DAC7551
SLAS441E – MARCH 2005 – REVISED APRIL 2007
12-Bit, Ultra-Low Glitch, Voltage Output
DIGITAL-TO-ANALOG CONVERTER
FEATURES
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DESCRIPTION
Relative Accuracy (INL): ±0.35LSB
Ultra-Low Glitch Energy: 0.1nV-s
Low Power Operation: 100µA at 2.7V
Power-On Reset to Zero Scale
Power Supply: 2.7V to 5.5V Single Supply
Power-Down: 0.05µA at 2.7V
12-Bit Linearity and Monotonicity
Rail-to-Rail Voltage Output
Settling Time: 5µs (Max)
SPI-Compatible Serial Interface with
Schmitt-Trigger Input: Up to 50MHz
Daisy-Chain Capability
Asynchronous Hardware Clear to Zero Scale
Specified Temperature Range:
– 40°C to +105°C
Small, 2 x 3 mm, 12-Lead SON Package
The DAC7551 is a single-channel, voltage-output
digital-to-analog converter (DAC) with exceptional
linearity and monotonicity, and a proprietary
architecture that minimizes glitch energy. The
low-power DAC7551 operates from a single 2.7V to
5.5V supply. The DAC7551 output amplifiers can
drive a 2kΩ, 200pF load rail-to-rail with 5µs settling
time; the output range is set using an external
voltage reference.
The 3-wire serial interface operates at clock rates up
to 50MHz and is compatible with SPI™, QSPI™,
Microwire™, and DSP interface standards. The parts
incorporate a power-on-reset circuit to ensure that
the DAC output powers up to 0V and remains there
until a valid write cycle to the device takes place. The
part contains a power-down feature that reduces the
current consumption of the device to under 2µA.
Small size and low-power operation make the
DAC7551 ideally suited for battery-operated, portable
applications. The power consumption is typically
0.5mW at 5V, 0.23mW at 3V, and reduces to 1µW in
power-down mode.
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 DAC7551 is available in a 12-lead SON
package and is specified over –40°C to +105°C.
FUNCTIONAL BLOCK DIAGRAM
VDD
IOVDD
VREFH
VFB
SCLK
_
SYNC
Interface
Logic
Shift
Register
DAC
Register
String
DAC
+
VOUT
SDIN
Power-On
Reset
SDO CLR
Power-Down
Logic
GND
VREFL
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, QSPI are trademarks of Motorola, Inc.
Microwire is a trademark of National Semiconductor Corp..
All other 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 © 2005–2007, Texas Instruments Incorporated
DAC7551
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SLAS441E – MARCH 2005 – REVISED APRIL 2007
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)
(1)
PRODUCT
PACKAGE-LEAD
PACKAGE
DESIGNATOR
DAC7551
SON-12
DRN
SPECIFIED
TEMPERATURE
RANGE
PACKAGE
MARKING
–40°C to +105°C
D51
For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI
website at www.ti.com.
ABSOLUTE MAXIMUM RATINGS (1)
Over operating free-air temperature range (unless otherwise noted).
UNIT
VDD , IOVDD to GND
–0.3V to 6V
Digital input voltage to GND
–0.3V to VDD + 0.3V
VOUT to GND
–0.3V to VDD + 0.3V
Operating temperature range
–40°C to +105°C
Storage temperature range
–65°C to +150°C
Junction temperature (TJ Max)
+150°C
Power dissipation (DRN)
Thermal impedance, θJA
79°C/W
Thermal impedance, θJC
48.57°C/W
ESD rating
(1)
2
(TJ max – TA)/θJA
Human body model (HBM)
4000V
Charged device model (CDM)
1500V
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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ELECTRICAL CHARACTERISTICS
all specifications at –40°C to +105°C, VDD = 2.7V to 5.5V, VREFH = VDD, VREFL = GND, RL = 2kΩ to GND, and CL = 200pF to
GND (unless otherwise noted).
