2.7 V to 5.5 V, 140 μA, Rail-to-Rail Output
12-Bit DAC in an SOT-23
AD5320
Rev. C
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FEATURES
Single 12-bit DAC
6-lead SOT-23 and 8-lead MSOP packages
Micropower operation: 140 μA @ 5 V
Power-down to 200 nA @ 5 V, 50 nA @ 3 V
2.7 V to 5.5 V power supply
Guaranteed monotonic by design
Reference derived from power supply
Power-on reset to zero volts
Three power-down functions
Low power serial interface with Schmitt-triggered inputs
On-chip output buffer amplifier, rail-to-rail operation
SYNC interrupt facility
APPLICATIONS
Portable battery-powered instruments
Digital gain and offset adjustment
Programmable voltage and current sources
Programmable attenuators
FUNCTIONAL BLOCK DIAGRAM
V
DD
V
OU
T
GND
AD5320
12-BIT
DAC
SCLK DIN
REF (+) REF (–)
REGISTER
NETWORK
POWER-DOWN
CONTROL LOGIC
DAC
REGISTER
OUTPUT
BUFFER
POWER-ON
RESET
SYNC
INPUT
CONTROL
LOGIC
00934-001
Figure 1.
GENERAL DESCRIPTION
The AD53201 is a single, 12-bit buffered voltage out digital-to-
analog converter (DAC) that operates from a single 2.7 V to
5.5 V supply consuming 115 μA at 3 V. Its on-chip precision
output amplifier allows rail-to-rail output swing to be achieved.
The AD5320 utilizes a versatile 3-wire serial interface that
operates at clock rates up to 30 MHz and is compatible with
standard SPI®, QSPI™, MICROWIRE™ and digital signal
processing (DSP) interface standards.
The reference for AD5320 is derived from the power supply
inputs and thus gives the widest dynamic output range. The
part incorporates a power-on reset circuit that ensures that the
DAC output powers up to zero volts and remains there until a
valid write takes place to the device. The part contains a power-
down feature that reduces the current consumption of the
device to 200 nA at 5 V and provides software selectable output
loads while in power-down mode. The part is put into power-
down mode over the serial interface.
The low power consumption of this part in normal operation
makes it ideally suited to portable, battery-operated equipment.
The power consumption is 0.7 mW at 5 V reducing to 1 μW in
power-down mode.
1 Patent pending; protected by U.S. Patent No. 5684481.
The AD5320 is one of a family of pin-compatible DACs. The
AD5300 is the 8-bit version and the AD5310 is the 10-bit
version. The AD5300/AD5310/AD5320 are available in 6-lead
SOT-23 packages and 8-lead MSOP packages.
PRODUCT HIGHLIGHTS
1. Available in 6-lead SOT-23 and 8-lead MSOP packages.
2. Low power, single-supply operation. This part operates
from a single 2.7 V to 5.5 V supply and typically consumes
0.35 mW at 3 V and 0.7 mW at 5 V, making it ideal for
battery-powered applications.
3. The on-chip output buffer amplifier allows the output of
the DAC to swing rail-to-rail with a slew rate of 1 V/μs.
4. Reference derived from the power supply.
5. High speed serial interface with clock speeds up to
30 MHz. Designed for very low power consumption. The
interface only powers up during a write cycle.
6. Power-down capability. When powered down, the DAC
typically consumes 50 nA at 3 V and 200 nA at 5 V.
AD5320
Rev. C | Page 2 of 20
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications....................................................................................... 1
Functional Block Diagram .............................................................. 1
General Description......................................................................... 1
Product Highlights ........................................................................... 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Timing Characteristics ................................................................ 4
Absolute Maximum Ratings............................................................ 5
ESD Caution.................................................................................. 5
Pin Configurations and Function Descriptions ........................... 6
Terminology ...................................................................................... 7
Typical Performance Characteristics ............................................. 8
Theory of Operation ...................................................................... 11
D/A Section................................................................................. 11
Resistor String............................................................................. 11
Output Amplifier........................................................................ 11
Serial Interface ................................................................................ 12
Input Shift Register .................................................................... 12
SYNC Interrupt .......................................................................... 12
Power-On Reset.......................................................................... 12
Power-Down Modes .................................................................. 13
Microprocessor Interfacing........................................................... 14
AD5320 to ADSP-2101/ADSP-2103 Interface ....................... 14
AD5320 to 68HC11/68L11 Interface....................................... 14
AD5320 to 80C51/80L51 Interface .......................................... 14
AD5320 to MICROWIRE Interface......................................... 14
Applications..................................................................................... 15
Using REF19x as a Power Supply for AD5320 ....................... 15
Bipolar Operation Using the AD5320..................................... 15
Using AD5320 with an Opto-Isolated Interface .................... 15
Power Supply Bypassing and Grounding................................ 16
Outline Dimensions ....................................................................... 17
Ordering Guide .......................................................................... 17
REVISION HISTORY
11/05—Rev. B to Rev. C
Updated Format..................................................................Universal
Changes to Table 4............................................................................ 6
Updated Outline Dimensions....................................................... 17
Changes to Ordering Guide .......................................................... 17
AD5320
Rev. C | Page 3 of 20
SPECIFICATIONS
VDD = 2.7 V to 5.5 V; RL = 2 kΩ to GND; CL = 200 pF to GND; all specifications TMIN to TMAX, unless otherwise noted.
