TI DAC8814IBDBT

DAC8814
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SBAS338 – JANUARY 2005
Quad, Serial Input 16-Bit Multiplying Digital-to-Analog Converter
FEATURES
DESCRIPTION
•
•
•
The DAC8814 is a quad, 16-bit, current-output digital-to-analog converter (DAC) designed to operate
from a single +2.7 V to 5.0 V supply.
•
•
•
•
•
•
•
The applied external reference input voltage VREF
determines the full-scale output current. An internal
feedback resistor (RFB) provides temperature tracking
for the full-scale output when combined with an
external I-to-V precision amplifier.
A doubled buffered serial data interface offers
high-speed, 3-wire, SPI and microcontroller compatible inputs using serial data in (SDI), clock (CLK), and
a chip-select (CS). In addition, a serial data out pin
(SDO) allows for daisy-chaining when multiple packages are used. A common level-sensitive load DAC
strobe (LDAC) input allows simultaneous update of all
DAC outputs from previously loaded input registers.
Additionally, an internal power on reset forces the
output voltage to zero at system turn on. An MSB pin
allows system reset assertion (RS) to force all registers to zero code when MSB = 0, or to half-scale
code when MSB = 1.
APPLICATIONS
•
•
•
Automatic Test Equipment
Instrumentation
Digitally Controlled Calibration
The DAC8814 is available in an SSOP package.
VREFA B C D
D0
D1
D2
D3
D4
D5
D6
D7
D8
D9
D10
D11
D12
D13
D14
D15
A0
A1
SDO
SDI
RFBA
Input
Register
R
DAC A
Register
R
DAC A
IOUTA
AGNDA
RFBB
16
Input
Register
R
DAC B
Register
R
DAC B
IOUTC
AGNDB
RFBC
Input
Register
R
DAC C
Register
R
DAC C
IOUTC
AGNDC
CS
CLK
RFBD
EN
DAC A
B
C
D
2:4
Decode
DGND
Input
Register
R
DAC D
Register
R
DAC D
IOUTD
AGNDD
Power-on
Reset
RS
MSB
AGNDF
LDAC
VSS
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
SPI is a trademark of Motorola, Inc.
PRODUCT PREVIEW information concerns products in the formative or design phase of development. Characteristic data and other
specifications are design goals. Texas Instruments reserves the
right to change or discontinue these products without notice.
Copyright © 2005, Texas Instruments Incorporated
PRODUCT PREVIEW
•
•
•
Relative Accuracy: 1 LSB Max
Differential Nonlinearity: 1 LSB Max
2-mA Full-Scale Current ±20%,
with VREF = ±10 V
0.5 µs Settling Time
Midscale or Zero-Scale Reset
Four Separate 4Q Multiplying Reference
Inputs
Reference Bandwidth: 10 MHz
Reference Dynamics: -105 dB THD
SPI™-Compatible 3-Wire Interface:
50 MHz
Double Buffered Registers Enable
Simultaneous Multichannel Change
Internal Power On Reset
Industry-standard Pin Configuration
DAC8814
www.ti.com
SBAS338 – JANUARY 2005
This integrated circuit can be damaged by ESD. Texas Instruments 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.
PACKAGE/ORDERING INFORMATION (1)
PRODUCT
MINIMUM
RELATIVE
ACCURACY
(LSB)
DIFFERENTIAL
NONLINEARITY
(LSB)
SPECIFIED
TEMPERATURE
RANGE
PACKAGELEAD
PACKAGE
DESIGNATOR
DAC8814C
±1
±1
-40°C to +85°C
SSOP-28
DB
DAC8814B
±4
±1.5
-40°C to +85°C
SSOP-28
DB
(1)
ORDERING
NUMBER
TRANSPORT
MEDIA,
QUANTITY
DAC8814ICDBT
Tape and Reel, 250
DAC8814ICDBR
Tape and Reel, 2500
DAC8814IBDBT
Tape and Reel, 250
DAC8814IBDBR
Tape and Reel, 2500
For the most current specifications and package information, see the Package Option Addendum located at the end of this data sheet or
refer to our web site at www.ti.com.
