TI DAC7554IDGS 12-bit, quad, ultralow glitch, voltage output digital-to-analog converter Datasheet

DAC7554
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SLAS399A – OCTOBER 2004 – REVISED NOVEMBER 2004
12-BIT, QUAD, ULTRALOW GLITCH, VOLTAGE OUTPUT
DIGITAL-TO-ANALOG CONVERTER
FEATURES
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DESCRIPTION
2.7-V to 5.5-V Single Supply
12-Bit Linearity and Monotonicity
Rail-to-Rail Voltage Output
Settling Time: 5 µs (Max)
Ultralow Glitch Energy: 0.1 nVs
Ultralow Crosstalk: –100 dB
Low Power: 880 µA (Max)
Per-Channel Power Down: 2 µA (Max)
Power-On Reset to Zero Scale
SPI-Compatible Serial Interface: Up to 50 MHz
Simultaneous or Sequential Update
Specified Temperature Range: –40°C to 105°C
Small 10-Lead MSOP Package
The DAC7554 is a quad-channel, voltage-output DAC
with exceptional linearity and monotonicity. Its proprietary architecture minimizes undesired transients
such as code to code glitch and channel to channel
crosstalk. The low-power DAC7554 operates from a
single 2.7-V to 5.5-V supply. The DAC7554 output
amplifiers can drive a 2-kΩ, 200-pF load rail-to-rail
with 5-µs settling time; the output range is set using
an external voltage reference.
The 3-wire serial interface operates at clock rates up
to 50 MHz and is compatible with SPI, QSPI,
Microwire, and DSP interface standards. The outputs
of all DACs may be updated simultaneously or
sequentially. The parts incorporate a power-on-reset
circuit to ensure that the DAC outputs power up to
zero volts and remain there until a valid write cycle to
the device takes place. The parts contain a
power-down feature that reduces the current consumption of the device to under 1 µA.
APPLICATIONS
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Portable Battery-Powered Instruments
Digital Gain and Offset Adjustment
Programmable Voltage and Current Sources
Programmable Attenuators
Industrial Process Control
The small size and low-power operation makes the
DAC7554 ideally suited for battery-operated portable
applications. The power consumption is typically 3.5
mW at 5 V, 1.65 mW at 3 V, and reduces to 1 µW in
power-down mode.
The DAC7554 is available in a 10-lead MSOP package and is specified over –40°C to 105°C.
FUNCTIONAL BLOCK DIAGRAM
VDD
SCLK
SYNC
REFIN
Input
Register
DAC
Register
String
DAC A
Buffer
VOUTA
Input
Register
DAC
Register
String
DAC B
Buffer
VOUTB
Input
Register
DAC
Register
String
DAC C
Buffer
VOUTC
Input
Register
DAC
Register
String
DAC D
Buffer
VOUTD
Interface
Logic
DIN
Power-On
Reset
DAC7554
Power-Down
Logic
GND
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.
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 © 2004, Texas Instruments Incorporated
DAC7554
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SLAS399A – OCTOBER 2004 – REVISED NOVEMBER 2004
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
PRODUCT
PACKAGE
PACKAGE
DESIGNATOR
SPECIFIED
TEMPERATURE
RANGE
PACKAGE
MARKING
DAC7554
10 MSOP
DGS
–40°C TO 105°C
D754
ORDERING
NUMBER
TRANSPORT
MEDIA
DAC7554IDGS
80-piece Tube
DAC7554IDGSR
2500-piece Tape
and Reel
ABSOLUTE MAXIMUM RATINGS
over operating free-air temperature range (unless otherwise noted) (1)
UNIT
VDD to GND
–0.3 V to 6 V
Digital input voltage to GND
–0.3 V to VDD + 0.3 V
Vout to GND
–0.3 V to VDD+ 0.3 V
Operating temperature range
–40°C to 105°C
Storage temperature range
–65°C to 150°C
Junction temperature (TJ Max)
(1)
2
150°C
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.
