DAC081S101
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SNAS323C – JUNE 2005 – REVISED FEBRUARY 2013
DAC081S101 8-Bit Micro Power Digital-to-Analog Converter with Rail-to-Rail Output
Check for Samples: DAC081S101
FEATURES
DESCRIPTION
•
•
•
•
•
•
•
•
The DAC081S101 is a full-featured, general purpose
8-bit voltage-output digital-to-analog converter (DAC)
that can operate from a single +2.7V to 5.5V supply
and consumes just 175 µA of current at 3.6 Volts.
The on-chip output amplifier allows rail-to-rail output
swing and the three wire serial interface operates at
clock rates up to 30 MHz over the specified supply
voltage range and is compatible with standard SPI™,
QSPI, MICROWIRE and DSP interfaces. Competitive
devices are limited to 20 MHz clock rates at supply
voltages in the 2.7V to 3.6V range.
1
23
Guaranteed Monotonicity
Low Power Operation
Rail-to-Rail Voltage Output
Power-on Reset to Zero Volts Output
SYNC Interrupt Facility
Wide Power Supply Range (+2.7V to +5.5V)
Small Packages
Power Down Feature
APPLICATIONS
•
•
•
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Battery-Powered Instruments
Digital Gain and Offset Adjustment
Programmable Voltage & Current Sources
Programmable Attenuators
The supply voltage for the DAC081S101 serves as its
voltage reference, providing the widest possible
output dynamic range. A power-on reset circuit
ensures that the DAC output powers up to zero volts
and remains there until there is a valid write to the
device. A power-down feature reduces power
consumption to less than a microWatt.
The low power consumption and small packages of
the DAC081S101 make it an excellent choice for use
in battery operated equipment.
The DAC081S101 is a direct replacement for the
AD5300 and is one of a family of pin compatible
DACs, including the 10-bit DAC101S101 and the 12bit DAC121S101. The DAC081S101 operates over
the extended industrial temperature range of −40°C
to +105°C.
Table 1. Key Specifications
VALUE
Resolution
8 bits
DNL
+0.04, -0.02 LSB (typ)
Output Settling Time
3 µs (typ)
Zero Code Error
3.8mV (typ)
−0.07 %FS (typ)
Full-Scale Error
Power Consumption
Normal Mode
Pwr Down Mode
0.63 mW (3.6V) / 1.41 mW (5.5V) typ
0.14 µW (3.6V) / 0.33 µW (5.5V) typ
1
2
3
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..
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 © 2005–2013, Texas Instruments Incorporated
DAC081S101
SNAS323C – JUNE 2005 – REVISED FEBRUARY 2013
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Pin Configuration
SOT
VOUT
1
6
VSSOP
SYNC
GND
2
5
SCLK
VA
3
4
DIN
VA
1
8
GND
NC
NC
2
7
3
6
DIN
SCLK
VOUT
4
5
SYNC
Block Diagram
VA
GND
POWER-ON
RESET
DAC081S101
REF(+) REF(-)
DAC
REGISTER
VOUT
BUFFER
8-BIT DAC
8
8
POWER-DOWN
CONTROL
LOGIC
INPUT
CONTROL
LOGIC
SCLK
SYNC
1k
100k
DIN
Pin Descriptions
Name
SOT-23
Pin No.
VSSOP
Pin No.
VOUT
1
4
DAC Analog Output Voltage.
GND
2
8
Ground reference for all on-chip circuitry.
VA
3
1
Power supply and Reference input. Should be decoupled to GND.
DIN
4
7
Serial Data Input. Data is clocked into the 16-bit shift register on the falling
edges of SCLK after the fall of SYNC.
SCLK
5
6
Serial Clock Input. Data is clocked into the input shift register on the falling
edges of this pin.
5
Frame synchronization input for the data input. When this pin goes low, it
enables the input shift register and data is transferred on the falling edges
of SCLK. The DAC is updated on the 16th clock cycle unless SYNC is
brought high before the 16th clock, in which case the rising edge of SYNC
acts as an interrupt and the write sequence is ignored by the DAC.
SYNC
6
NC
2, 3
Description
No Connect. There is no internal connection to these pins.
