BURR-BROWN DAC701 User Manual

Page 1
®
DAC701
DAC701
DAC703
Monolithic 16-Bit
DIGITAL-TO-ANALOG CONVERTERS
FEATURES
V
HIGH ACCURACY:
DESCRIPTION
The DAC70X family comprise of complete 16-bit digital-to-analog converters that includes a precision buried-zener voltage reference and a low-noise, fast­settling output operational amplifier (voltage output models), all on one small monolithic chip. A combina­tion of current-switch design techniques accomplishes not only 15-bit monotonicity over the entire specified temperature range, but also a maximum end-point linearity error of ±0.0015% of full-scale range. Total full-scale gain drift is limited to ±10ppm/°C maximum (LH and CH grades).
OUT
Linearity Error
MODELS
OUT
±0.0015% of FSR max
Differential Linearity Error max
±0.003% of FSR
DAC702
DAC702 DAC703
MONOTONIC (at 15 bits) OVER FULL
SPECIFICATION TEMPERATURE RANGE
PIN-COMPATIBLE WITH DAC70, DAC71,
DAC72
DUAL-IN-LINE PLASTIC AND HERMETIC
CERAMIC AND SOIC
Digital inputs are complementary binary coded and are TTL-, LSTTL-, 54/74C- and 54/74HC-compatible over the entire temperature range. Outputs of 0 to +10V, ±10V, 0 to –2mA, and ±1mA are available.
These D/A converters are packaged in hermetic 24-pin ceramic side-brazed or molded plastic. The DIP-pack­aged parts are pin-compatible with the voltage and current output DAC71 and DAC72 model families. The DAC702 is also pin-compatible with the DAC70 model family. In addition, the DAC703 is offered in a 24-pin SOIC package for surface mount applications.
SBAS143
16-Bit
Ladder
Digital Inputs
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
Internet: http://www.burr-brown.com/ • FAXLine: (800) 548-6133 (US/Canada Only) • Cable: BBRCORP • Telex: 066-6491 • FAX: (520) 889-1510 • Immediate Product Info: (800) 548-6132
© 1983 Burr-Brown Corporation PDS-494M Printed in U.S.A. March, 1998
Resistor Network
And
Current
Switches
Reference
Circuit
Voltage Models Only
1
Gain Adjust +V
CC
–V
CC
V
DD
Reference Output
Common
Summing Junction Output
®
DAC701, 702, 703
Page 2
SPECIFICATIONS
At +25°C and rated power supplies, unless otherwise noted.
DAC702/703J DAC701/702/703K DAC701/702/703B, S DAC701/702/703L, C PARAMETER MIN TYP MAX MIN TYP MAX MIN TYP MAX MIN TYP MAX UNITS INPUT DIGITAL INPUT
Resolution 16 ✻✻✻Bits Digital Inputs
V
IH
V
IL
I
IH
I
IL
TRANSFER CHARACTERISTICS ACCURACY
Linearity Error Differential Linearity
Error
Differential Linearity
Error at Bipolar Zero
(DAC702/703) Gain Error Zero Error Monotonicity Over Spec.
Temp Range 13 14 15 Bits DRIFT (over specification
temperature range) Total Error Over
Temperature Range
(all models) Total Full Scale Drift:
DAC701 ±10 ±30 ±8.5 ±18 ±6 ±13 ppm of FSR/°C
DAC702/703 ±10 ±25 ±7 ±15 ✻✻ppm of FSR/°C Gain Drift (all models) ±10 ±30 ±25 ±7 ±15 ±5 ±10 ppm/°C Zero Drift:
DAC701 ±2.5 ±5 ±1.5 ±3 ✻✻ppm of FSR/°C
DAC702/703 ±5 ±15 ±12 ±4 ±10 ±2.5 ±5 ppm of FSR/°C Differential Linearity
Over Temp.
Linearity Error Over Temp.
