The DAC729 sets the standard in very high accuracy
digital-to-analog conversion. It is supplied from the
factory at a guaranteed linearity of 16 bits, and is user-
adjustable to 18-bit linearity (1LSB = FSR/262144).
To attain this high level of accuracy, the design takes
advantage of Burr-Brown’s thin-film monolithic DAC
process, dielectric op amp process, hybrid capabilities,
and advanced test and laser-trim techniques.
The DAC729 hybrid layout is specifically partitioned
to minimize the effects of external load-current-
induced thermal errors. The op amp design consists of
a fast settling precision op amp with a current buffer
within the feedback loop. This buffer isolates the load
from the precision op amp, which results in a fast
settling (8µs to 16 bits) output. The standard 40-pin
package offers full hermeticity, contributing to the
excellent reliability of the DAC729.
9
10
11
12
International Airport Industrial Park • Mailing Address: PO Box 11400, Tucson, AZ 85734 • Street Address: 6730 S. Tucson Blvd., Tucson, AZ 85706 • Tel: (520) 746-1111 • Twx: 910-952-1111
= +5V, using internal reference op amp, unless otherwise noted. COB =
±10V
FSR, CSB = 0V to +10V FSR.
DAC729JH
PARAMETER
REFERENCE
Output (pin 32) :Voltage
Source
Temperature Coefficient
Short-Circuit Duration
Power Supply Sensitivity
POWER SUPPLY REQUIREMENTS
Voltage: +V
CC
–V
CC
V
DD
Current: +V
CC
–V
CC
V
DD
Power Dissipation (Rated Supplies)
ENVIRONMENTAL SPECIFICATIONS
Temperature Range: Specification
Storage
* Specifications same as DAC729JH.
NOTES: (1) TTL- and CMOS-compatible. (2) Specified for V
OUT
mode using the internal op amp. (3)
±0.00076%
of full-scale range is 1/2LSB for 16-bit resolution. (4)
FSR means full-scale range, 20V for
±10V
range, etc. (5) Adjustable to zero error with an external potentiometer. (6) COB is complementary offset binary (bipolar); CSB
is complementary straight binary (unipolar). (7) Using the MSB adjustment circuit, the user may improve the DAC linearity to 1/2LSB of this specification with gain and
offset errors adjusted to zero at 25°C. (8) Maximum represents 3σ limit, not 100% production tested. (9) At the major carry; 20000 to 1FFFF
HEX
and from 1FFFF to
20000
HEX
. (10) Maximum with no degradation in specifications. External loads must be constant.
0
–60
+70
+150
*
*
*
*
°C
°C
+13.5
–16.5
+4.75
+15
–15
+5
+30
–45
+18
1.22
+16.5
–13.5
+5.25
+40
–60
+25
1.63
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
V
V
V
mA
mA
mA
W
Current
(10)
+9.990
+10.000
+10.010
*
*
*
V
mA
ppm/°C
%/V
MIN
TYP
MAX
MIN
DAC729KH
TYP
MAX
UNITS
+4
±2
±4
Indefinite to Common
0.00025
0.003
*
*
*
Indefinite to Common
*
*
ABSOLUTE MAXIMUM RATINGS
(1)
V
DD
to Common ........................................................................ 0V to +7V
+V
CC
to Common .................................................................... 0V to +18V
–V
CC
to Common .................................................................... 0V to –18V
Digital Data Inputs (pins 1-18) to Common ............................ –0.5V to V
DD
Reference Voltage In (pin 31) ................................................ +9V to +11V
Reference Out (pin 32) to Common ............... Indefinite Short to Common
External Voltage Applied to D/A Output (pin 29) ..................... –5V to +5V
External Voltage Applied to Feedback Resistors
(pins 25, 26, 27, 28) .......................................................... –15V to +15V
V
OUT
(pin 23) ................................................... Indefinite Short to Common
Power Dissipation ........................................................................ 3000mW
Storage Temperature ...................................................... –60°C to +150°C
Lead Temperature (soldering, 10s) ............................................... +300°C
NOTE: (1) Stresses above those listed under “Absolute Maximum Ratings” may
cause permanent damage to the device. Exposure to absolute maximum
conditions for extended periods may affect device reliability.
ORDERING INFORMATION
PRODUCT
DAC729JH
DAC729KH
DAC729KH-BI
PACKAGE
40-Pin Hermetic DIP
40-Pin Hermetic DIP
40-Pin Hermetic DIP
TEMPERATURE RANGE
0°C to +70°C
0°C to +70°C
0°C to +70°C
PACKAGE INFORMATION
PRODUCT
DAC729JH
DAC729KH
DAC729KH-BI
PACKAGE
40-Pin Hermetic DIP
40-Pin Hermetic DIP
40-Pin Hermetic DIP
PACKAGE DRAWING
NUMBER
(1)
214
214
214
NOTE: (1) For detailed drawing and dimension table, please see end of data
sheet, or Appendix C of Burr-Brown IC Data Book.
The information provided herein is believed to be reliable; however, BURR-BROWN assumes no responsibility for inaccuracies or omissions. BURR-BROWN
assumes no responsibility for the use of this information, and all use of such information shall be entirely at the user’s own risk. Prices and specifications are subject
to change without notice. No patent rights or licenses to any of the circuits described herein are implied or granted to any third party. BURR-BROWN does not
authorize or warrant any BURR-BROWN product for use in life support devices and/or systems.
