AD7112:  Dual CMOS Multiplying DAC with Anti-Log Transfer Function for Audio Volume Control Applications

The LOGDAC ™ AD7112 is a monolithic dual multiplying D/A converter featuring a wide dynamic range and excellent DAC-to-DAC matching. Both DACs can attenuate an analog input signal over the range 0 to 88.5 dB in 0.375 dB steps. It is available in skinny 0.3" wide 20-pin DIPs and in 20-terminal surface mount packages.

The degree of attenuation in either channel is determined by the 8-bit word applied to the on-board decode logic. This 8-bit word is decoded into a 17-bit weord thich is then loaded into one of the 17-bit data latches, determined by DACA/DACB. The fine step resolution over the entire dynamic range is due to the use of these 17-bit DACs.

The AD7112 is easily interfaced to a standard 8-bit MPU bus via an 8-bit data port and standard microprocessor control lines. It should be noted that the AD7112 is exactly pin-compatible with the AD7528, an industry standard dual 8-bit multiplying DAC. This allows an easy upgrading of existing AD7528 designs which would benefit both from the wider dyanmic range and the finer step resolution offered by the AD7112.

The AD7112 is fabricated in Linear Compatible CMOS (LC²MOS), an advanced, mixed technology process that combines precision bipolar circuits with low power CMOS logic.

LOGDAC is a registered trademark of Analog Devices, Inc.