DAC8531E/250G4 [TI]
低功耗轨到轨输出 16 位串行输入数模转换器 | DGK | 8 | -40 to 105;
| 型号： | DAC8531E/250G4 |
| 厂家： | 
TEXAS INSTRUMENTS |
| 描述： | 低功耗轨到轨输出 16 位串行输入数模转换器 | DGK | 8 | -40 to 105 转换器 数模转换器 |
| 文件： | 总19页 (文件大小：360K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
DAC8531
SBAS192B – MARCH 2001 – REVISED JUNE 2003
Low-Power, Rail-to-Rail Output, 16-Bit Serial Input
DIGITAL-TO-ANALOG CONVERTER
DESCRIPTION
FEATURES
The DAC8531 is a low-power, single, 16-bit buffered voltage
output Digital-to-Analog Converter (DAC). Its on-chip preci-
sion output amplifier allows rail-to-rail output swing to be
achieved. The DAC8531 uses a versatile three-wire serial
interface that operates at clock rates up to 30MHz and is
compatible with standard SPI™, QSPI™, Microwire™, and
Digital Signal Processor (DSP) interfaces.
ꢀꢀmicroPower OPERATION: 250
µA at 5V
ꢀ POWER-ON RESET TO ZERO
ꢀ POWER SUPPLY: +2.7V to +5.5V
ENSURED MONOTONIC BY DESIGN
ꢀ
ꢀ SETTLING TIME: 10µs to ±0.003 FSR
ꢀ LOW-POWER SERIAL INTERFACE WITH
The DAC8531 requires an external reference voltage to set
the output range of the DAC. The DAC8531 incorporates a
power-on reset circuit that ensures that the DAC output
powers up at 0V and remains there until a valid write takes
place to the device. The DAC8531 contains a power-down
feature, accessed over the serial interface, that reduces the
current consumption of the device to 200nA at 5V.
SCHMITT-TRIGGERED INPUTS
ꢀ ON-CHIP OUTPUT BUFFER AMPLIFIER,
RAIL-TO-RAIL OPERATION
ꢀ SYNC INTERRUPT FACILITY
ꢀ PACKAGES: MSOP-8 and 3x3 SON-8 (same
size as QFN)
The low power consumption of this part in normal operation
makes it ideally suited to portable battery-operated equip-
ment. The power consumption is 2mW at 5V reducing to 1µW
in power-down mode.
APPLICATIONS
The DAC8531 is available in both MSOP-8 and 3x3 SON-8
(same size as QFN) packages.
ꢀ PROCESS CONTROL
ꢀ DATA ACQUISITION SYSTEMS
ꢀ CLOSED-LOOP SERVO-CONTROL
ꢀ PC PERIPHERALS
ꢀ PORTABLE INSTRUMENTATION
ꢀ PROGRAMMABLE ATTENUATION
VDD
VFB
VREF
Ref (+)
16-Bit DAC
VOUT
16
DAC Register
16
SYNC
SCLK
DIN
Power-Down
Control Logic
Resistor
Network
Shift Register
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.
All trademarks are the property of their respective owners.
Copyright © 2001-2003, Texas Instruments Incorporated
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
www.ti.com
ABSOLUTE MAXIMUM RATINGS(1)
ELECTROSTATIC
DISCHARGE SENSITIVITY
This integrated circuit can be damaged by ESD. Texas Instru-
ments recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling
and installation procedures can cause damage.
VDD 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 Range (TJ max) ........................................ +150°C
Power Dissipation ........................................................ (TJ max — TA)/θJA
θJA Thermal Impedance ......................................................... 206°C/W
θJC Thermal Impedance .......................................................... 44°C/W
Lead Temperature, Soldering:
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.
Vapor Phase (60s) ............................................................... +215°C
Infrared (15s) ........................................................................ +220°C
NOTE: (1) 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.
PACKAGE/ORDERING INFORMATION
MINIMUM
RELATIVE
DIFFERENTIAL
SPECIFICATION
ACCURACY NONLINEARITY
PACKAGE
PACKAGE-LEAD DESIGNATOR(1)
TEMPERATURE
RANGE
PACKAGE
MARKING
ORDERING
NUMBER
TRANSPORT
MEDIA, QUANTITY
PRODUCT
(LSB)
(LSB)
DAC8531E
±64
"
±1
"
MSOP-8
DGK
"
–40°C to +105°C
D31
"
DAC8531E/250
DAC8531E/2K5
Tape and Reel, 250
Tape and Reel, 2500
"
"
"
DAC8531I
DAC8531I
±64
"
±1
"
SON-8
"
DRB
"
–40°C to +105°C
D31
"
DAC8531IDRBT
DAC8531IDRBR
Tape and Reel, 250
Tape and Reel, 2500
"
NOTE: (1) For the most current specifications and package information, refer to our web site at www.ti.com.
