TAS5414B-Q1_16 Datasheet, PDF (14/46 Pages) Texas Instruments – FOUR-CHANNEL AUTOMOTIVE DIGITAL AMPLIFIERS

TAS5414B-Q1
TAS5424B-Q1
SLOS673 – DECEMBER 2011
DESCRIPTION OF OPERATION
www.ti.com
OVERVIEW
The TAS5414B-Q1 and TAS5424B-Q1 are single-chip, four-channel, analog-input audio amplifiers for use in the
automotive environment. The design uses an ultra-efficient class-D technology developed by Texas Instruments,
but with changes needed by the automotive industry. This technology allows for reduced power consumption,
reduced heat, and reduced peak currents in the electrical system. The device realizes an audio sound system
design with smaller size and lower weight than traditional class-AB solutions.
There are eight core design blocks:
• Preamplifier
• PWM
• Gate drive
• Power FETs
• Diagnostics
• Protection
• Power supply
• I²C serial communication bus
Preamplifier
The preamplifier is a high-input-impedance, low-noise, low-offset-voltage input stage with adjustable gain. The
high input impedance allows the use of low-cost input capacitors while still achieving extended low-frequency
response. The preamplifier is powered by a dedicated, internally regulated supply, which gives it excellent noise
immunity and channel separation. Also included in the preamp are:
1. Mute Pop-and-Click Control— The device ramps the gain gradually when a mute or play command is
received. Another form of click and pop can be caused by the start or stopping of switching in a class-D
amplifier. The TAS5414B-Q1 and TAS5424B-Q1 incorporate a patented method to reduce the pop energy
during the switching startup and shutdown sequence. Fault conditions require rapid protection response by
the TAS5414B-Q1 and the TAS5424B-Q1, which do not have time to ramp the gain down in a pop-free
manner. The device transitions into Hi-Z mode when an OV, UV, OC, OT, or DC fault is encountered. Also,
activation of the STANDBY pin may not be pop-free.
2. Gain Control—The four gain settings are set in the preamplifier via I²C control registers. The gain is set
outside of the global feedback resistors of the device, thus allowing for stability of the system at all gain
settings with properly loaded conditions.
Pulse-Width Modulator (PWM)
The PWM converts the analog signal from the preamplifier into a switched signal of varying duty cycle. This is
the critical stage that defines the class-D architecture. In the TAS5414B-Q1 and TAS5424B-Q1, the modulator is
an advanced design with high bandwidth, low noise, low distortion, excellent stability, and full 0–100%
modulation capability. The patented PWM uses clipping recovery circuitry to eliminate the deep saturation
characteristic of PWMs when the input signal exceeds the modulator waveform.
Gate Drive
The gate driver accepts the low-voltage PWM signal and level shifts it to drive a high-current, full-bridge, power
FET stage. The device uses proprietary techniques to optimize EMI and audio performance.
Power FETs
The BTL output for each channel comprises four rugged N-channel 30-V 65 mΩ FETs for high efficiency and
maximum power transfer to the load. These FETs are designed to handle large voltage transients during load
dump.
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Copyright © 2011, Texas Instruments Incorporated