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
2
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Absolute Maximum Ratings
(1) (2)
Supply Voltage, VA
6.5V
−0.3V to (VA + 0.3V)
Voltage on any Input Pin
Input Current at Any Pin (3)
10 mA
Package Input Current (3)
20 mA
Power Consumption at TA = 25°C
See (4)
(5)
ESD Susceptibility
Human Body Model
Machine Model
2500V
250V
Soldering Temperature, Infrared,
10 Seconds (6)
235°C
−65°C to +150°C
Storage Temperature
(1)
(2)
(3)
(4)
(5)
(6)
Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for
which the device is functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see
the Electrical Characteristics. The guaranteed specifications apply only for the test conditions listed. Some performance characteristics
may degrade when the device is not operated under the listed test conditions.
All voltages are measured with respect to GND = 0V, unless otherwise specified
When the input voltage at any pin exceeds the power supplies (that is, less than GND, or greater than VA), the current at that pin should
be limited to 10 mA. The 20 mA maximum package input current rating limits the number of pins that can safely exceed the power
supplies with an input current of 10 mA to two.
The absolute maximum junction temperature (TJmax) for this device is 150°C. The maximum allowable power dissipation is dictated by
TJmax, the junction-to-ambient thermal resistance (θJA), and the ambient temperature (TA), and can be calculated using the formula
PDMAX = (TJmax − TA) / θJA. The values for maximum power dissipation will be reached only when the device is operated in a severe
fault condition (e.g., when input or output pins are driven beyond the power supply voltages, or the power supply polarity is reversed).
Obviously, such conditions should always be avoided.
Human body model is 100 pF capacitor discharged through a 1.5 kΩ resistor. Machine model is 220 pF discharged through ZERO
Ohms.
See the section entitled "Surface Mount" found in any post 1986 National Semiconductor Linear Data Book for methods of soldering
surface mount devices.
Operating Ratings
(1) (2)
−40°C ≤ TA ≤ +105°C
Operating Temperature Range
Supply Voltage, VA (3)
+2.7V to 5.5V
Any Input Voltage (4)
−0.1 V to (VA + 0.1 V)
Output Load
0 to 1500 pF
SCLK Frequency
(1)
(2)
(3)
(4)
Up to 30 MHz
Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for
which the device is functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see
the Electrical Characteristics. The guaranteed specifications apply only for the test conditions listed. Some performance characteristics
may degrade when the device is not operated under the listed test conditions.
All voltages are measured with respect to GND = 0V, unless otherwise specified
To guarantee accuracy, it is required that VA be well bypassed.
The analog inputs are protected as shown below. Input voltage magnitudes up to VA + 300 mV or to 300 mV below GND will not
damage this device. However, errors in the conversion result can occur if any input goes above VA or below GND by more than 100 mV.
For example, if VA is 2.7VDC, ensure that −100mV ≤ input voltages ≤2.8VDC to ensure accurate conversions.
I/O
TO INTERNAL
CIRCUITRY
GND
Package Thermal Resistances
Package
θJA
8-Lead VSSOP
240°C/W
6-Lead SOT
250°C/W
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Electrical Characteristics
Values shown in this table are design targets and are subject to change before product release.
The following specifications apply for VA = +2.7V to +5.5V, RL = 2kΩ to GND, CL = 200 pF to GND, fSCLK = 30 MHz, input
code range 4 to 251. Boldface limits apply for TMIN ≤ TA ≤ TMAX: all other limits TA = 25°C, unless otherwise specified.
Parameter
Test Conditions
Typical
(1)
Limits
(1)
Units
(Limits)
STATIC PERFORMANCE
INL
DNL
Resolution
8
Monotonicity
8
Bits (min)
+0.16
+0.75
LSB (max)
−0.12
−0.75
LSB (min)
+0.04
+0.1
LSB (max)
−0.02
−0.1
LSB (min)
Integral Non-Linearity
Differential Non-Linearity
Bits (min)
ZE
Zero Code Error
IOUT = 0
+3.8
+15
mV (max)
FSE
Full-Scale Error
IOUT = 0
−0.07
−1.0
%FSR (max)
GE
Gain Error
All ones Loaded to DAC register
−0.10
±1.0
%FSR (max)
ZCED
Zero Code Error Drift
TC GE
Gain Error Tempco
−20
µV/°C
VA = 3V
−0.7
ppm/°C
VA = 5V
−1.0
ppm/°C
OUTPUT CHARACTERISTICS
Output Voltage Range
ZCO
FSO
Zero Code Output
Full Scale Output
Maximum Load Capacitance
(1)
(2)
4
Output Short Circuit Current
V (min)
V (max)
VA = 3V, IOUT = 10 µA
2.0
mV
VA = 3V, IOUT = 100 µA
5.0
mV
VA = 5V, IOUT = 10 µA
3.0
mV
VA = 5V, IOUT = 100 µA
5.4
mV
VA = 3V, IOUT = 10 µA
2.986
V
VA = 3V, IOUT = 100 µA
2.976
V
VA = 5V, IOUT = 10 µA
4.976
V
VA = 5V, IOUT = 100 µA
4.970
V
RL = ∞
1500
pF
RL = 2kΩ
1500
pF
1.3
Ohm
VA = 5V, VOUT = 0V,
Input code = FFh
−63
mA
VA = 3V, VOUT = 0V,
Input code = FFh
−50
mA
VA = 5V, VOUT = 5V,
Input code = 00h
74
mA
VA = 3V, VOUT = 3V,
Input code = 00h
53
mA
DC Output Impedance
IOS
0
VA
(2)
Typical figures are at TJ = 25°C, and represent most likely parametric norms. Test limits are guaranteed to TI's AOQL (Average
Outgoing Quality Level).
