AD584

REV. A

–7–

istics and long-term stability of the device will be essentially the

same as that of a unit used in the standard three-terminal mode.

Figure 13. Two-Terminal –5 Volt Reference

The AD584 can also be used in a two-terminal mode to develop

positive supply through an appropriate supply resistor. The per-

formance characteristics will be similar to those of the negative

two-terminal connection. The only advantage of this connection

over the standard three-terminal connection is that a lower pri-

mary supply can be used, as low as 0.5 volts above the desired

output voltage. This type of operation will require considerable

attention to load and primary supply regulation to be sure the

AD584 always remains within its regulating range of 1 mA to

5 mA (2 mA to 5 mA for operation beyond 85

°C).

10 VOLT REFERENCE WITH MULTIPLYING CMOS D/A

OR A/D CONVERTERS

The AD584 is ideal for application with the entire AD7520

series of 10- and 12-bit multiplying CMOS D/A converters,

especially for low power applications. It is equally suitable for

the AD7574 8-bit A/D converter. In the standard hook-up as

shown in Figure 14, the standard output voltages are inverted

by the amplifier/DAC configuration to produce converted volt-

age ranges. For example, a +10 V reference produces a 0 V to

–10 V range. If an AD308 amplifier is used, total quiescent sup-

ply current will typically be 2 mA. The AD584 will normally be

used in the –10 volt mode with the AD7574 to give a 0 volt to

+10 volt ADC range. This is shown in Figure 16. Bipolar out-

put applications and other operating details can be found in the

data sheets for the CMOS products.

Figure 14. Low Power 10-Bit CMOS DAC Application

PRECISION D/A CONVERTER REFERENCE

The AD562, like many D/A converters, is designed to operate

with a +10 volt reference element (Figure 15). In the AD562,

this 10 volt reference voltage is converted into a reference cur-

rent of approximately 0.5 mA via the internal 19.95 k

Ω resistor

(in series with the external 100

Ω trimmer). The gain tempera-

ture coefficient of the AD562 is primarily governed by the tem-

perature tracking of the 19.95 k

Ω resistor and the 5k/10k span

resistors; this gain T.C. is guaranteed to 3 ppm/

°C. Thus, using

the AD584L (at 5 ppm/

°C) as the 10 volt reference guarantees a

Figure 15. Precision 12-Bit D/A Converter