Burr-Brown DAC709KH Microprocessor-compatible 16-bit digital-to-analog converter Datasheet

DAC707
DAC708
DAC709
®
Microprocessor-Compatible
16-BIT DIGITAL-TO-ANALOG CONVERTERS
● HIGH ACCURACY:
Linearity Error ±0.003% of FSR max
Differential Linearity Error ±0.006% of FSR
max
● MONOTONIC (TO 14 BITS) OVER
SPECIFIED TEMPERATURE RANGE
● HERMETICALLY SEALED
FEATURES
● TWO-CHIP CONSTRUCTION
● HIGH-SPEED 16-BIT PARALLEL, 8-BIT
(BYTE) PARALLEL, AND SERIAL INPUT
MODES
● DOUBLE-BUFFERED INPUT REGISTER
CONFIGURATION
● VOUT AND IOUT MODELS
● LOW COST PLASTIC VERSIONS
AVAILABLE (DAC707JP/KP)
DESCRIPTION
The DAC708 and DAC709 are 16-bit converters designed to interface to an 8-bit microprocessor bus. 16bit data is loaded in two successive 8-bit bytes into
parallel 8-bit latches before being transferred into the
D/A latch. The DAC708 and DAC709 are current and
voltage output models respectively and are in 24-pin
hermetic DIPs. Input coding is Binary Two’s Complement (bipolar) or Unipolar Straight Binary (unipolar,
when an external logic inverter is used to invert the
MSB). In addition, the DAC708/709 can be loaded
serially (MSB first).
Data is written into a 16-bit latch and subsequently the
D/A latch. The DAC707 has bipolar voltage output
and input coding is Binary Two’s Complement (BTC).
All models have Write and Clear control lines as well
as input latch enable lines. In addition, DAC708 and
DAC709 have Chip Select control lines. In the bipolar
mode, the Clear input sets the D/A latch to give zero
voltage or current output. They are all 14-bit accurate
and are complete with reference, and for the DAC707,
and DAC709, a voltage output amplifier. All models
are available with an optional burn-in screening.
The DAC707 is designed to interface to a 16-bit bus.
8-Bit
(DAC708, 709)
or
16-Bit (DAC707)
Serial
(DAC708, 709)
Latch Enables/
Mode Select
CLEAR
WRITE
CHIP SELECT
Reference
Circuit
High
Byte
Latch
D/A
Latch
Serial
Data
Low
Byte
Latch
16-Bit
D/A
Converter
Bipolar
Offset
Summing Junction (708, 709)
10V Range (708, 709)
VOUT
DAC707 or DAC709
Only
Control
Logic
DAC707/708/709 Block Diagram
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PDS-557H
SPECIFICATIONS
ELECTRICAL
At TA = +25°C, VCC = ±15V, VDD = +5V, and after a 10-minute warm-up, unless otherwise noted.
DAC707/708/709KH,
DAC707KP
DAC707JP
PRODUCT
MIN
TYP
MAX
MIN
TYP
MAX
DAC707/708/
709BH, SH
MIN
TYP
MAX
UNITS
*
Bits
*
*
*
*
V
V
µA
µA
*
*
±0.0015
±0.05
*
*
*
±0.003
±0.10
*
% of FSR(4)
% of FSR
% of FSR
%
% of FSR
Bits
% of FSR/%VCC
% of FSR/%VDD
INPUT
DIGITAL INPUT
Resolution
Bipolar Input Code (all models)
Unipolar Input Code(1) (DAC708/709 only)
Logic Levels(2): VIH
VIL
IIH (VI = +2.7V)
IIL (VI = +0.4V)
16
Binary Two’s Complement
+2.0
–1.0
*
*
Unipolar Straight Binary
*
*
*
*
*
*
+5.5
+0.8
1
1
*
*
*
*
TRANSFER CHARACTERISTICS
ACCURACY(3)
Linearity Error
Differential Linearity Error(5)
at Bipolar Zero(5, 6)
Gain Error(7)
Zero Error(7)
Monotonicity Over Spec Temp Range
Power Supply Sensitivity: +VCC, –VCC
VDD
±0.003
±0.0045
