AD AD5381

40-Channel, 3 V/5 V, Single-Supply,
12-Bit, Voltage Output DAC
AD5381
FEATURES
INTEGRATED FUNCTIONS
Guaranteed monotonic
INL error: ±1 LSB max
On-chip 1.25 V/2.5 V, 10 ppm/°C reference
Temperature range: –40°C to +85°C
Rail-to-rail output amplifier
Power-down
Package type: 100-lead LQFP (14 mm × 14 mm)
User Interfaces:
Parallel
Serial (SPI®/QSPI™/MICROWIRE™/DSP compatible,
featuring data readback)
I2C® compatible
Channel monitor
Simultaneous output update via LDAC
Clear function to user programmable code
Amplifier boost mode to optimize slew rate
User programmable offset and gain adjust
Toggle mode enables square wave generation
Thermal monitors
APPLICATIONS
Variable optical attenuators (VOA)
Level setting (ATE)
Optical micro-electro-mechanical systems (MEMs)
Control systems
Instrumentation
FUNCTIONAL BLOCK DIAGRAM
DVDD (×3)
DGND (×3)
AVDD (×5)
AGND (×5)
DAC GND (×5)
REFGND
REFOUT/REFIN
SIGNAL GND (×5)
PD
SER/PAR
AD5381
1.25V/2.5V
REFERENCE
FIFO EN
CS/(SYNC/AD 0)
WR/(DCEN/AD 1)
12
SDO
DB0
12
INTERFACE
CONTROL
LOGIC
FIFO
+
STATE
MACHINE
+
CONTROL
LOGIC
12
12
DAC 12
REG 0
DAC 0
VOUT0
m REG 0
R
c REG 0
R
12
INPUT 12
REG 1
12
A5
A0
12
12
DAC 12
REG 1
DAC 1
VOUT1
VOUT2
m REG 1
R
c REG 1
VOUT4
12
REG 1
RESET
VOUT3
R
REG 0
POWER-ON
RESET
INPUT 12
REG 6
12
12
BUSY
12
DAC 12
REG 6
VOUT5
DAC 6
VOUT6
m REG 6
R
c REG 6
R
CLR
VOUT 0………VOUT 38
12
INPUT 12
REG 7
12
39-TO-1
MUX
12
12
DAC 12
REG 7
DAC 7
VOUT7
VOUT8
m REG 7
R
c REG 7
R
VOUT38
×5
VOUT 39/MON_OUT
LDAC
03732-0-001
DB11/(DIN/SDA)
DB10/(SCLK/SCL)
DB9/(SPI/I2C)
DB8
INPUT 12
REG 0
Figure 1.
Rev. A
Information furnished by Analog Devices is believed to be accurate and reliable.
However, no responsibility is assumed by Analog Devices for its use, nor for any
infringements of patents or other rights of third parties that may result from its use.
Specifications subject to change without notice. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.326.8703
© 2004 Analog Devices, Inc. All rights reserved.
