to the supply lines is removed.
8.4.5 Supply voltage protection
If the supply voltage drops below 10 V, the UnderVoltage Protection (UVP) circuit is
activated and the system will shut down directly. This switch-off will be silent and without
pop noise. When the supply voltage rises above the threshold level, the system is
restarted again after 100 ms.
If the supply voltage exceeds 36 V the OverVoltage Protection (OVP) circuit is activated
and the power stages will shut down. It is re-enabled as soon as the supply voltage drops
below the threshold level. The system is restarted again after 100 ms.
It should be noted that supply voltages > 40 V may damage the TDA8932B. Two
conditions should be distinguished:
1. If the supply voltage is pumped to higher values by the TDA8932B application itself
(see also Section 14.3 ), the OVP is triggered and the TDA8932B is shut down. The
supply voltage will decrease and the TDA8932B is protected against any overstress.
2. If a supply voltage > 40 V is caused by other or external causes, then the TDA8932B
will shut down, but the device can still be damaged since the supply voltage will
remain > 40 V in this case. The OVP protection is not a supply voltage clamp.
An additional UnBalance Protection (UBP) circuit compares the positive analog supply
voltage (V
DDA
) and the negative analog supply voltage (V
SSA
) and is triggered if the
voltage difference between them exceeds a certain level. This level depends on the sum
of both supply voltages. The unbalance threshold levels can be defined as follows:
• LOW-level threshold: V
P(th)(ubp)l
< 8 ⁄
5
×
V
HVPREF
• HIGH-level threshold: V
P(th)(ubp)h
> 8 ⁄
3
×
V
HVPREF
In a symmetrical supply the UBP is released when the unbalance of the supply voltage is
within 6 % of its starting value.
Table 6 shows an overview of all protection and the effect on the output signal.
Table 6. Protection overview
Protection Restart
When fault is removed Every 100 ms
OTP no yes
OCP yes no
WP yes no
UVP no yes
OVP no yes
UBP no yes