±0.006
±0.012
±0.0015
±0.003
±0.003
*
*
±0.003
±0.006
±0.006
±0.15
*
±0.07
±0.05
±0.30
±0.1
±0.0015
±0.0001
±0.006
±0.001
*
*
*
*
*
*
±0.003
*
±30
*
*
*
±2.5
*
±0.15
±25
±25
±5
±12
+0.009,
–0.006
±0.006
*
*
±7
±1.5
±4
±0.10
±15
±15
±3
±10
*
8
4
*
*
*
13
DRIFT (Over Spec Temp Range(3))
Total Error Over Temp Range(8)
Total Full Scale Drift
Gain Drift
Zero Drift: Unipolar (DAC708/709 only)
Bipolar (all models)
Differential Linearity Over Temp(5)
14
±0.08
±10
±10
±5
±15
±0.012
14
±0.012
Linearity Error Over Temp(5)
SETTLING TIME (to ±0.003% of FSR)(9)
Voltage Output Models
Full Scale Step (2kΩ load)
1LSB Step at Worst Case Code(10)
Slew Rate
Current Output Models
Full Scale Step (2mA): 10 to 100Ω Load
1kΩ Load
4
2.5
10
*
*
*
*
8
4
% of FSR
ppm of FSR/°C
ppm/°C
ppm of FSR/°C
ppm of FSR/°C
% of FSR
% of FSR
µs
µs
V/µs
350
1
*
*
ns
µs
0 to +10
±5, ±10
*
*
*
*
V
V
V
mA
Ω
OUTPUT
VOLTAGE OUTPUT MODELS
Output Voltage Range
DAC709: Unipolar (USB Code)
Bipolar (BTC Code)
DAC707 Bipolar (BTC Code)
Output Current
Output Impedance
Short Circuit to Common Duration
±5
±10
*
0.15
Indefinite
CURRENT OUTPUT MODELS
Output Current Range (±30% typ)
DAC708: Unipolar (USB Code)
Bipolar (BTC Code)
Unipolar Output Impedance (±30% typ)
Bipolar Output Impedance (±30% typ)
Compliance Voltage
*
*
*
*
*
0 to –2
±1
4.0
2.45
±2.5
*
*
*
*
*
mA
mA
kΩ
kΩ
V
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.
®
DAC707/708/709
2
ELECTRICAL (CONT)
At TA = +25°C, VCC = ±15V, VDD = +5V, and after a 10-minute warm-up, unless otherwise noted.
DAC707/708/709KH,
DAC707KP
DAC707JP
PRODUCT
DAC707/708/
709BH, SH
MIN
TYP
MAX
MIN
TYP
MAX
MIN
TYP
MAX
UNITS
+13.5
–13.5
+4.5
+15
–15
+5
+16.5
–16.5
+5.5
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
V
V
V
+10
–13
+5
*
*
*
+25
–25
+10
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
mA
mA
mA
mA
mA
mA
370
*
800
950
*
*
*
*
mW
mW
–25
+85
–55
–65
+125
+150
°C
°C
°C
°C
°C
POWER SUPPLY REQUIREMENTS
Voltage (all models): +VCC
–VCC
VDD
Current (No Load, +15V Supplies)
Current Output Models: +VCC
–VCC
VDD
Voltage Output Models: +VCC
–VCC
VDD
+16
–18
+5
Power Dissipation (±15V supplies)
Current Output Models
Voltage Output Models
+30
–30
+10
535
TEMPERATURE RANGE
Specification: BH Grades
JP, KP, KH Grades
SH Grades
Storage: Ceramic
Plastic
0
–60
+70
*
*
+100
–65
*
+150
*
*Specification same as for models in column to the left.
NOTES: (1) MSB must be inverted externally prior to DAC708/709 input. (2) Digital inputs are TTL, LSTTL, 54/74C, 54/74HC and 54/74HTC compatible over the specified
temperature range. (3) DAC708 (current-output models) are specified and tested with an external output operational amplifier connected using the internal feedback
resistor in all tests. (4) FSR means Full Scale Range. For example, for ±10V output, FSR = 20V. (5) ±0.0015% of Full Scale Range is equal to 1 LSB in 16-bit resolution,
±0.003% of Full Scale Range is equal to 1 LSB in 15-bit resolution. ±0.006% of Full Scale Range is equal to 1 LSB in 14-bit resolution. (6) Error at input code 0000H.