SETTLING TIME (to
±0.003% of FSR) DAC701/703 (V
Full Scale Step, 2k Load 4 8 ✻✻ ✻✻ µs
1LSB Step at
Worst-Case Code Slew Rate 10 ✻✻✻V/µs DAC702 (I Full Scale Step (2mA),
10 to 100 Load 350 1000 ✻✻ ✻✻ ns
1k Load 1 3 ✻✻ ✻✻ µs
OUTPUT VOLTAGE OUTPUT
MODELS
DAC701 (CSB Code) 0 to +10 V DAC703 (COB Code) ±10 ✻✻✻V
Output Current ±5 ✻✻✻ mA
Output Impedance 0.15 ✻✻✻
Short Circuit to
CURRENT OUTPUT
MODELS
DAC702 (COB Code)
Output Impedance Compliance Voltage ±2.5 ✻✻✻V
(1)
+2.4 +V –1.0 +0.8 ✻✻✻✻✻✻V
✻✻✻✻✻✻V
CC
, VI = +2.7V +40 ✻✻✻µA
, VI = +0.4V –0.35 –0.5 ✻ ✻ ✻✻ ✻✻ mA
(2)
(4)
(4)
(4) (5) (5, 6)
(7)
(4)
±0.0015 ±0.006 ±0.003 ✻✻ ±0.00075 ±0.0015 % of FSR
±0.003 ±0.012 ±0.006 ✻✻ ±0.0015 ±0.003 % of FSR
±0.003 ±0.006 ±0.0015 ±0.003 ✻✻% of FSR ±0.07 ±0.30 ±0.15 ±0.05 ±0.10 ✻✻ % ±0.05 ±0.10 ✻ ✻ ✻✻ ✻✻% of FSR
±0.08 ±0.15 ±0.05 ±0.10 ✻✻% of FSR
±0.012 +0.009, +0.006, % of FSR
(3)
–0.006 –0.003
(4)
OUT
(8)
Models)
OUT
Models)
(9)
±0.012 ±0.006 ±0.003 % of FSR
2.5 ✻✻✻µs
Common Duration Indefinite ✻✻✻
(10)
(10)
±1 ✻✻✻mA
2.45 ✻✻✻k
®
DAC701, 702, 703
2
Page 3
SPECIFICATIONS (CONT)
At +25°C and rated power supplies, unless otherwise noted.
DAC702/703J DAC701/702/703K DAC701/702/703B, S DAC701/702/703L, C
PARAMETER MIN TYP MAX MIN TYP MAX MIN TYP MAX MIN TYP MAX UNITS REFERENCE VOLTAGE
Voltage +6.3 +6.0 +6.3 +6.6 +6.24 +6.3 +6.36 ✻✻✻ V Source Current Available
for External Loads +2.5 +1.5 ✻✻✻✻✻ mA Temperature Coefficient ±10 ±25 ±15 ✻✻ ppm/°C Short Circuit to Common
Duration Indefinite ✻✻✻
POWER SUPPLY REQUIREMENTS
Voltage: +V
Current (No Load):
CC
–V
CC
V
DD
DAC702
(I
Models)
OUT
+V
CC
–V
CC
V
DD
DAC701/703
(V
Models)
OUT
+V
CC
–V
CC
V
DD
Power Dissipation:
(V
DD
DAC702 365 790 630 ✻✻ mW
= +5.0V)
(11)
DAC701/703 530 940 780 ✻✻ mW
Power Supply Rejection:
+V
CC
–V
CC
V
DD
TEMPERATURE RANGE
Specification:
B, C Grades –25 +85 ✻✻°C
S Grades –55 +125 °C
J, K, L Grades 0 +70 ✻✻ 0 +70 °C Storage: Ceramic –60 +150 ✻✻✻✻°C
Plastic, SOIC –60 +100 ✻✻ °C
Specification same as model to the left. NOTES: (1) Digital inputs are TTL, LSTTL, 54/74C, 54/74HC, and 54/74HTC compatible over the operating voltage range of V
temperature range. The input switching threshold remains at the TTL threshold of 1.4V over the supply range of V 0V to +0.8V and +2.4V to +10V respectively, the change in the D/A converter output voltage will not exceed ±0.0015% of FSR for the LH and CH grades, ±0.003% of FSR for the BH grade and ±0.006% of FSR for the KG grade. (2) DAC702 (current-output models) is specified and tested with an external output operational amplifier connected using the internal feedback resistor in all parameters except settling time. (3) FSR means full-scale range and is 20V for the ±10V range (DAC703), 10V for the 0 to +10V range (DAC701). FSR is 2mA for the ±1mA range (DAC702). (4) ±0.0015% of full-scale range is equivalent to 1LSB in 15-bit resolution. ±0.003% of full-scale range is equivalent to 1LSB in 14-bit resolution. ±0.006% of full-scale range is equivalent to 1LSB in 13-bit resolution. (5) Adjustable to zero with external trim potentiometer. Adjusting the gain potentiometer rotates the transfer function around the zero point. (6) Error at input code FFFF adjusted to zero at +25°C. (8) Maximum represents the 3σ limit. Not 100% tested for this parameter. (9) At the major carry, 7FFF on output impedance and output current is ±30%. (11) Power dissipation is an additional 40mW when V
13.5 15 16.5 ✻✻✻✻✻✻✻✻✻ V
13.5 15 16.5 ✻✻✻✻✻✻✻✻✻ V +4.5 +5 +16.5 ✻✻✻✻✻✻✻✻✻ V
+10 +25 ✻✻ ✻✻ ✻✻ mA –13 –25 ✻✻ ✻✻ ✻✻ mA
+4 +8 ✻✻ ✻✻ ✻✻ mA
+16 +30 ✻✻ ✻✻ ✻✻ mA –18 –30 ✻✻ ✻✻ ✻✻ mA
+4 +8 ✻✻ ✻✻ ✻✻ mA
±0.0015 ±0.006 ✻✻ ✻±0.003 ✻✻% of FSR/%V ±0.0015 ±0.006 ✻✻ ✻±0.003 ✻✻% of FSR/%V ±0.0001 ±0.001 ✻✻ ✻✻ ✻✻% of FSR/%V
= +5V to +15V and over the specified
= +5V to +15V. As logic “0” and logic “1” inputs vary over
DD
for DAC701, 7FFFH for DAC702 and DAC703. (7) With gain and zero errors
H
is operated at +15V.
DD
DD
to 8000H and 8000H to 7FFFH. (10) Tolerance
H
CC CC DD
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
DAC701, 702, 703
®
Page 4
CONNECTION DIAGRAMS
Digital Inputs
MSB
1 2 3 4 5
16-Bit
Ladder
6
Resistor Network
7 8
9 10 11 12
and
Current
Switches
Reference
Circuit
Voltage Models
Only
PIN ASSIGNMENTS
ALL PACKAGES
PIN # DAC702 DAC701/703
1 Bit 1 (MSB) Bit 1 (MSB) 2 Bit 2 Bit 2 3 Bit 3 Bit 3 4 Bit 4 Bit 4 5 Bit 5 Bit 5 6 Bit 6 Bit 6 7 Bit 7 Bit 7 8 Bit 8 Bit 8
9 Bit 9 Bit 9 10 Bit 10 Bit 10 11 Bit 11 Bit 11 12 Bit 12 Bit 12 13 Bit 13 Bit 13 14 Bit 14 Bit 14 15 Bit 15 Bit 15 16 Bit 16 (LSB) Bit 16 (LSB) 17 R 18 V 19 –V 20 Common Common 21 I 22 Gain Adjust Gain Adjust 23 +V 24 +6.3V Reference Output +6.3V Reference Output
FEEDBACK
DD
CC
OUT
CC
Summing Junction (Zero Adjust)
V
–V
+V
OUT
V
DD
CC
CC
24 23 22
0.0022µF
21
LSB
20 19 18 17 16 15
Digital Inputs
14 13
(4)
R
F
ABSOLUTE MAXIMUM RATINGS
+VCC to Common ........................................................................ 0V, +18V
–V
CC
V
DD
Digital Data Inputs to Common ................................................ –1V, +18V
Reference Out to Common ...........................Indefinite Short to Common
External Voltage Applied to R
External Voltage Applied to D/A Output (DAC701/703).......... –5V to +5V
V
OUT
Power Dissipation .................................................................................1W
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.
(2)
+V
–V
V
CC
CC
(1)
DD
270k
3.9M
(2)
(2)
NOTES: (1) Can be tied to +VCC instead of having separate V
0.1µF to 1.0µF. (3) Potentiometers are 10k to 100k. (4) 5k (DAC701), 10k (DAC702/703).