AD5381
TABLE OF CONTENTS
General Description ......................................................................... 3
BUSY and LDAC Functions...................................................... 25
Specifications..................................................................................... 4
FIFO Operation in Parallel Mode ............................................ 25
AD5381-5 Specifications ............................................................. 4
Power-On Reset.......................................................................... 25
AD5381-3 Specifications ............................................................. 6
Power-Down ............................................................................... 25
AC Characteristics........................................................................ 7
AD5381 Interfaces.......................................................................... 26
Timing Characteristics..................................................................... 8
DSP, SPI, MICROWIRE Compatible Serial Interfaces .......... 26
Serial Interface Timing ................................................................ 8
I2C Serial Interface ..................................................................... 28
I2C Serial Interface Timing........................................................ 10
Parallel Interface......................................................................... 30
Parallel Interface Timing ........................................................... 11
Microprocessor Interfacing....................................................... 31
Absolute Maximum Ratings.......................................................... 13
Application Information................................................................ 33
Pin Configuration and Function Descriptions........................... 14
Power Supply Decoupling ......................................................... 33
Terminology .................................................................................... 17
Typical Configuration Circuit .................................................. 33
Typical Performance Characteristics ........................................... 18
AD5381 Monitor Function ....................................................... 34
Functional Description .................................................................. 21
Toggle Mode Function............................................................... 34
DAC Architecture—General..................................................... 21
Thermal Monitor Function....................................................... 34
On-Chip Special Function Registers (SFR) ............................ 22
Optical Attenuators .................................................................... 35
SFR Commands .......................................................................... 22
Utilizing the AD5381 FIFO....................................................... 35
Hardware Functions....................................................................... 25
Outline Dimensions ....................................................................... 36
Reset Function ............................................................................ 25
Ordering Guide .......................................................................... 36
Asynchronous Clear Function.................................................. 25
REVISION HISTORY
6/04—Data Sheet Changed from Rev. 0 to Rev. A
Changes to Ordering Guide ...........................................................36
5/04—Revision 0: Initial Version
Rev. A | Page 2 of 36
AD5381
GENERAL DESCRIPTION
The AD5381 is a complete, single-supply, 40-channel, 12-bit
DAC available in a 100-lead LQFP package. All 40 channels
have an on-chip output amplifier with rail-to-rail operation.
The AD5381 includes a programmable internal 1.25 V/2.5 V,
10 ppm/°C reference, an on-chip channel monitor function that
multiplexes the analog outputs to a common MON_OUT pin
for external monitoring, and an output amplifier boost mode