(For unipolar connection on DAC708/709, the MSB must be inverted externally prior to D/A input.) (7) Adjustable to zero with external trim potentiometer. Adjusting the
gain potentiometer rotates the transfer function around the bipolar zero point. (8) With gain and zero errors adjusted to zero at +25°C. (9) Maximum represents the 3σ
limit. Not 100% tested for this parameter. (10) The bipolar worst-case code change is FFFFH to 0000H and 0000H to FFFFH. For unipolar (DAC708/709 only) it is 7FFFH
to 8000H and 8000H to 7FFFH.
PACKAGE INFORMATION
ABSOLUTE MAXIMUM RATINGS
PRODUCT
PACKAGE
PACKAGE DRAWING
NUMBER(1)
DAC707JP
DAC707KP
28-Pin Plastic DBL Wide DIP
28-Pin Plastic DBL Wide DIP
215
215
DAC707BH
28LD Side Brazed
Hermetic Dip
28LD Side Brazed
Hermetic DIP
28LD Side Brazed
Hermetic DIP
149
24LD Side Brazed
Hermetic DIP
24LD Side Brazed
Hermetic DIP
24LD Side Brazed
Hermetic DIP
165
DAC707KH
DAC707SH
DAC708BH
DAC708KH
DAC708SH
DAC709BH
DAC709KH
DAC709SH
24LD Side Brazed
Hermetic DIP
24LD Side Brazed
Hermetic DIP
24LD Side Brazed
Hermetic DIP
VDD to COMMON ........................................................................ 0V, +15V
+VCC to COMMON ..................................................................... 0V, +18V
–VCC to COMMON ...................................................................... 0V, –18V
Digital Data Inputs to COMMON ..................................... –0.5V, VDD +0.5
DC Current any input ..................................................................... ±10mA
Reference Out to COMMON ...................... Indefinite Short to COMMON
VOUT (DAC707, DAC709) ........................... Indefinite Short to COMMON
External Voltage Applied to RF (pin 13 or 14, DAC708) .................. ±18V
External Voltage Applied to D/A Output
(pin 1, DAC707; pin 14, DAC709) ......................................................... ±5V
Power Dissipation ........................................................................ 1000mW
Storage Temperature ..................................................... –60°C to +150°C
Lead Temperature (soldering, 10s) ................................................. 300°C
149
149
165
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.
165
165
ELECTROSTATIC
DISCHARGE SENSITIVITY
165
165
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.
NOTE: (1) For detailed drawing and dimension table, please see end of data
sheet, or Appendix C of Burr-Brown IC Data Book.
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.
®
3
DAC707/708/709
ORDERING INFORMATION
PRODUCT
TEMPERATURE
RANGE
INPUT
CONFIGURATION
OUTPUT
CONFIGURATION
DAC707JP
DAC707JP-BI(1)
DAC707KP
DAC707KP-BI(1)
DAC707KH
DAC707KH-BI(1)
DAC707BH
DAC707BH-BI(1)
DAC707SH
DAC707SH-BI(1)
0°C to +70°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
–25°C to +85°C
–25°C to +85°C
–55°C to +125°C
–55°C to +125°C
16-bit port
16-bit port
16-bit port
16-bit port
16-bit port
16-bit port
16-bit port
16-bit port
16-bit port
16-bit port
±10V output
±10V output
±10V output
±10V output
±10V output
±10V output
±10V output
±10V output
±10V output
±10V output
DAC708KH
DAC708BH
DAC708SH
0°C to +70°C
–25°C to +85°C
–55°C to +125°C
8-bit port
8-bit port
8-bit port
±1mA output
±1mA output
±1mA output
DAC709KH
DAC709BH
DAC709SH
0°C to +70°C
–25°C to +85°C
–55°C to +125°C
8-bit port
8-bit port
8-bit port
±10V output
±10V output
±10V output
NOTE: (1) 25 piece minimum order.
CONNECTION DIAGRAMS
DAC708/709
A1
D7 (D15)
24
2
23
3
22
4
D6 (D14)
High
Byte
Latch
5
D5 (D13)
21
7
D3 (D11)
Low
Byte
Latch
8
D2 (D10)
D1 (D9)
D0 (D8)/S1
DAC709
Only
14
V OUT
(2)
2
DCOM
ACOM
3.9MΩ
Analog Common
270k Ω
SJ
(3)
GA
(1)
Gain Adjust
+VCC
+V
CC
–V
CC
WR
13
VDD
+
(2)
CS
NOTES: (1) Potentiometer is
10k Ω to 100kΩ . (2) Decoupling
capcitors are 0.1µF to 1.0µF.