DAC7554
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SLAS399A – OCTOBER 2004 – REVISED NOVEMBER 2004
ELECTRICAL CHARACTERISTICS
VDD = 2.7 V to 5.5 V, REFIN = VDD, RL = 2 kΩ to GND; CL = 200 pF to GND; all specifications –40°C to 105°C, unless
otherwise specified
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNITS
STATIC PERFORMANCE (1)
Resolution
12
Relative accuracy
Differential nonlinearity
Specified monotonic by design
±1
LSB
±0.08
± 0.5
LSB
±12
mV
Offset error
Zero-scale error
Bits
±0.35
±12
All zeroes loaded to DAC register
Gain error
Full-scale error
mV
±0.15
%FSR
±0.5
%FSR
Zero-scale error drift
7
µV/°C
Gain temperature coefficient
3
ppm of FSR/°C
PSRR
OUTPUT
VDD = 5 V
0.75
mV/V
CHARACTERISTICS (2)
Output voltage range
Output voltage settling time
0
RL = 2 kΩ; 0 pF < CL < 200 pF
Slew rate
REFIN
V
5
µs
1
Capacitive load stability
RL = ∞
470
RL = 2 kΩ
Digital-to-analog glitch impulse
1 LSB change around major carry
Channel-to-channel crosstalk
1-kHz full-scale sine wave, outputs unloaded
V/µs
pF
1000
0.1
nV-s
–100
dB
Digital feedthrough
0.1
nV-s
Output noise density (10-kHz offset frequency)
70
nV/rtHz
–85
dB
Total harmonic distortion
FOUT = 1 kHz, FS = 1 MSPS, BW = 20 kHz
1
Ω
VDD = 5 V
50
mA
VDD = 3 V
20
Coming out of power-down mode, VDD = 5 V
15
Coming out of power-down mode, VDD = 3 V
15
DC output impedance
Short-circuit current
Power-up time
µs
LOGIC INPUTS (2)
±1
µA
0.3 VDD
V
3
pF
5.5
V
700
880
µA
550
830
0.2
2
0.05
2
Input current
VIN_L, Input low voltage
VDD = 5 V
VIN_H, Input high voltage
VDD = 3 V
0.7 VDD
V
Pin capacitance
POWER REQUIREMENTS
VDD
2.7
IDD(normal operation)
VDD = 3.6 V to 5.5 V
DAC active and excluding load current
VIH = VDD and VIL = GND
VDD = 2.7 V to 3.6 V
IDD (all power-down modes)
VDD = 3.6 V to 5.5 V
VIH = VDD and VIL = GND
VDD = 2.7 V to 3.6 V
Reference input impedance
25
µA
kΩ
POWER EFFICIENCY
IOUT/IDD
(1)
(2)
ILOAD = 2 mA, VDD = 5 V
93%
Linearity tested using a reduced code range of 48 to 4048; output unloaded.
Specified by design and characterization, not production tested.
3
DAC7554
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SLAS399A – OCTOBER 2004 – REVISED NOVEMBER 2004
TIMING CHARACTERISTICS (1) (2)
VDD = 2.7 V to 5.5 V, RL = 2 kΩ to GND; all specifications –40°C to 105°C, unless otherwise specified
PARAMETER
TEST CONDITIONS
t1 (3)
SCLK cycle time
t2
SCLK HIGH time
t3
SCLK LOW time
t4
SYNC falling edge to SCLK falling edge setup
time
t5
Data setup time
t6
Data hold time
t7
SCLK falling edge to SYNC rising edge
t8
Minimum SYNC HIGH time
(1)
(2)
(3)
MIN
VDD = 2.7 V to 3.6 V
20
VDD = 3.6 V to 5.5 V
20
VDD = 2.7 V to 3.6 V
10
VDD = 3.6 V to 5.5 V
10
VDD = 2.7 V to 3.6 V
10
VDD = 3.6 V to 5.5 V
10
VDD = 2.7 V to 3.6 V
4
VDD = 3.6 V to 5.5 V
4
VDD = 2.7 V to 3.6 V
5
VDD = 3.6 V to 5.5 V
5
VDD = 2.7 V to 3.6 V
4.5
VDD = 3.6 V to 5.5 V
4.5
VDD = 2.7 V to 3.6 V
0
VDD = 3.6 V to 5.5 V
0
VDD = 2.7 V to 3.6 V
20
VDD = 3.6 V to 5.5 V
20
All input signals are specified with tR = tF = 1 ns (10% to 90% of VDD) and timed from a voltage level of (VIL + VIH)/2.
See Serial Write Operation timing diagram Figure 1.