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNITS
±0.35
±1
LSB
±0.08
± 0.5
LSB
±12
mV
±12
mV
STATIC PERFORMANCE (1)
Resolution
12
Relative accuracy
Differential nonlinearity
Specified monotonic by design
Bits
Offset error
Zero-scale error
All zeroes loaded to DAC register
Gain error
Full-scale error
±0.15
%FSR
±0.5
%FSR
Zero-scale error drift
7
µV/°C
Gain temperature coefficient
3
ppm of
FSR/°C
PSRR
VDD = 5V
0.75
mV/V
OUTPUT CHARACTERISTICS (2)
Output voltage range
Output voltage settling time
2 x VREFL
RL = 2kΩ, 0pF < CL < 200pF
Slew rate
Capacitive load stability
Digital-to-analog glitch impulse
VREFH
V
5
µs
1.8
RL = ∞
V/µs
470
RL = 2kΩ
pF
1000
1 LSB change around major carry
0.1
0.1
nV-s
Output noise density
10kHz offset frequency
120
nV/√Hz
Total harmonic distortion
fOUT = 1kHz, fS = 1MSPS, BW = 20kHz
–85
dB
1
Ω
Digital feedthrough
DC output impedance
Short-circuit current
Power-up time
VDD = 5V
50
VDD = 3V
20
Coming out of power-down mode, VDD = 5V
15
Coming out of power-down mode, VDD = 3V
15
nV-s
mA
µs
REFERENCE INPUT
VREFH Input range
VREFL Input range
0
VREFL < VREFH
0
Reference input impedance
Reference current
VDD
GND
VDD
100
V
V
kΩ
VREF = VDD = 5V
50
100
VREF = VDD = 3V
30
60
µA
LOGIC INPUTS (2)
Input current
VIN_L, Input low voltage
IOVDD ≥ 2.7V
VIN_H, Input high voltage
IOVDD ≥ 2.7V
Pin capacitance
(1)
(2)
±1
µA
0.3 IOVDD
V
3
pF
0.7 IOVDD
V
Linearity tested using a reduced code range of 30 to 4065; output unloaded.
Specified by design and characterization; not production tested. For 1.8V < IOVDD < 2.7V, it is recommended that VIH ≥ 0.8 IOVDD, and
VIL ≤ 0.2 IOVDD.
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ELECTRICAL CHARACTERISTICS (continued)
all specifications at –40°C to +105°C, VDD = 2.7V to 5.5V, VREFH = VDD, VREFL = GND, RL = 2kΩ to GND, and CL = 200pF to
GND (unless otherwise noted).
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNITS
POWER REQUIREMENTS
VDD
2.7
5.5
V
IOVDD (3)
1.8
VDD
V
IDD
(4)
Normal operation (DAC
active and excluding load
current)
All power-down modes
VDD = 3.6V to 5.5V, VIH = IOVDD, VIL = GND
150
200
VDD = 2.7V to 3.6V, VIH = IOVDD, VIL = GND
100
150
VDD = 3.6V to 5.5V, VIH = IOVDD, VIL = GND
0.2
2
VDD = 2.7V to 3.6V, VIH = IOVDD, VIL = GND
0.05
2
µA
µA
POWER EFFICIENCY
IOUT/IDD
ILOAD = 2mA, VDD = 5V
93
%
TEMPERATURE RANGE
Specified performance
(3)
(4)
4
–40
IOVDD operates down to 1.8V with slightly degraded timing, as long as VIH ≥ 0.8 IOVDD and VIL ≤ 0.2 IOVDD.
IDD tested with digital input code = 0032.
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°C
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SLAS441E – MARCH 2005 – REVISED APRIL 2007
PIN CONFIGURATION
VDD
1
12
IOVDD
VREFH
2
11
SDO
VREFL
3
10
SDIN
9
SCLK
8
SYNC
7
CLR
DAC7751
VFB
4
VOUT
5
GND
6
Thermal
Pad(1)
Pin Descriptions
PIN
NO.
(1)
NAME
DESCRIPTION
1
VDD
Analog voltage supply input
2
VREFH
Positive reference voltage input
3
VREFL
Negative reference voltage input
4
VFB
DAC amplifier sense input.
5
VOUT
Analog output voltage from DAC
6
GND (1)
Ground.
7
CLR
Asynchronous input to clear the DAC registers. When CLR is low, the DAC register is set to 000h and the output
voltage to 0V.
