TDA8591 데이터 시트보기 (PDF) - Philips Electronics

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TDA8591

4 × 44W into 4 Ω or 4 × 75W into 2 Ω quad BTL car radio power amplifier

Philips Electronics 

Philips Semiconductors

4 × 44 W into 4 Ω or 4 × 75 W into 2 Ω

quad BTL car radio power amplifier

Preliminary specification

TDA8591J

7 FUNCTIONAL DESCRIPTION

The TDA8591J is an audio power amplifier with four

independent Bridge Tied Load (BTL) amplifiers with high

output power and low distortion. The gain of each amplifier

is fixed at 26 dB. The TDA8591J has two-pin mode control

which allows the amplifiers to be switched to standby (off)

with the STBY pin, and the MUTE/ON pin to be used to

switch between mute mode (input signal suppressed) and

amplifier operating mode.

Special attention is paid to dynamic behaviour:

• A fast mute that switches all amplifiers to mute mode at

low supply voltage and suppresses noise during engine

start

• No plops when switching between standby and mute

modes

• Slow offset change when switching from mute mode to

operating mode (can be adjusted by an external

capacitor)

• A fast mute function by discharging the external mute

capacitor quickly

The following protection circuits are included to prevent

the IC from being damaged:

• Thermal shutdown:

At junction temperature Tvj > 170 °C, all power stages

are switched off to prevent a further increase in

temperature

• Soft thermal clipping:

At junction temperature Tvj > 155 °C, the gain reduces

as temperature increases, resulting in less output power

and decreasing temperature and therefore no thermal

shutdown (no break in the audio)

• Short-circuit protection:

If a short-circuit to ground or supply voltage occurs at

one or more of the output pins, or across the load of one

or more of the channels, the following action occurs to

reduce power dissipation and case temperature

(see Figs 5 and 6):

– All amplifiers switch off for approximately 20 ms

– After 20 ms the amplifiers switch on again

– If the short-circuit persists, the amplifiers switch off for

another 20 ms period and the action repeats

• ESD protection:

– Human body model 2000 V

– Machine model 200 V

• Protection against open ground pins and outputs

short-circuited to supply ground (see Fig.30)

• All outputs protected are against open power supply

pins and outputs short-circuited to power supply voltage

(see Fig.31)

• With a reversed polarity power supply an external diode

conducts and a fuse blows and therefore the reversed

polarity voltage will not damage the device (see Fig.32).

7.1 Diagnostic facility

A diagnostic facility is available from the status of pin DIAG

for the following conditions:

• In normal operation, the level on the DIAG pin is

continuously HIGH (see Fig.3)

• When a temperature pre-warning occurs due to the

junction temperature Tvj reaching 145 °C, the DIAG pin

goes continuously LOW

• When there is distortion over 2.5% because of clipping,

the DIAG pin has a pulsed output as shown in Fig.4

• When a short-circuit is detected, the short-circuit

protection becomes active and DIAG goes continuously

LOW for the period of the short-circuit (see Figs 5 and 6)

• With an extreme output offset, input leakage current

causes a DC output offset voltage and results in power

dissipation in the loudspeakers. Therefore, if the

DC output offset voltage of a bridge is larger than 2 V,

DIAG is pulled LOW to indicate an error condition.

The DIAG pin has an open-drain output to allow several

devices to be tied together. An external pull-up resistor is

needed.

2002 Jan 14

7

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