Maximum SCLK frequency is 50 MHz at VDD = 2.7 V to 5.5 V.
t1
SCLK
t8
t2
t3
t4
t7
SYNC
t5
DIN
LD1
t6
LD0
SEL1
SEL0
D11
D1
D0
Figure 1. Serial Write Operation
4
TYP
X
MAX
UNITS
ns
ns
ns
ns
ns
ns
ns
ns
DAC7554
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SLAS399A – OCTOBER 2004 – REVISED NOVEMBER 2004
PIN DESCRIPTION
DGS Package
(Top View)
VOUTA
VOUTB
GND
VOUTC
VOUTD
1
10
2
9
3
8
4
7
5
6
REFIN
SYNC
VDD
DIN
SCLK
Terminal Functions
TERMINAL
NO.
DESCRIPTION
NAME
1
VOUTA
Analog output voltage from DAC A
2
VOUTB
Analog output voltage from DAC B
3
GND
Ground
4
VOUTC
Analog output voltage from DAC C
5
VOUTD
Analog output voltage from DAC D
6
SCLK
Serial clock input
7
DIN
Serial data input
8
VDD
Analog voltage supply input
9
SYNC
Frame synchronization input. The falling edge of the FS pulse indicates the start of a serial data frame shifted out to
the DAC7554
10
REFIN
Analog input. External reference
5
DAC7554
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SLAS399A – OCTOBER 2004 – REVISED NOVEMBER 2004
TYPICAL CHARACTERISTICS
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR
vs
DIGITAL INPUT CODE
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR
vs
DIGITAL INPUT CODE
1
1
Channel B
VDD = 5 V
Linearity Error − LSB
VREF = 4.096 V
0.5
0
−0.5
−0.5
−1
−1
0.5
0
−0.25
−0.5
0
512
1024
1536
2048
2560
Digital Input Code
3072
3584
0.25
0
−0.25
−0.5
0
4096
1536
2048
2560
Digital Input Code
3072
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR
vs
DIGITAL INPUT CODE
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR
vs
DIGITAL INPUT CODE
3584
4096
1
VREF = 4.096 V
Channel D
VDD = 5 V
Linearity Error − LSB
Linearity Error − LSB
1024
Figure 3.
Channel C
0.5
0
−0.5
−1
VREF = 4.096 V
VDD = 5 V
0.5
0
−0.5
−1
Differential Linearity Error − LSB
Differential Linearity Error − LSB
512
Figure 2.
1
0.5
0.25
0
−0.25
0.5
0.25
0
−0.25
−0.5
0
512
1024
1536
2048
Digital Input Code
Figure 4.
6
VDD = 5 V
0
0.5
0.25
VREF = 4.096 V
0.5
Differential Linearity Error − LSB
Differential Linearity Error − LSB
Linearity Error − LSB
Channel A
2560
3072
3584
4096
−0.5
0
512
1024
1536
2048
2560
Digital Input Code
Figure 5.
3072
3584
4096
DAC7554
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SLAS399A – OCTOBER 2004 – REVISED NOVEMBER 2004
TYPICAL CHARACTERISTICS (continued)
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR
vs
DIGITAL INPUT CODE
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR
vs
DIGITAL INPUT CODE
1
1
VREF = 2.5 V
VDD = 2.7 V
Linearity Error − LSB
Linearity Error − LSB
Channel A
0.5
0
−0.5
0.5
0.25
0
−0.25
−0.5
0
512
1024
1536
2048
2560
Digital Input Code
3072
3584
4096
−0.5
0.5
0.25
0
−0.25
−0.5
0
512
1024
1536
2048
2560
Digital Input Code
3072
3584
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR
vs
DIGITAL INPUT CODE
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR
vs
DIGITAL INPUT CODE
4096
1
Channel C
VREF = 2.5 V
Channel D
VDD = 2.7 V
Linearity Error − LSB
Linearity Error − LSB
0
Figure 7.
0.5
0
−0.5
−1
VREF = 2.5 V
VDD = 2.7 V
0.5
0
−0.5
−1
Differential Linearity Error − LSB
Differential Linearity Error − LSB
VDD = 2.7 V
Figure 6.
1
0.5
0.25
0
−0.25
−0.5
VREF = 2.5 V
−1
Differential Linearity Error − LSB
Differential Linearity Error − LSB
−1
Channel B
0.5
0
512
1024
1536
2048
2560
Digital Input Code
Figure 8.
3072
3584
4096
0.5
0.25
0
−0.25
−0.5
0
512
1024
1536
2048
2560
3072
3584
4096
Digital Input Code
Figure 9.