(3)
(3)
supply. (2) Decoupling capacitors are
DD
(1)
to Common ........................................................................ 0V, –18V
to Common .......................................................................... 0V, +18V
(DAC702) ......................................... ±18V
F
(DAC701/703) .......................................Indefinite Short to Common
ELECTROSTATIC DISCHARGE SENSITIVITY
This integrated 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 degrada­tion 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 its published specifications.
®
DAC701, 702, 703
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Page 5
PACKAGE/ORDERING INFORMATION
PACKAGE ERROR, MAX DRIFT, DRAWING OUTPUT TEMPERATURE AT+25
PRODUCT PACKAGE NUMBER
DAC703JP 24-Pin Plastic DIP 167 ±1mA, ±10V 0°C to +70°C ±0.006 ±30 DAC703KP 24-Pin Plastic DIP 167 ±1mA, ±10V 0°C to +70°C ±0.003 ±25
DAC701KH 24-Pin Ceramic DIP 165 0 to –2mA, 0 to +10V 0°C to +70°C ±0.003 ±25 DAC702KH 24-Pin Ceramic DIP 165 ±1mA, ±10V 0°C to +70°C ±0.003 ±25 DAC703KH 24-Pin Ceramic DIP 165 ±1mA, ±10V 0°C to +70°C ±0.003 ±25
DAC701BH 24-Pin Ceramic DIP 165 0 to –2mA, 0 to +10V –25°C to +85°C ±0.003 ±15 DAC702BH 24-Pin Ceramic DIP 165 ±1mA, ±10V –25°C to +85°C ±0.003 ±15 DAC703BH 24-Pin Ceramic DIP 165 ±1mA, ±10V –25°C to +85°C ±0.003 ±15
DAC701LH 24-Pin Ceramic DIP 165 0 to –2mA, 0 to +10V 0°C to +70°C ±0.0015 ±10 DAC702LH 24-Pin Ceramic DIP 165 ±1mA, ±10V 0°C to +70°C ±0.0015 ±10 DAC703LH 24-Pin Ceramic DIP 165 ±1mA, ±10V 0°C to +70°C ±0.0015 ±10
DAC701CH 24-Pin Ceramic DIP 165 0 to –2mA, 0 to +10V –25°C to +85°C ±0.0015 ±10 DAC702CH 24-Pin Ceramic DIP 165 ±1mA, ±10V –25°C to +85°C ±0.0015 ±10 DAC703CH 24-Pin Ceramic DIP 165 ±1mA, ±10V –25°C to +85°C ±0.0015 ±10
DAC701SH 24-Pin Ceramic DIP 165 0 to –2mA, 0 to +10V –55°C to +125°C ±0.003 ±15 DAC702SH 24-Pin Ceramic DIP 165 ±1mA, ±10V –55°C to +125°C ±0.003 ±15 DAC703SH 24-Pin Ceramic DIP 165 ±1mA, ±10V –55°C to +125°C ±0.003 ±15
DAC703JU 24-Pin SOIC 239 ±10V 0°C to +70°C ±0.006 ±30 DAC703KU 24-Pin SOIC 239 ±10V 0°C to +70°C ±0.003 ±25
NOTE: (1) For detailed drawing and dimension table, please see end of data sheet, or Appendix C of Burr-Brown IC Data Book.
(1)
CONFIGURATION RANGE (% of FSR) (ppm/°C)
LINEARITY GAIN
°C MAX
®
5
DAC701, 702, 703
Page 6
DISCUSSION OF SPECIFICATIONS
DIGITAL INPUT CODES
The DAC701/702/703 accept complementary digital input codes in either binary format (CSB, unipolar or COB, bipolar). The COB models DAC702/703 may be connected by the user for either complementary offset binary (COB) or complementary two’ s complement (CTC ) codes (see Table I).
ANALOG OUTPUT
DIGITAL Complementary Complementary Complementary
INPUT Straight Binary Offset Binary Two’s Complement
CODES (CSB) (COB) (CTC)*
0000
H
7FFF
H
8000
H
FFFF
H
* Invert the MSB of the COB code with an external inverter to obtain CTC code.