that allows optimization of the amplifier slew rate. The AD5381
contains a double-buffered parallel interface that features a
20 ns WR pulse width, an SPI/QSPI/MICROWIRE/DSP
compatible serial interface with interface speeds in excess of
30 MHz, and an I2C compatible interface that supports a
400 kHz data transfer rate.
An input register followed by a DAC register provides double
buffering, allowing the DAC outputs to be updated independently or simultaneously using the LDAC input.
Each channel has a programmable gain and offset adjust
register that allows the user to fully calibrate any DAC channel.
Power consumption is typically 0.25 mA/channel with boost
mode disabled.
Table 1. Other Low Voltage Single-Supply DACs in Product Family
Model
AD5380BST-5
AD5380BST-3
AD5384BBC-5
AD5384BBC-3
AD5382BST-5
AD5382BST-3
AD5383BST-5
AD5383BST-3
AD5390BST-5
AD5390BCP-5
AD5390BST-3
AD5390BCP-3
AD5391BST-5
AD5391BCP-5
AD5391BST-3
AD5391BCP-3
AD5392BST-5
AD5392BCP-5
AD5392BST-3
AD5392BCP-3
Resolution
14 Bits
14 Bits
14 Bits
14 Bits
14 Bits
14 Bits
12 Bits
12 Bits
14 Bits
14 Bits
14 Bits
14 Bits
12 Bits
12 Bits
12 Bits
12 Bits
14 Bits
14 Bits
14 Bits
14 Bits
AVDD Range
4.5 V to 5.5 V
2.7 V to 3.6 V
4.5 V to 5.5 V
2.7 V to 3.6 V
4.5 V to 5.5 V
2.7 V to 3.6 V
4.5 V to 5.5 V
2.7 V to 3.6 V
4.5 V to 5.5 V
4.5 V to 5.5 V
2.7 V to 3.6 V
2.7 V to 3.6 V
4.5 V to 5.5 V
4.5 V to 5.5 V
2.7 V to 3.6 V
2.7 V to 3.6 V
4.5 V to 5.5 V
4.5 V to 5.5 V
2.7 V to 3.6 V
2.7 V to 3.6 V
Output Channels
40
40
40
40
32
32
32
32
16
16
16
16
16
16
16
16
8
8
8
8
Linearity Error (LSB)
±4
±4
±4
±4
±4
±4
±1
±1
±3
±3
±3
±3
±1
±1
±1
±1
±3
±3
±3
±3
Package Description
100-Lead LQFP
100-Lead LQFP
100-Lead CSPBGA
100-Lead CSPBGA
100-Lead LQFP
100-Lead LQFP
100-Lead LQFP
100-Lead LQFP
52-Lead LQFP
64-Lead LFCSP
52-Lead LQFP
64-Lead LFCSP
52-Lead LQFP
64-Lead LFCSP
52-Lead LQFP
64-Lead LFCSP
52-Lead LQFP
64-Lead LFCSP
52-Lead LQFP
64-Lead LFCSP
Package Option
ST-100
ST-100
BC-80
BC-80
ST-100
ST-100
ST-100
ST-100
ST-52
CP-64
ST-52
CP-64
ST-52
CP-64
ST-52
CP-64
ST-52
CP-64
ST-52
CP-64
Table 2. 40-Channel, Bipolar Voltage Output DAC
Model
AD5379ABC
Resolution
14 Bits
Analog Supplies
±11.4 V to ±16.5 V
Output Channels
40
Linearity Error
±3
Rev. A | Page 3 of 36
Package
108-Lead CSPBGA
Package Option
BC-108
AD5381
SPECIFICATIONS
AD5381-5 SPECIFICATIONS
Table 3. AVDD = 4.5 V to 5.5 V; DVDD = 2.7 V to 5.5 V, AGND = DGND = 0 V; External REFIN = 2.5 V;
all specifications TMIN to TMAX, unless otherwise noted
Parameter
ACCURACY
Resolution
Relative Accuracy2 (INL)
Differential Nonlinearity (DNL)
Zero-Scale Error
Offset Error
Offset Error TC
Gain Error
Gain Temperature Coefficient3
DC Crosstalk3
REFERENCE INPUT/OUTPUT
Reference Input3
Reference Input Voltage
DC Input Impedance
Input Current
Reference Range
Reference Output4
Output Voltage
Reference TC
OUTPUT CHARACTERISTICS3
Output Voltage Range2
Short-Circuit Current
Load Current
Capacitive Load Stability
RL = ∞
RL = 5 kΩ
DC Output Impedance
MONITOR PIN
Output Impedance
Three-State Leakage Current
LOGIC INPUTS (EXCEPT SDA/SCL)3
VIH, Input High Voltage
VIL, Input Low Voltage
Input Current
Pin Capacitance
LOGIC INPUTS (SDA, SCL ONLY)
VIH, Input High Voltage
VIL, Input Low Voltage
IIN, Input Leakage Current
VHYST, Input Hysteresis
CIN, Input Capacitance
Glitch Rejection
AD5381-51
Unit
12
±1
±1
±4
±4
±5
±0.024
±0.06
2
0.5
Bits
LSB max
LSB max
mV max
mV max
µV/°C typ
% FSR max
% FSR max
ppm FSR/°C typ
LSB max
2.5
1
±10
1 to VDD/2
V
MΩ min
µA max
V min/max
Test Conditions/Comments
Output unloaded
2.495/2.505
1.22/1.28
±10
±15
V min/max
V min/max
ppm/°C max
ppm/°C max
0/AVDD
40
±1
V min/max
mA max
mA max
200
1000
0.5
pF max
pF max
Ω max
500
100
Ω typ
nA typ
2
0.8
±10
10
V min
V max
µA max
pF max
0.7 DVDD
0.3 DVDD
±1
0.05 DVDD
8
50
V min
V max
µA max
V min
pF typ
ns max
Guaranteed monotonic over temperature
Measured at Code 32 in the linear region
At 25 °C
TMIN to TMAX
±1% for specified performance, AVDD = 2 × REFIN + 50 mV
Typically 100 MΩ
Typically ±30 nA
Enabled via CR8 in the AD5381 control register.