PRODUCT PREVIEW
ABSOLUTE MAXIMUM RATINGS (1)
DAC8814
UNIT
VDD to GND
-0.3 to +8
V
VSS to GND
-0.3 to -7
V
VREF to GND
-18 to +18
V
Logic inputs and output to GND
-0.3 to + 8
V
V(IOUT) to GND
-0.3 to VDD + 0.3
V
AGNDX to DGND
-0.3 to +0.3
V
±50
mA
Input current to any pin except supplies
Package power dissipation
Thermal resistance, θJA
(TJmax - TA)/θJA
28-Lead shrink surface-mount (RS-28)
Maximum junction temperature (TJmax)
2
°C
-40 to +85
°C
°C
RS-28 (Vapor phase 60s)
215
°C
RS-28 (Infrared 15s)
220
°C
Storage temperature range
(1)
°C/W
150
-65 to + 150
Operating temperature range, Model A
Lead temperature
100
Stresses above those listed under absolute maximum ratings may cause permanent damage to the device. This is a stress rating only;
functional operation of the device at these or any other conditions above those indicated in the operational sections of this specification
is not implied. Exposure to absolute maximum conditions for extended periods may affect device reliability.
DAC8814
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SBAS338 – JANUARY 2005
ELECTRICAL CHARACTERISTICS
(1)
VDD = 2.7 V to 5.0 V ±10%; VSS = 0 V, IOUTX = Virtual GND, AGNDX = 0 V, VREFA, B, C, D = 10 V, TA = full operating
temperature range, unless otherwise noted.
DAC8814
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNIT
STATIC PERFORMANCE (2)
Resolution
16
Bits
INL
DAC8814B
±4
LSB
INL
DAC8814C
±1
LSB
Differential nonlinearity
DNL
DAC8814B
±1.5
LSB
DNL
DAC8814C
±1
LSB
Output leakage current
IOUTX
Data = 0000h, TA = 25°C
10
nA
IOUTX
Data = 0000h, TA = TA max
20
nA
Full-scale gain error
GFSE
Data = FFFFh
Full-scale tempco (3)
TCVFS
Relative accuracy
Feedback resistor
RFBX
±0.75
VDD = 5 V
±3
mV
1
ppm/°C
5
kΩ
VREFX Range
VREFX
-15
Input resistance
RREFX
4
Input resistance match
RREFX
Input
capacitance (3)
Channel-to-channel
CREFX
6
15
V
8
kΩ
1
%
5
pF
PRODUCT PREVIEW
REFERENCE INPUT
ANALOG OUTPUT
Output current
Output
capacitance (3)
IOUTX
Data = FFFFh
COUTX
Code-dependent
1.25
2.5
80
mA
pF
LOGIC INPUTS AND OUTPUT
Input low voltage
Input high voltage
Input leakage current
Input capacitance (3)
VIL
VDD = +2.7 V
0.6
V
VIL
VDD = +5 V
0.8
V
VIH
VDD = +2.7 V
2.1
VIH
VDD = +5 V
2.4
IIL
CIL
Logic output low voltage
VOL
IOL = 1.6 mA
Logic output high voltage
VOH
IOH = 100 µA
INTERFACE
V
V
1
µA
10
pF
0.4
V
4
V
TIMING (3), (4)
Clock width high
tCH
25
ns
Clock width low
tCL
25
ns
CS to Clock setup
tCSS
0
ns
Clock to CS hold
tCSH
25
tPD
2
tLDAC
25
ns
Data setup
tDS
20
ns
Data hold
tDH
20
ns
Load setup
tLDS
5
ns
Load hold
tLDH
25
ns
Clock to SDO prop delay
Load DAC pulsewidth
(1)
(2)
(3)
(4)
ns
20
ns
Specifications subject to change without notice.
All static performance tests (except IOUT) are performed in a closed-loop system using an external precision OPA277 I-to-V converter
amplifier. The DAC8814 RFB terminal is tied to the amplifier output. Typical values represent average readings measured at +25°C.
These parameters are specified by design and not subject to production testing.
All input control signals are specified with tR = tF = 2.5 ns (10% to 90% of 3 V) and timed from a voltage level of 1.5 V.
3
DAC8814
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SBAS338 – JANUARY 2005
ELECTRICAL CHARACTERISTICS (continued)
VDD = 2.7 V to 5.0 V ±10%; VSS = 0 V, IOUTX = Virtual GND, AGNDX = 0 V, VREFA, B, C, D = 10 V, TA = full operating
temperature range, unless otherwise noted.
