Datasheet

AD580
Rev. B | Page 7 of 8
THE AD580 AS A LOW POWER, LOW VOLTAGE,
PRECISION REFERENCE FOR DATA CONVERTERS
The AD580 has a number of features that make it ideally suited
for use with A/D and D/A data converters used in complex
microprocessor-based systems. The calibrated 2.500 V output
minimizes user trim requirements and allows operation from a
single, low voltage supply. Low power consumption (1 mA
quiescent current) is commensurate with that of CMOS-type
devices, while the low cost and small package complements the
decreasing cost and size of the latest converters.
Figure 12 shows the AD580 used as a reference for the AD7542
12-bit CMOS DAC with complete microprocessor interface.
The AD580 and the AD7542 are specified to operate from a
single 5 V supply, thus eliminating the need to provide a 15 V
power supply for the sole purpose of operating a reference. The
AD7542 includes three 4-bit data registers, a 12-bit DAC
register, and address decoding logic. It may thus be interfaced
directly to a 4-, 8- or 16-bit data bus. Only 8 mA of quiescent
current from the single 5 volt supply is required to operate the
AD7542 which is packaged in a small, 16-pin DIP. The AD544
output amplifier is also low power, requiring only 2.5 mA
quiescent current. Its laser-trimmed offset voltage preserves the
±1/2 LSB linearity of the AD7542KN without user trims, and it
typically settles to ±1/2 LSB in less than 3 µs. It will provide the
0 V to –2.5 V output swing from ±5 V supplies.
00525-B-012
7
D0
6
D1
5
D2
4
D3
AD7542
CLR
13
FROM SYSTEM RESET
FROM ADDRESS BUS
A0
10
A0
A1
11
A1
WR
9
FROM WR
CS
812
3
1514
16
1
2
FROM ADDRESS DECODER
AD7 AD0
SYSTEM
8-BIT DATA BUS
AD544L
DGND
–5V
ANALOG
INPUT
AGND
I
OUT2
I
OUT1
RFB
V
REF
V
DD
22pF
200Ω
500Ω
GAIN
ADJUST
E
OUT
+E
+5V
–E
AD580
Figure 12. Low Power, Low Voltage Reference for the AD7542
Microprocessor-Compatible, 12-Bit DAC