3
DAC729
PIN CONNECTIONS
Top View
(MSB) Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7
Bit 8
Bit 9
1
2
3
4
5
6
7
8
9
40 V
POT
39 Bit 1 Adjust
38 Bit 2 Adjust
37 Bit 3 Adjust
36 Bit 4 Adjust
35 Reference Adjust
34 Gain Adjust
33 Reference Common
32 Reference Out
31 Reference In
30 Analog Common
29 I
OUT
28 5kΩ Feedback
27 5kΩ Feedback
26 10kΩ Feedback
25 10kΩ Feedback
24 Summing Junction
23 V
OUT
22 +V
CC
(15V)
21 –V
CC
(15V)
DIP
Bit 10 10
Bit 11 11
Bit 12 12
Bit 13 13
Bit 14 14
Bit 15 15
Bit 16 16
Bit 17 17
(LSB) Bit 18 18
V
DD
(5V) 19
Digital Common 20
DAC729
4
ELECTROSTATIC
DISCHARGE SENSITIVITY
Any integral circuit can be damaged by ESD. Burr-Brown
recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling
and installation procedures can cause damage.
ESD damage can range from subtle performance degrada-
tion to complete device failure. Precision integrated circuits
may be more susceptible to damage because very small
parametric changes could cause the device not to meet
published specifications.
BURN-IN SCREENING
Burn-in screening is an option available for the DAC729
family of products. Burn-in duration is 160 hours at 100°C
(or equivalent combination of time and temperature).
All units are tested after burn-in to ensure that grade speci-
fications are met.
gain is well over 500,000V/V. Since thermal feedback is the
major limitation of gain for mono op amps, the amplifier
was designed as a high gain, fast settling mono op amp,
followed by a monolithic, unity-gain current buffer to isolate
the thermal effects of external loads from the input stage
gain transistors. The op amp and buffer are separated from
the DAC chip, minimizing thermally-induced linearity er-
rors in the DAC circuit. The op amp, like the reference, is
not dedicated to the DAC729. The user may want to add a
network, or select a different amplifier. The DAC729 inter-
nal op amp is intended to be the best choice for accuracy,
settling time, and noise.
THE DAC CHIP
The heart of the DAC729 is a monolithic current source and
switch integrated circuit. The absolute linearity, differential
linearity, and the temperature performance of the DAC729
are the result of the design, which utilizes the excellent
element matching of the current sources and switch transis-
tors to each other, and the tracking of the current setting
resistors to the feed back resistors. Older discrete designs
cannot achieve the performance of this monolithic DAC
design.
The two most significant bits are binarily weighted inter-
digitated current sources. The currents for bits 3 through 18
are scaled with both current source weighting and an R-2R
ladder. The circuit design is optimized for low noise and low
superposition error, with the current sources arranged to
minimize both code-dependent thermal errors and IR drop
errors. As a result, the superposition errors are typically less
than 20µV.
The DAC chip is biased from a servo amplifier feeding into
the base line of the current sources. This servo amplifier sets
the collector current to be mirrored and scaled in the DAC
chip current sources, as shown in Figure 11. The reference
current for the servo is established by the reference voltage
applied to pin 31 feeding an internal resistor (20kΩ) to the
virtual ground of the servo amplifier.
THEORY OF OPERATION
The DAC729 is an 18-bit digital-to-analog converter sys-
tem, including a precision reference, low noise, fast settling
operational amplifier, and an 18-bit current source/DAC
chip contained in a hermetic 40-pin ceramic dual-in-line
package. Refer to Figure 11 for a schematic diagram of the
DAC729.
THE INTERNAL REFERENCE
The reference consists of a very low temperature coefficient
closed-loop reference zener circuit that has been tempera-
ture-drift-compensated by laser-trimming a zener current to
achieve less than 1ppm/°C temperature drift of V
REF
.
By strapping pin 32 (Reference Out) to pin 31 (Reference
In), the DAC will be properly biased from the internal
reference. The internal reference may be fine adjusted using
pin 35 as shown in Figure 7. The reference has an output
buffer that will supply 4mA for use external to the DAC729.
This load must remain constant because changing load on
the reference may change the reference current to the DAC.
In systems where several components need to track the same
system reference, the DAC729 may be used with an external
10V reference, however, the internal reference has lower
noise (6µVp-p) and better stability than other references
available.
THE OPERATIONAL AMPLIFIER
To support a DAC of this accuracy, the operational amplifier
must have a maximum gain-induced error of less than
1/3LSB, independent of output swing (the op amp must be
linear!) To support 15 bits (1/2-bit linearity), the op amp
must have a gain of 130,000V/V. For 18 bits, the minimum
DISCUSSION
OF SPECIFICATIONS
DIGITAL INPUT CODES
The DAC729 accepts complementary digital input codes in
either binary format (CSB for Unipolar or COB for Bipolar;
see Table I).
DAC ANALOG OUTPUT
DIGITAL INPUT
COB
20V FSR
CSB
10V FSR
00 0000 0000 0000 0000 + Full Scale 9.999924V + Full Scale 9.999962V
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