DAC8814
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNIT
SUPPLY CHARACTERISTICS
Power supply range
Positive supply current
Negative supply current
Power dissipation
Power supply sensitivity
VDD
2.7
RANGE
5.5
V
IDD
Logic inputs = 0 V
2
5
µA
IDD
VDD = +4.5 V to +5.5 V
2
5
µA
IDD
VDD = +2.7 V to +3.6 V
1
2.5
µA
ISS
Logic inputs = 0 V, VSS = -5 V
PDISS
PSS
1
µA
Logic inputs = 0 V
0.001
0.0275
mW
∆VDD = ±5%
0.006
%
AC CHARACTERISTICS (5)
Output voltage settling time
PRODUCT PREVIEW
Reference multiplying BW
ts
To ±0.1% of full-scale,
Data = 0000h to FFFFh to 0000h
0.5
ts
To ±0.0051% of full-scale,
Data = 0000h to FFFFh to 0000h
1
µs
10
MHz
Q
VREFX = 10 V, Data = 0000h to 8000h to 0000h
1
nV/s
Feedthrough error
VOUTX/VREFX
Data = 0000h, VREFX = 100 mVRMS, f = 100 kHz
-70
Crosstalk error
VOUTA/VREFB
Data = 0000h, VREFB = 100 mVRMS,
Adjacent channel, f = 100 kHz
-90
DAC glitch impulse
Digital feedthrough
Total harmonic distortion
Output spot noise voltage
(5)
4
BW -3 dB VREFX = 100 mVRMS, Data = FFFFH, CFB = 15 pF
µs
Q
THD
en
CS = 1 and fCLK = 1 MHz
VREF = 5 VPP, Data = FFFFh, f = 1 kHz
2
-105
f = 1 kHz, BW = 1 Hz
All ac characteristic tests are performed in a closed-loop system using an OPA627 I-to-V converter amplifier.
12
dB
dB
nV/s
dB
nV/√Hz
DAC8814
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SBAS338 – JANUARY 2005
PIN CONFIGURATIONS
DAC8814
(TOP VIEW)
AGNDA
IOUTA
VREFA
RFBA
MSB
RS
VDD
CS
CLK
SDI
RFBB
VREFB
IOUTB
AGNDB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
AGNDD
IOUTD
VREFD
RFBD
DGND
VSS
AGNDF
LDAC
SDO
NC(1)
RFBC
VREFC
IOUTC
AGNDC
PRODUCT PREVIEW
NOTE (1): NC − No internal connection
PIN DESCRIPTION
PIN
NAME
1, 14, 15, 28
AGNDA, AGNDB, AGNDC, AGNDD
DAC A, B, C, D Analog ground.
DESCRIPTION
2, 13, 16, 27
IOUTA, IOUTB, IOUTC, IOUTD
DAC A, B, C, D Current output.
3, 12, 17, 26
VREFA, VREFB, VREFC, VREFD
DAC A, B, C, D Reference voltage input terminal. Establishes DAC A, B, C, D full-scale
output voltage. Can be tied to VDD.
4, 11, 18, 25
RFBA, RFBB, RFBC, RFBD
Establish voltage output for DAC A, B, C, D by connecting to external amplifier output.
5
MSB
MSB Bit set during a reset pulse (RS) or at system power on if tied to ground or VDD.
6
RS
Reset pin, active low. Input register and DAC registers are set to all zeros or half scale
code (8000h) determined by the voltage on the MSB pin. Register data = 8000h when
MSB = 1.
7
VDD
Positive power supply input. Specified range of operation 5 V ±10%.
8
CS
Chip-select; active low input. Disables shift register loading when high. Transfers shift
register data to input register when CS/LDAC goes high. Does not affect LDAC operation.
9
CLK
Clock input; positive edge triggered clocks data into shift register
10
SDI
Serial data input; data loads directly into the shift register.
19
NC
Not connected; leave floating.
20
SDO
Serial data output; input data loads directly into shift register. Data appears at SDO, 19
clock pulses after input at the SDI pin.
21
LDAC
Load DAC register strobe; level sensitive active low. Tranfers all input register data to the
DAC registers. Asynchronous active low input. See Table 1 for operation.
