TDF8591TH_1

© NXP B.V. 2008. All rights reserved.

Product data sheet

Rev. 01 — 5 March 2008

9 of 34

NXP Semiconductors

TDF8591TH

2

× 100 W SE (4 Ω) or 1 × 310 W BTL (4 Ω) class-D amplifier

[3]

Only complete shut down of amplifier in case of a short-circuit. In all other cases current limiting resulting in

clipping output signal.

[4]

Fault condition detected during (every) transition between standby-to-mute and during restart after

activation of OCP (short-circuit to one of the supply lines).

6.5 Diagnostic output

Pin DIAG is pulled LOW when the OCP is triggered. With a continuous short-circuited load

a switching pattern in the voltage on pin DIAG is observed (see Figure 6). A permanent

LOW on pin DIAG indicates a short-circuit to the supply lines whereas a short-circuited

load causes a switching DIAG pin (see Section 6.4.3).

pull-up. An example of a circuit to read out and level shift the diagnostic data is given in

Figure 7. V5V represents a logic supply that is used in the application by the

microprocessor that reads out the DIAG data.

6.6 Differential inputs

For a high Common Mode Rejection Ratio (CMRR) 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 channels can be inverted, so that a load can be connected between

the two output filters. In this case the system operates as a mono BTL amplifier.

The input configuration for a mono BTL application is illustrated in Figure 8.

In the stereo SE configuration it is also recommended to connect the two differential

inputs in anti-phase. This has advantages for the current handling of the supply voltage at

low signal frequencies (supply pumping).

Fig 7.

DIAG readout circuit with level shift

001aad840

100 k

Ω

100 k

Ω

27 k

Ω

5.6 V

10 k

Ω

DIAG

DIAG

out

SGND

M2

V5V

M1