Table 1.
B Version1
Parameter Min Typ Max Unit Test Conditions/Comments
STATIC PERFORMANCE2
Resolution 12 Bits
Relative Accuracy ±16 LSB See Figure 5
Differential Nonlinearity ±1 LSB Guaranteed monotonic by design (see Figure 6)
Zero-Code Error 5 40 mV All zeroes loaded to DAC register (see Figure 9)
Full-Scale Error −0.15 −1.25 % of FSR All ones loaded to DAC register (see Figure 9)
Gain Error ±1.25 % of FSR
Zero-Code Error Drift −20 μV/°C
Gain Temperature Coefficient −5 ppm of FSR/°C
OUTPUT CHARACTERISTICS3
Output Voltage Range 0 VDD V
Output Voltage Settling Time 8 10 μs 1/4 scale to 3/4 scale change (400 hex to C00 hex)
RL = 2 kΩ, 0 pF < CL < 200 pF (see Figure 19)
12 μs RL = 2 kΩ, CL = 500 pF
Slew Rate 1 V/μs
Capacitive Load Stability 470 pF RL = ∞
1000 pF RL = 2 kΩ
Digital-to-Analog Glitch Impulse 20 nV-s 1 LSB change around major carry (see Figure 22)
Digital Feedthrough 0.5 nV-s
DC Output Impedance 1 Ω
Short Circuit Current 50 mA VDD = 5 V
20 mA VDD = 3 V
Power-Up Time 2.5 μs Coming out of power-down mode, VDD = 5 V
5 μs Coming out of power-down mode, VDD = 3 V
LOGIC INPUTS3
Input Current ±1 μA
VINL, Input Low Voltage 0.8 V VDD = 5 V
VINL, Input Low Voltage 0.6 V VDD = 3 V
VINH, Input High Voltage 2.4 V VDD = 5 V
VINH, Input High Voltage 2.1 V VDD = 3 V
Pin Capacitance 3 pF
POWER REQUIREMENTS
VDD 2.7 5.5 V
IDD (Normal Mode) DAC active and excluding load current
VDD = 4.5 V to 5.5 V 140 250 μA VIH = VDD and VIL = GND
VDD = 2.7 V to 3.6 V 115 200 μA VIH = VDD and VIL = GND
IDD (All Power-Down Modes)
VDD = 4.5 V to 5.5 V 0.2 1 μA VIH = VDD and VIL = GND
VDD = 2.7 V to 3.6 V 0.05 1 μA VIH = VDD and VIL = GND
POWER EFFICIENCY
IOUT/IDD 93 % ILOAD = 2 mA, VDD = 5 V
1 Temperature range is as follows: B Version: −40°C to +105°C.
2 Linearity calculated using a reduced code range of 48 to 4047; output unloaded.
3 Guaranteed by design and characterization, not production tested.
AD5320
Rev. C | Page 4 of 20
TIMING CHARACTERISTICS
VDD = 2.7 V to 5.5 V, all specifications TMIN to TMAX, unless otherwise noted.
Table 2.
Limit at TMIN, TMAX
Parameter1, 2VDD = 2.7 V to 3.6 V VDD = 3.6 V to 5.5 V Unit Description
t1350 33 ns min SCLK cycle time
t2 13 13 ns min SCLK high time
t3 22.5 13 ns min SCLK low time
t4 0 0 ns min SYNC to SCLK rising edge setup time
t5 5 5 ns min Data setup time
t6 4.5 4.5 ns min Data hold time
t7 0 0 ns min SCLK falling edge to SYNC rising edge
t8 50 33 ns min Minimum SYNC high time
1 All input signals are specified with tr = tf = 5 ns (10% to 90% of VDD) and timed from a voltage level of (VIL + VIH)/2.