TABLE I. Digital Input Codes.
ACCURACY Linearity
This specification describes one of the most important mea­sures of performance of a D/A converter. Linearity error is the deviation of the analog output from a straight line drawn through the end points (all bits ON point and all bits OFF point).
Differential Linearity Error
Differential linearity error (DLE) of a D/A converter is the deviation from an ideal 1LSB change in the output from one adjacent output state to the next. A differential linearity error specification of ±1/2LSB means that the output step sizes can be between 1/2LSB and 3/2LSB when the input changes from one adjacent input state to the next. A negative DLE specification of no more than –1LSB (–0.006% for 14-bit resolution) insures monotonicity.
Monotonicity
Monotonicity assures that the analog output will increase or remain the same for increasing input digital codes. The DAC701/702/703 are specified to be monotonic to 14 bits over the entire specification temperature range.
DAC701 DAC702/703 DAC702/703
+ Full Scale + Full Scale –1LSB +1/2 Full Scale Bipolar Zero – Full Scale +1/2 Full Scale –1LSB + Full Scale
–1LSB
Zero – Full Scale Bipolar Zero
Zero Drift
Zero drift is a measure of the change in the output with
(DAC701) applied to the digital inputs over the
FFFF
H
specified temperature range. For the bipolar models, zero is measured at 7FFFH (bipolar zero) applied to the digital inputs. This code corresponds to zero volts (DAC703) or zero milliamps (DAC702) at the analog output. The maxi­mum change in offset at t
MIN
or t
is referenced to the
MAX
zero error at +25°C and is divided by the temperature change. This drift is expressed in parts per million of full scale range per degree centigrade (ppm of FSR/°C).
SETTLING TIME
Settling time of the D/A is the total time required for the analog output to settle within an error band around its final value after a change in digital input. Refer to Figure 1 for typical values for this family of products.
Voltage Output
Settling times are specified to ±0.003% of FSR (±1/2LSB for 14 bits) for two input conditions: a full-scale range change of 20V (DAC703) or 10V (DAC701) and a 1LSB change at the “major carry,” the point at which the worst­case settling time occurs. (This is the worst-case point since all of the input bits change when going from one code to the next).
Current Output
Settling times are specified to ±0.003% of FSR for a full­scale range change for two output load conditions: one for 10 to 100 and one for 1000. It is specified this way because the output RC time constant becomes the dominant factor in determining settling time for large resistive loads.
1
DAC702
0.1
0.01
Full-Scale Range (±% of FSR)
Final-Value Error Band, Percent of
0.001
RL = 100
0.01 0.1 1 10 Settling Time (µs)
R
= 1k
L
DAC701
DAC703
DRIFT Gain Drift
Gain drift is a measure of the change in the full-scale range output over temperature expressed in parts per million per degree centigrade (ppm/°C). Gain drift is established by: (1) testing the end point differences for each D/A at t and t
; (2) calculating the gain error with respect to the
MAX
MIN
, +25°C
+25°C value; and (3) dividing by the temperature change.
®
DAC701, 702, 703
FIGURE 1. Final-Value Error Band vs Full-Scale Range
Settling Time.
COMPLIANCE VOLTAGE
Compliance voltage applies only to current output models. It is the maximum voltage swing allowed on the output current pin while still being able to maintain specified accuracy.
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POWER SUPPLY SENSITIVITY
Digital Input
H
Input = FFFF
Gain
Adjust
Rotates
the Line
Range of Gain Adjust
1LSB
Full Scale
Range
+ Full Scale
– Full Scale
Range and Offset Adjust
Offset Adjust Translates the Line
H
Input =
0000
MSB on All Others Off 7FFF
H
Analog Output
Power supply sensitivity is a measure of the effect of a change in a power supply voltage on the D/A converter output. It is defined as a percent of FSR change in the output per percent of change in either the positive supply (+VCC), negative supply (–V
) or logic supply (VDD) about the
CC
nominal power supply voltages (see Figure 2). It is specified for DC or low frequency changes. The typical
performance curve in Figure 2 shows the effect of high frequency changes in power supply voltages.
less. The 3.9M and 270k resistors (±20% carbon or better) should be located close to the D/A converter to prevent noise pickup. If it is not convenient to use these high-value resistors, an equivalent “T” network, as shown in Figure 3, may be substituted in place of the 3.9M part. A
0.001µF to 0.01µF ceramic capacitor should be connected from Gain Adjust to Common to prevent noise pickup. Refer to Figures 4 and 5 for the relationship of zero and gain adjustments to unipolar and bipolar D/A converters.