Control
Lines
CLR
–VCC
–VCC
+VCC
270k Ω
GA
BPO
SJ
ACOM
(1)
+VCC
+
Gain
Adjust
3.9MΩ
(1)
+
(2)
(2)
+
Offset Adjust
VOUT
Connect for bipolar operation.
R F2
Connect for 10V range.
Leave pin 13 open for 20V range.
1
V DD
(2)
17
10kΩ
10kΩ
VDD
(3)
15
DAC707
–VCC
18
10
12
Offset
Adjust
19
16
VDD
Digital
Common
20
9
11
DCOM
16-Bit Reference
Circuit
Ladder
Resistor
Network
and
Current
Switches
D/A
Latch
6
D4 (D12)
Data
Inputs
1
28 D0 (LSB)
27 D1
RF
3
26 D2
4
25 D3
5
24 D4
6
23 D5
7
22 D6
8
21 D7
(2)
16-Bit
Ladder
Resistor
Network
and
Current
Switches
CLR
9
WR
10
A1
11
A0
12
(MSB) D15
13
16 D12
D14
14
15 D13
Control Lines
Latch Enable Lines
Input Latch
A0
D/A Latch
A2
Register
Enable
Lines
20 D8
19 D9
18 D10
17 D11
Digital Inputs
NOTES: (1) Potentiometers are 10k Ω to 100k Ω.
(2) Decoupling capcitors are 0.1µF to 1.0µF.
(3) Bypass, 0.0022µF to 0.01µF.
®
DAC707/708/709
4
Digital
Inputs
DESCRIPTION OF PIN FUNCTIONS
DESIGNATOR
DAC707
Pin
DESCRIPTION
#
DAC708/709
DESIGNATOR
DESCRIPTION
VOUT
Voltage output for DAC707 (±10V)
1
A2
Latch enable for D/A latch (Active low)
VDD
Logic supply (+5V)
2
A0
Latch enable for “low byte” input (Active low). When
both A0 and A1 are logic “0”, the serial input mode is
selected and the serial input is enabled.
DCOM
Digital common
3
A1
Latch enable for “high byte” input (Active low). When
both A0 and A1 are logic “0”, the serial input mode is
selected and the serial input is enabled.
ACOM
Analog common
4
D7 (D15)
Input for data bit 7 if enabling low byte (LB) latch or
data bit 15 if enabling the high byte (HB) latch.
SJ
Summing junction of the internal output op amp for the
DAC707. Offset adjust circuit is connected to the
summing junction of the output amplifier. Refer to Block
Diagram.
5
D6 (D14)
Input for data bit 6 if enabling LB latch or data bit 14 if
enabling the HB latch.
GA
Gain adjust pin. Refer to Connection Diagram for gain
adjust circuit.
6
D5 (D13)
Data bit 5 (LB) or data bit 13 (HB)
+VCC
Positive supply voltage (+15V)
7
D4 (D12)
Data bit 4 (LB) or data bit 12 (HB)
–VCC
Negative supply voltage (–15V)
8
D3 (D11)
Data bit 3 (LB) or data bit 11 (HB)
CLR
Clear line. Sets the input latch to zero and sets the D/A
latch to the input code that gives bipolar zero on the
D/A output (Active low)
9
D2 (D10)
Data bit 2 (LB) or data bit 10 (HB)
WR
Write control line (Active low)
10
D1 (D9)
Data bit 1 (LB) or data bit 9 (HB)
A1
Enable for D/A converter latch (Active low)
11
D0 (D8)/SI
Data bit 0 (LB) or data bit 8 (HB). Serial input when
serial mode is selected.
A0
Enable for input latch (Active low)
12
DCOM
Digital common
D15 (MSB)
Data bit 15 (Most Significant Bit)
13
RF2
Feedback resistor for internal or external operational
amplifier. Connect to pin 14 when a 10V output range
is desired. Leave open for a 20V output range.
