Datasheet AD587 (Analog Devices) - 10

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AD587 APPLICATIONS INFORMATION USING THE AD587 WITH CONVERTERS +VIN
The AD587 is an ideal reference for a variety of 8-bit, 12-bit,
2
14-bit, and 16-bit ADCs and DACs. Several examples follow.
+VIN V 10V OUT 6 I 10 V Reference with Multiplying CMOS DACs or ADCs L = + IBIAS R AD587 C RC 500Ω
The AD587 is ideal for applications with 10-bit and 12-bit
MIN GND
multiplying CMOS DACs. In the standard hookup, shown in
4
21 -0 Figure 18, the AD587 is paired with the AD7545 12-bit multi- 530 00 plying DAC and the AD711 high speed BiFET op amp. The Figure 20. Precision Current Source amplifier DAC configuration produces a unipolar 0 V to −10 V
Precision High Current Supply
output range. Bipolar output applications and other operating details can be found in the individual product data sheets. For higher currents, the AD587 can easily be connected to a power PNP or power Darlington PNP device. The circuits in
+15V +15V R2
Figure 21 and Figure 22 can deliver up to 4 A to the load. The
0.1µF +15V
0.1 μF capacitor is required only if the load has a significant
C1 33pF +V 0.1µF IN
capacitive component. If the load is purely resistive, improved
AD587 VDD RFB
high frequency supply rejection results can be obtained by
OUT1 VOUT VREF
removing the capacitor.
AD711 VOUT AD7545 TRIM 10kΩ AGND 0V TO –10V +VIN GND DGND 0.1µF
19 0 0-
220Ω DB11 TO DB0 –15V
53 00
2N6285
Figure 18. Low Power 12-Bit CMOS DAC Application The AD587 can also be used as a precision reference for multi- ple DACs. Figure 19 shows the AD587, the AD7628 dual DAC, and the AD712 dual op amp hooked up for single-supply
0.1µF
operation to produce 0 V to −10 V outputs. Because both DACs are on the same die and share a common reference and output
2
op amps, the DAC outputs will exhibit similar gain temperature
+VIN
coefficients (TCs).
10V AD587 VOUT 6 IL = + IBIAS RC +15V RC +15V GND
22
0.1µF 4
0 0- 53
+VIN RFB A
00
VREFA OUT A V
Figure 21. Precision High Current Source
OUT DAC A AD587 V +VIN AGND OUTA = DB0 0 TO –10V GND DATA AD7628 AD712 INPUTS DB7 RFB B 220Ω OUT B 18 VREFB DAC B 2N6285 VOUTB = DGND 0 TO –10V
0 -02 30 05 0
0.1µF
Figure 19. AD587 as a 10 V Reference for a CMOS Dual DAC
Precision Current Source 2
The design of the AD587 allows it to be easily configured as a cur-
+VIN
rent source. By choosing the control resistor (RC) via the equation
V AD587 V OUT OUT 6 +10V @ 4A
shown in Figure 20, the user can vary the load current from the quiescent current (2 mA typically) to approximately 10 mA.
GND 4
3 -02 530 00 Figure 22. Precision High Current Voltage Source Rev. H | Page 10 of 12 Document Outline FEATURES FUNCTIONAL BLOCK DIAGRAM GENERAL DESCRIPTION PRODUCT HIGHLIGHTS TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS THEORY OF OPERATION APPLYING THE AD587 NOISE PERFORMANCE AND REDUCTION TURN-ON TIME DYNAMIC PERFORMANCE LOAD REGULATION TEMPERATURE PERFORMANCE NEGATIVE REFERENCE VOLTAGE FROM AN AD587 APPLICATIONS INFORMATION USING THE AD587 WITH CONVERTERS 10 V Reference with Multiplying CMOS DACs or ADCs Precision Current Source Precision High Current Supply OUTLINE DIMENSIONS ORDERING GUIDE