Texas Instruments | 14-Bit, Parallel Input Multiplying Digital-to-Analog Converter (Rev. B) | Datasheet | Texas Instruments 14-Bit, Parallel Input Multiplying Digital-to-Analog Converter (Rev. B) Datasheet

Texas Instruments 14-Bit, Parallel Input Multiplying Digital-to-Analog Converter (Rev. B) Datasheet
DAC8806
DA
C8
806
www.ti.com
SBAS385B – APRIL 2006 – REVISED FEBRUARY 2008
14-Bit, Parallel Input Multiplying Digital-to-Analog Converter
FEATURES
APPLICATIONS
•
•
•
•
•
•
•
•
•
•
•
1
2
•
•
•
•
•
•
•
±0.5 LSB DNL
±1 LSB INL
14-Bit Monotonic
Low Noise: 10 nV/√Hz
Low Power: IDD = 2 µA
Analog Power Supply: +2.7 V to +5.5 V
1.66 mA Full-Scale Current,
with VREF = 10 V
Settling Time: 0.5 µs
4-Quadrant Multiplying Reference
Reference Bandwidth: 8 MHz
Reference Input: ±15 V
Reference Dynamics: –105 dB THD
SSOP-28 Package
Industry-Standard Pin Configuration
Automatic Test Equipment
Instrumentation
Digitally Controlled Calibration
Industrial Control PLCs
DESCRIPTION
The DAC8806, a multiplying digital-to-analog
converter (DAC), is designed to operate from a single
2.7 V to 5.5 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, current-to-voltage (I/V) precision amplifier.
A
parallel
interface
offers
high-speed
communications. The DAC8806 is packaged in a
space-saving SSOP-28 package and has an
industry-standard pinout.
VDD
R1
DAC8806
RCOM
R1
REF
R2
ROFS
RFB
ROFS
RFB
D0
¼
D13
DAC
Parallel Bus
Input
Register
AGND
WR
RST
LDAC
IOUT
DAC
Register
Control
Logic
DGND
1
2
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.
All trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2006–2008, Texas Instruments Incorporated
DAC8806
www.ti.com
SBAS385B – APRIL 2006 – REVISED FEBRUARY 2008
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.
ORDERING INFORMATION (1)
PRODUCT
MINIMUM
RELATIVE
ACCURACY
(LSB)
DIFFERENTIAL
NONLINEARITY
(LSB)
PACKAGELEAD
(DESIGNATOR)
SPECIFIED
TEMPERATURE
RANGE
PACKAGE
MARKING
DAC8806I
±1
±1
DB-28 (SSOP)
–40°C to +85°C
DAC8806
(1)
ORDERING
NUMBER
TRANSPORT MEDIA,
QUANTITY
DAC8806IDB
Tubes, 48
DAC8806IDBR
Tape and Reel, 2000
For the most current package and ordering information see the Package Option Addendum at the end of this document, or see the TI
web site at www.ti.com.
ABSOLUTE MAXIMUM RATINGS (1)
Over operating free-air temperature range (unless otherwise noted)
DAC8806
UNIT
–0.3 to +7
V
Digital input voltage to GND
–0.3 to +VDD + 0.3
V
V (IOUT) to GND
–0.3 to +VDD + 0.3
V
–40 to +85
°C
±25
V
–65 to +150
°C
+125
°C
(TJ max – TA)/RθJA
W
VDD to GND
Operating temperature range
REF, ROFS, RFB, R1, RCOM to AGND, and DGND
Storage temperature range
Junction temperature range (TJ max)
Power dissipation
55
°C/W
Human body model (HBM)
4000
V
Charged device model (CDM)
1000
V
Thermal impedance, RθJA
ESD rating
(1)
2
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.
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SBAS385B – APRIL 2006 – REVISED FEBRUARY 2008
ELECTRICAL CHARACTERISTICS
All specifications at –40°C to +85°C, VDD = +2.7 V to +5.5 V, IOUT = virtual GND, GND = 0 V, VREF = 10 V, and TA = full
operating temperature, unless otherwise noted.