0.030
SUPPLY
0.025
0.020
0.015
0.01
0.005
0
% of FSR Error Per % of Change in V
1 10 100 1k 10k 100k
Power Supply Ripple Frequency (Hz)
–15V Supply
+5V
Supply
+15V
Supply
FIGURE 2. Power Supply Rejection vs Power Supply Ripple
Frequency.
REFERENCE SUPPLY
All models have an internal low-noise +6.3V reference voltage derived from an on-chip buried zener diode. This reference voltage, available to the user, has a tolerance of ±5% (KH models) and ±1% (BH models). A minimum of
1.5mA is available for external loads. Since the output impedance of the reference output is typically 1W, the external load should remain constant.
If a varying load is to be driven by the reference supply, an external buffer amplifier is recommended to drive the load in order to isolate the bipolar offset (connected internally to the reference) from load variations.
180k 180k3.9MΩ
FIGURE 3. Equivalent Resistances.
+ Full Scale
1LSB
Range of
Zero Adjust
Zero Adjust
Translates
the Line
FIGURE 4.
Analog Output
Input =
Full Scale Range
FFFF
Relationship of Zero and Gain Adjustments for
Gain Adjust
Rotates the Line
H
Digital Input
Unipolar D/A Converters, DAC701.
10k
Range
of Gain
Adjust
Input =
0000
H
OPERATING INSTRUCTIONS
POWER SUPPLY CONNECTIONS
For optimum performance and noise rejection, power sup­ply decoupling capacitors should be added as shown in the Connection Diagram. 1µF tantalum capacitors should be located close to the D/A converter.
EXTERNAL ZERO AND GAIN ADJUSTMENT
Zero and gain may be trimmed by installing external zero and gain potentiometers. Connect these potentiometers as shown in the Connection Diagram and adjust as described below. TCR of the potentiometers should be 100ppm/°C or
FIGURE 5. Relationship of Zero and Gain Adjustments for
Bipolar D/A Converters, DAC702 and DAC703.
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DAC701, 702, 703
®
Page 8
Zero Adjustment
For unipolar (CSB) configurations, apply the digital input code that produces zero voltage or zero current output and adjust the zero potentiometer for zero output.
For bipolar (COB, CTC) configurations, apply the digital input code that produces zero output voltage or current. See Table II for corresponding codes and the Connection Dia­gram for zero adjustment circuit connections. Zero calibra­tion should be made before gain calibration.
Gain Adjustment
Apply the digital input that gives the maximum positive output voltage. Adjust the gain potentiometer for this posi­tive full scale voltage. See Table II for positive full scale voltages and the Connection Diagram for gain adjustment circuit connections.
INSTALLATION CONSIDERATIONS
This D/A converter family is laser-trimmed to 14-bit linear­ity. The design of the device makes the 16-bit resolution available. If 16-bit resolution is not required, bit 15 and bit 16 should be connected to V resistor.
Due to the extremely high resolution and linearity of the D/A converter, system design problems such as grounding and contact resistance become very important. For a 16-bit converter with a 10V full-scale range, 1LSB is 153µV. With a load current of 5mA, series wiring and connector resis­tance of only 30m will cause the output to be in error by 1LSB. To understand what this means in terms of a system layout, the resistance of #23 wire is about 0.021/ft. Ne­glecting contact resistance, less than 18 inches of wire will produce a 1LSB error in the analog output voltage!
