TDF8591TH datasheet(8/34 Pages) NXP

8 / 34 page

TDF8591TH_1

Product data sheet

Rev. 01 — 5 March 2008

8 of 34

NXP Semiconductors

TDF8591TH

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

6.4.4 Window protection

The WP checks the conditions at the output pins 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 pins to VDD or VSS the start-up

procedure is interrupted and the TDF8591TH waits until the short-circuit to the supply

lines has been removed. Because the test is done before enabling the power stages,

no large currents will ﬂow in the event of a short-circuit.

• When the ampliﬁer is completely shut down due to activation of the OCP by a

short-circuit to one of the supply lines, the window protection will then be activated

during restart (after 100 ms). As a result the ampliﬁer will not start up until the

short-circuit to the supply lines is removed.

6.4.5 Supply voltage protections

If the supply voltage drops below

±12.5 V, the UVP circuit is activated and the

TDF8591TH switch-off will be silent and without pop noise. When the supply voltage rises

above

±12.5 V, the TDF8591TH is restarted again after 100 ms.

If the supply voltage exceeds

±33 V the OVP circuit is activated and the power stages will

shut down. It is re-enabled as soon as the supply voltage drops below

±33 V. So in this

case no timer of 100 ms is started. The maximum operating supply voltage is

±29 V and if

the supply voltage is above the maximal allowable voltage of

±34 V (see Section 7), the

TDF8591TH can be damaged, irrespective of an activated OVP. See Section 12.6

“Pumping effects” for more information about the use of the OVP.

An additional UBP circuit compares the positive analog (VDDA) and the negative analog

(VSSA) supply voltages and is triggered if the voltage difference between them exceeds

the unbalance threshold level, which is expressed as follows:

When the supply voltage difference VDDA − VSSA exceeds Vth(unb), the TDF8591TH

switches off and is restarted again after 100 ms.

Example: With a symmetrical supply of VDDA = 20 V and VSSA = −20 V, the unbalance

protection circuit will be triggered if the unbalance exceeds approximately 6 V.

In Table 4 an overview is given of all protections and the effect on the output signal.

[1]

Ampliﬁer gain will depend on junction temperature and heat sink size.

[2]

Thermal foldback will inﬂuence restart timing depending on heat sink size.

Table 4.

Overview protections TDF8591TH

Protection name

Complete shut down Restart directly

Restart every 100 ms

DIAG

Y[1]

OTP

Y[2]

N[2]

OCP

N[3]

Y[3]

N[3]

Y[4]

UVP

OVP

UBP

th unb

()

0.15

DDA

SSA

–

()

≈

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