22
AGNDF
High current analog force ground.
23
VSS
24
DGND
Negative bias power-supply input. Specified range of operation -0.3 V to -5.5 V.
Digital ground.
5
DAC8814
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SBAS338 – JANUARY 2005
TYPICAL CHARACTERISTICS: VDD = +5 V
At TA = +25°C, +VDD = +5 V, unless otherwise noted.
Channel A
LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Graphic
Forthcoming
PRODUCT PREVIEW
Figure 1.
Figure 2.
LINEARITY ERROR
vs DIGITAL INPUT CODE
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Figure 3.
6
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Figure 4.
DAC8814
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SBAS338 – JANUARY 2005
TYPICAL CHARACTERISTICS: VDD = +5 V (continued)
At TA = +25°C, +VDD = +5 V, unless otherwise noted.
Graphic
Forthcoming
Figure 5.
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Figure 6.
PRODUCT PREVIEW
LINEARITY ERROR
vs DIGITAL INPUT CODE
7
DAC8814
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SBAS338 – JANUARY 2005
TYPICAL CHARACTERISTICS: VDD = +5 V (continued)
At TA = +25°C, +VDD = +5 V, unless otherwise noted.
Channel B
LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Graphic
Forthcoming
PRODUCT PREVIEW
Figure 7.
Figure 8.
LINEARITY ERROR
vs DIGITAL INPUT CODE
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Figure 9.
8
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Figure 10.
DAC8814
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SBAS338 – JANUARY 2005
TYPICAL CHARACTERISTICS: VDD = +5 V (continued)
At TA = +25°C, +VDD = +5 V, unless otherwise noted.
Graphic
Forthcoming
Figure 11.
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Figure 12.
PRODUCT PREVIEW
LINEARITY ERROR
vs DIGITAL INPUT CODE
9
DAC8814
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SBAS338 – JANUARY 2005
TYPICAL CHARACTERISTICS: VDD = +5 V (continued)
At TA = +25°C, +VDD = +5 V, unless otherwise noted.
Channel C
LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Graphic
Forthcoming
PRODUCT PREVIEW
Figure 13.
Figure 14.
LINEARITY ERROR
vs DIGITAL INPUT CODE
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Figure 15.
10
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Figure 16.
DAC8814
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SBAS338 – JANUARY 2005
TYPICAL CHARACTERISTICS: VDD = +5 V (continued)
At TA = +25°C, +VDD = +5 V, unless otherwise noted.
Graphic
Forthcoming
Figure 17.
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Figure 18.
PRODUCT PREVIEW
LINEARITY ERROR
vs DIGITAL INPUT CODE
11
DAC8814
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SBAS338 – JANUARY 2005
TYPICAL CHARACTERISTICS: VDD = +5 V (continued)
At TA = +25°C, +VDD = +5 V, unless otherwise noted.
Channel D
LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Graphic
Forthcoming
PRODUCT PREVIEW
Figure 19.
Figure 20.
LINEARITY ERROR
vs DIGITAL INPUT CODE
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Figure 21.
12
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Figure 22.
DAC8814
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SBAS338 – JANUARY 2005
TYPICAL CHARACTERISTICS: VDD = +5 V (continued)
At TA = +25°C, +VDD = +5 V, unless otherwise noted.
Graphic
Forthcoming
Figure 23.
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Figure 24.
PRODUCT PREVIEW
LINEARITY ERROR
vs DIGITAL INPUT CODE
13
DAC8814
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SBAS338 – JANUARY 2005
TYPICAL CHARACTERISTICS: VDD = +5 V (continued)
At TA = +25°C, +VDD = +5 V, unless otherwise noted.
SUPPLY CURRENT
vs LOGIC INPUT VOLTAGE
REFERENCE MULTIPLYING BANDWIDTH
6
0
−6
−12
−18
−24
−30
−36
−42
−48
−54
−60
−66
−72
−78
−84
−90
−96
−102
−108
−114
1.6
VDD = +5.0V
1.2
Attenuation (dB)
Supply Current, IDD (mA)
1.4
1.0
0.8
0.6
0.4
0.2
VDD = +2.7V
0
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
10
1k
10k
100k
1M
Figure 25.
Figure 26.