8
SYNC
Frame synchronization input. The falling edge of the SYNC pulse indicates the start of a serial data frame shifted out
to the DAC7551.
9
SCLK
Serial clock input
10
SDIN
Serial data input
11
SDO
Serial data output
12
IOVDD
I/O voltage supply input
Thermal pad should be connected to GND.
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SERIAL WRITE OPERATION
t1
SCLK
t8
t2
t3
t4
t7
SYNC
t5
SDIN
t6
D15
D14
D13
D12
D11
D1
D0
Input Word n
D15
D0
t9
SDO
Input Word n+1
D15
D0
D14
Input Word n
Undefined
t10
CLR
Figure 1. Serial Write Operation Timing Diagram
TIMING CHARACTERISTICS (1) (2)
All specifications at –40°C to +105°C, VDD = 2.7V to 5.5V, and RL = 2kΩ to GND (unless otherwise noted).
PARAMETER
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
t9
SCLK falling edge to SDO valid
t10
CLR pulse width low
(1)
(2)
(3)
(4)
6
TEST CONDITIONS
MIN
TYP
MAX
VDD = 2.7V to 3.6V
20
VDD = 3.6V to 5.5V
20
VDD = 2.7V to 3.6V
6.5
VDD = 3.6V to 5.5V
6.5
VDD = 2.7V to 3.6V
6.5
VDD = 3.6V to 5.5V
6.5
VDD = 2.7V to 3.6V
4
VDD = 3.6V to 5.5V
4
VDD = 2.7V to 3.6V
3
VDD = 3.6V to 5.5V
3
VDD = 2.7V to 3.6V
3
VDD = 3.6V to 5.5V
3
VDD = 2.7V to 3.6V
0
t1– 10ns (4)
VDD = 3.6V to 5.5V
0
t1– 10ns (4)
VDD = 2.7V to 3.6V
20
VDD = 3.6V to 5.5V
20
VDD = 2.7V to 3.6V
10
VDD = 3.6V to 5.5V
10
VDD = 2.7V to 3.6V
10
VDD = 3.6V to 5.5V
10
ns
ns
ns
ns
ns
ns
All input signals are specified with tR = tF = 1ns (10% to 90% of VDD) and timed from a voltage level of (VIL + VIH)/2.
See Figure 1, Serial Write Operation timing diagram.
Maximum SCLK frequency is 50MHz at VDD = 2.7V to 5.5V.
SCLK falling edge to SYNC rising edge time shold not exceed (t1– 10ns) in order to latch the correct data.
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UNITS
ns
ns
ns
ns
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TYPICAL CHARACTERISTICS
At TA = +25°C, unless otherwise noted.
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR
vs DIGITAL INPUT CODE
1.0
VDD = 5V, VREFH = 4.096V, VREFL = GND
0.5
LE (LSB)
LE (LSB)
1.0
0
-1.0
-1.0
0.50
0.50
0.25
0.25
0
-0.25
-0.50
512
1024
1536
2048
2560
3072
3584
-0.25
0
4096
512
1024
1536
2048
2560
3072
Digital Input Code
Digital Input Code
Figure 2.
Figure 3.
ZERO-SCALE ERROR
vs FREE-AIR TEMPERATURE
ZERO-SCALE ERROR
vs FREE-AIR TEMPERATURE
1.00
3584
4096
1.00
VDD = 5V
VREFH = 4.096V
VREFL = GND
0.75
Zero-Scale Error (mV)
Zero-Scale Error (mV)
0
-0.50
0
0.50
0.25
0
VDD = 2.7V
VREFH = 2.5V
VREFL = GND
0.75
0.50
0.25
0
-40
20
-10
50
80
105
-40
50
Figure 4.
Figure 5.
FULL-SCALE ERROR
vs FREE-AIR TEMPERATURE
FULL-SCALE ERROR
vs FREE-AIR TEMPERATURE
80
105
80
105
0
Full-Scale Error (mV)
-0.50
-1.00
20
Free-Air Temperature (°C)
-0.25
-0.75
-10
Free-Air Temperature (°C)
0
Full-Scale Error (mV)
0
-0.5
DLE (LSB)
DLE (LSB)
-0.5
VDD = 2.7V, VREFH = 2.5V, VREFL = GND
0.5
VDD = 5V
VREFH = 4.096V
VREFL = GND
-40
-10
-0.25
VDD = 2.7V
VREFH = 2.5V
VREFL = GND
-0.50
-0.75
-1.00
20
50
80
105
-40
-10
20
50
Free-Air Temperature (°C)
Free-Air Temperature (°C)
Figure 6.