CR10 selects the reference voltage.
At ambient. Optimized for 2.5 V operation. CR10 = 1.
CR10 = 0
Temperature Range: +25°C to +85°C
Temperature Range: –40°C to +85°C
DVDD = 2.7 V to 5.5 V
Total for all pins. TA = TMIN to TMAX.
SMBus compatible at DVDD < 3.6 V
SMBus compatible at DVDD < 3.6 V
Input filtering suppresses noise spikes of less than 50 ns
Rev. A | Page 4 of 36
AD5381
Parameter
LOGIC OUTPUTS (BUSY, SDO)3
VOL, Output Low Voltage
VOH, Output High Voltage
VOL, Output Low Voltage
VOH, Output High Voltage
High Impedance Leakage Current
High Impedance Output Capacitance
LOGIC OUTPUT (SDA)3
VOL, Output Low Voltage
AD5381-51
Unit
Test Conditions/Comments
0.4
DVDD – 1
0.4
DVDD – 0.5
±1
5
V max
V min
V max
V min
µA max
pF typ
DVDD = 5 V ± 10%, sinking 200 µA
DVDD = 5 V ± 10%, sourcing 200 µA
DVDD = 2.7 V to 3.6 V, sinking 200 µA
DVDD = 2.7 V to 3.6 V, sourcing 200 µA
SDO only
SDO only
V max
V max
µA max
pF typ
ISINK = 3 mA
ISINK = 6 mA
Three-State Leakage Current
Three-State Output Capacitance
POWER REQUIREMENTS
AVDD
DVDD
Power Supply Sensitivity3
∆Midscale/∆ΑVDD
AIDD
0.4
0.6
±1
8
4.5/5.5
2.7/5.5
V min/max
V min/max
–85
0.375
0.475
1
2
20
80
dB typ
mA/channel max
mA/channel max
mA max
µA max
µA max
mW max
DIDD
AIDD (Power-Down)
DIDD (Power-Down)
Power Dissipation
1
Outputs unloaded, Boost off. 0.25 mA/channel typ.
Outputs unloaded, Boost on. 0.325 mA /channel typ.
VIH = DVDD, VIL = DGND
Outputs unloaded, Boost off, AVDD = DVDD = 5 V
AD5381-5 is calibrated using an external 2.5 V reference. Temperature range for all versions: –40°C to +85°C.
Accuracy guaranteed from VOUT = 10 mV to AVDD – 50 mV.
3
Guaranteed by characterization, not production tested.
4
Default on the AD5381-5 is 2.5 V. Programmable to 1.25 V via CR10 in the AD5381 control register; operating the AD5381-5 with a 1.25 V reference will lead to
degraded accuracy specifications.
2
Rev. A | Page 5 of 36
AD5381
AD5381-3 SPECIFICATIONS
Table 4. AVDD = 2.7 V to 3.6 V; DVDD = 2.7 V to 5.5 V, AGND = DGND = 0 V; External REFIN = 1.25 V;
all specifications TMIN to TMAX, unless otherwise noted
Parameter
ACCURACY
Resolution
Relative Accuracy2 (INL)
Differential Nonlinearity (DNL)
Zero-Scale Error
Offset Error
Offset Error TC
Gain Error
Gain Temperature Coefficient3
DC Crosstalk3
REFERENCE INPUT/OUTPUT
Reference Input3
Reference Input Voltage
DC Input Impedance
Input Current
Reference Range
Reference Output4
Output Voltage
Reference TC
OUTPUT CHARACTERISTICS3
Output Voltage Range2
Short-Circuit Current
Load Current
Capacitive Load Stability
RL = ∞
RL = 5 kΩ
DC Output Impedance
MONITOR PIN
Output Impedance
Three-State Leakage Current
LOGIC INPUTS (EXCEPT SDA/SCL)3
VIH, Input High Voltage