7
DAC7554
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SLAS399A – OCTOBER 2004 – REVISED NOVEMBER 2004
TYPICAL CHARACTERISTICS (continued)
ZERO-SCALE ERROR
vs
FREE-AIR TEMPERATURE
ZERO-SCALE ERROR
vs
FREE-AIR TEMPERATURE
10
10
VDD = 5 V,
VREF = 4.096 V
VDD = 2.7 V,
VREF = 2.5 V
Channel C
5
Channel D
0
Channel B
Zero−Scale Error − mV
Zero−Scale Error − mV
Channel A
Channel A
5
Channel C
Channel D
0
Channel B
−5
−40
−10
20
50
−5
−40
80
TA − Free-Air Temperature − °C
80
Figure 11.
FULL-SCALE ERROR
vs
FREE-AIR TEMPERATURE
FULL-SCALE ERROR
vs
FREE-AIR TEMPERATURE
5
VDD = 2.7 V,
VREF = 2.5 V
Channel A
Channel C
Channel D
0
Channel B
−5
−10
20
50
80
TA − Free-Air Temperature − °C
Figure 12.
8
50
Figure 10.
VDD = 5 V,
VREF = 4.096 V
−10
−40
20
TA − Free-Air Temperature − °C
Channel C
Channel A
Full−Scale Error − mV
Full−Scale Error − mV
5
−10
Channel D
0
Channel B
−5
−10
−40
−10
20
50
80
TA − Free-Air Temperature − °C
Figure 13.
DAC7554
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SLAS399A – OCTOBER 2004 – REVISED NOVEMBER 2004
TYPICAL CHARACTERISTICS (continued)
SINK CURRENT AT NEGATIVE RAIL
SOURCE CURRENT AT POSITIVE RAIL
0.2
5.50
Typical for All Channels
VDD = 2.7 V,
Vref = 2.5 V
0.15
VO − Output Voltage − V
VO − Output Voltage − V
Typical for All Channels
0.1
VDD = 5.5 V,
Vref = 4.096 V
VDD = Vref = 5.5 V
5.40
5.30
0.05
DAC Loaded with 000h
0
0
5
10
ISINK − Sink Current − mA
DAC Loaded with FFFh
5.20
15
0
5
10
ISOURCE − Source Current − mA
Figure 14.
Figure 15.
SOURCE CURRENT AT POSITIVE RAIL
SUPPLY CURRENT
vs
DIGITAL INPUT CODE
15
700
2.7
Typical for All Channels
I DD − Supply Current − µ A
VO − Output Voltage − V
600
2.6
VDD = Vref = 2.7 V
2.5
500
VDD = 5.5 V,
Vref = 4.096 V
VDD = 2.7 V,
Vref = 2.5 V
400
300
200
100
All Channels Powered, No Load
DAC Loaded with FFFh
2.4
0
5
10
ISOURCE − Source Current − mA
Figure 16.
15
0
0
512 1024 1536 2048 2560 3072 3584 4096
Digital Input Code
Figure 17.
9
DAC7554
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SLAS399A – OCTOBER 2004 – REVISED NOVEMBER 2004
TYPICAL CHARACTERISTICS (continued)
SUPPLY CURRENT
vs
FREE-AIR TEMPERATURE
SUPPLY CURRENT
vs
SUPPLY VOLTAGE
800
700
VDD = 5.5 V,
Vref = 4.096 V
600
VDD = 2.7 V,
Vref = 2.5 V
500
All DACs Powered,
No Load,
Vref = 2.5 V
650
I DD − Supply Current − µ A
I DD − Supply Current − µ A
700
400
300
200
600
550
500
450
100
All Channels Powered, No Load
0
−40
−10
20
50
80
TA − Free-Air Temperature − °C
400
2.7
110
3.8
4.1
4.5
4.8
5.2
5.5
Figure 18.
Figure 19.
SUPPLY CURRENT
vs
LOGIC INPUT VOLTAGE
HISTOGRAM OF CURRENT CONSUMPTION - 5.5 V
2000
VDD = 5.5 V,
Vref = 4.096 V
TA = 25C,
SCL Input (All Other Inputs = GND)
1800
1500
f − Frequency − Hz
I DD − Supply Current − µ A
3.4
VDD − Supply Voltage − V
2200
VDD = 5.5 V,
Vref = 4.096 V
1400
1000
1000
500
600
VDD = 2.7 V,
Vref = 2.5 V
200
0
0
1
2
3
4
VLOGIC − Logic Input Voltage − V
Figure 20.
10
3.1
5
282 339 395 452 508 565 621 678 734 791
IDD − Current Consumption − A
Figure 21.