ELECTRICAL CHARACTERISTICS
VDD = +2.7V to +5.5V. –40°C to +105°C, unless otherwise specified.
DAC8531E
TYP
PARAMETER
CONDITIONS
MIN
MAX
UNITS
STATIC PERFORMANCE(1)
Resolution
Relative Accuracy
Differential Nonlinearity
Zero Code Error
Full-Scale Error
Gain Error
Zero Code Error Drift
Gain Temperature Coefficient
16
Bits
% of FSR
LSB
±0.098
±1
+20
–1.25
±1.25
Ensured Monotonic by Design
All Zeroes Loaded to DAC Register
All Ones Loaded to DAC Register
+5
–0.15
mV
% of FSR
% of FSR
µV/°C
±20
±5
ppm of FSR/°C
OUTPUT CHARACTERISTICS(2)
Output Voltage Range
Output Voltage Settling Time
0
VREF
10
V
To ±0.003% FSR
0200H to FD00H
8
µs
RL = 2kΩ; 0pF < CL < 200pF
R
L = 2kΩ; CL = 500pF
12
1
470
1000
20
µs
V/µs
pF
Slew Rate
Capacitive Load Stability
RL = ∞
RL = 2kΩ
pF
Code Change Glitch Impulse
Digital Feedthrough
1LSB Change Around Major Carry
nV-s
nV-s
Ω
0.5
1
DC Output Impedance
Short-Circuit Current
VDD = +5V
VDD = +3V
50
20
mA
mA
Power-Up Time
Coming Out of Power-Down Mode
VDD = +5V
2.5
5
µs
µs
Coming Out of Power-Down Mode
VDD = +3V
REFERENCE INPUT
Reference Current
VREF = VDD = +5V
35
20
45
30
VDD
µA
µA
V
V
REF = VDD = +3.6V
Reference Input Range
0
Reference Input Impedance
150
kΩ
NOTES: (1) Linearity calculated using a reduced code range of 485 to 64714; output unloaded. (2) Ensured by design and characterization, not production tested.
DAC8531
2
SBAS192B
www.ti.com
ELECTRICAL CHARACTERISTICS (Cont.)
VDD = +2.7V to +5.5V. –40°C to +105°C, unless otherwise specified.
DAC8531E
TYP
PARAMETER
CONDITIONS
MIN
MAX
UNITS
LOGIC INPUTS(2)
Input Current
±1
0.8
0.6
µA
V
V
V
V
V
V
V
V
INL, Input LOW Voltage
INL, Input LOW Voltage
INH, Input HIGH Voltage
INH, Input HIGH Voltage
VDD = +5V
VDD = +3V
VDD = +5V
VDD = +3V
2.4
2.1
Pin Capacitance
3
pF
POWER REQUIREMENTS
VDD
2.7
5.5
V
I
DD (normal mode)
VDD = +3.6V to +5.5V
DD = +2.7V to +3.6V
DD (all power-down modes)
DAC Active and Excluding Load Current
VIH = VDD and VIL = GND
250
240
400
390
µA
µA
V
I
VIH = VDD and VIL = GND
V
V
DD = +3.6V to +5.5V
DD = +2.7V to +3.6V
VIH = VDD and VIL = GND
VIH = VDD and VIL = GND
0.2
0.05
1
1
µA
µA
POWER EFFICIENCY
OUT/IDD
I
ILOAD = 2mA, VDD = +5V
89
%
TEMPERATURE RANGE
Specified Performance
–40
+105
°C
PIN DESCRIPTION
PIN CONFIGURATIONS
PIN
NAME
DESCRIPTION
Top View
MSOP-8, SON-8
1
2
3
4
VDD
VREF
VFB
Power-Supply Input, +2.7V to +5.5V.
Reference Voltage Input
Feedback connection for the output amplifier.
VOUT
Analog output voltage from DAC. The output ampli-
fier has rail-to-rail operation.
1
2
3
4
VDD
VREF
VFB
8
7
6
5
GND
DIN
5
SYNC
Level-triggered control input (active LOW). This is
the frame sychronization signal for the input data.
When SYNC goes LOW, it enables the input shift
register and data is transferred in on the falling
edges of the following clocks. The DAC is updated
following the 24th clock cycle unless SYNC is taken
HIGH before this edge, in which case the rising
edge of SYNC acts as an interrupt and the write
sequence is ignored by the DAC8531.
DAC8531
SCLK
SYNC
VOUT
6
7
SCLK
DIN
Serial Clock Input. Data can be transferred at rates
up to 30MHz.
Serial Data Input. Data is clocked into the 24-bit
input shift register on the falling edge of the serial
clock input.