DAC8806
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
STATIC PERFORMANCE
Resolution
14
Relative accuracy
Bits
DAC8806
Differential nonlinearity
±0.5
±1
LSB
±1
LSB
5
nA
Output leakage current
Data = 0000h, TA = +25°C
Output leakage current
Data = 0000h, TA = TMAX
10
nA
Full-scale gain error
Unipolar, data = 3FFFh
1
±4
LSB
Bipolar, data = 3FFFh
1
±4
LSB
ppm/°C
Full-scale temperature coefficient
1
2
Bipolar zero scale error
±1
±3
LSB
±0.1
±1
LSB/V
PSRR
Power-supply rejection ratio; VDD = 5 V ±10%
OUTPUT CHARACTERISTICS (1)
Output current
Output capacitance
Code dependent
1.66
mA
50
pF
REFERENCE INPUT
VREF range
–15
RREF
Input resistance (unipolar)
4.5
Input capacitance
6
15
V
7.5
kΩ
5
pF
R1/R2
R1/R2 resistance (bipolar)
9
12
15
kΩ
ROFS, RFB
Feedback and offset resistance
9
12
15
kΩ
0.6
V
0.8
V
LOGIC INPUTS AND OUTPUT (1)
Input low voltage
VIL VDD = +2.7 V
Input high voltage
VIH VDD = +2.7 V
2.1
V
VIH VDD = +5 V
2.4
V
VIL VDD = +5 V
Input leakage current
Input capacitance
IIL
0.001
CIL
1
µA
8
pF
INTERFACE TIMING, VDD = +5.0V (1) (See Figure 40 and Table 1)
tDS Data to WR setup time
20
ns
tDH Data to WR hold time
0
ns
tWR WR pulse width
20
ns
tLDAC LDAC pulse width
20
ns
Data setup time
tRST RST pulse width
20
ns
Data hold time
tLWD WR to LDAC delay time
0
ns
INTERFACE TIMING, VDD = +2.7V (1) (See Figure 40 and Table 1)
tDS Data to WR setup time
35
ns
tDH Data to WR hold time
0
ns
tWR WR pulse width
35
ns
tLDAC LDAC pulse width
35
ns
Data setup time
tRST RST pulse width
35
ns
Data hold time
tLWD WR to LDAC delay time
0
ns
(1)
Specified by design and characterization; not production tested.
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SBAS385B – APRIL 2006 – REVISED FEBRUARY 2008
ELECTRICAL CHARACTERISTICS (continued)
All specifications at –40°C to +85°C, VDD = +2.7 V to +5.5 V, IOUT = virtual GND, GND = 0 V, VREF = 10 V, and TA = full
operating temperature, unless otherwise noted.
DAC8806
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
POWER REQUIREMENTS
VDD
2.7
IDD (normal operation)
Logic inputs = 0V
VDD = +4.5 V to +5.5 V
VIH = VDD and VIL = GND
VDD = +2.7 V to +3.6 V
VIH = VDD and VIL = GND
5.5
V
5
µA
3
5
µA
1
2.5
µA
AC CHARACTERISTICS (2)
Output current settling time
0.5
µs
Reference multiplying BW
VREF = 5 VPP, Data = 3FFFh
8
MHz
DAC glitch impulse
VREF = 0 V to 10 V,
Data = 1FFFh to 2000h to 1FFFh
2
nV–s
Feedthrough error VOUT/VREF
Data = 0000h, VREF = 10 kHz; ±10 VPP
–70
dB
Digital feedthrough
LDAC = logic low, VREF = –10 V to +10 V
Any code change
2
nV–s
Total harmonic distortion
VREF = 6 VRMS, Data = 3FFF, f = 1 kHz
–105
dB
10
nV/√Hz
Output spot noise voltage
(2)
Specified by design and characterization; not production tested.
TERMINAL FUNCTIONS
PIN ASSIGNMENTS
PIN #
NAME
1
REF
DESCRIPTION
Reference input and 4-quadrant Resistor (R2).
RCOM
Center tap of two 4-quadrant resistors
(R1 and R2).
REF
1
28
RST
RCOM
2
27
NC
2
R1
3
26
NC
3
R1
4
ROFS
Bipolar offset resistor
5
RFB
Internal matching feedback resistor
6
IOUT
DAC current output
7
AGND
Analog ground
8
LDAC
Digital input load DAC control. When LDAC is high,
data is loaded from input register into a DAC
register, updating the DAC output.