DAC GLITCH
DAC SETTLING TIME
Code: 7FFFh to 8000h
Output Voltage (5V/div)
Output Voltage (50mV/div)
PRODUCT PREVIEW
14
100
10M
Bandwidth (Hz)
Logic Input Voltage (V)
Voltage Output Settling
Trigger Pulse
Trigger Pulse
Time (0.2µs/div)
Time (0.1µs/div)
Figure 27.
Figure 28.
100M
DAC8814
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SBAS338 – JANUARY 2005
TYPICAL CHARACTERISTICS: VDD = +2.7 V
At TA = +25°C, +VDD = +2.7 V, unless otherwise noted.
Channel A
Graphic
Forthcoming
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Figure 29.
Figure 30.
LINEARITY ERROR
vs DIGITAL INPUT CODE
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Figure 31.
PRODUCT PREVIEW
LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Figure 32.
15
DAC8814
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SBAS338 – JANUARY 2005
TYPICAL CHARACTERISTICS: VDD = +2.7 V (continued)
At TA = +25°C, +VDD = +2.7 V, unless otherwise noted.
LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Figure 33.
PRODUCT PREVIEW
16
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Figure 34.
DAC8814
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SBAS338 – JANUARY 2005
TYPICAL CHARACTERISTICS: VDD = +2.7 V (continued)
At TA = +25°C, +VDD = +2.7 V, unless otherwise noted.
Channel B
Graphic
Forthcoming
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Figure 35.
Figure 36.
LINEARITY ERROR
vs DIGITAL INPUT CODE
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Figure 37.
PRODUCT PREVIEW
LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Figure 38.
17
DAC8814
www.ti.com
SBAS338 – JANUARY 2005
TYPICAL CHARACTERISTICS: VDD = +2.7 V (continued)
At TA = +25°C, +VDD = +2.7 V, unless otherwise noted.
LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Figure 39.
PRODUCT PREVIEW
18
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Figure 40.
DAC8814
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SBAS338 – JANUARY 2005
TYPICAL CHARACTERISTICS: VDD = +2.7 V (continued)
At TA = +25°C, +VDD = +2.7 V, unless otherwise noted.
Channel C
Graphic
Forthcoming
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Figure 41.
Figure 42.
LINEARITY ERROR
vs DIGITAL INPUT CODE
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Figure 43.
PRODUCT PREVIEW
LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Figure 44.
19
DAC8814
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SBAS338 – JANUARY 2005
TYPICAL CHARACTERISTICS: VDD = +2.7 V (continued)
At TA = +25°C, +VDD = +2.7 V, unless otherwise noted.
LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Figure 45.
PRODUCT PREVIEW
20
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Figure 46.
DAC8814
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SBAS338 – JANUARY 2005
TYPICAL CHARACTERISTICS: VDD = +2.7 V (continued)
At TA = +25°C, +VDD = +2.7 V, unless otherwise noted.
Channel D
Graphic
Forthcoming
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Figure 47.
Figure 48.
LINEARITY ERROR
vs DIGITAL INPUT CODE
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Figure 49.
PRODUCT PREVIEW
LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Figure 50.
21
DAC8814
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SBAS338 – JANUARY 2005
TYPICAL CHARACTERISTICS: VDD = +2.7 V (continued)
At TA = +25°C, +VDD = +2.7 V, unless otherwise noted.
LINEARITY ERROR
vs DIGITAL INPUT CODE
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
Graphic
Forthcoming
Graphic
Forthcoming
Figure 51.
Figure 52.
PRODUCT PREVIEW
PARAMETER MEASUREMENT INFORMATION
SDI
A1
A0
D15 D14 D13 D13 D12
D1
D11 D10
CLK
D0
Input REG. LD
tCSS
CS
tds
tdh
tch
tcsh
tcl
tlds
LDAC
tpd
SDO
tLDH
tLDAC
Figure 53. DAC8814 Timing Diagram
THEORY OF OPERATION
CIRCUIT OPERATION
The DAC8814 contains four, 16-bit, current-output, digital-to-analog converters (DACs) respectively. Each DAC
has its own independent multiplying reference input. The DAC8814 uses a 3-wire SPI compatible serial data
interface, with a configurable asynchronous RS pin for half-scale (MSB = 1) or zero-scale (MSB = 0) preset. In
addition, an LDAC strobe enables four channel simultaneous updates for hardware synchronized output voltage
changes.