8
GND
Ground reference point for all circuitry on the part.
DAC8531
SBAS192B
3
www.ti.com
TIMING CHARACTERISTICS(1, 2)
VDD = +2.7V to +5.5V; all specifications –40°C to +105°C unless otherwise noted.
DAC8531E
TYP
PARAMETER
DESCRIPTION
CONDITIONS
MIN
MAX
UNITS
(3)
t1
SCLK Cycle Time
VDD = 2.7V to 3.6V
VDD = 3.6V to 5.5V
50
33
ns
ns
t2
t3
t4
SCLK HIGH Time
SCLK LOW Time
VDD = 2.7V to 3.6V
VDD = 3.6V to 5.5V
13
13
ns
ns
VDD = 2.7V to 3.6V
VDD = 3.6V to 5.5V
22.5
13
ns
ns
SYNC to SCLK Rising
Edge Setup Time
VDD = 2.7V to 3.6V
VDD = 3.6V to 5.5V
0
0
ns
ns
t5
t6
t7
Data Setup Time
Data Hold Time
VDD = 2.7V to 3.6V
VDD = 3.6V to 5.5V
5
5
ns
ns
VDD = 2.7V to 3.6V
VDD = 3.6V to 5.5V
4.5
4.5
ns
ns
SCLK Falling Edge to
SYNC Rising Edge
VDD = 2.7V to 3.6V
VDD = 3.6V to 5.5V
0
0
ns
ns
t8
Minimum SYNC HIGH Time
VDD = 2.7V to 3.6V
VDD = 3.6V to 5.5V
50
33
ns
ns
NOTES: (1) All input signals are specified with tR = tF = 5ns (10% to 90% of VDD) and timed from a voltage level of (VIL + VIH)/2. (2) See Serial Write Operation timing
diagram, below. (3) Maximum SCLK frequency is 30MHz at VDD = +3.6V to +5.5V and 20MHz at VDD = +2.7V to +3.6V.
SERIAL WRITE OPERATION
t1
SCLK
t8
t2
t3
t7
t4
SYNC
t6
t5
DB23
DB0
DIN
DAC8531
4
SBAS192B
www.ti.com
TYPICAL CHARACTERISTICS: VDD = 5V
At TA = +25°C, VDD = 5V, unless otherwise noted.
NOTE: All references to IDD include IREF current.
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(–40°C)
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(+25°C)
64
48
64
48
32
32
16
0
16
0
–16
–32
–48
–64
–16
–32
–48
–64
2.0
1.5
2.0
1.5
1.0
1.0
0.5
0.0
0.5
0.0
–0.5
–1.0
–1.5
–2.0
–0.5
–1.0
–1.5
–2.0
0000H 2000H 4000H 6000H 8000H A000H C000H E000H FFFFH
0000H 2000H 4000H 6000H 8000H A000H C000H E000H FFFFH
Digital Input Code
Digital Input Code
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(+105°C)
ZERO-SCALE ERROR vs TEMPERATURE
20
64
48
32
15
10
16
0
–16
–32
–48
–64
5
0
2.0
1.5
–5
1.0
0.5
0.0
–0.5
–1.0
–1.5
–2.0
–10
–15
–20
–40
0
40
80
120
0000H 2000H 4000H 6000H 8000H A000H C000H E000H FFFFH
Temperature (°C)
Digital Input Code
FULL-SCALE ERROR vs TEMPERATURE
IDD HISTOGRAM
20
2000
1500
1000
500
0
15
10
5
0
–5
–10
–15
–20
–40
0
40
80
120
100 130 160 190 220 250 280 310 340 370 400
Temperature (°C)
IDD (µA)
DAC8531
SBAS192B
5
www.ti.com
TYPICAL CHARACTERISTICS: VDD = 5V (Cont.)
At TA = +25°C, VDD = 5V, unless otherwise noted.
NOTE: All references to IDD include IREF current.
SOURCE AND SINK CURRENT CAPABILITY
DAC Loaded with FFFFH
SUPPLY CURRENT vs DIGITAL INPUT CODE
5
4
3
2
1
0
500
400
300
200
100
0
DAC Loaded with 0000H
0
5
10
15
0000H 2000H 4000H 6000H 8000H A000H C000H E000H FFFFH
Digital Input Code
ISOURCE/SINK (mA)
POWER-SUPPLY CURRENT vs TEMPERATURE
SUPPLY CURRENT vs SUPPLY VOLTAGE
350
350
300
250
200
150
100
50
VREF tied to VDD
.