Write control digital input. Active low. When WR is
taken to logic low, data is loaded from the digital
input pins (D0–D13) into a14-bit input register.
ROFS
4
25
D0
RFB
5
24
D1
4-quadrant resistor (R1).
IOUT
6
23
VDD
AGND
7
22
DGND
LDAC
8
21
D2
WR
9
20
D3
9
WR
D13
10
19
D4
10–21
D13–D2
D12
11
18
D5
22
DGND
23
VDD
24, 25
D1, D0
26, 27
NC
No connection
28
RST
Reset. Active low. When RST is taken to logic low,
the DAC register is set to zero code, resulting in the
DAC output being set to 0 V.
DAC8806
D11
4
12
17
D6
D10
13
16
D7
D9
14
15
D8
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Digital input data bits. D13 is MSB.
Digital ground
Positive power supply
Digital Input data bits. D0 is LSB.
Copyright © 2006–2008, Texas Instruments Incorporated
Product Folder Link(s): DAC8806
DAC8806
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SBAS385B – APRIL 2006 – REVISED FEBRUARY 2008
TYPICAL CHARACTERISTICS: VDD = +5V
At TA = +25°C, unless otherwise noted.
LINEARITY ERROR
vs DIGITAL INPUT CODE
1.0
1.0
TA = +25°C
VREF = 10V
0.8
0.6
0.6
0.4
0.4
0.2
0
-0.2
0
-0.2
-0.4
-0.6
-0.6
-0.8
-0.8
-1.0
0
1.0
2048
4096
6144
8192 10240 12288 14336 16383
Code
0
2048
4096
6144
8192 10240 12288 14336 16383
Code
Figure 1.
Figure 2.
LINEARITY ERROR
vs DIGITAL INPUT CODE
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
1.0
TA = -40° C
VREF =10V
0.8
TA = -40° C
VREF = 10V
0.8
0.6
0.6
0.4
0.4
DNL (LSB)
INL (LSB)
0.2
-0.4
-1.0
0.2
0
-0.2
0.2
0
-0.2
-0.4
-0.4
-0.6
-0.6
-0.8
-0.8
-1.0
-1.0
0
1.0
2048
4096
6144
8192 10240 12288 14336 16383
Code
0
2048
4096
6144
8192 10240 12288 14336 16383
Code
Figure 3.
Figure 4.
LINEARITY ERROR
vs DIGITAL INPUT CODE
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
1.0
TA = +85°C
VREF = 10V
0.8
TA = +85°C
VREF = 10V
0.8
0.6
0.6
0.4
0.4
DNL (LSB)
INL (LSB)
TA = +25°C
VREF = 10V
0.8
DNL (LSB)
INL (LSB)
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
0.2
0
-0.2
0.2
0
-0.2
-0.4
-0.4
-0.6
-0.6
-0.8
-0.8
-1.0
-1.0
0
2048
4096
6144
8192 10240 12288 14336 16383
Code
0
Figure 5.
2048
4096
6144
8192 10240 12288 14336 16383
Code
Figure 6.
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DAC8806
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SBAS385B – APRIL 2006 – REVISED FEBRUARY 2008
TYPICAL CHARACTERISTICS: VDD = +5V (continued)
At TA = +25°C, unless otherwise noted.
REFERENCE MULTIPLYING BANDWIDTH
UNIPOLAR MODE
180
6
0
-6
-12
-18
-24
-30
-36
-42
-48
-54
-60
-66
-72
-78
-84
-90
-96
-102
-108
-114
10
VDD = +5.0V
120
100
80
60
40
VDD = +2.7V
20
0
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
0x0000
100
1k
Logic Input Voltage (V)
10M
100M
REFERENCE MULTIPLYING BANDWIDTH
BIPOLAR MODE
100
1k
10k
100k
1M
10M
100M
6
0
-6
-12
-18
-24
-30
-36
-42
-48
-54
-60
-66
-72
-78
-84
-90
-96
-102
-108
-114
10
Attenuation (dB)
Codes from
Full-scale to
Midscale
0x3FFF
0x3000
0x2800
0x2400
0x2200
0x2100
0x2080
0x2040
0x2020
0x2010
0x2008
0x2004
0x2002
0x2001
0x2000
Digital Code
REFERENCE MULTIPLYING BANDWIDTH
BIPOLAR MODE
Codes from
Midscale to
Zero Scale
100
1k
10k
100k
1M
10M
0x0000
0x1000
0x1800
0x1400
0x1200
0x1100
0x1080
0x1040
0x1020
0x1010
0x1008
0x1004
0x1002
0x1001
0x2000
100M
Bandwidth (Hz)
Figure 9.