This parameter is guaranteed by design and/or characterization and is not tested in production.
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Electrical Characteristics (continued)
Values shown in this table are design targets and are subject to change before product release.
The following specifications apply for VA = +2.7V to +5.5V, RL = 2kΩ to GND, CL = 200 pF to GND, fSCLK = 30 MHz, input
code range 4 to 251. Boldface limits apply for TMIN ≤ TA ≤ TMAX: all other limits TA = 25°C, unless otherwise specified.
Parameter
Test Conditions
Typical
(1)
Limits
(1)
Units
(Limits)
LOGIC INPUT
IIN
VIL
Input Current (3)
Input Low Voltage (3)
VIH
Input High Voltage (3)
CIN
Input Capacitance (3)
±1
µA (max)
VA = 5V
0.8
V (max)
VA = 3V
0.5
V (max)
VA = 5V
2.4
V (min)
VA = 3V
2.1
V (min)
3
pF (max)
POWER REQUIREMENTS
IA
PC
IOUT / IA
(3)
Normal Mode
fSCLK = 30 MHz
VA = 5.5V
256
328
µA (max)
VA = 3.6V
174
224
µA (max)
Normal Mode
fSCLK = 20 MHz
VA = 5.5V
221
294
µA (max)
VA = 3.6V
154
200
µA (max)
Normal Mode
fSCLK = 0
VA = 5.0V
142
µA (max)
VA = 3.0V
107
µA (max)
All PD Modes,
fSCLK = 30 MHz
VA = 5.0V
83
µA (max)
VA = 3.0V
42
µA (max)
All PD Modes,
fSCLK = 20 MHz
VA = 5.0V
56
µA (max)
VA = 3.0V
28
µA (max)
All PD Modes,
fSCLK = 0 (3)
VA = 5.5V
0.06
1.0
VA = 3.6V
0.04
1.0
µA (max)
Normal Mode
fSCLK = 30 MHz
VA = 5.5V
1.41
1.80
mW (max)
VA = 3.6V
0.63
0.81
mW (max)
Normal Mode
fSCLK = 20 MHz
VA = 5.5V
1.22
1.62
mW (max)
VA = 3.6V
0.55
0.72
mW (max)
Normal Mode
fSCLK = 0
VA = 5.0V
0.71
µW (max)
VA = 3.0V
0.32
µW (max)
All PD Modes,
fSCLK = 30 MHz
VA = 5.0V
0.42
µW (max)
VA = 3.0V
0.13
µW (max)
All PD Modes,
fSCLK = 20 MHz
VA = 5.0V
0.28
µW (max)
VA = 3.0V
0.08
All PD Modes,
fSCLK = 0 (3)
VA = 5.5V
0.33
5.5
µW (max)
VA = 3.6V
0.14
3.6
µW (max)
Supply Current (output unloaded)
Power Consumption (output
unloaded)
Power Efficiency
ILOAD = 2mA
µA (max)
µW (max)
VA = 5V
91
%
VA = 3V
94
%
This parameter is guaranteed by design and/or characterization and is not tested in production.
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AC and Timing Characteristics
Values shown in this table are design targets and are subject to change before product release.
The following specifications apply for VA = +2.7V to +5.5V, RL = 2kΩ to GND, CL = 200 pF to GND, fSCLK = 30 MHz, input
code range 4 to 251. Boldface limits apply for TMIN ≤ TA ≤ TMAX: all other limits TA = 25°C, unless otherwise specified.