2 See Figure 2.
3 Maximum SCLK frequency is 30 MHz at VDD = 3.6 V to 5.5 V and 20 MHz at VDD = 2.7 V to 3.6 V.
00934-002
SCLK
DIN DB15 DB0
t
4
t
1
t
3
t
2
t
8
t
7
t
6
t
5
SYNC
Figure 2. Serial Write Operation
AD5320
Rev. C | Page 5 of 20
ABSOLUTE MAXIMUM RATINGS
TA = 25°C, unless otherwise noted.
Table 3.
Parameter Ratings
VDD to GND −0.3 V to +7 V
Digital Input Voltage to GND −0.3 V to VDD + 0.3 V
VOUT to GND −0.3 V to VDD + 0.3 V
Operating Temperature Range
Industrial (B Version) −40°C to +105°C
Storage Temperature Range −65°C to +150°C
Junction Temperature (TJ Max) 150°C
SOT-23 Package
Power Dissipation (TJ Max − TA)/θJA
θJA Thermal Impedance 240°C/W
Lead Temperature, Soldering
Vapor Phase (60 sec) 215°C
Infrared (15 sec) 220°C
MSOP Package 450 mW
Power Dissipation (TJ Max − TA)/θJA
θJA Thermal Impedance 206°C/W
θJC Thermal Impedance 44°C/W
Lead Temperature, Soldering
Vapor Phase (60 sec) 215°C
Infrared (15 sec) 220°C
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
ESD CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on
the human body and test equipment and can discharge without detection. Although this product features
proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy
electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance
degradation or loss of functionality.
AD5320
Rev. C | Page 6 of 20
PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS
AD5320
TOP VIEW
(Not to Scale)
V
OUT 1
GND
2
V
DD 3
SYNC
SCLK
DIN
6
5
4
00934-003
Figure 3. SOT-23 Pin Configuration
AD5320
TOP VIEW
(Not to Scale)
V
DD 1
NC
2
NC
3
V
OUT 4
SYNC
SCLK
DIN
GND
8
7
6
5
00934-004
NC = NO CONNECT
Figure 4. MSOP Pin Configuration
Table 4. Pin Function Descriptions
SOT-23
Pin No.
MSOP
Pin No.
Mnemonic
Description
1 4 VOUT Analog Output Voltage from DAC. The output amplifier has rail-to-rail operation.
2 8 GND Ground Reference Point for All Circuitry on the Part.
3 1 VDD Power Supply Input. These parts can be operated from 2.5 V to 5.5 V and VDD should be decoupled
to GND.
4 7 DIN Serial Data Input. This device has a 16-bit shift register. Data is clocked into the register on the falling
edge of the serial clock input.
5 6 SCLK Serial Clock Input. Data is clocked into the input shift register on the falling edge of the serial clock
input. Data can be transferred at rates up to 30 MHz.
6 5 SYNC Level Triggered Control Input (Active Low). This is the frame synchronization 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 16th 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 DAC.
2, 3 NC No Connect.
AD5320
Rev. C | Page 7 of 20
TERMINOLOGY
Relative Accuracy
For the DAC, relative accuracy or integral nonlinearity (INL) is
a measure of the maximum deviation, in LSBs, from a straight
line passing through the endpoints of the DAC transfer
function. A typical INL vs. code plot can be seen in Figure 5.
Differential Nonlinearity
Differential nonlinearity (DNL) is the difference between the
measured change and the ideal 1 LSB change between any two
adjacent codes. A specified differential nonlinearity of ±1 LSB
maximum ensures monotonicity. This DAC is guaranteed
monotonic by design. A typical DNL vs. code plot can be seen
in Figure 6.
Zero-Code Error
Zero-code error is a measure of the output error when zero
code (000 hex) is loaded to the DAC register. Ideally, the output
should be 0 V. The zero-code error is always positive in the
AD5320 because the output of the DAC cannot go below 0 V
due to a combination of the offset errors in the DAC and output
amplifier. Zero-code error is expressed in mV. A plot of zero-
code error vs. temperature can be seen in Figure 9.
Full-Scale Error
Full-scale error is a measure of the output error when full-scale
code (FFF Hex) is loaded to the DAC register. Ideally the output
should be VDD − 1 LSB. Full-scale error is expressed in percent
of full-scale range. A plot of full-scale error vs. temperature can
be seen in Figure 9.
Gain Error
This is a measure of the span error of the DAC. It is the
deviation in slope of the DAC transfer characteristic from ideal
expressed as a percent of the full-scale range.
Total Una dju s te d Error
Total unadjusted error (TUE) is a measure of the output error
considering all the various errors. A typical TUE vs. code plot
can be seen in Figure 7.
Zero-Code Error Drift
This is a measure of the change in zero-code error with a
change in temperature. It is expressed in μV/°C.