Figure 10.
MIDSCALE DAC GLITCH
MIDSCALE DAC GLITCH
VREF = 10V
Code: 1FFFh to 2000h
LDAC Pulse
Output Voltage (20mV)
VREF = 10V
Output Voltage (20mV)
1M
Figure 8.
Bandwidth (Hz)
Code: 2000h to 1FFFh
LDAC Pulse
Time (0.5ms)
Time (0.5ms)
Figure 11.
6
100k
Figure 7.
Attenuation (dB)
6
0
-6
-12
-18
-24
-30
-36
-42
-48
-54
-60
-66
-72
-78
-84
-90
-96
-102
-108
-114
10
10k
Bandwidth (Hz)
Digital Code
140
0x3FFF
0x2000
0x1000
0x0800
0x0400
0x0200
0x0100
0x0080
0x0040
0x0020
0x0010
0x0008
0x0004
0x0002
0x0001
Attenuation (dB)
Supply Current, IDD (mA)
160
Digital Code
SUPPLY CURRENT
vs LOGIC INPUT VOLTAGE
Figure 12.
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SBAS385B – APRIL 2006 – REVISED FEBRUARY 2008
TYPICAL CHARACTERISTICS: VDD = +5V (continued)
At TA = +25°C, unless otherwise noted.
FULL-SCALE ERROR vs TEMPERATURE
4.8
3.8
BIPOLAR-ZERO ERROR vs TEMPERATURE
1.5
VREF = 10V
1.0
Bipolar-Zero Error (mV)
2.8
Full-Scale Error (mV)
VREF = 10V
1.8
0.8
0
-0.8
-1.8
-2.8
0.5
0
-0.5
-1.0
-3.8
-1.5
-4.8
-60
-40
-20
0
20
40
60
80
100
-60
-40
-20
0
20
40
Temperature (°C)
Temperature (°C)
Figure 13.
Figure 14.
60
80
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SBAS385B – APRIL 2006 – REVISED FEBRUARY 2008
TYPICAL CHARACTERISTICS: VDD = +2.7V
At TA = +25°C, unless otherwise noted.
LINEARITY ERROR
vs DIGITAL INPUT CODE
1.0
1.0
TA = +25°C
VREF = 10V
0.8
0.6
0.6
0.4
0.4
0.2
0
-0.2
0
-0.2
-0.4
-0.6
-0.6
-0.8
-0.8
-1.0
0
1.0
2048
4096
6144
8192 10240 12288 14336 16383
Code
0
2048
6144
8192 10240 12288 14336 16383
Code
Figure 16.
LINEARITY ERROR
vs DIGITAL INPUT CODE
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
1.0
TA = -40°C
VREF = 10V
0.8
0.6
0.4
0.4
DNL (LSB)
0.6
0.2
0
-0.2
0.2
0
-0.2
-0.4
-0.4
-0.6
-0.6
-0.8
-0.8
-1.0
-1.0
0
1.0
2048
4096
6144
8192 10240 12288 14336 16383
Code
0
2048
4096
6144
8192 10240 12288 14336 16383
Code
Figure 17.
Figure 18.
LINEARITY ERROR
vs DIGITAL INPUT CODE
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
1.0
TA = +85°C
VREF = 10V
0.8
TA = +85°C
VREF = 10V
0.8
0.6
0.4
0.4
INL (LSB)
0.6
0.2
0
-0.2
0.2
0
-0.2
-0.4
-0.4
-0.6
-0.6
-0.8
-0.8
-1.0
-1.0
0
2048
4096
6144
8192 10240 12288 14336 16383
Code
0
Figure 19.
8
4096
Figure 15.
