TDA8920C NXP Semiconductors, TDA8920C Datasheet - Page 10

• Manufacturer Part Number: TDA8920C
• Description: The TDA8920C is a high-efficiency class-D audio power amplifier
• Manufacturer: NXP Semiconductors

NXP Semiconductors
TDA8920C_2
Product data sheet
8.3.3 Window Protection (WP)
When OCP is activated, the power transistors are turned off. They are turned on again
during the next switching cycle. If the output current is still greater than the OCP threshold,
they will be immediately switched off again. This switching will continue until C
discharged. The amplifier will then be switched off completely and a restart sequence
initiated.
After a fixed period of 100 ms, the amplifier will attempt to switch on again, but will fail if
the output current still exceeds the OCP threshold. The amplifier will continue trying to
switch on every 100 ms. The average power dissipation will be low in this situation
because the duty cycle is low.
Switching the amplifier on and off in this way will generate unwanted ‘audio holes’. This
can be avoided by increasing the value of C
switch-off. C
frequency-dependent impedance drops at the speakers.
The amplifier will switch on, and remain in Operating mode, once the overcurrent
condition has been removed. OCP ensures the TDA8920C amplifier is fully protected
against short-circuit conditions while avoiding audio holes.
Table 4.
[1]
Window Protection (WP) checks the conditions at the output terminals of the power stage
and is activated:
Type
TDA8920C
•
•
OVP can be triggered by supply pumping; see
During the start-up sequence, when the TDA8920C is switching from Standby to
Mute.
Start-up will be interrupted If a short-circuit is detected between one of the output
terminals and pin VDDP1/VDDP2 or VSSP1/VSSP2. The TDA8920C will wait until the
short-circuit to the supply lines has been removed before resuming start-up. The short
circuit will not generate large currents because the short-circuit check is carried out
before the power stages are enabled.
When the amplifier is shut down completely because the OCP circuit has detected a
short circuit to one of the supply lines.
Section
lines has been removed.
WP will be activated when the amplifier attempts to restart after 100 ms (see
Current limiting behavior during low output impedance conditions at different
values of C
PROT
8.3.2). The amplifier will not start-up again until the short circuit to the supply
will also prevent the amplifier switching off due to transient
V
(V)
29.5 500
P
PROT
Rev. 02 — 11 June 2009
V
I
(mV, p-p) f (Hz) C
20
1000
20
1000
1000
Section
(pF)
10
10
15
15
220
PROT
PROT
13.6.
(up to 220 pF) to delay amplifier
yes
yes
yes
no
PWM output stops
Short
(Z
yes
th
2
= 0 )
110 W class-D power amplifier
Short
(Z
yes
yes
yes
no
no
th
= 0.5 )
TDA8920C
© NXP B.V. 2009. All rights reserved.
Short
(Z
OVP
no
OVP
no
no
PROT
th
= 1 )
[1]
[1]
is fully
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