Gain Error Drift
This is a measure of the change in gain error with changes in
temperature. It is expressed in (ppm of full-scale range)/°C.
Digital-to-Analog Glitch Impulse
Digital-to-analog glitch impulse is the impulse injected into the
analog output when the input code in the DAC register changes
state. It is normally specified as the area of the glitch in nV
seconds and is measured when the digital input code is changed
by 1 LSB at the major carry transition (7FF Hex to 800 Hex); see
Figure 22.
Digital Feedthrough
Digital feedthrough is a measure of the impulse injected into
the analog output of the DAC from the digital inputs of the
DAC but is measured when the DAC output is not updated. It
is specified in nV seconds and measured with a full-scale code
change on the data bus, that is, from all 0s to all 1s and vice
versa.
AD5320
Rev. C | Page 8 of 20
TYPICAL PERFORMANCE CHARACTERISTICS
INL @ 5V
INL @ 3V
CODE
INL ERROR (LSBs)
16
12
4
–4
–12
8
0
–8
–16
0 800 1600 2400 40003200
00934-005
T
A
= 25°C
Figure 5. Typical INL Plot
CODE
DNL ERROR (LSBs)
1.0
0.5
0
–0.5
–1.0
0 1000 2000 3000 4000
00934-006
DNL @ 3V
DNL @ 5V
T
A
= 25°C
Figure 6. Typical DNL Plot
CODE
TUE (LSBs)
16
8
0
–8
–16
0 800 1600 2400 40003200
00934-007
TUE @ 3V
TUE @ 5V
T
A
= 25°C
Figure 7. Typical Total Unadjusted Error Plot
MAX INL
MAX DNL
MIN INL
MIN DNL
TEMPERATURE (°C)
–40 0 40 80 120
00934-008
16
12
4
–4
–12
8
0
–8
–16
ERROR (LSBs)
Figure 8. INL Error and DNL Error vs. Temperature
V
DD
= 5V
ZS ERROR
FS ERROR
30
20
30
0
10
20
10
TEMPERATURE (°C)
ERROR (mV)
–40 0 40 80 120
00934-009
Figure 9. Zero-Scale Error and Full-Scale Error vs. Temperature
2500
2000
500
50 190
1500
1000
0
FREQUENCY
V
DD
= 3V
V
DD
= 5V
60 70 80 90 100 110 120 130 140 150 160 170 180
00934-010
I
DD
(µA)
Figure 10. IDD Histogram with VDD = 3 V and VDD = 5 V
AD5320
Rev. C | Page 9 of 20
DAC LOADED WITH FFF HEX
DAC LOADED WITH 000 HEX
I
SOURCE/SINK
(mA)
V
OUT
(V)
3
2
1
0
05 10
00934-011
T
A
= 25°C
15
Figure 11. Source and Sink Current Capability with VDD = 3 V
5
4
3
2
1
DAC LOADED WITH 000 HEX
DAC LOADED WITH FFF HEX
I
SOURCE/SINK
(mA)
V
OUT
(V)
0
0510
00934-012
15
T
A
= 25°C
Figure 12. Source and Sink Current Capability with VDD = 5 V
CODE
I
DD
(µA)
0 800 1600 2400 3200 4000
00934-013
500
400
0
300
200
100
V
DD
= 5V
V
DD
= 3V
Figure 13. Supply Current vs. Code
TEMPERATURE °C
I
DD
(µA)
300
200
150
50
0
–40 0 40 80 120
00934-014
V
DD
= 5V
Figure 14. Supply Current vs. Temperature
VDD (V)
2.7 3.2 3.73.7 4.2 4.7 5
00934-015
300
250
200
150
100
50
0
IDD (µA)
TA = 25°C
Figure 15. Supply Current vs. Supply Voltage
2.7 3.2 3.7 4.7 5.24.2
00934-016
1.0
0.9
0
0.4
0.3
0.2
0.1
0.8
0.6
0.7
0.5
–40°C
CONDITION
THREE-STATE
V
DD
(V)
I
DD
(µA)
+25°C
+105°C
Figure 16. Power-Down Current vs. Supply Voltage
AD5320
Rev. C | Page 10 of 20
TA = 25°C
VDD = 5V
VLOGIC (V)
IDD (µA)
800
600
400
200
0
054321
00934-017
VDD = 3V
Figure 17. Supply Current vs. Logic Input Voltage
V
OUT
CLK
CH1 1V, CH2 5V, TIME BASE = 1µs/DIV
CH2
CH1
00934-018
VDD = 5V
FULL-SCALE CODE CHANGE
000 HEX – FFF HEX
TA = 25°C
OUTPUT LOADED WITH
2kΩAND 200pF TO GND
Figure 18. Full-Scale Settling Time
V
OUT
CLK
CH1 1V, CH2 5V, TIME BASE = 1µs/DIV
00934-019
C
H1
C
H2 V
DD
= 5V
HALF-SCALE CODE CHANGE
400 HEX – C00 HEX
T
A
= 25°C
OUTPUT LOADED WITH
2kΩAND 200pF TO GND
Figure 19. Half-Scale Settling Time
CH1
CH2
CH1 1V, CH 2 1V, TIME BASE = 20µs/DIV
00934-020
2kΩ LOAD TO V
DD
V
DD
V
OUT
Figure 20. Power-On Reset to 0 V
CH1 1V, CH2 5V, TIME BASE = 5µs/DIV
00934-021
CH2
CH1
CLK
V
OUT
V
DD
= 5V
Figure 21. Exiting Power-Down (800 Hex Loaded)
LOADED WITH 2kΩ
