Preamplifier; C. Subwoofer Amplifier Stage - Hitachi 55HK6T64U Service Manual

C. SUBWOOFER AMPLIFIER STAGE

PREAMPLIFIER (DRV632)
Description
The DRV632 is a 2-VRMS pop-free stereo line driver designed to allow the removal of the output dc-
blocking capacitors for reduced component count and cost. The device is ideal for single-supply electronics
where size and cost are critical design parameters.
Designed using TI's patented DirectPath™ technology, The DRV632 is capable of driving 2 VRMS into a
10-kΩ load with 3.3-V supply voltage. The device has differential inputs and uses external gain-setting resistors
to support a gain range of ±1 V/V to ±10 V/V, and gain can be configured individually for each channel. Line
outputs have ±8-kV IEC ESD protection, requiring just a simple resistor-capacitor ESD protection circuit. The
DRV632 has built-in active-mute control for pop-free audio on/off control. The DRV632 has an external
undervoltage detector that mutes the output when the power supply is removed, ensuring a pop-free shutdown.
Using the DRV632 in audio products can reduce component count considerably compared to traditional
methods of generating a 2-VRMS output. The DRV632 does not require a power supply greater than 3.3 V to
generate its 5.6-Vpp output, nor does it require a split-rail power supply. The DRV632 integrates its own charge
pump to generate a negative supply rail that provides a clean, pop-free ground-biased 2-VRMS output.
The DRV632 is available in a 14-pin TSSOP.
Features

Stereo DirectPath™ Audio Line Driver
o 2 Vrms Into 10 kΩ With 3.3-V Supply

Low THD+N < 0.01% at 2 Vrms Into 10 kΩ

High SNR, >90 dB

600-Ω Output Load Compliant

Differential Input and Single-Ended Output

Adjustable Gain by External Gain-Setting Resistors

Low DC Offset, <1 mV

Ground-Referenced Outputs Eliminate DC-Blocking Capacitors
o Reduce Board Area
o Reduce Component Cost
o Improve THD+N Performance
o No Degradation of Low-Frequency Response Due to Output Capacitors

Short-Circuit Protection

Click- and Pop-Reduction Circuitry

External Undervoltage Mute

Active Mute Control for Pop-Free Audio On/Off Control

Space-Saving TSSOP Package
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