TDA8920C Datasheet, PDF (10/40 Pages) NXP Semiconductors – 2 X110 W class-D power amplifier

NXP Semiconductors
TDA8920C
2 × 110 W class-D power amplifier
If an impedance drop occurs (e.g. due to dynamic behavior of the loudspeaker) OCP is
activated. The maximum output current stays limited to 9.2 A but the amplifier will not
switch off completely, preventing audio holes from occurring. The result is a clipped output
signal.
See Section 13.7 for more information on this maximum output current limiting feature.
8.3.3 Window Protection (WP)
Window Protection (WP) checks the conditions at the output terminals of the power stage
and is activated:
• During the start-up sequence, when pin MODE is switched from standby to mute. In
the event of a short-circuit at one of the output terminals to pin VDDPn or pin VSSPn,
the start-up procedure is interrupted. The TDA8920C waits until the short-circuit to the
supply lines is removed. No large currents will flow in the event of a short-circuit
because the test is done before the power stages are enabled.
• When the amplifier shuts down completely due to OCP activation because of a
short-circuit to one of the supply lines; WP is activated during a restart after 100 ms.
The amplifier will not start up until the short-circuit to the supply lines is removed.
8.3.4 Supply voltage protection
If the supply voltage drops below the minimum supply voltage, the UnderVoltage
Protection (UVP) circuit is activated and the system shuts down correctly. If the internal
clock is used, the switch-off will be silent and without pop noise. When the supply voltage
rises above the threshold level, the system restarts after 100 ms.
If the supply voltage exceeds the maximum supply voltage, the OVP circuit is activated
and the power stages are shut down. When the supply voltage drops below the threshold
level, the system restarts after 100 ms.
An additional UnBalance Protection (UBP) circuit compares the positive analog voltage
(on pin VDDA) and the negative analog supply voltage (on pin VSSA) and is triggered if
the voltage difference exceeds a factor of two.
When the supply voltage difference drops below the threshold level, the system restarts
after 100 ms.
Example: With a symmetrical supply of ±30 V, the protection circuit is triggered if the
unbalance exceeds approximately 15 V; see Section 13.7.
An overview is given of all protection strategies and their respective effects on the output
signal in Table 4.
TDA8920C_1
Preliminary data sheet
Rev. 01 — 29 September 2008
© NXP B.V. 2008. All rights reserved.
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