Figure 7.
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TYPICAL CHARACTERISTICS (continued)
At TA = +25°C, unless otherwise noted.
SINK CURRENT
AT NEGATIVE RAIL
SOURCE CURRENT
AT POSITIVE RAIL
5.5
0.20
VDD = VREFH = 5.5V
0.15
Output Voltage, VO (V)
Output Voltage, VO (V)
Typical
VDD = 2.7V
VREFH = 2.5V
VREFL = GND
0.10
VDD = 5.5V
VREFH = 4.096V
VREFL = GND
0.05
VREFL = GND
5.4
5.3
DAC Loaded with FFFFh
DAC Loaded with 0000h
5.2
0
0
5
10
0
15
5
Figure 9.
SOURCE CURRENT
AT POSITIVE RAIL
SUPPLY CURRENT
vs DIGITAL INPUT CODE
250
VDD = VREFH = 2.7V
VDD = 5.5V
VREFH = 4.096V
VREFL = GND
200
VREFL = GND
2.6
IDD (mA)
Output Voltage, VO (V)
15
Figure 8.
2.7
150
VDD = 2.7V
VREFH = 2.5V
VREFL = GND
100
2.5
50
Powered, No Load
DAC Loaded with FFFFh
0
2.4
ISOURCE (mA)
1536 2048 2560
Digital Input Code
Figure 10.
Figure 11.
SUPPLY CURRENT
vs FREE-AIR TEMPERATURE
SUPPLY CURRENT
vs SUPPLY VOLTAGE
0
5
200
10
110
105
IDD (mA)
150
VDD = 2.7V
VREFH = 2.5V
VREFL = GND
125
512
0
15
VDD = 5.5V
VREFH = 4.096V
VREFL = GND
175
IDD (mA)
10
ISOURCE (mA)
ISINK (mA)
1024
3072
3584
4096
DAC Powered, No Load
VREFH = 2.5V
VREFL = GND
100
95
Powered, No Load
100
90
-40
8
-10
20
50
80
110
2.7
3.1
3.5
3.9
4.3
Free-Air Temperature (°C)
VDD (V)
Figure 12.
Figure 13.
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5.5
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TYPICAL CHARACTERISTICS (continued)
At TA = +25°C, unless otherwise noted.
SUPPLY CURRENT
vs LOGIC INPUT VOLTAGE
HISTOGRAM OF CURRENT CONSUMPTION - 5.5V
2000
1600
TA = +25°C
SCLK Input
All Other Input = GND
1500
VDD = 5.5V
VREFH = 4.096V
VREFL = GND
800
Frequency (Hz)
IDD (mA)
1200
1000
VDD = 2.7V
VREFH = 2.5V
VREFL = GND
400
Digital Input Code = 2048
VDD = 5.5V
VREFH = 4.096V
VREFL = GND
500
0
0
0
1
2
3
4
128
5
VLOGIC (V)
136
144 152 160 168 176
Current Consumption (mA)
Figure 14.
HISTOGRAM OF CURRENT CONSUMPTION - 2.7V
Digital Input Code = 2048
VDD = 2.7V
VREFH = 2.5V
VREFL = GND
4096
VDD = 5V
VREFH = 4.096V
VREFL = GND
TA = +25°C
2
Total Error (mV)
Frequency (Hz)
3584
TOTAL ERROR - 5V
4
1000
500
0
-2
0
-4
117
124
131 138 145 152 159
Current Consumption (mA)
166
0
173
512
Figure 16.
1024
1536 2048 2560
Digital Input Code
3072
Figure 17.
TOTAL ERROR - 2.7V
EXITING POWER-DOWN MODE
5
4
VDD = 2.7V
VREFH = 2.5V
VREFL = GND
TA = +25°C
4
Output Voltage (V)
2
Total Error (mV)
192
Figure 15.