DAC7554
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SLAS399A – OCTOBER 2004 – REVISED NOVEMBER 2004
TYPICAL CHARACTERISTICS (continued)
HISTOGRAM OF CURRENT CONSUMPTION - 2.7 V
TOTAL ERROR - 5 V
2000
VDD = 5 V,
Vref = 4.096 V,
TA = 25C
Channel B Output
VDD = 2.7 V,
Vref = 2.5 V
6
Channel C Output
4
Total Error - mV
f − Frequency − Hz
1500
1000
Channel A Output
2
0
−2
500
Channel D Output
−4
0
−6
0
280 327 373 420 467 513 560 607 653 700
IDD − Current Consumption − A
6
TOTAL ERROR - 2.7 V
EXITING POWER-DOWN MODE
5
VDD = 5 V,
Vref = 4.096 V,
Power-Up Code 4000
4
Channel C Output
Channel B Output
0
−2
VO − Output Voltage − V
Total Error - mV
Figure 23.
Channel A Output
2
1024 1536 2048 2560 3072 3584 4095
Digital Input Code
Figure 22.
VDD = 2.7 V,
Vref = 2.5 V,
TA = 25C
4
512
3
2
1
−4
Channel D Output
−6
0
512
1024 1536 2048 2560 3072 3584 4095
Digital Input Code
Figure 24.
0
t − Time − 4 s/div
Figure 25.
11
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TYPICAL CHARACTERISTICS (continued)
LARGE-SIGNAL SETTLING TIME - 5 V
LARGE-SIGNAL SETTLING TIME - 2.7 V
5
3
Vref = 2.5 V
VDD = 2.7 V,
Output Loaded With 200 pF to GND
Code 41 to 4055
VDD = 5 V,
Vref = 4.096 V
Output Loaded With 200 pF to GND
Code 41 to 4055
VO − Output Voltage − V
VO − Output Voltage − V
4
3
2
2
1
1
0
0
t − Time − 5 s/div
Figure 27.
MIDSCALE GLITCH
WORST-CASE GLITCH
VO -
VO -
(5 mV/Div)
(5 mV/Div)
Figure 26.
Trigger Pulse
Trigger Pulse
Time - (400 nS/Div)
Figure 28.
12
t − Time − 5 s/div
Time - (400 nS/Div)
Figure 29.
DAC7554
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TYPICAL CHARACTERISTICS (continued)
CHANNEL-TO-CHANNEL CROSSTALK
FOR A FULL-SCALE SWING
VO -
VO -
(5 mV/Div)
(5 mV/Div)
DIGITAL FEEDTHROUGH ERROR
Trigger Pulse
Trigger Pulse
Time - (400 nS/Div)
Time - (400 nS/Div)
Figure 30.
Figure 31.
TOTAL HARMONIC DISTORTION
vs
OUTPUT FREQUENCY
THD − Total Harmonic Distortion − dB
−40
VDD = 5 V, Vref = 4.096 V
−1 dB FSR Digital Input, Fs = 1 Msps
Measurement Bandwidth = 20 kHz
−50
−60
−70
THD
−80
2nd Harmonic
−90
−100
3rd Harmonic
0
1
2
3
4
5
6
7
8
Output Frequency (Tone) − kHz
9
10
Figure 32.
13
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3-Wire Serial Interface
The DAC7554 digital interface is a standard 3-wire SPI/QSPI/Microwire/DSP-compatible interface.
Table 1. Serial Interface Programming
CONTROL
14
DATA BITS
LD1
LD0
Sel1
Sel0
DB11-DB0
0
0
0
0
data
0
0
0
1
0
0
1
0
0
0
1
0
1
0
0
DAC(s)
FUNCTION
A
Input register updated
data
B
Input register updated
data
C
Input register updated
1
data
D
Input register updated
0
0
data
A
DAC register updated, output updated
1
0
1
data
B
DAC register updated, output updated
1
1
0
data
C
DAC register updated, output updated
0
1
1
1
data
D
DAC register updated, output updated
1
0
0
0
data
A
Input register and DAC register updated, output updated
1
0
0
1
data
B
Input register and DAC register updated, output updated
1
0
1
0
data
C
Input register and DAC register updated, output updated
1
0
1
1
data
D
Input register and DAC register updated, output updated
1
1
0
0
data
A-D
Input register updated
1
1
0
1
data
A-D
DAC register updated, output updated
1
1
1
0
data
A-D
Input register and DAC register updated, output updated
1
1
data
--
1
1
Sel1
Sel0
Power-Down Mode - See Table 2
0
0
Channel A
0
1
Channel B
1
0
Channel C
1
1
Channel D
LD1
LD0
FUNCTION
0
0
Single channel store. The selected input register is updated.