AND 200pF TO GND
CODE CHANGE:
800 HEX TO 7FF HEX
500ns/DIV
V
OUT
(V)
00934-022
2.54
2.52
2.50
2.48
2.46
2.56
Figure 22. Digital-to-Analog Glitch Impulse
AD5320
Rev. C | Page 11 of 20
THEORY OF OPERATION
D/A SECTION
The AD5320 DAC is fabricated on a CMOS process. The
architecture consists of a string DAC followed by an output
buffer amplifier. Because there is no reference input pin, the
power supply (VDD) acts as the reference. Figure 23 shows a
block diagram of the DAC architecture.
V
DD
VOUT
GND
RESISTOR
STRING
REF (+)
REF (–) OUTPUT
AMPLIFIER
DAC REGISTER
00934-023
Figure 23. DAC Architecture
Since the input coding to the DAC is straight binary, the ideal
output voltage is given by:
⎟
⎠
⎞
⎜
⎝
⎛
×= 4096
D
VV DD
OUT
where D = decimal equivalent of the binary code that is loaded
to the DAC register; it can range from 0 to 4095.
RESISTOR STRING
The resistor string section is shown in Figure 24. It is simply a
string of resistors, each of value R. The code loaded to the DAC
register determines at which node on the string the voltage is
tapped off to be fed into the output amplifier. The voltage is
tapped off by closing one of the switches connecting the string
to the amplifier. Because it is a string of resistors, it is
guaranteed monotonic.
R
R
R
R
R
TO OUTPUT
AMPLIFIER
00934-024
Figure 24. Resistor String
OUTPUT AMPLIFIER
The output buffer amplifier is capable of generating rail-to-rail
voltages on its output that gives an output range of 0 V to VDD. It
is capable of driving a load of 2 kΩ in parallel with 1000 pF to
GND. The source and sink capabilities of the output amplifier
can be seen in Figure 11 and Figure 12. The slew rate is 1 V/μs
with a half-scale settling time of 8 μs with the output unloaded.
AD5320
Rev. C | Page 12 of 20
SERIAL INTERFACE
The AD5320 has a 3-wire serial interface (SYNC, SCLK, and
DIN) that is compatible with SPI®, QSPITM, and
MICROWIRETM interface standards as well as most DSPs. See
Figure 2 for a timing diagram of a typical write sequence.
The write sequence begins by bringing the SYNC line low. Data
from the DIN line is clocked into the 16-bit shift register on the
falling edge of SCLK. The serial clock frequency can be as high
as 30 MHz, making the AD5320 compatible with high speed
DSPs. On the 16th falling clock edge, the last data bit is clocked
in and the programmed function is executed (that is, a change
in DAC register contents and/or a change in the mode of
operation). At this stage, the SYNC line can be kept low or be
brought high. In either case, it must be brought high for a
minimum of 33 ns before the next write sequence so that a
falling edge of SYNC can initiate the next write sequence.
Because the SYNC buffer draws more current when VIN = 2.4 V
than it does when VIN = 0.8 V, SYNC should be idled low
between write sequences for even lower power operation of the
part. As previously mentioned, SYNC must be brought high
again just before the next write sequence.
INPUT SHIFT REGISTER
The input shift register is 16 bits wide (see Figure 25). The first two
bits are “don’t cares.” The next two 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
twelve bits are the data bits. These are transferred to the DAC
register on the 16th falling edge of SCLK.
SYNC INTERRUPT
In a normal write sequence, the SYNC line is kept low for at
least 16 falling edges of SCLK and the DAC is updated on the
16th falling edge. However, if SYNC is brought high before the
16th falling edge, then 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
nor a change in the operating mode occurs (see Figure 26).