D14
Data bit 14
14
VOUT
RF1 (DAC708)
Voltage output for DAC709 or feedback resistor for
use with an external output op amp for the DAC708.
Refer to Connection Diagram for connection of
external op amp to DAC708.
D13
Data bit 13
15
ACOM
Analog common
D12
Data bit 12
16
SJ (DAC709)
IOUT (DAC708)
Summing junction of the internal output op amp for the
DAC709, or the current output for the DAC708. Refer
to Connection Diagram for connection of external op
amp to DAC708.
D11
Data bit 11
17
BPO
Bipolar offset. Connect to pin 16 when operating in the
bipolar mode. Leave open for unipolar mode.
D10
Data bit 10
18
GA
Gain adjust pin
D9
Data bit 9
19
+VCC
Positive supply voltage (+15V)
D8
Data bit 8
20
–VCC
Negative supply voltage (–15V)
D7
Data bit 7
21
CLR
Clear line. Sets the high and low byte input registers
to zero and, for bipolar operation, sets the D/A register
to the input code that gives bipolar zero on the D/A
output. (In the unipolar mode, invert the MSB prior to
the D/A.)
D6
Data bit 6
22
WR
Write control line
D5
Data bit 5
23
CS
Chip select control line
D4
Data bit 4
24
VDD
Logic supply (+5V)
D3
Data bit 3
25
No pin
D2
Data bit 2
26
No pin
D1
Data bit 1
27
No pin
D0 (LSB)
Data bit 0 (Least Significant Bit)
28
No pin
(The DAC708 and DAC709 are in 24-pin packages)
®
5
DAC707/708/709
DISCUSSION OF
SPECIFICATIONS
the MSB must be inverted). This code corresponds to zero
volts (DAC707 and DAC709) or zero milliamps (DAC708)
at the analog output. The maximum change in offset at tMIN
or tMAX is referenced to the zero error at +25°C and is divided
by the temperature change. This drift is expressed in FSR/
°C.
DIGITAL INPUT CODES
For bipolar operation, the DAC707/708/709 accept positivetrue binary two’s complement input code. For unipolar
operation (DAC708/709 only) the input code is positive-true
straight-binary provided that the MSB input is inverted with
an external inverter. See Table I.
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.
Unipolar Straight Binary(1)
(DAC708/709 only; connected
for Unipolar operation)
Binary Two's Complement
(Bipolar operation;
all models)
7FFFH
0000H
FFFFH
8000H
+1/2 Full Scale –1LSB(2)
Zero
+Full Scale
+1/2 Full Scale
+Full Scale
Zero
–1LSB
–Full Scale
Final-Value Error Band
Percent of Full-Scale Range (±% of FSR)
ANALOG OUTPUT
Digital
Input
Codes
NOTES: (1) MSB must be inverted externally. (2) Assumes MSB is inverted
externally.
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 (–Full Scale point and +Full Scale
point).
DAC707
DAC709
DAC708
0.1
R L = 100Ω
0.01
R L = 1kΩ
0.001
0.01
0.1
1
10
Settling Time (µs)
FIGURE 1. Final-Value Error Band Versus Full-Scale Range
Settling Time.
Differential Linearity Error
Differential Linearity Error (DLE) of a D/A converter is the
deviation from an ideal 1LSB change in the output when the
input changes from one adjacent code to the next. A differential linearity error specification of ±1/2LSB means that the
output step size can be between 1/2LSB and 3/2LSB when
the input changes between adjacent codes. A negative DLE
specification of –1LSB maximum (–0.006% for 14-bit resolution) insures monotonicity.
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 (±10V) or 10V (±5V or 0 to 10V) 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.)
Monotonicity
Monotonicity assures that the analog output will increase or
remain the same for increasing input digital codes. The
DAC707/708/709 are specified to be monotonic to 14 bits
over the entire specification temperature range.
Current Output
Settling times are specified to ±0.003% of FSR for a fullscale range change for two output load conditions: one for
10Ω to 100Ω and one for 1000Ω. It is specified this way
because the output RC time constant becomes the dominant
factor in determining settling time for large resistive loads.
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 at tMIN, +25°C and tMAX; (2)
calculating the gain error with respect to the +25°C value;
and (3) dividing by the temperature change.
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.