In Figures 6, 7, and 8, lead and contact resistances are represented by R R
is constant, R2 simply introduces a gain error and can be
L
through R5. As long as the load resistance
1
removed during initial calibration. R output voltage is sensed at Common, and therefore intro­duces no error. If RL is variable, then R2 should be less than R
/216 to reduce voltage drops due to wiring to less than
L MIN
1LSB. For example, if R than 0.08. R
should be located as close as possible to the
L
L MIN
D/A converter for optimum performance. The effect of R negligible.
through a single 1k
DD
is part of RL, if the
3
is 5k, then R2 should be less
is
4
In many applications it is impractical to sense the output voltage at the output pin. Sensing the output voltage at the system ground point is permissible with the DAC700 family because the D/A converter is designed to have a constant return current of approximately 2mA flowing from Com­mon. The variation in this current is under 20µA (with changing input codes), therefore R4 can be as large as 3 without adversely affecting the linearity of the D/A con­verter. The voltage drop across R4 (R4 x 2mA) appears as a zero error and can be removed with the zero calibration adjustment. This alternate sensing point (the system ground point) is shown in Figures 6, 7, and 8.
Figures 7 and 8 show two methods of connecting the current output models (DAC702) with external precision output op amps. By sensing the output voltage at the load resistor (ie, by connecting R
to the output of A1 at RL), the effect of R
F
and R2 is greatly reduced. R1 will cause a gain error but is independent of the value of R initial calibration adjustments. The effect of R
and can be eliminated by
L
is negligible
2
because it is inside the feedback loop of the output op amp and is therefore greatly reduced by the loop gain.
DAC701
5k
R
F
4k
R
DAC
R
Common
Alternate Ground
Sense Connection
To +V
CC
To –V
CC
To V
DD
* R = 2k (DAC701 and DAC703)
B
1µF
1µF
1µF
R
4
System Ground Point
A
*
B
V
1
OUT
+V
COM
–V
+V
COM
R
2
R
R
3
Sense Output
±15VDC
Supply
+5VDC Supply
L
FIGURE 6. Output Circuit for Voltage Models.
1
®
DAC701, 702, 703
8
Page 9
VOLTAGE OUTPUT MODELS
A
1
R
DAC
DAC702
R
6
Common
I
OUT
R
1
R
L
R
3
+5VDC
Supply
±15VDC
Supply
+V
COM
–V
System Ground Point
+V
COM
Alternate Ground
Sense Connection
R
4
To +V
CC
To –V
CC
To V
DD
1µF
1µF
1µF
2.45k
R
F
*
R
2
DAC702
10k
R
DAC
R
F
*
R
F
R
5
R
7
Sense Output
+5R
7
R=+
F
R
1
R
R
6
=
DAC
R
ANALOG OUTPUT
DAC701 UNIPOLAR DAC703 BIPOLAR
DIGITAL INPUT CODE 16-BIT 15-BIT 14-BIT 16-BIT 15-BIT 14-BIT
1LSB (µV) 153 305 610 305 610 1224 0000 FFFF
H
H
(V) +9.99985 +9.99969 +9.99939 +9.99960 +9.99939 +9.99878 (V) 0 0 0 –10.0000 –10.0000 –10.0000
ANALOG OUTPUT MODEL
ANALOG OUTPUT
DAC702 BIPOLAR
DIGITAL INPUT CODE 16-BIT 15-BIT 14-BIT
1LSB (µA) 0.031 0.061 0.122 0000 FFFF
H
H
(mA) –0.99997 –0.99994 –0.99988 (mA) +1.00000 +1.00000 +1.00000
TABLE II. Digital Input and Analog Output Relationships.
If the output cannot be sensed at Common or the system ground point as mentioned above, the differential output circuit shown in Figure 8 is recommended. In this circuit the output voltage is sensed at the load common and not at the D/A converter common as in the previous circuits. The value of R
and R7 must be adjusted for maximum common-mode
6
rejection at R
. Note that if R3 is negligible, the circuit of
L
Figure 8 can be reduced to the one shown in Figure 7. Again the effect of R4 is negligible.
DAC702
R
F
*
R
F
R
DAC
Alternate Ground
Sense Connection
To +V
CC
To –V
CC
To V
DD
1µF
1µF
1µF
R
B
2.45k
*
DAC702
R should be equal to the output impedance at the current output
B
to compensate for the bias current drift of A . Use standard 10%, 1/4W carbon composition or equivalent resistors.
