TDA8950 datasheet(11/39 Pages) PHILIPS

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TDA8950_2

Product data sheet

Rev. 02 — 11 June 2009

11 of 39

NXP Semiconductors

TDA8950

× 150 W class-D power ampliﬁer

8.3.4 Supply voltage protection

If the supply voltage drops below the minimum supply voltage threshold, VP(uvp), the UVP

circuit will be activated and the system will shut down. Once the supply voltage rises

above VP(uvp) again, the system will restart after a delay of 100 ms.

If the supply voltage exceeds the maximum supply voltage threshold, VP(ovp), the OVP

circuit will be activated and the power stages will be shut down. When the supply voltage

drops below VP(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| >

× V

DDA). When the supply voltage difference drops below the unbalance threshold,

VP(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.

[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.

• Stereo operation: to avoid acoustical phase differences, the inputs should be in

antiphase and the speakers should be connected in antiphase. This conﬁguration:

– minimizes power supply peak current

– minimizes supply pumping effects, especially at low audio frequencies

• Mono BTL operation: the inputs must be connected in anti-parallel. The output of one

channel is inverted and the speaker load is connected between the two outputs of the

TDA8950. In practice (because of the OCP threshold) the output power can be

boosted to twice the output power that can be achieved with the single-ended

conﬁguration.

The input conﬁguration for a mono BTL application is illustrated in Figure 7.

Table 5.

Overview of TDA8950 protection circuits

Protection name

Complete

shutdown

Restart directly

Restart after

100 ms

Pin PROT

detection

TFB[1]

NNNN

OTP

OCP

Y[2]

N[2]

Y[2]

N[3]

UVP

OVP

UBP

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