POWER-ON RESET
The AD5320 contains a power-on reset circuit that controls the
output voltage during power-up. The DAC register is filled with
zeros and the output voltage is 0 V. It remains there until a valid
write sequence is made to the DAC. This is useful in applica-
tions where it is important to know the state of the output of the
DAC while it is in the process of powering up.
DB15 (MSB) DB0 (LSB)
X PD0 D11 D10 D9 D8 D7 D6 D5 D4PD1XD3 D2 D1 D0
DATA BITS
00934-025
0
0
1
1
0
1
0
1
NORMAL OPERATION
1kΩTO GND
100kΩTO GND
THREE–STATE
POWER-DOWN MODES
Figure 25. Input Register Contents
DB15 DB0 DB15
SCLK
S
YNC
DIN
INVALID WRITE SEQUENCE:
SYNC HIGH BEFORE 16TH FALLING EDGE
VALID WRITE SEQUENCE, OUTPUT UPDATES
ON THE 16TH FALLING EDGE
DB0
00934-028
Figure 26. SYNC Interrupt Facility
AD5320
Rev. C | Page 13 of 20
POWER-DOWN MODES
The AD5320 contains four separate modes of operation. These
modes are software-programmable by setting two bits (DB13
and DB12) in the control register. Table 5 shows how the state
of the bits corresponds to the mode of operation of the device.
Table 5. Modes of Operation for the AD5320
DB13 DB12 Operating Mode
0 0 Normal Operation
Power-Down Modes
0 1 1 kΩ to GND
1 0 100 kΩ to GND
1 1 Three-State
When both bits are set to 0, the part works with its normal power
consumption of 140 μA at 5 V. However, for the three power-down
modes, the supply current falls to 200 nA at 5 V (50 nA at 3 V). Not
only does the supply current fall, but the output stage is also inter-
nally switched from the output of the amplifier to a resistor net-
work 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 1 kΩ resistor, the output is connected
internally to GND through a 100 kΩ resistor, or it is left open-
circuited (three-state). The output stage is illustrated in Figure 27.
RESISTOR
STRING DAC
RESISTOR
NETWORK
POWER-DOWN
CIRCUITRY
VOUT
00934-026
AMPLIFIER
Figure 27. Output Stage During Power-Down
The bias generator, output amplifier, resistor string, and other
associated linear circuitry are 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 2.5 μs for VDD = 5 V and 5 μs for VDD = 3 V
(see Figure 21).
AD5320
Rev. C | Page 14 of 20
MICROPROCESSOR INTERFACING
AD5320 TO ADSP-2101/ADSP-2103 INTERFACE
Figure 28 shows a serial interface between the AD5320 and the
ADSP-2101/ADSP-2103. The ADSP-2101/ADSP-2103 should
be set up to operate in the serial port (SPORT) transmit alter-
nate framing mode. The ADSP-2101/ADSP-2103 SPORT are
programmed through the SPORT control register and should
be configured as follows: internal clock operation, active low
framing, and 16-bit word length. Transmission is initiated by
writing a word to the Tx register after the SPORT has been
enabled.
AD5320 TO 68HC11/68L11 INTERFACE
Figure 29 shows a serial interface between the AD5320 and the
68HC11/68L11 microcontroller. SCK of the 68HC11/68L11
drives the SCLK of the AD5320, while the MOSI output drives
the serial data line of the DAC. The SYNC signal is derived
from a port line (PC7). For correct operation of this interface,
the 68HC11/68L11 should be configured so that the CPOL bit
is a 0 and the CPHA bit is a 1. When data is being transmitted
to the DAC, the SYNC line is taken low (PC7). When the
68HC11/68L11 are configured, data appearing on the MOSI
output is valid on the falling edge of SCK as shown in Figure 29.
Serial data from the 68HC11/68L11 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
AD5320, PC7 is left low after the first eight bits are transferred,
and a second serial write operation is performed to the DAC
and PC7 is taken high at the end of this procedure.
DIN
SCLK
SYNC
PC7
SCK
MOSI
68HC11/68L11*
*ADDITIONAL PINS OMITTED FOR CLARITY
00934-029
AD5320*
Figure 29. AD5320 to 68HC11/68L11 Interface
AD5320 TO 80C51/80L51 INTERFACE
Figure 30 shows a serial interface between the AD5320 and the
80C51/80L51 microcontrollers. TXD of the 80C51/80L51 drives
SCLK of the AD5320, while RXD drives the serial data line of
the part. The SYNC signal is again 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 AD5320, P3.3 is
taken low. The 80C51/80L51 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 this cycle. The 80C51/ 80L51 output the serial
data in a format that has the LSB first. The AD5320 requires its
data with the MSB as the first bit received. The 80C51/80L51
transmit routine should consider this.
