General description

1.1 Amplifiers

The TDF8553 has a complementary quad audio power amplifier that uses BCDMOS technology. It contains four amplifiers configured in Bridge Tied Load (BTL) to drive speakers for front and rear left and right channels. The I2C-bus allows diagnostic information of each amplifier and its speaker to be read separately. Both front and both rear channel amplifiers can be configured independently in line driver mode with a gain of 20 dB (differential output) or amplifier mode with a gain of 26 dB (BTL output).

1.2 Voltage regulators

The TDF8553 has a multiple output voltage regulator with two power switches.

The voltage regulator contains the following:

• Four switchable regulators and two standby regulators

• Two power switches with loss-of-ground protection and surge protection

• Second supply pin to reduce dissipation by means of an external DC-to-DC converter

Features

Amplifiers

I2C-bus control

Can drive a 2Ωload with a battery voltage of up to 16 V and a 4 Ωload with a

battery voltage of up to 18 V

DC load detection, open, short and present

AC load (tweeter) detection

Programmable clip detect; 1 or 4

Programmable thermal protection pre-warning

Independent short-circuit protection per channel

Selectable line driver (20 dB) and amplifier mode (26 dB)

Loss-of-ground and open VPsafe

All outputs protected from short-circuit to ground, to VPor across the load

All pins protected from short-circuit to ground

Soft thermal-clipping to prevent audio holes

Low battery detection

Voltage regulators

I2C-bus control

Good stability for any regulator with almost any output capacitor value

Six voltage regulators (microcontroller, display, audio processor, tuner, bus, mechanical digital and drive)

Selectable output voltages for regulators 1, 4 and 5

Low dropout voltage PNP output stages

High supply voltage ripple rejection

Low noise for all regulators

Two power switches (antenna switch and amplifier switch)

Standby regulators 2 and 6 (microcontroller and bus supply) operational during load dump and thermal shut-down

Low standby quiescent current (only regulators 2 and 6 operational)

Second supply pin for connecting optional external DC-to-DC converter to reduce internal dissipation

Backup functionality for regulator 2

Protection

If connection to the battery voltage is reversed, all regulator voltages will be zero

Able to withstand output voltages up to 18 V (supply line may be short-circuited)

Thermal protection to avoid thermal breakdown

Load-dump protection

Regulator outputs protected from DC short-circuit to ground or to supply voltage

All regulators protected by foldback current limiting

Power switches protected from loss-of-ground and surge conditions

Applications

Boost amplifier and voltage regulator for car radios and CD/MD players