POWER SUPPLY SENSITIVITY
Power supply sensitivity is a measure of the effect of a
change in a power supply voltage on the D/A converter
Zero Drift
Zero Drift is a measure of the change in the output with
0000H applied to the D/A converter inputs over the specified
temperature range. (For the DAC708/709 in unipolar mode,
®
DAC707/708/709
1
6
Zero Adjustment
% of FSR Error Per % of Change in VSUPPLY
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 (–VCC) or logic supply (VDD) about the
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.
For unipolar (USB) configurations, apply the digital input
code that produces zero voltage or zero current output and
adjust the zero potentiometer for zero output.
For bipolar (BTC) configurations, apply the digital input
code that produces zero output voltage or current. See Table
II for corresponding codes and connection diagrams for zero
adjustments circuit connections. Zero calibration should be
made before gain calibration.
0.030
Gain Adjustment
0.025
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 Diagrams for gain adjustment
circuit connections.
–15V Supply
0.020
0.015
+5V
Supply
0.010
+15V
Supply
0.005
Range of
Gain Adjust
0
1
10
100
1k
10k
+ Full Scale
100k
Power Supply Ripple Frequency (Hz)
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.
Full Scale Range
Analog Output
1LSB
FIGURE 2. Power Supply Rejection Versus Power Supply
Ripple Frequency.
Range of
Zero
Adjust
Gain Adjust
Rotates the Line
Input =
0000 H
Input = FFFFH
Digital Input
Zero Adjust Translates the Line
EXTERNAL ZERO AND GAIN ADJUSTMENT
FIGURE 4. Relationship of Zero and Gain Adjustments for
Unipolar D/A Converters, DAC708 and
DAC709.
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
less. The 3.9MΩ and 270kΩ 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 3.9MΩ resistor.
A 0.001µF to 0.01µF ceramic capacitor should be connected
from GAIN ADJUST to ANALOG COMMON to prevent
noise pickup. Refer to Figures 4 and 5 for the relationship of
zero and gain adjustments to unipolar D/A converters.
3.9MΩ
180kΩ
+ Full Scale
1LSB
Analog Output
Input = 8000H
Gain Adjust
Rotates
the Line
Full Scale
Range
Range of
Gain Adjust
Offset Adjust
Translates
the Line
Range and
Offset Adjust
Input = 7FFFH
Input = 0000H
180kΩ
– Full Scale
10kΩ
Digital Input
FIGURE 5. Relationship of Zero and Gain Adjustments for
Bipolar D/A Converters, DAC707 and DAC708/
709
FIGURE 3. Equivalent Resistances.
®
7
DAC707/708/709
VOLTAGE OUTPUT MODELS
Digital
Input
Code
One LSB
FFFFH
0000H
Analog Output
Unipolar, 0 to +10V(1)
16-Bit
15-Bit
14-Bit
Units
153
+9.99985
0
305
+9.99969
0
610
+9.99939
0
µV
V
V
Analog Output
Digital
Input
Code
One LSB
7FFFH
8000H
Bipolar, ±10V
Bipolar, ±5V
16-Bit
15-Bit
14-Bit
16-Bit
15-Bit
14-Bit
Units
305
+9.99960
–10.0000
610
+9.99939
–10.0000
1224
+9.99878
–10.0000
153
+4.99980
–5.0000
305
+4.99970
–5.0000
610
+4.99939
–5.0000
µV
V
V
CURRENT OUTPUT MODELS
Analog Output
Digital
Input
Code
One LSB
FFFFH
0000H
Analog Output
Digital
Input
Code
Unipolar, 0 to –2mA (1)
16-Bit
15-Bit
14-Bit
Units
0.031
–1.99997
0
0.061
–1.99994
0
0.122
–1.99988
0
µA
mA
mA
One LSB
7FFFH
8000H
Bipolar, ±1mA
16-Bit
15-Bit
14-Bit
Units
0.031
–0.99997
+1.00000
0.061
–0.99994
+1.00000
0.122
–0.99988
+1.00000
µA
mA
mA
NOTE: (1) MSB assumed to be inverted externally.
TABLE II. Digital Input and Analog Output Voltage/Current Relationships.