2000
1500
184
0
-2
VDD = 5V
VREFH = 4.096V
VREFL = GND
Power-Up Code = 4000
3
2
1
0
-4
0
512
1024
1536
2048
2560
3072
3584
4096
Time (4ms/div)
Digital Input Code
Figure 18.
Figure 19.
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TYPICAL CHARACTERISTICS (continued)
At TA = +25°C, unless otherwise noted.
LARGE-SIGNAL SETTLING TIME - 5V
Output Loaded with 200pF to GND
Code 0041 to 4055
4
3
LARGE-SIGNAL SETTLING TIME - 2.7V
3
Output Voltage, VO (V)
Output Voltage, VO (V)
5
VDD = 5V
VREFH = 4.096V
VREFL = GND
2
1
0
Output Loaded with 200pF to GND
Code 0041 to 4055
2
VDD = 2.7V
VREFH = 2.5V
VREFL = GND
1
0
Time (5ms/div)
Figure 20.
Figure 21.
MIDSCALE GLITCH
WORST-CASE GLITCH
VO (5mV/div)
VO (5mV/div)
Time (5ms/div)
Trigger Pulse
Trigger Pulse
Time (400ns/div)
Time (400ns/div)
Figure 22.
Figure 23.
DIGITAL FEEDTHROUGH ERROR
TOTAL HARMONIC DISTORTION
vs OUTPUT FREQUENCY
-40
VDD = 5.5V
VREFH = 4.096V
VREFL = GND
fS = 1MSPS
-1dB FSR Digital Input
Measurement Bandwidth = 20kHz
VO (5mV/div)
-50
THD (dB)
-60
-70
THD
-80
2nd Harmonic
-90
3rd Harmonic
Trigger Pulse
Time (400ns/div)
-100
0
Figure 24.
10
1
2
3
4
5
6
7
Output Frequency, Tone (kHz)
Figure 25.
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THEORY OF OPERATION
DIGITAL-TO-ANALOG CONVERTER
VREFH
The architecture of the DAC7551 consists of a string
DAC followed by an output buffer amplifier. Figure 26
shows a generalized block diagram of the DAC
architecture.
VREFH
100kW
RDIVIDER
VREFH - VREFL
2
100kW
R
VFB
50kW
DAC
Register
VOUT
REF(+)
Resistor String
REF(-)
R
To Output Amplifier
(2x Gain)
VREFL
Figure 26. Typical DAC Architecture
The input coding to the DAC7551 is unsigned binary,
which gives the ideal output voltage as:
VOUT = 2 x VREFL + (VREFH – VREFL) x D/4096
R
Where D = decimal equivalent of the binary code that
is loaded to the DAC register, which ranges from 0 to
4095.
R
RESISTOR STRING
The resistor string section is shown in Figure 27. 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. It is specified monotonic
because it is a string of resistors.
VREFL
Figure 27. Typical Resistor String
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OUTPUT BUFFER AMPLIFIERS
The output buffer amplifier is capable of generating
rail-to-rail voltages on its output, giving an output
range of 0V to VDD. It is capable of driving a load of
2kΩ in parallel with up to 1000pF to GND. The
source and sink capabilities of the output amplifier
can be seen in the typical curves. The slew rate is
1.8V/µs with a half-scale settling time of 3µs with the
output unloaded.
DAC External Reference Input
The DAC7551 contains VREFH and VREFL reference
inputs, which are unbuffered. The VREFH reference
voltage can be as low as 0.25V, and as high as VDD
because there is no restriction of headroom and
footroom from any reference amplifier.
It is recommended to use a buffered reference in the
external circuit (for example, the REF3140). The
input impedance is typically 100kΩ.