D/A Converter
The DAC8814 contains four current-steering R-2R ladder DACs. Figure 54 shows a typical equivalent DAC.
Each DAC contains a matching feedback resistor for use with an external I-to-V converter amplifier. The RFBX pin
is connected to the output of the external amplifier. The IOUTX terminal is connected to the inverting input of the
external amplifier. The AGNDX pin should be Kelvin-connected to the load point in the circuit requiring the full
16-bit accuracy.
22
DAC8814
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SBAS338 – JANUARY 2005
The DAC is designed to operate with both negative or positive reference voltages. The VDD power pin is only
used by the logic to drive the DAC switches on and off. Note that a matching switch is used in series with the
internal 5 kΩ feedback resistor. If users are attempting to measure the value of RFB, power must be applied to
VDD in order to achieve continuity. An additional VSS bias pin is used to guard the substrate during high
temperature applications to minimize zero-scale leakage currents that double every 10°C. The DAC output
voltage is determined by VREF and the digital data (D) according to Equation 1:
V OUT VREF D
65536
(1)
Note that the output polarity is opposite of the VREF polarity for dc reference voltages.
VDD
RRR
VREFX
RFBX
2R
2R
2R
R
5 k
S2
S1
IOUTX
AGNDF
VCC
DGND
Digital Interface Connections Omitted For Clarity.
Switches S1 and S2 are Closed, VDD Most be Powered.
Figure 54. Typical Equivalent DAC Channel
The DAC is also designed to accommodate ac reference input signals. The DAC8814 accommodates input
reference voltages in the range of -12 V to +12 V. The reference voltage inputs exhibit a constant nominal input
resistance of 5 kΩ, ± 30%. On the other hand, the DAC outputs IOUTA, B, C, D are code-dependent and produce
various output resistances and capacitances.
The choice of external amplifier should take into account the variation in impedance generated by the DAC8814
on the amplifiers' inverting input node. The feedback resistance, in parallel with the DAC ladder resistance,
dominates output voltage noise. For multiplying mode applications, an external feedback compensation capacitor
(CFB) may be needed to provide a critically damped output response for step changes in reference input
voltages.
Figure 26 shows the gain vs frequency performance at various attenuation settings using a 23 pF external
feedback capacitor connected across the IOUTX and RFBX terminals. In order to maintain good analog
performance, power supply bypassing of 0.01 µF, in parallel with 1 µF, is recommended. Under these conditions,
clean power supply with low ripple voltage capability should be used. Switching power supplies is usually not
suitable for this application due to the higher ripple voltage and PSS frequency-dependent characteristics. It is
best to derive the DAC8814 5-V supply from the system analog supply voltages. (Do not use the digital 5-V
supply.) See Figure 55.
23
PRODUCT PREVIEW
AGNDX
From Other DACS AGND
DAC8814
www.ti.com
SBAS338 – JANUARY 2005
15 V
2R
5V
+
Analog
Power
Supply
R
VDD
RRR
RFBX
VREFX
2R
2R
2R
R
5 k
15 V
S2
S1
IOUTX
VCC
AGNDF
AGNDX
From Other DACS AGND
VSS
Digital Interface Connections Omitted For Clarity.
Switches S1 and S2 are Closed, VDD Most be Powered.
DGND
PRODUCT PREVIEW
Figure 55. Recommended Kelvin-Sensed Hookup
24
VOUT
A1
+
VEE
Load
DAC8814
www.ti.com
SBAS338 – JANUARY 2005
VREF A B C D
CS
EN
VDD
CLK
SDO
D0
D1
D2
D3
D4
D5
D6
D7
D8
D9
D10
D11
D12
D13
D14
D15
A0
A1
16
RFBA
DAC A
Register R
Input
Register R
DAC A
IOUTA
AGNDA
RFBB
DAC B
Register R
Input
Register R
DAC B
ADC A
B
C
D
2:4
Decode
IOUTC
AGNDB
RFBC
DAC C
Register R
Input
Register R
DAC C
IOUTC
PRODUCT PREVIEW
SDI
AGNDC
RFBD
DAC D
Register R
Input
Register R
DAC D
IOUTD
AGNDD
Set MSB
Set
MSB
Poweron
Reset
DGND
AGNDF
MSB
LDAC
RS
VSS
Figure 56. System Level Digital Interfacing
SERIAL DATA INTERFACE
The DAC8814 uses a 3-wire (CS, SDI, CLK) SPI-compatible serial data interface. Serial data of the DAC8814 is
clocked into the serial input register in an 16-bit data-word format. MSB bits are loaded first. Table 2 defines the
16 data-word bits for the DAC8814.