300
250
200
150
100
50
0
0
–40
0
40
80
120
2.7
3.2
3.7
4.2
4.7
5.2
5.7
Temperature (°C)
VDD (V)
POWER-DOWN CURRENT vs SUPPLY VOLTAGE
SUPPLY CURRENT vs LOGIC INPUT VOLTAGE
100
90
80
70
60
50
40
30
20
10
0
700
600
500
400
300
200
100
+105°C
–40°C
+25°C
2.7
3.2
3.7
4.2
4.7
5.2
5.7
0
1
2
3
4
5
VDD (V)
VLOGIC (V)
DAC8531
6
SBAS192B
www.ti.com
TYPICAL CHARACTERISTICS: VDD = 5V (Cont.)
At TA = +25°C, VDD = 5V, unless otherwise noted.
FULL-SCALE SETTLING TIME
FULL-SCALE SETTLING TIME
Scope Trigger (5.0V/div)
Scope Trigger (5.0V/div)
Large-Signal Output (1.0V/div)
Small-Signal Error (1mV/div)
Small-Signal Error (1mV/div)
Full-Scale Code Change
FFFFH to 0000H
Output Loaded with
2kΩ and 200pF to GND
Full-Scale Code Change
0000H to FFFFH
Output Loaded with
2kΩ and 200pF to GND
Large-Signal Output (1.0V/div)
Time (2µs/div)
Time (2µs/div)
HALF-SCALE SETTLING TIME
Scope Trigger (5.0V/div)
HALF-SCALE SETTLING TIME
Scope Trigger (5.0V/div)
Large-Signal Output (1.0V/div)
Small-Signal Error (1mV/div)
Small-Signal Error (1mV/div)
Large-Signal Output (1V/div)
Half-Scale Code Change
4000H to C000H
Output Loaded with
2kΩ and 200pF to GND
Half-Scale Code Change
C000H to 4000H
Output Loaded with
2kΩ and 200pF to GND
Time (2µs/div)
Time (2µs/div)
EXITING POWER-DOWN
(8000H Loaded)
POWER-ON RESET TO 0V
Loaded with 2kΩ to VDD
.
Scope Trigger (5.0V/div)
VDD (2V/div)
VOUT (1V/div)
Output (1.0V/div)
Time (2µs/div)
Time (50µs/div)
DAC8531
SBAS192B
7
www.ti.com
TYPICAL CHARACTERISTICS: VDD = 5V (Cont.)
At TA = +25°C, VDD = 5V, unless otherwise noted.
CODE CHANGE GLITCH
Glitch Waveform (50mV/div)
Time (2µs/div)
TYPICAL CHARACTERISTICS: VDD = 2.7V
At TA = +25°C, VDD = 2.7V, unless otherwise noted.
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(+25°C)
(–40°C)
64
48
64
48
32
32
16
0
16
0
–16
–32
–48
–64
–16
–32
–48
–64
2.0
1.5
2.0
1.5
1.0
1.0
0.5
0.0
0.5
0.0
–0.5
–1.0
–1.5
–2.0
–0.5
–1.0
–1.5
–2.0
0000H 2000H 4000H 6000H 8000H A000H C000H E000H FFFFH
0000H 2000H 4000H 6000H 8000H A000H C000H E000H FFFFH
Digital Input Code
Digital Input Code
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(+105°C)
ZERO-SCALE ERROR vs TEMPERATURE
20
15
64
48
32
16
0
10
–16
–32
–48
–64
5
0
2.0
1.5
–5
1.0
0.5
0.0
–0.5
–1.0
–1.5
–2.0
–10
–15
–20
–40
0
40
80
120
0000H 2000H 4000H 6000H 8000H A000H C000H E000H FFFFH
Temperature (°C)
Digital Input Code
DAC8531
8
SBAS192B
www.ti.com
TYPICAL CHARACTERISTICS: VDD = 2.7V
At TA = +25°C, VDD = 2.7V, unless otherwise noted.
NOTE: All references to IDD include IREF current.
FULL-SCALE ERROR vs TEMPERATURE
IDD HISTOGRAM
20
15
2000
1500
1000
500
0
10
5
0
–5
–10
–15
–20
–40
0
40
80
120
100 130 160 190 220 250 280 310 340 370 400
Temperature (°C)
IDD (µA)
SUPPLY CURRENT vs DIGITAL INPUT CODE
SOURCE AND SINK CURRENT CAPABILITY
DAC Loaded with FFFFH
500
400
300
200
100
0
3.0
2.5
2.0
1.5
1.0
0.5
0.0
DAC Loaded with 0000H
0000H 2000H 4000H 6000H 8000H A000H C000H E000H FFFFH
Digital Input Code
0
5
10
ISOURCE/SINK (mA)
15
SUPPLY CURRENT vs LOGIC INPUT VOLTAGE
POWER SUPPLY CURRENT vs TEMPERATURE
200
350
300
250
200
150
100
50
180
160
140
120
100
80
0
–40
0
40
80
120
0
0.5
1
1.5
2
2.5
3
VLOGIC (V)
Temperature (°C)
DAC8531
SBAS192B
9
www.ti.com
TYPICAL CHARACTERISTICS: VDD = 2.7V (Cont.)