Parameter
fSCLK
Test Conditions
Typical
SCLK Frequency
Output Voltage Settling Time
ts
(1)
SR
40h to C0h code
change, RL = 2kΩ
CL ≤ 200 pF
3
Output Slew Rate
Glitch Impulse
Code change from 80h to 7Fh
Digital Feedthrough
Limits
Units
(Limits)
30
MHz (max)
5
µs (max)
1
V/µs
12
nV-sec
0.5
nV-sec
VA = 5V
6
µs
VA = 3V
39
µs
tWU
Wake-Up Time
1/fSCLK
SCLK Cycle Time
33
ns (min)
tH
SCLK High time
5
13
ns (min)
tL
SCLK Low Time
5
13
ns (min)
tSUCL
Set-up Time SYNC to SCLK Rising
Edge
−15
0
ns (min)
tSUD
Data Set-Up Time
2.5
5
ns (min)
tDHD
Data Hold Time
2.5
4.5
ns (min)
tCS
SCLK fall to rise of SYNC
VA = 5V
0
3
ns (min)
VA = 3V
−2
1
ns (min)
2.7 ≤ VA ≤ 3.6
9
20
ns (min)
3.6 ≤ VA ≤ 5.5
5
10
ns (min)
tSYNC
(1)
SYNC High Time
This parameter is guaranteed by design and/or characterization and is not tested in production.
Specification Definitions
DIFFERENTIAL NON-LINEARITY (DNL) is the measure of the maximum deviation from the ideal step size of 1
LSB, which is VREF / 256 = VA / 256.
DIGITAL FEEDTHROUGH is a measure of the energy injected into the analog output of the DAC from the digital
inputs when the DAC outputs are not updated. It is measured with a full-scale code change on the data bus.
FULL-SCALE ERROR is the difference between the actual output voltage with a full scale code (FFh) loaded
into the DAC and the value of VA x 255 / 256.
GAIN ERROR is the deviation from the ideal slope of the transfer function. It can be calculated from Zero and
Full-Scale Errors as GE = FSE - ZE, where GE is Gain error, FSE is Full-Scale Error and ZE is Zero Error.
GLITCH IMPULSE is the energy injected into the analog output when the input code to the DAC register
changes. It is specified as the area of the glitch in nanovolt-seconds.
INTEGRAL NON-LINEARITY (INL) is a measure of the deviation of each individual code from a straight line
through the input to output transfer function. The deviation of any given code from this straight line is measured
from the center of that code value. The end point method is used. INL for this product is specified over a limited
range, per the Electrical Tables.
LEAST SIGNIFICANT BIT (LSB) is the bit that has the smallest value or weight of all bits in a word. This value is
LSB = VREF / 2n
(1)
where VREF is the supply voltage for this product, and "n" is the DAC resolution in bits, which is 8 for the
DAC081S101.
MAXIMUM LOAD CAPACITANCE is the maximum capacitance that can be driven by the DAC with output
stability maintained.
6
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MONOTONICITY is the condition of being monotonic, where the DAC has an output that never decreases when
the output code increases.
MOST SIGNIFICANT BIT (MSB) is the bit that has the largest value or weight of all bits in a word. Its value is
1/2 of VA.
POWER EFFICIENCY is the ratio of the output current to the total supply current. The output current comes from
the power supply. The difference between the supply and output currents, is the power consumed by the device
without a load.
SETTLING TIME is the time for the output to settle within 1/2 LSB of the final value after the input code is
updated.
WAKE-UP TIME is the time for the output to settle to within 1/2 LSB of the final value after the device is
commanded to the active mode from any of the power down modes.
ZERO CODE ERROR is the output error, or voltage, present at the DAC output after a code of 00h has been
entered.
Transfer Characteristic
FSE
255 x VA
256
GE = FSE - ZE
FSE = GE + ZE
OUTPUT
VOLTAGE
ZE
0
0
255
DIGITAL INPUT CODE
Figure 1. Input / Output Transfer Characteristic
Timing Diagram
SCLK
1
tSUCL
13
14
15
16
tL
tH
tCS
|
tSYNC
2
|
|
1
fCLK
|
SYNC
DB15
DB0
|
DIN
| |
tDHD
tSUD
Figure 2. DAC081S101 Timing
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Typical Performance Characteristics
fSCLK = 30 MHz, TA = 25C, Input Code Range 4 to 251, unless otherwise stated
8
DNL at VA = 3.0V
DNL at VA = 5.0V
Figure 3.
Figure 4.