TA = -40°C
VREF = 10V
0.8
INL (LSB)
0.2
-0.4
-1.0
DNL (LSB)
TA = +25°C
0.8
DNL (LSB)
INL (LSB)
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
2048
4096
6144
8192 10240 12288 14336 16383
Code
Figure 20.
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SBAS385B – APRIL 2006 – REVISED FEBRUARY 2008
TYPICAL CHARACTERISTICS: VDD = +2.7V (continued)
At TA = +25°C, unless otherwise noted.
DAC GLITCH
DAC GLITCH
Output Voltage (20mV)
VREF = 10V
Output Voltage (20mV)
VREF = 10V
Code: 2000h to 1FFFh
LDAC Pulse
Code: 1FFFh to 2000h
LDAC Pulse
Time (0.5ms)
Time (0.5ms)
Figure 21.
Figure 22.
FULL-SCALE ERROR vs TEMPERATURE
4.8
3.8
BIPOLAR-ZERO ERROR vs TEMPERATURE
1.5
VREF = 10V
1.0
Bipolar-Zero Error (mV)
2.8
Full-Scale Error (mV)
VREF = 10V
1.8
0.8
0
-0.8
-1.8
-2.8
0.5
0
-0.5
-1.0
-3.8
-4.8
-60
-40
-20
0
20
40
60
80
100
-1.5
-60
-40
-20
0
20
40
Temperature (°C)
Temperature (°C)
Figure 23.
Figure 24.
60
80
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SBAS385B – APRIL 2006 – REVISED FEBRUARY 2008
TYPICAL CHARACTERISTICS
At TA = +25°C, unless otherwise noted.
IDD vs TEMPERATURE
DAC SETTLING TIME
5.0
4.5
Output Voltage (5V/div)
4.0
IDD (m A)
3.5
3.0
5.0V
2.5
2.0
1.5
Unipolar Mode
Voltage Output Settling
1.0
Trigger Pulse
2.7V
0.5
0
- 40
- 20
0
20
40
60
80
Time (0.5ms/div)
100
Temperature (°C)
1.0
Figure 26.
INTEGRAL NONLINEARITY vs VREF
UNIPOLAR MODE
INTEGRAL NONLINEARITY vs VREF
BIPOLAR MODE
0.6
0.4
0.4
INL (LSB)
0.6
0.2
0
-0.2
-0.4
-0.6
-0.8
-0.8
1.0
0
5
-1.0
10
-10
0
5
VREF (V)
Figure 27.
Figure 28.
DIFFERENTIAL NONLINEARITY vs VREF
UNIPOLAR MODE
DIFFERENTIAL NONLINEARITY vs VREF
BIPOLAR MODE
1.0
0.6
0.4
0.4
DNL (LSB)
0.6
0.2
0
-0.2
0
-0.2
-0.4
-0.6
-0.6
-0.8
-0.8
-5
0
5
10
VDD = 2.7V
0.2
-0.4
-1.0
10
VDD = 5V
0.8
VDD = 2.7V
-10
-5
VREF (V)
VDD = 5V
0.8
DNL (LSB)
0
-0.2
-0.6
-5
VDD = 2.7V
0.2
-0.4
-10
VDD = 5V
0.8
VDD = 2.7V
-1.0
10
1.0
VDD = 5V
0.8
INL (LSB)
Figure 25.
-1.0
-10
-5
0
VREF (V)
VREF (V)
Figure 29.
Figure 30.
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10
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SBAS385B – APRIL 2006 – REVISED FEBRUARY 2008
TYPICAL CHARACTERISTICS (continued)
At TA = +25°C, unless otherwise noted.
INTEGRAL NONLINEARITY vs
VDD UNIPOLAR MODE
1.0
0.4
INL (LSB)
0.4
0.2
0
-0.2
0
-0.2
-0.4
-0.6
-0.6
-0.8
-0.8
1.0
2.3
2.8
3.3
3.8
4.3
4.8
-1.0
5.3 5.5
4.3
4.8
DIFFERENTIAL NONLINEARITY vs
VDD BIPOLAR MODE
1.0
DNL (LSB)
0.4
0
-0.2
0
-0.2
-0.4
-0.6
-0.6
-0.8
-0.8
2.8
3.3
3.8
4.3
4.8
-1.0
5.3 5.5
VREF = 2.5V
0.2
-0.4
2.3
5.3 5.5
VREF = 10V
0.8
0.2
-65
3.8
DIFFERENTIAL NONLINEARITY vs
VDD UNIPOLAR MODE
0.4
-55
3.3
VDD (V)
0.6
-45
2.8
Figure 32.