INTERFACE LOGIC AND TIMING
DAC708/709
LOGIC TIMING - Parallel or Serial Data Input Over Temperature
ns, min
ns, max
TDW
Data valid to end of WR
80
TCW
CS valid to end of WR
80
TAW
A0, A1, A2 valid to end of WR
80
TWP
Write pulse width
80
TDH
Data hold after end of WR
0
The signals CHIP SELECT (CS), WRITE (WR), register
enables (A0, A1, and A2) and CLEAR (CLR), provide the
control functions for the microprocessor interface. They are
all active in the “low” or logic “0” state. CS must be low to
access any of the registers. A0 and A1 steer the input 8-bit
data byte to the low- or high-byte input latch respectively. A2
gates the contents of the two input latches through to the D/A
latch in parallel. The contents are then applied to the input of
the D/A converter. When WR goes low, data is strobed into
the latch or latches which have been enabled.
TIMING DIAGRAM
tCW
CS
tAW
A0, A1, A2
The serial input mode is activated when both A0 and A1 are
logic “0” simultaneously. The D0 (D8)/SI input data line
accepts the serial data MSB first. Each bit is clocked in by
a WR pulse. Data is strobed through to the D/A latch by A2
going to logic “0” the same as in the parallel input mode.
tDW
D0-D15, SI
tDH
WR
Each of the latches can be made “transparent” by maintaining its enable signal at logic “0”. However, as stated above,
when both A0 and A1 are logic “0” at the same time, the
serial mode is selected.
tWP
FIGURE 6. Logic Timing Diagram.
D/A latch is enabled by A1. Also, there is no serial-input
mode and no CHIP SELECT (CS) line.
The CLR line resets both input latches to all zeros and sets
the D/A latch to 0000H. This is the binary code that gives a
null, or zero, at the output of the D/A in the bipolar mode.
In the unipolar mode, activating CLR will cause the output
to go to one-half of full scale.
INSTALLATION
CONSIDERATIONS
The maximum clock rate of the latches is 10MHz. The
minimum time between write (WR) pulses for successive
enables is 20ns. In the serial input mode (DAC708 and
DAC709), the maximum rate at which data can be clocked
into the input shift register is 10MHz.
Due to the extremely-high accuracy 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 30mΩ will cause the output to be in error by 1LSB. To
understand what this means in terms of a system layout, the
resistance of typical 1 ounce copper-clad printed circuit
board material is approximately 1/2mΩ per square. In the
example above, a 10 milliinch-wide conductor 60 milliinches
long would cause a 1LSB error.
The timing of the control signals is given in Figure 6.
DAC707
The DAC707 interface timing is the same as that described
above except instead of two 8-bit separately-enabled input
latches, it has a single 16-bit input latch enabled by A0. The
®
DAC707/708/709
8
In Figures 7 and 8, lead and contact resistances are represented by R1 through R5. As long as the load resistance RL
is constant, R2 simply introduces a gain error and can be
removed with gain calibration. R3 is part of RL if the output
voltage is sensed at ANALOG COMMON.
DAC707/709
RF
10k Ω
MicroProcessor
Interface
4k Ω
Figures 8 and 9 show two methods of connecting the current
output model with an external precision output op amp. By
sensing the output voltage at the load resistor (connecting RF
to the output of the amplifier at RL) the effect of R1 and R2
is greatly reduced. R1 will cause a gain error but is independent of the value of RL and can be eliminated by initial
calibration adjustments. The effect of R2 is negligible because it is inside the feedback loop of the output op amp and
is therefore greatly reduced by the loop gain.
R2
2k Ω
0 to
2mA
RL
2mA
+1%
Analog Common
Digital
Common
Sense
Output
R3
Alternate Ground
Sense Connection
In many applications it is impractical to sense the output
voltage at ANALOG COMMON. Sensing the output voltage at the system ground point is permissible because these
converters have separate analog and digital common lines
and the analog return current is a near-constant 2mA and
varies by only 10µA to 20µA over the entire input code
range. R4 can be as large as 3Ω without adversely affecting
the linearity of the D/A converter. The voltage drop across
R4 is constant and appears as a zero error that can be nulled
with the zero calibration adjustment.
R4
1µF
1µF
+
+
System
Ground
+VCC
Analog
Common
–VCC
±VCC
Supply
Digital
Common
1µF
VDD
Supply
+
VDD
Another approach senses the output at the load as shown in
Figure 9. 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 R6 and R7 must be adjusted
for maximum common-mode rejection across RL. The effect
of R4 is negligible as explained previously.
