Pro Audio Design Forum

The THAT 626x is a family of two-channel “all-in-one” digitally controlled preamplifiers with integrated ADC drivers. Gain is programmable from -8 to +34 dB. The low-power (60 mW) devices can be powered from unipolar (+10 V and +5 V) or bipolar (±5 V) supplies. The 626x family includes three products distinguished primarily by step size. (1, 3 and 6 dB Ed.) All three parts offer excellent noise performance: at maximum gain: the 6261 EIN is -127 dBu; the 6263 and 6266 are -126 dBu. Dynamic range at minimum gain is up to 118.7 dB.

Their outputs interface directly to commonly used 5 V ADC ICs with 2Vrms differential full-scale inputs. Accordingly, these parts serve as a complete solution to connect an audio input to an A/D converter.

To minimize audibility of gain changes with signal, all 626x family members can be programmed to synchronize gain changes with signal zero crossings. To enable seamless external gain changes, a BUSY pin for each channel allows external events to be synchronized with zero crossings.

The parts are controlled via a 4-wire SPI interface running at up to 7.5 MHz (+3.3V supply). Multiple devices may be daisy-chained using one chip select.

Four general purpose logic outputs (GPOs) are available to control external circuitry (e.g., pad, phantom power). The GPOs may be synchronized with zero-crossings. Each channel may be set to low-power standby mode, and can be muted by about 62 dB.

The 626x comes in a 7X7 mm 48-pin QFN package. They are truly all-in-one mic preamps – from XLR to ADC.