VREF = 2.5V
1.8
2.3
VDD (V)
0.6
-1.0
1.8
Figure 31.
VREF = 10V
0.8
VREF = 2.5V
0.2
-0.4
1.8
2.3
2.8
3.3
3.8
4.3
4.8
5.3 5.5
VDD (V)
VDD (V)
Figure 33.
Figure 34.
BIPOLAR MULTIPLYING MODE THD
vs FREQUENCY
BIPOLAR MULTIPLYING MODE THD
vs FREQUENCY
500kHz Filter
80kHz Filter
30kHz Filter
Code 3FFFh
VREF = 6VRMS
VDD = +5V
Two OPA627s
C1 = 20pF
-75
-85
-95
-105
-115
-45
Total Harmonic Distortion (dB)
INL (LSB)
0.6
1.8
VREF = 10V
0.8
VREF = 2.5V
0.6
-1.0
DNL (LSB)
1.0
VREF = 10V
0.8
Total Harmonic Distortion (dB)
INTEGRAL NONLINEARITY vs
VDD BIPOLAR MODE
-55
-65
500kHz Filter
80kHz Filter
30kHz Filter
Code 0000h
VREF = 6VRMS
VDD = +5V
Two OPA627s
C1 = 20pF
-75
-85
-95
-105
-115
10
100
1000
10k 20k 30k
10
Frequency (Hz)
100
1000
10k 20k 30k
Frequency (Hz)
Figure 35.
Figure 36.
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TYPICAL CHARACTERISTICS (continued)
At TA = +25°C, unless otherwise noted.
UNIPOLAR MULTIPLYING MODE THD
vs FREQUENCY
Total Harmonic Distortion (dB)
-45
500kHz Filter
80kHz Filter
30kHz Filter
Code 3FFFh
VREF = 6VRMS
VDD = +5V
One OPA627
C1 = 20pF
-55
-65
-75
-85
-95
-105
-115
10
100
1000
10k 20k 30k
Frequency (Hz)
Figure 37.
THEORY OF OPERATION
The DAC8806 is a multiplying, single-channel current output, 14-bit DAC. The architecture, illustrated in
Figure 38, is an R-2R ladder configuration with the three MSBs segmented. Each 2R leg of the ladder is either
switched to GND or to the IOUT terminal. The IOUT terminal of the DAC is held at a virtual GND potential by the
use of an external I/V converter op amp. The R-2R ladder is connected to an external reference input (VREF) that
determines the DAC full-scale current. The R-2R ladder presents a code independent load impedance to the
external reference of 6 kΩ ±25%. The external reference voltage can vary in a range of –10 V to +10 V, thus
providing bipolar IOUT current operation. By using an external I/V converter op amp and the RFB resistor in the
DAC8806, an output voltage range of –VREF to +VREF can be generated.
R
R
R
RFB
VREF
2R
2R
2R
2R
2R
2R
2R
2R
2R
2R
2R
2R
RFB
IOUT
GND
Figure 38. Equivalent R-2R DAC Circuit
The DAC output voltage is determined by VREF and the digital data (D) according to Equation 1:
D
V OUT + −VREF
16384
(1)
Each DAC code determines the 2R-leg switch position to either GND or IOUT. The external I/V converter op amp
noise gain will also change because the DAC output impedance (as seen looking into the IOUT terminal) changes
versus code. Because of this, the external I/V converter op amp must have a sufficiently low offset voltage such
that the amplifier offset is not modulated by the DAC IOUT terminal impedance change. External op amps with
large offset voltages can produce INL errors in the transfer function of the DAC8806 because of offset
modulation versus DAC code. For best linearity performance of the DAC8806, an op amp (OPA277) is
recommended; see Figure 39. This circuit allows VREF to swing from –10 V to +10 V.