0
1
Single channel DAC update. The selected DAC register is updated with input register information.
1
0
Single channel update. The selected input and DAC register is updated.
1
1
Depends on the Sel1 and Sel0 Bits
CHANNEL SELECT
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POWER-DOWN MODE
In power-down mode, the DAC outputs are programmed to one of three output impedances, 1 kΩ, 100 kΩ, or
floating.
Table 2. Power-Down Mode Control
EXTENDED CONTROL
DATA BITS
FUNCTION
LD1
LD0
Sel1
Sel0
DB11
DB10
DB9
DB8
DB7
DB6-DB0
1
1
1
1
0
0
0
0
0
X
PWD Hi-Z (selected channel = A)
1
1
1
1
0
0
0
0
1
X
PWD 1 kΩ (selected channel = A)
1
1
1
1
0
0
0
1
0
X
PWD 100 kΩ (selected channel = A)
1
1
1
1
0
0
0
1
1
X
PWD Hi-Z (selected channel = A)
1
1
1
1
0
0
1
0
0
X
PWD Hi-Z (selected channel = B)
1
1
1
1
0
0
1
0
1
X
PWD 1 kΩ (selected channel = B)
1
1
1
1
0
0
1
1
0
X
PWD 100 kΩ (selected channel = B)
1
1
1
1
0
0
1
1
1
X
PWD Hi-Z (selected channel = B)
1
1
1
1
0
1
0
0
0
X
PWD Hi-Z (selected channel = C)
1
1
1
1
0
1
0
0
1
X
PWD 1 kΩ (selected channel = C)
1
1
1
1
0
1
0
1
0
X
PWD 100 kΩ (selected channel = C)
1
1
1
1
0
1
0
1
1
X
PWD Hi-Z (selected channel = C)
1
1
1
1
0
1
1
0
0
X
PWD Hi-Z (selected channel = D)
1
1
1
1
0
1
1
0
1
X
PWD 1 kΩ (selected channel = D)
1
1
1
1
0
1
1
1
0
X
PWD 100 kΩ (selected channel = D)
1
1
1
1
0
1
1
1
1
X
PWD Hi-Z (selected channel = D)
1
1
1
1
1
X
X
0
0
X
PWD Hi-Z (all channels)
1
1
1
1
1
X
X
0
1
X
PWD 1 kΩ (all channels)
1
1
1
1
1
X
X
1
0
X
PWD 100 kΩ (all channels)
1
1
1
1
X
X
1
1
X
PWD Hi-Z (all channels)
1
DB11
ALL CHANNELS FLAG
0
See DB7–DB10
1
DB10 and DB9 are Don't Care
DB10
DB9
0
0
Channel Select
Channel A
0
1
Channel B
1
0
Channel C
1
1
Channel D
DB8
DB7
0
0
Power-down Hi-Z
0
1
Power-down 1 kΩ
1
0
Power-down 100 kΩ
1
1
Power-down Hi-Z
Power-Down Mode
15
DAC7554
www.ti.com
SLAS399A – OCTOBER 2004 – REVISED NOVEMBER 2004
THEORY OF OPERATION
D/A SECTION
DAC External Reference Input
The architecture of the DAC7554 consists of a string
DAC followed by an output buffer amplifier. Figure 33
shows a generalized block diagram of the DAC
architecture.
There is a single reference input pin for the four
DACs. The reference input is unbuffered. The user
can have a reference voltage as low as 0.25 V and
as high as VDD because there is no restriction due to
headroom and footroom of any reference amplifier.
REFIN
_
Ref +
Resistor String
Ref −
DAC Register
VOUT
+
Power-On Reset
GND
Figure 33. Typical DAC Architecture
The input coding to the DAC7554 is unsigned binary,
which gives the ideal output voltage as:
VOUT = REFIN × D/4096
Where D = decimal equivalent of the binary code that
is loaded to the DAC register which can range from 0
to 4095.
To Output
Amplifier
REFIN
R
R
R
It is recommended to use a buffered reference in the
external circuit (e.g., REF3140). The input impedance
is typically 25 kΩ.