FIGURE 7. Preferred External Op Amp Configuration. FIGURE 8. Differential Sensing Output Op Amp
*
Common
R
I
OUT
4
System Ground Point
R
F
10k
R
B
A
COM
COM
R
2.45k
1
Sense Output
+V
–V
+V
DAC
1
R
1
R
2
R
3
±15VDC
Supply
+5VDC
Supply
R
L
The D/A converter and the wiring to its connectors should be located to provide optimum isolation from sources of RFI and EMI. The key concept in elimination of RF radiation or pickup is loop area; therefore, signal leads and their return conductors should be kept close together. This reduces the external magnetic field along with any radiation. Also, if a single lead and its return conductor are wired close together, they present a small flux-capture cross section for any external field. This reduces radiation pickup in the circuit.
Configuration.
9
DAC701, 702, 703
®
Page 10
APPLICATIONS
DRIVING AN EXTERNAL OP AMP WITH CURRENT OUTPUT D/A S
DAC702 is current output devices and will drive the sum­ming junction of an op amp to produce an output voltage as shown in Figure 9. Use of the internal feedback resistor is required to obtain specified gain accuracy and low gain drift.
DAC702 can be scaled for any desired voltage range with an external feedback resistor, but at the expense of increased drifts of up to ±50ppm/°C. The resistors in the DAC702 ratio track to ±1ppm/°C but their absolute TCR may be as high as ±50ppm/°C.
An alternative method of scaling th e output voltage of the D/A converter and preserving the low gain drift is shown in Figure 10.
OUTPUTS LARGER THAN 20V RANGE
For output voltage ranges larger than ±10V, a high voltage op amp may be employed with an external feedback resistor. Use I –2mA for unipolar voltage ranges (see Figure 11). Use protection diodes as shown when a high voltage op amp is used.
values of ±1mA for bipolar voltage ranges and
OUT
R
F
5k
0 to 2mA
4k
Common
I
OUT
V
OUT
FIGURE 9. External Op Amp Using Internal Feedback
Resistors.
R
F
5k
0 to 2mA
4k
Common
I
OUT
*, R2 TCR < ±10ppm/°C
R
1
*
R
1
I
R
V
OUT
*
2
FIGURE 10. External Op Amp Using Internal and External
Feedback Resistors to Maintain Low Gain Drift.
R
F
R
F
0 to 2mA
4k
BB3584
V
OUT
FIGURE 11. External Op Amp Using External Feedback
Resistors.
®
DAC701, 702, 703
10
Page 11
PACKAGE OPTION ADDENDUM
www.ti.com
30-Mar-2005
PACKAGING INFORMATION
Orderable Device Status
(1)
Package
Type
Package Drawing
Pins Package
Qty
Eco Plan
DAC701KH OBSOLETE CDIP SB JDM 24 TBD Call TI Call TI DAC703BH OBSOLETE CDIP SB JDM 24 TBD Call TI Call TI
DAC703BH-BI OBSOLETE CDIP SB JD 24 TBD Call TI Call TI
DAC703CH OBSOLETE CDIP SB JDM 24 TBD Call TI Call TI
DAC703CH-BI OBSOLETE CDIP SB JD 24 TBD Call TI Call TI
DAC703JP OBSOLETE PDIP NTA 24 TBD Call TI Call TI
DAC703KH OBSOLETE CDIP SB JDM 24 TBD Call TI Call TI
DAC703KH-4 OBSOLETE CDIP SB JDM 24 TBD Call TI Call TI
DAC703KH-BI OBSOLETE CDIP SB JDM 24 TBD Call TI Call TI
DAC703KP OBSOLETE PDIP NTA 24 TBD Call TI Call TI DAC703LH OBSOLETE CDIP SB JDM 24 TBD Call TI Call TI
DAC703SH OBSOLETE CDIP SB JDM 24 TBD Call TI Call TI
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in
a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device.
(2)
Lead/Ball Finish MSLPeak Temp
(3)
(2)
Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS) or Green (RoHS & no Sb/Br) - please check
http://www.ti.com/productcontent for the latest availability information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements
for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material)
(3)
MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder
temperature.
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In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
Addendum-Page 1
Page 12
IMPORTANT NOTICE
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