12
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VDD
U1
VDD ROFS RFB
+15V
U2
VREF
V+
IOUT
DAC8806
VOUT
OPA277
VGND
-15V
Figure 39. Voltage Output Configuration
tWR
WR
DATA
tDS
tDH
tLWD
LDAC
tLDAC
tRST
RST
Figure 40. DAC8806 Timing Diagram
Table 1. Function of Control Inputs
CONTROL INPUTS
RST
WR
LDAC
0
X
X
Asynchronous operation. The DAC register is set to zero code, resulting in the DAC output being set
to 0 V. The DAC input register contents are not reset by the RST signal.
1
0
0
Load the input register with all 14 data bits.
1
1
1
Load the DAC register with the contents of the input register.
1
0
1
The input and DAC register are transparent.
LDAC and WR are tied together and programmed as a pulse. The 14 data bits are loaded into the
input register on the falling edge of the pulse and then loaded into the DAC register on the rising
edge of the pulse.
1
1
REGISTER OPERATION
1
0
No register operation.
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APPLICATION INFORMATION
Multiplying Mode THD versus Frequency
Figure 35 and Figure 36 show the DAC8806 bipolar 4-quadrant multiplying mode total harmonic distortion (THD)
versus frequency. Figure 35 shows the bipolar mode THD with the DAC8806 set to a full-scale code of 3FFFh.
Figure 36 shows the bipolar multiplying mode THD with the DAC8806 set to a minus full-scale code of 0000h. In
both graphs, two OPA627s are used for both the DAC output op amp and the reference inverting amplifier. A 6
VRMS sine wave is used for the reference input VREF and is swept in frequency from 10 Hz to 30 kHz. The THD
levels versus frequency are illustrated at various DAC output filtering levels using an external ac-coupled
low-pass filter.
Figure 37 illustrates the DAC8806 unipolar 2-quadrant multiplying mode THD versus frequency. The DAC8806 is
set to a full-scale code of 3FFFh. A single OPA627 is used for the DAC output op amp.
Stability Circuit
For a current-to-voltage (I/V) design, as shown in Figure 41, the DAC8806 current output (IOUT) and the
connection with the inverting node of the op amp should be as short as possible and laid out according to correct
printed circuit board (PCB) layout design. For each code change there is a step function. If the gain bandwidth
product (GBP) of the op amp is limited and parasitic capacitance is excessive at the inverting node, then gain
peaking is possible. Therefore, a compensation capacitor C1 (4 pF to 20 pF, typ) can be added to the design for
circuit stability, as shown in Figure 41.
VDD
U1
VDD ROFS RFB
C1
VREF
VREF
DAC8806
IOUT
OPA277
GND
VOUT
U2
Figure 41. Gain Peaking Prevention Circuit with Compensation Capacitor
Bipolar Output Circuit
The DAC8806, as a 4-quadrant multiplying DAC, can be used to generate a bipolar output. The polarity of the
full-scale output (IOUT) is the inverse of the input reference voltage at VREF.
Using a dual op amp, such as the OPA2277, full 4-quadrant operation can be achieved with minimal
components. Figure 42 demonstrates a ±10 VOUT circuit with a fixed +10 V reference.
V OUT +
D * 1Ǔ
ǒ8192
14
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VREF
(2)
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VREF
U1
OPA2277
VDD
RCOM
R1
DAC8806
R1
REF
R2
ROFS
RFB
ROFS
RFB
D0
¼
D13
DAC
Parallel Bus
Input
Register
C1
IOUT
DAC
Register
U2
OPA2277
VOUT
AGND
WR
RST
LDAC
Control
Logic
DGND
Figure 42. Bipolar Output Circuit
Programmable Current Source Circuit
A DAC8806 can be integrated into the circuit in Figure 43 to implement an improved Howland current pump for
precise V/I conversions. Bidirectional current flow and high-voltage compliance are two features of the circuit.