R
GND
Figure 34. Typical Resistor String
On power up, all internal registers are cleared and all
channels are updated with zero-scale voltages. Until
valid data is written, all DAC outputs remain in this
state. This is particularly useful in applications where
it is important to know the state of the DAC outputs
while the device is powering up. In order not to turn
on ESD protection devices, VDD should be applied
before any other pin is brought high.
Power Down
The DAC7554 has a flexible power-down capability
as described in Table 2. Individual channels could be
powered down separately or all channels could be
powered down simultaneously. During a power-down
condition, the user has flexibility to select the output
impedance of each channel. During power-down
operation, each channel can have either 1-kΩ,
100-kΩ, or Hi-Z output impedance to ground.
SERIAL INTERFACE
RESISTOR STRING
The resistor string section is shown in Figure 34. It is
simply a string of resistors, each of value R. The
digital code loaded to the DAC register determines at
which node on the string the voltage is tapped off to
be fed into the output amplifier. The voltage is tapped
off by closing one of the switches connecting the
string to the amplifier. Because it is a string of
resistors, it is specified monotonic. The DAC7554
architecture uses four separate resistor strings to
minimize channel-to-channel crosstalk.
OUTPUT BUFFER AMPLIFIERS
The output buffer amplifier is capable of generating
rail-to-rail voltages on its output, which gives an
output range of 0 V to VDD. It is capable of driving a
load of 2 kΩ in parallel with up to 1000 pF to GND.
The source and sink capabilities of the output amplifier can be seen in the typical curves. The slew rate is
1 V/µs with a half-scale settling time of 3 µs with the
output unloaded.
16
The DAC7554 is controlled over a versatile 3-wire
serial interface, which operates at clock rates up to
50 MHz and is compatible with SPI, QSPI, Microwire,
and DSP interface standards.
16-Bit Word and Input Shift Register
The input shift register is 16 bits wide. DAC data is
loaded into the device as a 16-bit word under the
control of a serial clock input, SCLK, as shown in the
Figure 1 timing diagram. The 16-bit word, illustrated
in Table 1, consists of four control bits followed by 12
bits of DAC data. The data format is straight binary
with all zeroes corresponding to 0-V output and all
ones corresponding to full-scale output (VREF – 1
LSB). Data is loaded MSB first (Bit 15) where the first
two bits (LD1 and LD0) determine if the input register,
DAC register, or both are updated with shift register
input data. Bit 13 and bit 12 (Sel1 and Sel0)
determine whether the data is for DAC A, DAC B,
DAC C, DAC D, or all DACs. All channels are
updated when bits 15 and 14 (LD1 and LD0) are
high.
DAC7554
www.ti.com
The SYNC input is a level-triggered input that acts as
a frame synchronization signal and chip enable. Data
can only be transferred into the device while SYNC is
low. To start the serial data transfer, SYNC should be
taken low, observing the minimum SYNC to SCLK
falling edge setup time, t4. After SYNC goes low,
serial data is shifted into the device's input shift
register on the falling edges of SCLK for 16 clock
pulses. Any data and clock pulses after the sixteenth
falling edge of SCLK are ignored. No further serial
data transfer occurs until SYNC is taken high and low
again.
SYNC may be taken high after the falling edge of the
sixteenth SCLK pulse, observing the minimum SCLK
falling edge to SYNC rising edge time, t7.
After the end of serial data transfer, data is automatically transferred from the input shift register to the
input register of the selected DAC. If SYNC is taken
high before the sixteenth falling edge of SCLK, the
data transfer is aborted and the DAC input registers
are not updated.
INTEGRAL AND DIFFERENTIAL LINEARITY
The DAC7554 uses precision thin-film resistors providing exceptional linearity and monotonicity. Integral
linearity error is typically within (+/-) 0.35 LSBs, and
differential linearity error is typically within (+/-) 0.08
LSBs.
GLITCH ENERGY
The DAC7554 uses a proprietary architecture that
minimizes glitch energy. The code-to-code glitches
are so low, they are usually buried within the
wide-band noise and cannot be easily detected. The
DAC7554 glitch is typically well under 0.1 nV-s. Such
low glitch energy provides more than 10X improvement over industry alternatives.
CHANNEL-TO-CHANNEL CROSSTALK
The DAC7554 architecture is designed to minimize
channel-to-channel crosstalk. The voltage change in
one channel does not affect the voltage output in
another channel. The DC crosstalk is in the order of a
few microvolts. AC crosstalk is also less than –100
dBs. This provides orders of magnitude improvement
over certain competing architectures.