Data is placed on the SDI pin, and clocked into the register on the positive clock edge of CLK subject to the data
setup and data hold time requirements specified in the Interface Timing Specifications. Data can only be clocked
in while the CS chip select pin is active low. For the DAC8814, only the last 16 bits clocked into the serial register
are interrogated when the CS pin returns to the logic high state.
Since most microcontrollers output serial data in 8-bit bytes, three right-justified data bytes can be written to the
DAC8814. Keeping the CS line low between the first, second, and third byte transfers results in a successful
serial register update. Similarly, two right-justified data bytes can be written to the DAC8814. Keeping the CS line
low between the first and second byte transfer will result in a successful serial register update.
25
DAC8814
www.ti.com
SBAS338 – JANUARY 2005
Once the data is properly aligned in the shift register, the positive edge of the CS initiates the transfer of new
data to the target DAC register, determined by the decoding of address bits A1and A0. For the DAC8814,
Table 1, Table 2, Table 3 and Figure 53 define the characteristics of the software serial interface. Figure 57
shows the equivalent logic interface for the key digital control pins for the DAC8814.
To Input Register
Address
Decoder
CS
A
B
C
D
EN
Shift Register
CLK
SDI
19th/17th
CLOCK
SDO
Figure 57. DAC8814 Equivalent Logic Interface
PRODUCT PREVIEW
Two additional pins RS and MSB provide hardware control over the preset function and DAC register loading. If
these functions are not needed, the RS pin can be tied to logic high. The asynchronous input RS pin forces all
input and DAC registers to either the zero-code state (MSB = 0), or the half-scale state (MSB = 1).
POWER ON RESET
When the VDD power supply is turned on, an internal reset strobe forces all the Input and DAC registers to the
zero-code state or half-scale, depending on the MSB pin voltage. The VDD power supply should have a smooth
positive ramp without drooping in order to have consistent results, especially in the region of VDD = 1.5 V to
2.3 V. The VSS supply has no effect on the power-on reset performance. The DAC register data stays at zero or
half-scale setting until a valid serial register data load takes place.
ESD Protection Circuits
All logic-input pins contain back-biased ESD protection zener diodes connected to ground (DGND) and VDD as
shown in Figure 58.
VDD
DIGITAL
INPUTS
5 k
DGND
Figure 58. Equivalent ESD Protection Circuits
26
DAC8814
www.ti.com
SBAS338 – JANUARY 2005
PCB LAYOUT
In printed circuit board (PCB) layout, all analog ground AGNDX should be tied together.
Table 1. Control Logic Truth Table (1)
CS
CLK
LDAC
RS
MSB
H
X
H
H
X
No effect
Latched
Latched
L
L
H
H
X
No effect
Latched
Latched
L
↑+
H
H
X
Shift register data advanced one bit
Latched
Latched
L
H
H
H
X
No effect
Latched
Latched
↑+
L
H
H
X
No effect
Selected DAC updated with current SR contents
Latched
H
X
L
H
X
No effect
Latched
Transparent
H
X
H
H
X
No effect
Latched
Latched
H
X
↑+
H
X
No effect
Latched
Latched
H
X
H
L
0
No effect
Latched data = 0000h
Latched data = 0000h
X
↑+
H
L
H
No effect
Latched data = 8000h
Latched data = 8000h
(1)
SERIAL SHIFT REGISTER
INPUT REGISTER
DAC REGISTER
↑+ = Positive logic transition; X = Do not care
Bit
B17
(MSB)
B16
B15
B14
B13
B12
B11
B10
B9
B8
B7
B6
B5
B4
B3
B2
B1
B0
(LSB)
Data
A1
A0
D15
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
(1)
Only the last 18 bits of data clocked into the serial register (address + data) are inspected when the CS line positive edge returns to
logic high. At this point an internally-generated load strobe transfers the serial register data contents (bits D15-D0) to the decoded
DAC-input-register address determined by bits A1 and A0. Any extra bits clocked into the DAC8814 shift register are ignored, only the
last 18 bits clocked in are used. If double-buffered data is not needed, the LDAC pin can be tied logic low to disable the DAC registers.