FIGURE 7. DAC707/709 Bipolar Output Circuit (Voltage
Out).
DAC708
R1
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 to elimination of RF radiation or pickup
is small loop area. Signal leads and their return conductors
should be kept close together such that they present a small
flux-capture cross section for any external field.
RF1
RF
10k Ω
MicroProcessor
Interface
IOUT
2.45k Ω
R2
RB
RL
DAC708
Analog Common
Digital
Common
Sense
Output
R1
RF
R3
R2
Alternate Ground
Sense Connection
RDAC
R4
1µF
1µF
+
+
System
Ground
+VCC
Analog
Common
–VCC
R7
To System Ground
R3
FIGURE 9. Alternate Connection for Ground Sensing at the
Load (Current Output Models).
VDD
Supply
+
Sense
Output
R5
±VCC
Supply
Digital
Common
1µF
RL
R6
VDD
FIGURE 8. DAC708 Bipolar Output Circuit (with External
Op Amp).
®
9
DAC707/708/709
BURN-IN SCREENING
Burn-in screening is an option available for the DAC707.
Burn-in duration is 160 hours at the temperature shown
below (or equivalent combination of time and temperature).
Product
Temp. Range
signal lines need to be isolated. The data is applied to pin 11
in a serial bit stream, MSB first. The WR input is used as a
data strobe, clocking in each data bit. A RESET signal is
provided for system startup and reset. These three signals
are each optically isolated. Once the 16 bits of serial data
have been strobed into the input register pair, the data is
strobed through to the D/A register by the “carry” signal out
of a 4-bit binary synchronous counter that has counted the
16 WR pulses used to clock in the data. The circuit diagram
is given in Figure 10.
Burn-In Screening
DAC707JP-BI
0°C to 70°C
100°C
DAC707KP-BI
0°C to 70°C
100°C
DAC707KH-BI –25°C to +85°C
125°C
DAC707BH-BI –25°C to +85°C
125°C
DAC707SH-BI –55°C to +125°C
125°C
All units are tested after burn-in to ensure that grade specifications are met.
CONNECTING MULTIPLE DAC707s
TO A 16-BIT MICROPROCESSOR BUS
Figure 11 illustrates the method of connecting multiple
DAC707s to a 16-bit microprocessor bus. The circuit shown
has two DAC707s and uses only one address line to select
either the input register or the D/A register. An external
address decoder selects the desired converter.
APPLICATIONS
LOADING THE DAC709 SERIALLY
ACROSS AN ISOLATION BARRIER
A very useful application of the DAC709 is in achieving
low-cost isolation that preserves high accuracy. Using the
serial input feature of the input register pair, only three
®
DAC707/708/709
10
74LS161A
VDD
Synchronous Binary Counter
Carry Out
QA
ENT
QB
ENP
QC
Load
QD
A
B
In
C
CLR
CK D
2.2kΩ
0.001µF
No
Connection
+5V
1/4 74LS00
VDD
VDD
A 2 A1 A0 CS
2.2kΩ
330Ω
Analog
Output
WR
TIL117
DATA STROBE
1/6 7407
VDD
CLR
DAC708
or
DAC709
VDD
330Ω
2.2k Ω
Serial Input
(16-Bit Data
Stream)
1/6 7407
VDD
ACOM
DCOM
–VCC
+VCC
DO
1/4 74LS00
+
+
1/4 74LS00
VDD
VDD
330Ω
+
10kΩ
2.2kΩ
RESET
+
2.2µF
VDD
1/6 7407
+
Isolated
Power
Supply
Power
Supply
Voltage
–
Isolation Barrier
...
DATA STROBE
Serial Input
1
2
3
4
14
...
15
16
A2
Analog
Output
FIGURE 10. Serial Loading of Electrically Isolated DAC708/709.
WR
D16
16-Bit Data Bus
D0
A0
A1
µP
A15
A1
16-Bit
Address
Bus
Base
Address
Decoder
WR
VOUT 1
DAC707
CS1
A0
CS2
A1
A0
WR
VOUT 2
DAC707
FIGURE 11. Connecting Multiple DAC707s to a 16-Bit Microprocessor.
®
11
DAC707/708/709
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