SLAS399A – OCTOBER 2004 – REVISED NOVEMBER 2004
can exceed 1 MSPS if the waveform to be generated
consists of small voltage steps between consecutive
DAC updates. To obtain a high dynamic range,
REF3140 (4.096 V) or REF02 (5.0 V) are recommended for reference voltage generation.
Generating ±5-V, ±10-V, and ± 12-V Outputs For
Precision Industrial Control
Industrial control applications can require multiple
feedback loops consisting of sensors, ADCs, MCUs,
DACs, and actuators. Loop accuracy and loop speed
are the two important parameters of such control
loops.
Loop Accuracy:
In a control loop, the ADC has to be accurate. Offset,
gain, and the integral linearity errors of the DAC are
not factors in determining the accuracy of the loop.
As long as a voltage exists in the transfer curve of a
monotonic DAC, the loop can find it and settle to it.
On the other hand, DAC resolution and differential
linearity do determine the loop accuracy, because
each DAC step determines the minimum incremental
change the loop can generate. A DNL error less than
–1 LSB (non-monotonicity) can create loop instability.
A DNL error greater than +1 LSB implies unnecessarily large voltage steps and missed voltage targets.
With high DNL errors, the loop looses its stability,
resolution, and accuracy. Offering 12-bit ensured
monotonicity and ± 0.08 LSB typical DNL error, 755X
DACs are great choices for precision control loops.
Loop Speed:
Many factors determine control loop speed. Typically,
the ADC's conversion time, and the MCU's computation time are the two major factors that dominate
the time constant of the loop. DAC settling time is
rarely a dominant factor because ADC conversion
times usually exceed DAC conversion times. DAC
offset, gain, and linearity errors can slow the loop
down only during the start-up. Once the loop reaches
its steady-state operation, these errors do not affect
loop speed any further. Depending on the ringing
characteristics of the loop's transfer function, DAC
glitches can also slow the loop down. With its 1
MSPS (small-signal) maximum data update rate,
DAC7554 can support high-speed control loops.
Ultra-low glitch energy of the DAC7554 significantly
improves loop stability and loop settling time.
APPLICATION INFORMATION
Generating Industrial Voltage Ranges:
Waveform Generation
For control loop applications, DAC gain and offset
errors are not important parameters. This could be
exploited to lower trim and calibration costs in a
high-voltage control circuit design. Using a quad
operational amplifier (OPA4130), and a voltage reference (REF3140), the DAC7554 can generate the
wide voltage swings required by the control loop.
Due to its exceptional linearity, low glitch, and low
crosstalk, the DAC7554 is well suited for waveform
generation (from DC to 10 kHz). The DAC7554
large-signal settling time is 5 µs, supporting an
update rate of 200 KSPS. However, the update rates
17
DAC7554
www.ti.com
SLAS399A – OCTOBER 2004 – REVISED NOVEMBER 2004
Vtail
DAC7554
R1
REF3140
R2
Vref
_
REFIN
DAC7554
Vdac
+
V out V ref R2 1 Din V tail R2
4096
R1
R1
VOUT
OPA4130
Figure 35. Low-cost, Wide-swing Voltage Generator for Control Loop Applications
The output voltage of the configuration is given by:
(1)
Fixed R1 and R2 resistors can be used to coarsely
set the gain required in the first term of the equation.
Once R2 and R1 set the gain to include some
minimal over-range, a DAC7554 channel could be
used to set the required offset voltages. Residual
errors are not an issue for loop accuracy because
offset and gain errors could be tolerated. One
DAC7554 channel can provide the Vtail voltage, while
the other three DAC7554 channels can provide Vdac
voltages to help generate three high-voltage outputs.
For ±5-V operation: R1=10 kΩ, R2 = 15 kΩ, Vtail =
3.33 V, Vref = 4.096 V
For ±10-V operation: R1=10 kΩ, R2 = 39 kΩ, Vtail =
2.56 V, Vref = 4.096 V
For ±12-V operation: R1=10 kΩ, R2 = 49 kΩ, Vtail =
2.45 V, Vref = 4.096 V
18
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
DAC7554IDGS
ACTIVE
MSOP
DGS
10
100
TBD
CU NIPDAU
Level-1-220C-UNLIM
DAC7554IDGSR
ACTIVE
MSOP
DGS
10
2500
TBD
CU NIPDAU
Level-1-220C-UNLIM
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.
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Addendum-Page 1
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