Amplifier Sense Input
The DAC7551 contains an amplifier feedback input
pin, VFB. For voltage output operation, VFB must be
externally connected to VOUT. For better DC
accuracy, this connection should be made at load
points. The VFB pin is also useful for a variety of
applications, including digitally-controlled current
sources. The feedback input pin is internally
connected to the DAC amplifier negative input
terminal through a 100kΩ resistor. The amplifier
negative input terminal internally connects to ground
through another 100kΩ resistor (Figure 26). These
connections form a gain-of-two, noninverting,
amplifier configuration. Overall gain remains one
because the resistor string has a divide-by-two
configuration. The resistance seen at the VFB pin is
approximately 200kΩ to ground.
order to not turn on ESD protection devices, VDD and
IOVDD should be applied before any other pin (such
as VREFH) is brought high. The power-up sequence
of VDD and IOVDD is irrelevant. Therefore, IOVDD can
be brought up before VDD, or vice-versa.
Power Down
The DAC7551 has a flexible power-down capability.
During a power-down condition, the user has
flexibility to select the output impedance of the DAC.
During power-down operation, the DAC can have
either 1kΩ, 100kΩ, or Hi-Z output impedance to
ground.
Asynchronous Clear
The DAC7551 output is asynchronously set to
zero-scale voltage immediately after the CLR pin is
brought low. The CLR signal resets all internal
registers and therefore behaves like the Power-On
Reset. The DAC7551 updates at the first rising edge
of the SYNC signal that occurs after the CLR pin is
brought back to high.
IOVDD and Level Shifters
The DAC7551 can be used with different logic
families that require a wide range of supply voltages.
To enable this useful feature, the IOVDD pin must be
connected to the logic supply voltage of the system.
All DAC7551 digital input and output pins are
equipped with level-shifter circuits. Level shifters at
the input pins ensure that external logic-high
voltages are translated to the internal logic-high
voltage, with no additional power dissipation.
Similarly, the level shifter for the SDO pin translates
the internal logic-high voltage (VDD) to the external
logic-high level (IOVDD). For single-supply operation,
the IOVDD pin can be tied to the VDD pin.
Power-On Reset
On power up, all registers are cleared and the DAC
channel is updated with zero-scale voltage. The DAC
output remains in this state until valid data are
written. This setup is particularly useful in
applications where it is important to know the state of
the DAC output while the device is powering up. In
12
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DAC7551
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SLAS441E – MARCH 2005 – REVISED APRIL 2007
SERIAL INTERFACE
The DAC7551 is controlled over a versatile 3-wire
serial interface, which operates at clock rates up to
50MHz 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 are
loaded into the device as a 16-bit word under the
control of a serial clock input, SCLK, as shown in
Figure 1, the Serial Write Operation 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 0V output and all ones
corresponding to full-scale output (VREF – 1LSB).
Data are loaded MSB first (bit 15) where the first two
bits (DB15 and DB14) are don't care bits. Bit 13 and
bit 12 (DB13 and DB12) determine either normal
mode operation or power-down mode (see Table 1).
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 input shift
register on the falling edges of SCLK for 16 clock
pulses.
The SPI interface is enabled after SYNC becomes
low and the data are continuously shifted into the
shift register at each falling edge of SCLK. When
SYNC is brought high, the last 16 bits stored in the
shift register are latched into the DAC register, and
the DAC updates.
Daisy-Chain Operation
As long as SYNC is high, the SDO pin is in a
high-impedance state. When SYNC is brought low
the output of the internal shift register is tied to the
SDO pin. As long as SYNC is low, SDO duplicates
the SDIN signal with a 16-cycle delay. To support
multiple devices in a daisy chain, SCLK and SYNC
signals are shared across all devices, and SDO of
one DAC7551 should be tied to the SDIN of the next
DAC7551. For n devices in such a daisy chain, 16n
SCLK cycles are required to shift the entire input
data stream. After 16n SCLK falling edges are
received, following a falling SYNC, the data stream
becomes complete and SYNC can be brought high
to update n devices simultaneously. SDO operation
is specified at a maximum SCLK speed of 10MHz.
In daisy-chain mode, the use of a weak pull-down
resistor on the SDO output pin, which provides the
SDIN data for the next device in the chain, is
recommended. For standalone operation, the
maximum clock speed is 50MHz. For daisy-chain
operation, the maximum clock speed is 10MHz.
INTEGRAL AND DIFFERENTIAL LINEARITY
The DAC7551 uses precision thin-film resistors
providing exceptional linearity and monotonicity.