INL at VA = 3.0V
INL at VA = 5.0V
Figure 5.
Figure 6.
TUE at VA = 3.0V
TUE at VA = 5.0V
Figure 7.
Figure 8.
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Typical Performance Characteristics (continued)
fSCLK = 30 MHz, TA = 25C, Input Code Range 4 to 251, unless otherwise stated
DNL
vs.
VA
INL
vs.
VA
Figure 9.
Figure 10.
3V DNL
vs.
fSCLK
5V DNL
vs.
fSCLK
Figure 11.
Figure 12.
3V DNL
vs.
Clock Duty Cycle
5V DNL
vs.
Clock Duty Cycle
Figure 13.
Figure 14.
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Typical Performance Characteristics (continued)
fSCLK = 30 MHz, TA = 25C, Input Code Range 4 to 251, unless otherwise stated
10
3V DNL
vs.
Temperature
5V DNL
vs.
Temperature
Figure 15.
Figure 16.
3V INL
vs.
fSCLK
5V INL
vs.
fSCLK
Figure 17.
Figure 18.
3V INL
vs.
Clock Duty Cycle
5V INL
vs.
Clock Duty Cycle
Figure 19.
Figure 20.
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Typical Performance Characteristics (continued)
fSCLK = 30 MHz, TA = 25C, Input Code Range 4 to 251, unless otherwise stated
3V INL
vs.
Temperature
5V INL
vs.
Temperature
Figure 21.
Figure 22.
Zero Code Error
vs.
fSCLK
Zero Code Error
vs.
Clock Duty Cycle
Figure 23.
Figure 24.
Zero Code Error
vs.
Temperature
Full-Scale Error
vs.
fSCLK
Figure 25.
Figure 26.
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Typical Performance Characteristics (continued)
fSCLK = 30 MHz, TA = 25C, Input Code Range 4 to 251, unless otherwise stated
12
Full-Scale Error
vs.
Clock Duty Cycle
Full-Scale Error
vs.
Temperature
Figure 27.
Figure 28.
Supply Current
vs.
VA
Supply Current
vs.
Temperature
Figure 29.
Figure 30.
5V Glitch Response
Power-On Reset
Figure 31.
Figure 32.
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Typical Performance Characteristics (continued)
fSCLK = 30 MHz, TA = 25C, Input Code Range 4 to 251, unless otherwise stated
3V Wake-Up Time
5V Wake-Up Time
Figure 33.
Figure 34.
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FUNCTIONAL DESCRIPTION
DAC SECTION
The DAC081S101 is fabricated on a CMOS process with an architecture that consists of switches and a resistor
string that are followed by an output buffer. The power supply serves as the reference voltage. The input coding
is straight binary with an ideal output voltage of:
VOUT = VA x (D / 256)
(2)
where D is the decimal equivalent of the binary code that is loaded into the DAC register and can take on any
value between 0 and 255.
RESISTOR STRING
The resistor string is shown in Figure 35. This string consists of 4096 equal valued resistors with a switch at each
junction of two resistors, plus a switch to ground. The code loaded into the DAC register determines which switch
is closed, connecting the proper node to the amplifier. This configuration guarantees that the DAC is monotonic.
VA
R
R
R
To Output Amplifier
R
R
Figure 35. DAC Resistor String
OUTPUT AMPLIFIER
The output buffer amplifier is a rail-to-rail type, providing an output voltage range of 0V to VA. All amplifiers, even
rail-to-rail types, exhibit a loss of linearity as the output approaches the supply rails (0V and VA, in this case). For
this reason, linearity is specified over less than the full output range of the DAC. The output capabilities of the
amplifier are described in the Electrical Tables.
SERIAL INTERFACE
The three-wire interface is compatible with SPI, QSPI and MICROWIRE as well as most DSPs. See the Timing
Diagram for information on a write sequence.
A write sequence begins by bringing the SYNC line low. Once SYNC is low, the data on the DIN line is clocked
into the 16-bit serial input register on the falling edges of SCLK. On the 16th falling clock edge, the last data bit is
clocked in and the programmed function (a change in the mode of operation and/or a change in the DAC register
contents) is executed. At this point the SYNC line may be kept low or brought high. In either case, it must be
brought high for the minimum specified time before the next write sequence as a falling edge of SYNC is used to
initiate the next write cycle.
14
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Since the SYNC and DIN buffers draw more current when they are high, they should be idled low between write
sequences to minimize power consumption.
