The THAT 4305
Pre-trimmed High-voltage
Low-power Analog Engine®
A single chip Analog Engine optimized for high-voltage, low-power operation
incorporating a high performance voltage controlled amplifier and RMS-level
detector. The THAT4305 was introduced at this years Musikmesse in Frankfurt.
The THAT4305 is a single-chip
Analog Engine optimized for low-cost applications. It incorporates a
high-performance Blackmer® voltage-controlled amplifier (VCA) and log-responding
RMS-level sensor. The VCA and RMS detector are pre-trimmed at wafer stage to
deliver low distortion without further adjustment.
Available only in a small (QSOP) surface- mount package, the 4305 is aimed at
line-operated audio applications such as compressor/limiters, gates, and other
dynamic processors. The part normally operates from a split supply voltage up to
±16 Vdc, drawing only 3.5 mA at ±15 V. This IC also works at supply voltages as
low as ±4.5 V, making it useful in some battery-operated products as well.
The 4305 was developed specifically for use in low-cost dynamics processors,
drawing from THAT's long history and experience with such designs. Both VCA
control ports and the detector input and output are available for the designer
to connect as s/he sees fit. As a result, the part is extremely flexible and can
be configured for a wide range of applications including single- and multi-band
companders, digital overload protectors, voltage-controlled faders, level
indicators, etc.
What really sets the 4305 apart from other manufacturers’ offerings is the
transparent sound of its Blackmer VCA, coupled with its accurate true-RMS level
detector. This makes the IC useful in a wide range of analog audio products.
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Basic Specifications |
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(typical) |
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VCA Section |
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Gain Range: -60 to +60 dB
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Gain-Control Constant: ± 6.2
mV/dB |
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Output Noise: -97.5 dBV (typ,
0 dB gain) |
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Total Harmonic Distortion:
0.07 % |
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Dynamic Range: 117 dB |
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Detector Section |
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Averaging Method: Root Mean
Square (RMS) |
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Output Scaling: +6.2 mV/dB
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Dynamic Range: 60 dB
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Bandwidth: > 20 kHz
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Crest Factor: 10 (for 1 dB
reading error) |
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Overall |
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Power supply voltage: ±4.5 to
±16 V |
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Supply current: typically 3.5
mA (±15V) |
