TDA8932B_3 © NXP B.V. 21 June 2007. All rights reserved.
Product data sheet Rev. 03— 21 June 2007 11 of 48
NXP Semiconductors TDA8932B
Class-D audio amplifier

8.5 Diagnostic input and output

Whenever a protection is triggered, except for TF, pin DIAG is activated to LOW level (see
Table 6). An internal reference supply will pull-up the open-drain DIAG output to
approximately 2.4 V. This internal reference supply can deliver approximately 50 µA.
Pin DIAG refers to pin CGND. The diagnostic output signal during different short
conditions is illustrated in Figure 6. Using pin DIAG as input, a voltage < 0.8 V will put the
device into Fault mode.

8.6 Differential inputs

For a high common-mode rejection ratio and a maximum of flexibility in the application,
the audio inputs are fully differential. By connecting the inputs anti-parallel, the phase of
one of the two channels can be inverted, so that the amplifier can operate as a mono BTL
amplifier. The input configuration for a mono BTL application is illustrated in Figure 7.
In SE configuration it is also recommended to connect the two differential inputs in
anti-phase. This has advantages for the current handling of the power supply at low signal
frequencies and minimizes supply pumping (see also Section 14.8).

8.7 Output voltage buffers

When pin POWERUP is set HIGH, the half supply output voltage buffers are switched on
in asymmetrical supply configuration. The start-up will be pop free since the device starts
switching when the capacitor on pin HVPREF and the SE capacitors are completely
charged.
Output voltage buffers:
Fig 6. Diagnostic output for different short-circuit conditions
001aad759
≈ 50 ms
shorted load
amplifier
restart no restart
≈ 50 ms
0 V
2.4 V
Vo
short to
supply line
0 V
2.4 V
Vo
Fig 7. Input configuration for mono BTL application
001aad760
IN1P OUT1
audio
input
IN2P
IN2N
IN1N
OUT2