At TA = +25°C, VDD = 2.7V, unless otherwise noted.
FULL-SCALE SETTLING TIME
Scope Trigger (5.0V/div)
FULL-SCALE SETTLING TIME
Scope Trigger (5.0V/div)
Large-Signal Output (1.0V/div)
Small-Signal Error (1mV/div)
Small-Signal Error (1mV/div)
Large-Signal Output (1.0V/div)
Full-Scale Code Change
FFFFH to 0000H
Full-Scale Code Change
0000H to FFFFH
Output Loaded with
2kΩ and 200pF to GND
Output Loaded with
2kΩ and 200pF to GND
Time (2µs/div)
Time (2µs/div)
HALF-SCALE SETTLING TIME
Scope Trigger (5.0V/div)
HALF-SCALE SETTLING TIME
Scope Trigger (5.0V/div)
Large-Signal Output (1.0V/div)
Small-Signal Error (1mV/div)
Small-Signal Error (1mV/div)
Large-Signal Output (1.0V/div)
Half-Scale Code Change
4000H to C000H
Output Loaded with
2kΩ and 200pF to GND
Half-Scale Code Change
C000H to 4000H
Output Loaded with
2kΩ and 200pF to GND
Time (2µs/div)
Time (2µs/div)
EXITING POWER-DOWN
(8000H Loaded)
POWER-ON RESET to 0V
Scope Trigger (5.0V/div)
Output (1.0V/div)
Time (50µs/div)
Time (2µs/div)
DAC8531
10
SBAS192B
www.ti.com
TYPICAL CHARACTERISTICS: VDD = 2.7V (Cont.)
At TA = +25°C, VDD = 2.7V, unless otherwise noted.
CODE CHANGE GLITCH
Glitch Waveform (20mV/div)
Time (2µs/div)
RESISTOR STRING
THEORY OF OPERATION
DAC SECTION
Figure 2 shows the resistor string section. It is simply a string
of resistors, each of value R. The code loaded into the DAC
register determines at which node on the string the voltage
is tapped off to be fed into the output amplifier by closing one
of the switches connecting the string to the amplifier. It is
The architecture consists of a string DAC followed by an
output buffer amplifier. Figure 1 shows a block diagram of the
DAC architecture.
ensured monotonic because it is a string of resistors.
VDD
VFB
R
R
VOUT
REF (+)
Resistor String
REF(–)
DAC Register
Output
Amplifier
GND
To Output
Amplifier
R
FIGURE 1. DAC8531 Architecture.
The input coding to the DAC8531 is straight binary, so the
ideal output voltage is given by:
D
VOUT = VREF
•
65536
R
R
where D = decimal equivalent of the binary code that is
loaded to the DAC register; it can range from 0 to 65535.
FIGURE 2. Resistor String.
DAC8531
SBAS192B
11
www.ti.com
OUTPUT AMPLIFIER
SYNC buffer draws more current when the SYNC signal is
HIGH than it does when it is LOW, SYNC should be idled
LOW between write sequences for lowest power operation of
the part. As mentioned above, it must be brought HIGH again
just before the next write sequence.
The output buffer amplifier is capable of generating rail-to-rail
voltages on its output which gives an output range of
0V to VDD. It is capable of driving a load of 2kΩ in parallel with
1000pF to GND. The source and sink capabilities of the
output amplifier can be seen in the typical curves. The slew
rate is 1V/µs with a full-scale settling time of 8µs with the
output unloaded.
INPUT SHIFT REGISTER
The input shift register is 24 bits wide, as shown in Figure 3.
The first six bits are “don’t cares”. The next two bits (PD1 and
PD0) are control bits that control which mode of operation the
part is in (normal mode or any one of three power-down
modes). There is a more complete description of the various
modes in the Power-Down Modes section. The next 16 bits
are the data bits. These are transferred to the DAC register
on the 24th falling edge of SCLK.
The inverting input of the output amplifier is brought out to the
VFB pin. This allows for better accuracy in critical applications
by tying the VFB point and the amplifier output together
directly at the load. Other signal conditioning circuitry
may also be connected between these points for specific
applications.
SERIAL INTERFACE
SYNC INTERRUPT
The DAC8531 has a three-wire serial interface (SYNC,
SCLK, and DIN), which is compatible with SPI, QSPI, and
Microwire interface standards as well as most DSPs. See the
Serial Write Operation timing diagram for an example of a
typical write sequence.