INPUT SHIFT REGISTER
The input shift register, Figure 36, has sixteen bits. The first two bits are "don't cares" and are followed by two
bits that determine the mode of operation (normal mode or one of three power-down modes). The contents of the
serial input register are transferred to the DAC register on the sixteenth falling edge of SCLK. See Timing
Diagram, Figure 2.
LSB
MSB
X
X PD1 PD0 D7 D6 D5 D4 D3 D2 D1 D0
X
X
X
X
DATA BITS
0
0
1
1
0
1
0
1
Normal Operation
1 kW to GND
100 kW to GND
High Impedance
Power-Down Modes
Figure 36. Input Register Contents
Normally, the SYNC line is kept low for at least 16 falling edges of SCLK and the DAC is updated on the 16th
SCLK falling edge. However, if SYNC is brought high before the 16th falling edge, the shift register is reset and
the write sequence is invalid. The DAC register is not updated and there is no change in the mode of operation
or in the output voltage.
POWER-ON RESET
The power-on reset circuit controls the output voltage during power-up. Upon application of power the DAC
register is filled with zeros and the output voltage is 0 Volts and remains there until a valid write sequence is
made to the DAC.
POWER-DOWN MODES
The DAC081S101 has four modes of operation. These modes are set with two bits (DB13 and DB12) in the
control register.
Table 2. Modes of Operation
DB13
DB12
0
0
Normal Operation
Operating Mode
0
1
Power-Down with 1kΩ to GND
1
0
Power-Down with 100kΩ to GND
1
1
Power-Down with Hi-Z
When both DB13 and DB12 are 0, the device operates normally. For the other three possible combinations of
these bits the supply current drops to its power-down level and the output is pulled down with either a 1kΩ or a
100KΩ resistor, or is in a high impedance state, as described in Table 2.
The bias generator, output amplifier, the resistor string and other linear circuitry are all shut down in any of the
power-down modes. However, the contents of the DAC register are unaffected when in power-down, so when
coming out of power down the output voltage returns to the same voltage it was before entering power down.
Minimum power consumption is achieved in the power-down mode with SCLK disabled and SYNC and DIN idled
low. The time to exit power-down (Wake-Up Time) is typically tWU µsec as stated in the A.C. and Timing
Characteristics Table.
APPLICATION INFORMATION
The simplicity of the DAC081S101 implies ease of use. However, it is important to recognize that any data
converter that utilizes its supply voltage as its reference voltage will have essentially zero PSRR (Power Supply
Rejection Ratio). Therefore, it is necessary to provide a noise-free supply voltage to the device.
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DSP/MICROPROCESSOR INTERFACING
Interfacing the DAC081S101 to microprocessors and DSPs is quite simple. The following guidelines are offered
to hasten the design process.
ADSP-2101/ADSP2103 Interfacing
Figure 37 shows a serial interface between the DAC081S101 and the ADSP-2101/ADSP2103. The DSP should
be set to operate in the SPORT Transmit Alternate Framing Mode. It is programmed through the SPORT control
register and should be configured for Internal Clock Operation, Active Low Framing and 16-bit Word Length.
Transmission is started by writing a word to the Tx register after the SPORT mode has been enabled.
ADSP-2101/
ADSP2103
TFS
DT
SCLK
DAC081S101
SYNC
DIN
SCLK
Figure 37. ADSP-2101/2103 Interface
80C51/80L51 Interface
A serial interface between the DAC081S101 and the 80C51/80L51 microcontroller is shown in Figure 38. The
SYNC signal comes from a bit-programmable pin on the microcontroller. The example shown here uses port line
P3.3. This line is taken low when data is to transmitted to the DAC081S101. Since the 80C51/80L51 transmits 8bit bytes, only eight falling clock edges occur in the transmit cycle. To load data into the DAC, the P3.3 line must
be left low after the first eight bits are transmitted. A second write cycle is initiated to transmit the second byte of
data, after which port line P3.3 is brought high. The 80C51/80L51 transmit routine must recognize that the
80C51/80L51 transmits data with the LSB first while the DAC081S101 requires data with the MSB first.
80C51/80L51
P3.3
DAC081S101
SYNC
TXD
SCLK
RXD
DIN
Figure 38. 80C51/80L51 Interface
68HC11 Interface
A serial interface between the DAC081S101 and the 68HC11 microcontroller is shown in Figure 39. The SYNC
line of the DAC081S101 is driven from a port line (PC7 in the figure), similar to the 80C51/80L51.
