NXP公司的TDF8551J是采用BCDMOS技术的I2C总线控制4x45W功率放大器,包含有四个BTL配置的放大器,能驱动四个扬声器:两个前面和两个后面通路.每个放大器可独立配置,线路驱动模式的增益为20dB,放大模式的增益为26dB.此外, TDF8551J还集成了6个输出电压稳压器和两个功率开关.本文介绍了TDF8551J主要特性,方框图和测试与应用电路图.

TDF8551J: I2C-bus controlled 4x45 W power amplifier with six voltage regulators

The TDF8551J has a complementary quad audio power amplifier that uses BCDMOS technology. It contains four amplifiers configured in Bridge-Tied Load (BTL) to drive four speakers: two front and two rear channels. The I2C-bus enables 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).

The TDF8551J has six output voltage regulators and two power switches:

• 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

• Backup functionality for regulator 2

TDF8551J主要特性:

Amplifiers

I2C-bus control

Can drive a 2 load with a battery voltage of up to 16 V and a 4 load 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 3 %

Programmable thermal protection pre-warning

Independent short-circuit protection for each channel

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

Loss-of-ground and open VP safe

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

All pins protected from short-circuit to ground

Soft thermal-clipping to prevent audio holes

Low battery detection

Voltage regulators and switches

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 shutdown

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

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

Withstands 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