In a normal write sequence, the SYNC line is kept LOW for
at least 24 falling edges of SCLK and the DAC is updated on
the 24th falling edge. However, if SYNC is brought HIGH
before the 24th falling edge, this acts as an interrupt to the
write sequence. The shift register is reset and the write
sequence is seen as invalid. Neither an update of the DAC
register contents or a change in the operating mode occurs,
as shown in Figure 4.
The write sequence begins by bringing the SYNC line LOW.
Data from the DIN line is clocked into the 24-bit shift register
on the falling edge of SCLK. The serial clock frequency can
be as high as 30MHz, making the DAC8531 compatible with
high-speed (DSPs). On the 24th falling edge of the serial
clock, the last data bit is clocked in and the programmed
function is executed (i.e., a change in DAC register contents
and/or a change in the mode of operation).
POWER-ON RESET
The DAC8531 contains a power-on reset circuit that controls
the output voltage during power-up. On power-up, the DAC
register is filled with zeros and the output voltage is 0V; it
remains there until a valid write sequence is made to the
DAC. This is useful in applications where it is important to
know the state of the output of the DAC while it is in the
process of powering up.
At this point, the SYNC line may be kept LOW or brought
HIGH. In either case, it must be brought HIGH for a minimum
of 33ns before the next write sequence so that a falling edge
of SYNC can initiate the next write sequence. Since the
DB23
DB0
X
X
X
X
X
X
PD1 PD0 D15 D14 D13 D12 D11 D10 D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
FIGURE 3. Data Input Register.
24th Falling Edge
24th Falling Edge
CLK
SYNC
DIN
DB23
DB0
DB23
DB0
Invalid Write Sequence:
SYNC HIGH before 24th Falling Edge
Valid Write Sequence: Output Updates
on the 24th Falling Edge
FIGURE 4. SYNC Interrupt Facility.
DAC8531
12
SBAS192B
www.ti.com
POWER-DOWN MODES
MICROPROCESSOR
INTERFACING
The DAC8531 supports four separate modes of operation.
These modes are programmable by setting two bits (PD1
and PD0) in the control register. Table I shows how the state
of the bits corresponds to the mode of operation of the
device.
DAC8531 TO 8051 INTERFACE
Figure 6 shows a serial interface between the DAC8531 and
a typical 8051-type microcontroller. The setup for the inter-
face is as follows: TXD of the 8051 drives SCLK of the
DAC8531, while RXD drives the serial data line of the part.
The SYNC signal is derived from a bit-programmable pin on
the port. In this case, port line P3.3 is used. When data is to
be transmitted to the DAC8531, P3.3 is taken LOW. The
8051 transmits data only in 8-bit bytes; thus only eight falling
clock edges occur in the transmit cycle. To load data to the
DAC, P3.3 is left LOW after the first eight bits are transmitted
and a second write cycle is initiated to transmit the second
byte of data. P3.3 is taken HIGH following the completion of
the third write cycle. The 8051 outputs the serial data in a
format which has the LSB first. The DAC8531 requires its
data with the MSB as the first bit received. The 8051 transmit
routine must therefore take this into account, and “mirror” the
data as needed.
PD1 (DB17) PD0 (DB16)
OPERATING MODE
0
—
0
0
—
1
Normal Operation
Power-Down Modes
Output 1kΩ to GND
Output 100kΩ to GND
High-Z
1
0
1
1
TABLE I. Modes of Operation for the DAC8531.
When both bits are set to 0, the part works normally with its
typical current consumption of 250µA at 5V. However, for the
three power-down modes, the supply current falls to 200nA
at 5V (50nA at 3V). Not only does the supply current fall, but
the output stage is also internally switched from the output of
the amplifier to a resistor network of known values. This has
the advantage that the output impedance of the part is known
while the part is in power-down mode. There are three
different options. The output is connected internally to GND
through a 1kΩ resistor, a 100kΩ resistor, or it is left open-
circuited (High-Z). The output stage is illustrated in Figure 5.
80C51/80L51(1)
P3.3
DAC8531(1)
SYNC
TXD
RXD
SCLK
DIN
NOTE: (1) Additional pins omitted for clarity.
VFB
FIGURE 6. DAC8531 to 80C51/80L51 Interface.
Amplifier
VOUT
Resistor
String DAC
DAC8531 TO Microwire INTERFACE
Figure 7 shows an interface between the DAC8531 and any
Microwire compatible device. Serial data is shifted out on the
falling edge of the serial clock and is clocked into the
DAC8531 on the rising edge of the SK signal.
Power-Down
Circuitry
Resistor
Network
FIGURE 5. Output Stage During Power-Down.