Table 3. Address Decode
A1
A0
DAC DECODE
0
0
DAC A
0
1
DAC B
1
0
DAC C
1
1
DAC D
27
PRODUCT PREVIEW
Table 2. Serial Input Register Data Format, Data Loaded MSB First (1)
DAC8814
www.ti.com
SBAS338 – JANUARY 2005
APPLICATION INFORMATION
The DAC8814, a 2-quadrant multiplying DAC, can be used to generate a unipolar output. The polarity of the
full-scale output IOUT is the inverse of the input reference voltage at VREF.
Some applications require full 4-quadrant multiplying capabilities or bipolar output swing, as shown in Figure 59.
An additional external op amp A2 is added as a summing amp. In this circuit the first and second amps (A1 and
A2) provide a gain of 2X that widens the output span to 20 V. A 4-quadrant multiplying circuit is implemented by
using a 10-V offset of the reference voltage to bias A2. According to the following circuit transfer equation (
Equation 2), input data (D) from code 0 to full scale produces output voltages of VOUT = -10 V to VOUT = 10 V.
V OUT 32,D768 1 V
REF
(2)
10 k
10 k
10 V
5 k
A2
VREF
VOUT
−10 V < VOUT < +10V
VDD
VREFX
VFBX
PRODUCT PREVIEW
One Channel
DAC8814
VSS
IOUTX
A1
AGNDFA AGNDX
Digital Interface Connections Omitted For Clarity.
Figure 59. Four-Quadrant Multiplying Application Circuit
Cross-Reference
The DAC8814 has an industry-standard pinout. Table 4 provides the cross-reference information.
Table 4. Cross-Reference
28
DNL (LSB)
SPECIFIED
TEMPERATURE
RANGE
PACKAGE
DESCRIPTION
PACKAGE
OPTION
CROSSREFERENCE PART
PRODUCT
INL (LSB)
DAC8814ICDB
±1
±1
-40°C to +85°C
28-Lead MicroSOIC
SSOP-28
N/A
DAC8814IBDB
±4
±1.5
-40°C to +85°C
28-Lead MicroSOIC
SSOP-28
AD5544RS
PACKAGE OPTION ADDENDUM
www.ti.com
30-Mar-2005
PACKAGING INFORMATION
Orderable Device
Status (1)
Package
Type
Package
Drawing
Pins Package Eco Plan (2)
Qty
DAC8814IBDBR
PREVIEW
SSOP
DB
28
2500
TBD
Call TI
Call TI
DAC8814IBDBT
PREVIEW
SSOP
DB
28
250
TBD
Call TI
Call TI
DAC8814ICDBR
PREVIEW
SSOP
DB
28
2500
TBD
Call TI
Call TI
DAC8814ICDBT
PREVIEW
SSOP
DB
28
250
TBD
Call TI
Call TI
Lead/Ball Finish
MSL Peak Temp (3)
(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)
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.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is
provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the
accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take
reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on
incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited
information may not be available for release.
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
MECHANICAL DATA
MSSO002E – JANUARY 1995 – REVISED DECEMBER 2001
DB (R-PDSO-G**)
PLASTIC SMALL-OUTLINE
28 PINS SHOWN
0,38
0,22
0,65
28
0,15 M
15
0,25
0,09
8,20
7,40
5,60
5,00
Gage Plane
1
14
0,25
A
0°–ā8°
0,95
0,55
Seating Plane
2,00 MAX
0,10
0,05 MIN
PINS **
14
16
20
24
28
30
38
A MAX
6,50
6,50
7,50
8,50
10,50
10,50
12,90
A MIN
5,90
5,90
6,90
7,90
9,90
9,90
12,30
DIM
4040065 /E 12/01
NOTES: A.
B.
C.
D.
All linear dimensions are in millimeters.
This drawing is subject to change without notice.
Body dimensions do not include mold flash or protrusion not to exceed 0,15.
Falls within JEDEC MO-150
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
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