ADI AD1864P

The AD1864 is a complete dual 18-bit DAC offering excellent THD+N, while requiring no external components. Two complete signal channels are included. This results in cophased voltage or current output signals and eliminates the need for output demultiplexing circuitry. The monolithic AD1864 chip includes CMOS logic elements, bipolar and MOS linear elements and laser-trimmed thin-film resistor elements, all fabricated on Analog Devices BiMOS II process. The DACs on the AD1864 chip employ a partially-segmented architecture. The first four MSBs of each DAC are segmented into 15 elements. The 14 LSBs are produced using standard R-2R techniques. Segment and R-2R resistors are laser-trimmed to provide extremely low total harmonic distortion. This architecture minimizes errors at major code transitions resulting in low output glitch and eliminating the need for an external deglitcher. When used in the current output mode, the AD1864 provides two cophased ±1 mA output signals. Each channel is equipped with a high performance output amplifier. These amplifiers achieve fast settling and high slew rate, producing ±3V signals at load currents up to 8 mA. Each output amplifier is short-circuit protected and can withstand indefinite short circuits to ground. The AD1864 was designed to balance two sets of opposing requirements, channel separation and DAC matching. High channel separation is the result of careful layout techniques. At the same time, both channels of the AD1864 have been designed to ensure matched gain and linearity as well as tracking over time and temperature. This assures optimum performance when used in stereo and multi-DAC per channel applications. The AD1864 operates from ±5 V to ±12 V power supplies. The digital supplies, VL and -VI, can be separated from the analog supplies, Vs and -Vs, for reduced digital feedthrough. Separate analog and digital ground pins are also provided. The AD1864 typically dissipates only 225 mW, with a maximum power dissipation of 265 mW. The AD1864 is packaged in both a 24-pin plastic DIP and a 28-pin PLCC. Operation is guaranteed over the temperature range of -25°C to +70°C and over the voltage supply range of ±4.75 V to ±13.2 V.

• The AD1864 is a complete dual 18-bit audio DAC.
• 108 dB signal-to-noise ratio for low noise operation.
• THD+N is typically 0.0017%
• Interchannel gain and midscale matching.
• Output voltages and currents are cophased.
• Low glitch for improved sound quality.
• Both channels are 100% tested at 8 × Fs
• Low Power - only 225 mW typ, 265 mW max.
• 5-wire interface for individual DAC control.