MicrowireTM
CS
DAC8531(1)
SYNC
All linear circuitry is shut down when the power-down mode
is activated. However, the contents of the DAC register are
unaffected when in power-down. The time to exit
power-down is typically 2.5µs for VDD = 5V, and 5µs
for VDD = 3V. See the Typical Characteristics for more
information.
SCLK
DIN
SK
SO
NOTE: (1) Additional pins omitted for clarity.
Microwire is a registered trademark of National Semiconductor.
FIGURE 7. DAC8531 to Microwire Interface.
DAC8531
SBAS192B
13
www.ti.com
DAC8531 TO 68HC11 INTERFACE
power supply is quite noisy or if the system supply voltages
are at some value other than 5V. The REF02 will output a
steady supply voltage for the DAC8531. If the REF02 is
used, the typical current it needs to supply to the DAC8531
is 250µA. This is with no load on the output of the DAC.
When the DAC output is loaded, the REF02 also needs to
supply the current to the load. The total current required (with
a 5kΩ load on the DAC output) is:
Figure 8 shows a serial interface between the DAC8531 and
the 68HC11 microcontroller. SCK of the 68HC11 drives the
SCLK of the DAC8531, while the MOSI output drives the
serial data line of the DAC. The SYNC signal is derived from
a port line (PC7), similar to what was done for the 8051.
250µA + (5V/5kΩ) = 1.29mA
DAC8531(1)
SYNC
68HC11(1)
PC7
The load regulation of the REF02 is typically 0.005%/mA,
which results in an error of 322µV for the 1.29mA current
drawn from it. This corresponds to a 4.2LSB error.
SCK
SCLK
DIN
MOSI
NOTE: (1) Additional pins omitted for clarity.
BIPOLAR OPERATION USING THE DAC8531
The DAC8531 has been designed for single-supply operation
but a bipolar output range is also possible using the circuit in
Figure 10. The circuit shown will give an output voltage range
of ±VREF. Rail-to-rail operation at the amplifier output is achiev-
able using an OPA703 as the output amplifier.
FIGURE 8. DAC8531 to 68HC11 Interface.
The 68HC11 should be configured so that its CPOL bit is a
0 and its CPHA bit is a 1. This configuration causes data
appearing on the MOSI output to be valid on the falling edge
of SCK. When data is being transmitted to the DAC, the
SYNC line is taken LOW (PC7). Serial data from the 68HC11
is transmitted in 8-bit bytes with only eight falling clock edges
occurring in the transmit cycle. Data is transmitted MSB first.
In order to load data to the DAC8531, PC7 is left LOW after
the first eight bits are transferred, then a second and third
serial write operation is performed to the DAC and PC7 is
taken HIGH at the end of this procedure.
The output voltage for any input code can be calculated as
follows:
D
R1 + R2
R2
R1
VO = VREF
•
•
– VREF •
65536
R1
where D represents the input code in decimal (0–65535).
With VREF = 5V, R1 = R2 = 10kΩ:
10 • D
VO
=
– 5V
65536
APPLICATIONS
USING REF02 AS A POWER SUPPLY FOR
This is an output voltage range of ±5V with 0000H corre-
sponding to a –5V output and FFFFH corresponding to a +5V
output. Similarly, using VREF = 2.5V, ±2.5V output voltage
raw can be achieved.
THE DAC8531
Due to the extremely low supply current required by the
DAC8531, an alternative option is to use a REF02 +5V
precision voltage reference to supply the required voltage to
the part, as shown in Figure 9. This is especially useful if the
LAYOUT
A precision analog component requires careful layout, ad-
equate bypassing, and clean, well-regulated power supplies.
+15
As the DAC8531 offers single-supply operation, it will often
be used in close proximity with digital logic, microcontrollers,
microprocessors, and digital signal processors. The more
digital logic present in the design and the higher the switch-
ing speed, the more difficult it will be to keep digital noise
from appearing at the output.
+5V
REF02
285µA
Due to the single ground pin of the DAC8531, all return
currents, including digital and analog return currents, must
flow through the GND pin. Ideally, GND would be connected
directly to an analog ground plane. This plane would be
separate from the ground connection for the digital compo-
nents until they were connected at the power-entry point of
the system.
SYNC
Three-Wire
Serial
Interface
V
OUT = 0V to 5V
DAC8531
SCLK
DIN
FIGURE 9. REF02 as a Power Supply to the DAC8531.
DAC8531
14
SBAS192B
www.ti.com
The power applied to VDD should be well regulated and low
noise. Switching power supplies and DC/DC converters will
often have high-frequency glitches or spikes riding on the
output voltage. In addition, digital components can create
similar high-frequency spikes as their internal logic switches
states. This noise can easily couple into the DAC output
voltage through various paths between the power connec-
tions and analog output.