The 68HC11 should be configured with its CPOL bit as a zero and its CPHA bit as a one. This configuration
causes data on the MOSI output to be valid on the falling edge of SCLK. PC7 is taken low to transmit data to the
DAC. The 68HC11 transmits data in 8-bit bytes with eight falling clock edges. Data is transmitted with the MSB
first. PC7 must remain low after the first eight bits are transferred. A second write cycle is initiated to transmit the
second byte of data to the DAC, after which PC7 should be raised to end the write sequence.
68HC11
DAC081S101
PC7
SCK
MOSI
SYNC
SCLK
DIN
Figure 39. 68HC11 Interface
Microwire Interface
Figure 40 shows an interface between a Microwire compatible device and the DAC081S101. Data is clocked out
on the rising edges of the SCLK signal.
16
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MICROWIRE
DEVICE
DAC081S101
CS
SYNC
SK
SCLK
SO
DIN
Figure 40. Microwire Interface
USING REFERENCES AS POWER SUPPLIES
Recall the need for a quiet supply source for devices that use their power supply voltage as a reference voltage.
Since the DAC081S101 consumes very little power, a reference source may be used as the supply voltage. The
advantages of using a reference source over a voltage regulator are accuracy and stability. Some low noise
regulators can also be used for the power supply of the DAC081S101. Listed below are a few power supply
options for the DAC081S101.
LM4130
The LM4130 reference, with its 0.05% accuracy over temperature, is a good choice as a power source for the
DAC081S101. Its primary disadvantage is the lack of 3V and 5V versions. However, the 4.096V version is useful
if a 0 to 4.095V output range is desirable or acceptable. Bypassing the LM4130 VIN pin with a 0.1µF capacitor
and the VOUT pin with a 2.2µF capacitor will improve stability and reduce output noise. The LM4130 comes in a
space-saving 5-pin SOT23.
Input
Voltage
LM4130-4.1
C2
2.2 PF
C1
0.1 PF
DAC081S101
SYNC
VOUT = 0V to 4.080V
DIN
SCLK
Figure 41. The LM4130 as a power supply
LM4050
Available with accuracy of 0.44%, the LM4050 shunt reference is also a good choice as a power regulator for the
DAC081S101. It does not come in a 3 Volt version, but 4.096V and 5V versions are available. It comes in a
space-saving 3-pin SOT-23.
Input
Voltage
R
VZ
LM4050-4.1
or
LM4050-5.0
0.47 PF
DAC081S101
SYNC
VOUT = 0V to 5V
DIN
SCLK
Figure 42. The LM4050 as a power supply
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The minimum resistor value in the circuit of Figure 42 should be chosen such that the maximum current through
the LM4050 does not exceed its 15 mA rating. The conditions for maximum current include the input voltage at
its maximum, the LM4050 voltage at its minimum, the resistor value at its minimum due to tolerance, and the
DAC081S101 draws zero current. The maximum resistor value must allow the LM4050 to draw more than its
minimum current for regulation plus the maximum DAC081S101 current in full operation. The conditions for
minimum current include the input voltage at its minimum, the LM4050 voltage at its maximum, the resistor value
at its maximum due to tolerance, and the DAC081S101 draws its maximum current. These conditions can be
summarized as
R(min) = ( VIN(max) − VZ(min) / (IA(min) + IZ(max))
(3)
R(max) = ( VIN(min) − VZ(max) / (IA(max) + IZ(min) )
(4)
and
where VZ(min) and VZ(max) are the nominal LM4050 output voltages ± the LM4050 output tolerance over
temperature, IZ(max) is the maximum allowable current through the LM4050, IZ(min) is the minimum current
required by the LM4050 for proper regulation, IA(max) is the maximum DAC081S101 supply current, and IA(min)
is the minimum DAC081S101 supply current.
LP3985
The LP3985 is a low noise, ultra low dropout voltage regulator with a 3% accuracy over temperature. It is a good
choice for applications that do not require a precision reference for the DAC081S101. It comes in 3.0V, 3.3V and
5V versions, among others, and sports a low 30 µV noise specification at low frequencies. Since low frequency
noise is relatively difficult to filter, this specification could be important for some applications. The LP3985 comes
in a space-saving 5-pin SOT-23 and 5-bump DSBGA packages.
