TDA8922C
NXP Semiconductors
2 × 75 W class-D power amplifier
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 TDA8922C 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.
WP will be activated when the amplifier attempts to restart after 100 ms (see
Section 8.3.2). The amplifier will not start-up again until the short circuit to the supply
lines has been removed.
8.3.4 Supply voltage protection
If the supply voltage drops below the minimum supply voltage threshold, Vth(uvp), the UVP
circuit will be activated and the system will shut down. Once the supply voltage rises
above Vth(uvp) again, the system will restart after a delay of 100 ms.
If the supply voltage exceeds the maximum supply voltage threshold, Vth(ovp), the OVP
circuit will be activated and the power stages will be shut down. When the supply voltage
drops below Vth(ovp) again, the system will restart after a delay of 100 ms.
An additional UnBalance Protection (UBP) circuit compares the positive analog supply
voltage (on pin VDDA) with the negative analog supply voltage (on pin VSSA) and is
triggered if the voltage difference exceeds a factor of two (VDDA > 2 × |VSSA| OR |VSSA| >
2 × VDDA). When the supply voltage difference drops below the unbalance threshold,
Vth(ubp), the system restarts after 100 ms.
An overview of all protection circuits and their respective effects on the output signal is
provided in Table 5.
Table 5.
Overview of TDA8922C protection circuits
Protection name Complete
shutdown
Restart directly Restart after
100 ms
Pin PROT
detection
TFB[1]
OTP
OCP
WP
N
N
N
N
N
Y
N
N
N
N
Y
N
N[2]
Y
Y[2]
Y[2]
N[3]
Y
Y
N
UVP
OVP
UBP
N
Y
Y
N
Y
Y
N
Y
[1] Amplifier gain depends on the junction temperature and heatsink size.
[2] The amplifier shuts down completely only if the short-circuit impedance is below the impedance threshold
(Zth; see Section 8.3.2). In all other cases, current limiting results in a clipped output signal.
[3] Fault condition detected during any Standby-to-Mute transition or during a restart after OCP has been
activated (short-circuit to one of the supply lines).
8.4 Differential audio inputs
The audio inputs are fully differential ensuring a high common mode rejection ratio and
maximum flexibility in the application.
TDA8922C_1
© NXP B.V. 2009. All rights reserved.
Product data sheet
Rev. 01 — 7 September 2009
11 of 40
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