Integral linearity error is typically within ±0.35LSBs,
and differential linearity error is typically within
±0.08LSBs.
GLITCH ENERGY
The DAC7551 uses a proprietary architecture that
minimizes glitch energy. The code-to-code glitches
are so low that they are usually buried within the
wide-band noise and cannot be easily detected. The
DAC7551 glitch is typically well under 0.1nV-s. Such
low glitch energy provides more than a ten-time
improvement over industry alternatives.
Daisy-chain operation is used for updating
serially-connected devices on the rising edge of
SYNC.
Table 1. Serial Interface Programming
CONTROL
DATA BITS
DB15
DB14
DB13
(PD1)
DB12
(PD0)
DB11–DB0
X
X
0
0
data
Normal mode
X
X
0
1
X
Powerdown 1kΩ
X
X
1
0
X
Powerdown 100kΩ
X
X
1
1
X
Powerdown Hi-Z
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FUNCTION
13
DAC7551
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SLAS441E – MARCH 2005 – REVISED APRIL 2007
APPLICATION INFORMATION
WAVEFORM GENERATION
As a result of the exceptional linearity and low glitch
of the DAC7551, the device is well-suited for
waveform generation (from DC to 10kHz). The
DAC7551 large-signal settling time is 5µs, supporting
an update rate of 200kSPS. However, the update
rates can exceed 1MSPS if the waveform to be
generated consists of small voltage steps between
consecutive DAC updates. To obtain a high dynamic
range, REF3140 (4.096V) or REF02 (5.0V) are
recommended for reference voltage generation.
GENERATING ±5V, ±10V, AND ±12V
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.
slow the loop down. With its 1MSPS (small-signal)
maximum data update rate, DAC7551 can support
high-speed control loops. Ultralow glitch energy of
the DAC7551 significantly improves loop stability and
loop settling time.
GENERATING INDUSTRIAL VOLTAGE
RANGES
For control loop applications, DAC gain and offset
errors are not important parameters. This
consideration 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
DAC7551 can generate the wide voltage swings
required by the control loop.
Vtail
DAC7551
R1
REF3140
R2
Loop Accuracy
VREF
DAC offset, gain, and the integral linearity errors 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
–1LSB (non-monotonicity) can create loop instability.
A DNL error greater than +1LSB implies
unnecessarily large voltage steps and missed
voltage targets. With high DNL errors, the loop loses
its stability, resolution, and accuracy. Offering 12-bit
ensured monotonicity and ±0.08LSB typical DNL
error, DAC755x devices are great choices for
precision control loops.
Loop Speed
Many factors determine the control loop speed, such
as ADC conversion time, MCU speed, and DAC
settling time. Typically, the ADC conversion time,
and the MCU 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 transfer function, DAC glitches can also
VREFH
DAC7551
_
Vdac
+
VOUT
OPA4130
Figure 28. Low-cost, Wide-swing Voltage
Generator for Control Loop Applications
The output voltage of the configuration is given by:
ǒ
Ǔ
ǒ Ǔ
V OUT + V REF R2 ) 1 SDIN *V tail R2
4096
R1
R1
(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 single DAC7551 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
DAC7551 can provide the Vtail voltages, while four
additional DAC7551 devices can provide Vdac
voltages to generate four high-voltage outputs. A
single SPI interface is sufficient to control all five
DAC7551 devices in a daisy-chain configuration.
For ±5V operation:
R1 = 10kΩ, R2 = 15kΩ, Vtail = 3.33V, VREF = 4.096V
For ±10V operation:
R1 = 10kΩ, R2 = 39kΩ, Vtail = 2.56V, VREF = 4.096V
For ±12V operation:
R1 = 10kΩ, R2 = 49kΩ, Vtail = 2.45V, VREF = 4.096V
14
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PACKAGE OPTION ADDENDUM
www.ti.com
14-Oct-2022
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
Samples
(4/5)
(6)
DAC7551IDRNR
ACTIVE
USON
DRN
12
3000
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 105
D51
Samples
DAC7551IDRNT
ACTIVE
USON
DRN
12
250
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 105
D51
Samples
DAC7551IDRNTG4
ACTIVE
USON
DRN
12
250
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 105
D51
Samples
(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)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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