As with the GND connection, VDD should be connected to a
+5V power-supply plane or trace that is separate from the
connection for digital logic until they are connected at the
power-entry point. In addition, the 1µF to 10µF and 0.1µF
bypass capacitors are strongly recommended. In some situ-
ations, additional bypassing may be required, such as a
100µF electrolytic capacitor or even a “Pi” filter made up of
inductors and capacitors—all designed to essentially low-
pass filter the +5V supply, removing the high-frequency
noise.
R2
VREF
10kΩ
+5V
R1
10kΩ
OPA703
VFB
±5V
VOUT
VREF
DAC8531
10µF
0.1µF
–5V
Three-Wire
Serial
Interface
FIGURE 10. Bipolar Operation with the DAC8531.
DAC8531
SBAS192B
15
www.ti.com
PACKAGE DRAWINGS
DGK (R-PDSO-G8)
PLASTIC SMALL-OUTLINE PACKAGE
0,38
0,25
M
0,65
8
0,08
5
0,15 NOM
3,05
2,95
4,98
4,78
Gage Plane
0,25
0°–6°
1
4
0,69
3,05
2,95
0,41
Seating Plane
0,10
0,15
0,05
1,07 MAX
4073329/C 08/01
NOTES: A. All linear dimensions are in millimeters.
B. This drawing is subject to change without notice.
C. Body dimensions do not include mold flash or protrusion.
D. Falls within JEDEC MO-187
DAC8531
16
SBAS192B
www.ti.com
PACKAGE DRAWINGS (Cont.)
DAC8531
SBAS192B
17
www.ti.com
PACKAGE OPTION ADDENDUM
www.ti.com
19-May-2004
PACKAGING INFORMATION
ORDERABLE DEVICE
STATUS(1)
PACKAGE TYPE
PACKAGE DRAWING
PINS
PACKAGE QTY
DAC8531E/250
DAC8531E/2K5
DAC8531IDRBR
DAC8531IDRBT
ACTIVE
ACTIVE
ACTIVE
ACTIVE
VSSOP
VSSOP
SON
DGK
DGK
DRB
DRB
8
8
8
8
250
2500
3000
250
SON
(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.
IMPORTANT NOTICE
Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications,
enhancements, improvements, and other changes to its products and services at any time and to discontinue
any product or service without notice. Customers should obtain the latest relevant information before placing
orders and should verify that such information is current and complete. All products are sold subject to TI’s terms
and conditions of sale supplied at the time of order acknowledgment.
TI warrants performance of its hardware products to the specifications applicable at the time of sale in
accordance with TI’s standard warranty. Testing and other quality control techniques are used to the extent TI
deems necessary to support this warranty. Except where mandated by government requirements, testing of all
parameters of each product is not necessarily performed.
TI assumes no liability for applications assistance or customer product design. Customers are responsible for
their products and applications using TI components. To minimize the risks associated with customer products
and applications, customers should provide adequate design and operating safeguards.
TI does not warrant or represent that any license, either express or implied, is granted under any TI patent right,
copyright, mask work right, or other TI intellectual property right relating to any combination, machine, or process
in which TI products or services are used. Information published by TI regarding third-party products or services
does not constitute a license from TI to use such products or services or a warranty or endorsement thereof.
Use of such information may require a license from a third party under the patents or other intellectual property
of the third party, or a license from TI under the patents or other intellectual property of TI.
Reproduction of information in TI data books or data sheets is permissible only if reproduction is without
alteration and is accompanied by all associated warranties, conditions, limitations, and notices. Reproduction
of this information with alteration is an unfair and deceptive business practice. TI is not responsible or liable for
such altered documentation.
Resale of TI products or services with statements different from or beyond the parameters stated by TI for that
product or service voids all express and any implied warranties for the associated TI product or service and
is an unfair and deceptive business practice. TI is not responsible or liable for any such statements.
Following are URLs where you can obtain information on other Texas Instruments products and application
solutions:
Products
Applications
Audio
Amplifiers
amplifier.ti.com
www.ti.com/audio
Data Converters
dataconverter.ti.com
Automotive
www.ti.com/automotive
DSP
dsp.ti.com
Broadband
Digital Control
Military
www.ti.com/broadband
www.ti.com/digitalcontrol
www.ti.com/military
Interface
Logic
interface.ti.com
logic.ti.com
Power Mgmt
Microcontrollers
power.ti.com
Optical Networking
Security
www.ti.com/opticalnetwork
www.ti.com/security
www.ti.com/telephony
www.ti.com/video
microcontroller.ti.com
Telephony
Video & Imaging
Wireless
www.ti.com/wireless
Mailing Address:
Texas Instruments
Post Office Box 655303 Dallas, Texas 75265
Copyright 2004, Texas Instruments Incorporated
相关型号：
©2020 ICPDF网 联系我们和版权申明