Input
Voltage
LP3985
0.1 PF
1 PF
0.01 PF
DAC081S101
SYNC
VOUT = 0V to 5V
DIN
SCLK
Figure 43. Using the LP3985 regulator
An input capacitance of 1.0µF without any ESR requirement is required at the LP3985 input, while a 1.0µF
ceramic capacitor with an ESR requirement of 5mΩ to 500mΩ is required at the output. Careful interpretation
and understanding of the capacitor specification is required to ensure correct device operation.
LP2980
The LP2980 is an ultra low dropout regulator with a 0.5% or 1.0% accuracy over temperature, depending upon
grade. It is available in 3.0V, 3.3V and 5V versions, among others.
Input
Voltage
VIN
ON / OFF
VOUT
LP2980
1 PF
DAC081S101
SYNC
VOUT = 0V to 5V
DIN
SCLK
Figure 44. Using the LP2980 regulator
18
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Like any low dropout regulator, the LP2980 requires an output capacitor for loop stability. This output capacitor
must be at least 1.0µF over temperature, but values of 2.2µF or more will provide even better performance. The
ESR of this capacitor should be within the range specified in the LP2980 data sheet. Surface-mount solid
tantalum capacitors offer a good combination of small size and ESR. Ceramic capacitors are attractive due to
their small size but generally have ESR values that are too low for use with the LP2980. Aluminum electrolytic
capacitors are typically not a good choice due to their large size and have ESR values that may be too high at
low temperatures.
BIPOLAR OPERATION
The DAC081S101 is designed for single supply operation and thus has a unipolar output. However, a bipolar
output may be obtained with the circuit in Figure 45. This circuit will provide an output voltage range of ±5 Volts.
A rail-to-rail amplifier should be used if the amplifier supplies are limited to ±5V.
10 pF
R2
+5V
R1
+5V
10 PF
+
-
0.1 PF
±5V
+
DAC081S101
-5V
SYNC
VOUT
DIN
SCLK
Figure 45. Bipolar Operation
The output voltage of this circuit for any code is found to be
VO = (VA x (D / 256) x ((R1 + R2) / R1) - VA x R2 / R1)
(5)
where D is the input code in decimal form. With VA = 5V and R1 = R2,
VO = (10 x D / 256) - 5V
(6)
A list of rail-to-rail amplifiers suitable for this application are indicated in Table 3.
Table 3. Some Rail-to-Rail Amplifiers
AMP
PKGS
LMC7111
PDIP-8
SOT-23-5
Typ VOS
Typ ISUPPLY
0.9 mV
25 µA
LM7301
SO-8
SOT-23-5
0.03 mV
620 µA
LM8261
SOT-23-5
0.7 mV
1 mA
LAYOUT, GROUNDING, AND BYPASSING
For best accuracy and minimum noise, the printed circuit board containing the DAC081S101 should have
separate analog and digital areas. The areas are defined by the locations of the analog and digital power planes.
Both of these planes should be located in the same board layer. There should be a single ground plane. A single
ground plane is preferred if digital return current does not flow through the analog ground area. Frequently a
single ground plane design will utilize a "fencing" technique to prevent the mixing of analog and digital ground
current. Separate ground planes should only be utilized when the fencing technique is inadequate. The separate
ground planes must be connected in one place, preferably near the DAC081S101. Special care is required to
guarantee that digital signals with fast edge rates do not pass over split ground planes. They must always have a
continuous return path below their traces.
The DAC081S101 power supply should be bypassed with a 10µF and a 0.1µF capacitor as close as possible to
the device with the 0.1µF right at the device supply pin. The 10µF capacitor should be a tantalum type and the
0.1µF capacitor should be a low ESL, low ESR type. The power supply for the DAC081S101 should only be
used for analog circuits.
Avoid crossover of analog and digital signals and keep the clock and data lines on the component side of the
board. The clock and data lines should have controlled impedances.
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REVISION HISTORY
Changes from Revision B (February 2013) to Revision C
•
20
Page
Changed layout of National Data Sheet to TI format .......................................................................................................... 19
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PACKAGE OPTION ADDENDUM
www.ti.com
10-Dec-2020
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)
(4/5)
(6)
DAC081S101CIMK/NOPB
ACTIVE
SOT-23-THIN
DDC
6
1000
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 105
X65C
DAC081S101CIMKX/NOPB
ACTIVE
SOT-23-THIN
DDC
6
3000
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 105
X65C
DAC081S101CIMM/NOPB
ACTIVE
VSSOP
DGK
8
1000
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 105
X64C
DAC081S101CIMMX/NOPB
ACTIVE
VSSOP
DGK
8
3500
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 105
X64C
(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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