DIN
SCLK
SYNC
P3.3
TXD
RXD
80C51/80L51*
*ADDITIONAL PINS OMITTED FOR CLARITY
00934-030
AD5320*
Figure 30. AD5320 to 80C51/80L51 Interface
AD5320 TO MICROWIRE INTERFACE
Figure 31 shows an interface between the AD5320 and any
MICROWIRE-compatible device. Serial data is shifted out on
the falling edge of the serial clock and is clocked into the
AD5320 on the rising edge of the SK.
DIN
SCLK
SYNC
CS
SK
SO
MICROWIRE*
*ADDITIONAL PINS OMITTED FOR CLARITY
00934-031
AD5320*
Figure 31. AD5320 to MICROWIRE Interface
SCLK
DIN
SYNC
TFS
DT
SCLK
ADSP-2101/
ADSP-2103*
*ADDITIONAL PINS OMITTED FOR CLARITY
00934-027
AD5320*
Figure 28. AD5320 to ADSP-2101/ADSP-2103 Interface
AD5320
Rev. C | Page 15 of 20
APPLICATIONS
USING REF19X AS A POWER SUPPLY FOR AD5320
Because the supply current required by the AD5320 is
extremely low, an alternative option is to use a REF19x voltage
reference (REF195 for 5 V or REF193 for 3 V) to supply the
required voltage to the part (see Figure 32). This is especially
useful if the power supply is noisy or if the system supply
voltages are at some value other than 5 V or 3 V (such as 15 V).
The REF19x outputs a steady supply voltage for the AD5320. If
the low dropout REF195 is used, the current it needs to supply
to the AD5320 is 140 μA. This is with no load on the output of
the DAC. When the DAC output is loaded, the REF195 also
needs to supply the current to the load. The total current
required (with a 5 kΩ load on the DAC output) is:
140 μA + (5 V/5 kΩ) = 1.14 mA
The load regulation of the REF195 is typically 2 ppm/mA,
which results in an error of 2.3 ppm (11.5 μV) for the 1.14 mA
current drawn from it. This corresponds to a 0.009 LSB error.
REF195
AD5320
DIN
SCLK
SYNC
15
V
5V
140µA
V
OUT
= 0V TO 5V
3-WIRE
SERIAL
INTERFACE
00934-032
Figure 32. REF195 as Power Supply to AD5320
BIPOLAR OPERATION USING THE AD5320
The AD5320 is designed for single-supply operation but a bipolar
output range is also possible using the circuit in Figure 33. The
circuit below gives an output voltage range of ±5 V. Rail-to-rail
operation at the amplifier output is achievable using an AD820 or
an OP295 as the output amplifier.
The output voltage for any input code can be calculated as
follows:
⎥
⎦
⎤
⎢
⎣
⎡⎟
⎠
⎞
⎜
⎝
⎛
×−
⎟
⎠
⎞
⎜
⎝
⎛+
×
⎟
⎠
⎞
⎜
⎝
⎛
×= 1
2
1
21
4096 R
R
V
R
RR
D
VV DDDD
O
where D represents the input code in decimal (0 to 4095).
With VDD = 5 V, R1 = R2 = 10 kΩ:
V
D
VO5
4096
10 −
⎟
⎠
⎞
⎜
⎝
⎛×
=
This is an output voltage range of ±5 V with 000 hex
corresponding to a −5 V output and FFF hex corresponding to
a +5 V output.
3-WIRE SERIAL INTERFACE
+5V
AD5320
10µF 0.1µF
V
DD
V
OUT
R1 = 10kΩ
R2 = 10k
Ω
+5V
±5
V
–5V
AD820/
OP295
00934-033
Figure 33. Bipolar Operation with the AD5320
USING AD5320 WITH AN OPTO-ISOLATED
INTERFACE
For process control applications in industrial environments, it is
often necessary to use an opto-isolated interface to protect and
isolate the controlling circuitry from any hazardous common-
mode voltages that can occur in the area where the DAC is
functioning. Opto-isolators provide isolation in excess of 3 kV.
Because the AD5320 uses a 3-wire serial logic interface, it
requires only three opto-isolators to provide the required
isolation (see Figure 34). The power supply to the part also
needs to be isolated. This is done by using a transformer. On the
DAC side of the transformer, a 5 V regulator provides the 5 V
supply required for the AD5320.