With a matched resistor network, the load current of the circuit is shown by Equation 3:
(R2 ) R3)ńR1
IL +
VREF D
R3
(3)
The value of R3 in the previous equation can be reduced to increase the output current drive of U3. U3 can drive
±20 mA in both directions with voltage compliance limited up to 15 V by the U3 voltage supply. Elimination of the
circuit compensation capacitor (C1) in the circuit is not suggested as a result of the change in the output
impedance (ZO), according to Equation 4:
R1ȀR3(R1 ) R2)
ZO +
R1(R2Ȁ ) R3Ȁ) * R1Ȁ(R2 ) R3)
(4)
As shown in Equation 4, ZO with matched resistors is infinite and the circuit is optimum for use as a current
source. However, if unmatched resistors are used, ZO is positive or negative with negative output impedance
being a potential cause of oscillation. Therefore, by incorporating C1 into the circuit, possible oscillation problems
are eliminated. The value of C1 can be determined for critical applications; for most applications, however, a
value of several pF is suggested.
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R2¢
15kW
C1
10pF
VDD
R1¢
150kW
U3
R3¢
50kW
U1
U2
VREF
VREF
VOUT
OPA277
VDD ROFS RFB
DAC8806
IOUT
R1
150kW
R2
15kW
R3
50W
IL
OPA277
LOAD
GND
Figure 43. Programmable Bidirectional Current Source Circuit
Cross-Reference
The DAC8806 has an industry-standard pinout. Table 2 provides the cross-reference information.
Table 2. Cross-Reference
16
PRODUCT
BIT
INL
(LSB)
DAC8806IDB
14
±1
DNL
(LSB)
SPECIFIED
TEMPERATURE
RANGE
PACKAGE
DESCRIPTION
PACKAGE
OPTION
CROSSREFERENCE
PART
±1
–40°C to +85°C
SSOP-28
SSOP-28
LTC1591AIG
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Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision A (June 2006) to Revision B .................................................................................................... Page
•
•
•
•
•
Changed front page block diagram........................................................................................................................................ 1
Fixed typo on 2nd Interface Timing subheader; changed from 5.0V to 2.7V ........................................................................ 3
Changed pin 28 description text in Terminal Functions table................................................................................................ 4
Changed first row description text in Table 1 ...................................................................................................................... 13
Changed Figure 42 ............................................................................................................................................................. 15
Changes from Original (April 2006) to Revision A .......................................................................................................... Page
•
•
Changed from "voltage-to-current" to "current-to-voltage"..................................................................................................... 1
Changed from (V/I) to (I/V) .................................................................................................................................................. 14
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PACKAGE OPTION ADDENDUM
www.ti.com
12-Feb-2008
PACKAGING INFORMATION
Orderable Device
Status (1)
Package
Type
Package
Drawing
Pins Package Eco Plan (2)
Qty
DAC8806IDB
ACTIVE
SSOP
DB
28
50
Green (RoHS &
no Sb/Br)
CU NIPDAU
Level-2-260C-1 YEAR
DAC8806IDBG4
ACTIVE
SSOP
DB
28
50
Green (RoHS &
no Sb/Br)
CU NIPDAU
Level-2-260C-1 YEAR
DAC8806IDBR
ACTIVE
SSOP
DB
28
2000 Green (RoHS &
no Sb/Br)
CU NIPDAU
Level-2-260C-1 YEAR
DAC8806IDBRG4
ACTIVE
SSOP
DB
28
2000 Green (RoHS &
no Sb/Br)
CU NIPDAU
Level-2-260C-1 YEAR
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), Pb-Free (RoHS Exempt), 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.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and
package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS
compatible) as defined above.
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
PACKAGE MATERIALS INFORMATION
www.ti.com
30-Jan-2009
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device
DAC8806IDBR
Package Package Pins
Type Drawing
SSOP
DB
28
SPQ
Reel
Reel
Diameter Width
(mm) W1 (mm)
2000
330.0
16.4
Pack Materials-Page 1
A0 (mm)
B0 (mm)
K0 (mm)
P1
(mm)
W
Pin1
(mm) Quadrant
8.1
10.4
2.5
12.0
16.0
Q1
PACKAGE MATERIALS INFORMATION
www.ti.com
30-Jan-2009
*All dimensions are nominal
Device
Package Type
Package Drawing
Pins
SPQ
Length (mm)
Width (mm)
Height (mm)
DAC8806IDBR
SSOP
DB
28
2000
346.0
346.0
33.0
Pack Materials-Page 2
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
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• DALLAS, TEXAS 75265
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