V
DD
0.1µF
V
DD
10kΩ
10kΩ
V
DD
10kΩ
5V
REGULATOR
V
OUT
GND
DIN
SYNC
SCLK
POWER 10µF
V
DD
SYNC
SCLK
DATA
AD5320
00934-034
Figure 34. AD5320 with An Opto-Isolated Interface
AD5320
Rev. C | Page 16 of 20
POWER SUPPLY BYPASSING AND GROUNDING
When accuracy is important in a circuit, it is helpful to consider
carefully the power supply and ground return layout on the
board. The printed circuit board containing the AD5320 should
have separate analog and digital sections, each having its own
area of the board. If the AD5320 is in a system where other
devices require an AGND to DGND connection, the connec-
tion should be made at one point only. This ground point
should be as close as possible to the AD5320.
The power supply to the AD5320 should be bypassed with 10 μF
capacitors and 0.1 μF capacitors. The capacitors should be physi-
cally as close as possible to the device with the 0.1 μF capacitors
ideally against the device. The 10 μF capacitors are the tantalum
bead type. It is important that the 0.1 μF capacitors have low
effective series resistance (ESR) and effective series inductance
(ESI), such as common ceramic types of capacitors. The 0.1 μF
capacitors provide a low impedance path to ground for high
frequencies caused by transient currents due to internal logic
switching.
The power supply line itself should have as large a trace as
possible to provide a low impedance path and reduce glitch
effects on the supply line. Clocks and other fast switching
digital signals should be shielded from other parts of the board
by digital ground. Avoid crossover of digital and analog signals
if possible. When traces cross on opposite sides of the board,
ensure that they run at right angles to each other to reduce
feedthrough effects through the board. The best board layout
technique is the microstrip technique where the component
side of the board is dedicated to the ground plane only and the
signal traces are placed on the solder side. However, this is not
always possible with a two-layer board.
AD5320
Rev. C | Page 17 of 20
OUTLINE DIMENSIONS
1 3
45
2
6
2.90 BSC
1.60 BSC 2.80 BSC
1.90
BSC
0.95 BSC
0.22
0.08
10°
4°
0°
0.50
0.30
0.15 MAX
1.30
1.15
0.90
SEATING
PLANE
1.45 MAX
0.60
0.45
0.30
PIN 1
INDICATOR
COMPLIANT TO JEDEC STANDARDS MO-178-AB
Figure 35. 6-Lead Small Outline Transistor Package [SOT-23]
(RT-6)
Dimensions shown in millimeters
COMPLIANT TO JEDEC STANDARDS MO-187-AA
0.80
0.60
0.40
8°
0°
4
8
1
5
PIN 1
0.65 BSC
SEATING
PLANE
0.38
0.22
1.10 MAX
3.20
3.00
2.80
COPLANARITY
0.10
0.23
0.08
3.20
3.00
2.80
5.15
4.90
4.65
0.15
0.00
0.95
0.85
0.75
Figure 36. 8-Lead Mini Small Outline Package [MSOP]
(RM-8)
Dimensions shown in millimeters
ORDERING GUIDE
Model
Temperature Range
Package Description
Branding
Package Option
AD5320BRM −40°C to +105°C 8-Lead Mini Small Outline Package [MSOP] D4B RM-8
AD5320BRM-REEL −40°C to +105°C 8-Lead Mini Small Outline Package [MSOP] D4B RM-8
AD5320BRM-REEL7 −40°C to +105°C 8-Lead Mini Small Outline Package [MSOP] D4B RM-8
AD5320BRMZ1−40°C to +105°C 8-Lead Mini Small Outline Package [MSOP] D9N RM-8
AD5320BRMZ-REEL1−40°C to +105°C 8-Lead Mini Small Outline Package [MSOP] D9N RM-8
AD5320BRMZ-REEL71−40°C to +105°C 8-Lead Mini Small Outline Package [MSOP] D9N RM-8
AD5320BRT-500RL7 −40°C to +105°C 6-Lead Small Outline Transistor Package [SOT-23] D4B RT-6
AD5320BRT-REEL −40°C to +105°C 6-Lead Small Outline Transistor Package [SOT-23] D4B RT-6
AD5320BRT-REEL7 −40°C to +105°C 6-Lead Small Outline Transistor Package [SOT-23] D4B RT-6
AD5320BRTZ-500RL71−40°C to +105°C 6-Lead Small Outline Transistor Package [SOT-23] D9N RT-6
AD5320BRTZ-REEL1−40°C to +105°C 6-Lead Small Outline Transistor Package [SOT-23] D9N RT-6
AD5320BRTZ-REEL71−40°C to +105°C 6-Lead Small Outline Transistor Package [SOT-23] D9N RT-6
1 Z = Pb-free part.
AD5320
Rev. C | Page 18 of 20
NOTES
AD5320
Rev. C | Page 19 of 20
NOTES
AD5320
Rev. C | Page 20 of 20
NOTES
© 2005 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D00934-0-11/05(C)