VIL, Input Low Voltage
Input Current
Pin Capacitance
LOGIC INPUTS (SDA, SCL ONLY)
VIH, Input High Voltage
VIL, Input Low Voltage
IIN, Input Leakage Current
VHYST, Input Hysteresis
CIN, Input Capacitance
Glitch Rejection
AD5381-31
Unit
12
±1
±1
±4
±4
±5
±0.024
±0.06
2
0.5
Bits
LSB max
LSB max
mV max
mV max
µV/°C typ
% FSR max
% FSR max
ppm FSR/°C typ
LSB max
1.25
1
±10
1 to AVDD/2
V
MΩ min
µA max
V min/max
1.247/1.253
2.43/2.57
±10
±15
V min/max
V min/max
ppm/°C max
ppm/°C max
0/AVDD
40
±1
V min/max
mA max
mA max
200
1000
0.5
pF max
pF max
Ω max
500
100
Ω typ
nA typ
2
0.8
±10
10
V min
V max
µA max
pF max
0.7 DVDD
0.3 DVDD
±1
0.05 DVDD
8
50
V min
V max
µA max
V min
pF typ
ns max
Test Conditions/Comments
Output unloaded
Guaranteed monotonic over temperature
Measured at Code 64 in the linear region
At 25 °C
TMIN to TMAX
±1% for specified performance
Typically 100 MΩ
Typically ±30 nA
Enabled via CR8 in the AD5381 control register.
CR10 selects the reference voltage.
At ambient. Optimized for 1.25 V operation. CR10 = 0.
CR10 = 1
Temperature Range: +25°C to +85°C
Temperature Range: –40°C to +85°C
DVDD = 2.7 V to 3.6 V
Rev. A | Page 6 of 36
Total for all pins. TA = TMIN to TMAX.
SMBus compatible at DVDD< 3.6 V
SMBus compatible at DVDD< 3.6 V
Input filtering suppresses noise spikes of less than 50 ns
AD5381
Parameter
LOGIC OUTPUTS (BUSY, SDO)3
VOL, Output Low Voltage
VOH, Output High Voltage
High Impedance Leakage Current
High Impedance Output Capacitance
LOGIC OUTPUT (SDA)3
VOL, Output Low Voltage
AD5381-31
Unit
Test Conditions/Comments
0.4
DVDD – 0.5
±1
5
V max
V min
µA max
pF typ
Sinking 200 µA
Sourcing 200 µA
SDO only
SDO only
V max
V max
µA max
pF typ
ISINK = 3 mA
ISINK = 6 mA
Three-State Leakage Current
Three-State Output Capacitance
POWER REQUIREMENTS
AVDD
DVDD
Power Supply Sensitivity3
∆Midscale/∆ΑVDD
AIDD
0.4
0.6
±1
8
2.7/3.6
2.7/5.5
V min/max
V min/max
–85
0.375
0.475
1
2
20
48
dB typ
mA/channel max
mA/channel max
mA max
µA max
µA max
mW max
DIDD
AIDD (Power-Down)
DIDD (Power-Down)
Power Dissipation
Outputs unloaded, Boost off. 0.25 mA/channel typ
Outputs unloaded, Boost on. 0.325 mA/channel typ
VIH = DVDD, VIL = DGND
Outputs unloaded, Boost off, AVDD = DVDD = 3 V
1
AD5381-3 is calibrated using an external 1.25 V reference. Temperature range is –40°C to +85°C.
Accuracy guaranteed from VOUT = 10 mV to AVDD – 50 mV.
Guaranteed by characterization, not production tested.
4
Default on the AD5381-3 is 1.25 V. Programmable to 2.5 V via cr10 in the AD5381 control register; operating the AD5381-3 with a 2.5 V reference will lead to degraded
accuracy specifications and limited input code range.
2
3
AC CHARACTERISTICS1
Table 5. AVDD = 4.5 V to 5.5 V; DVDD = 2.7 V to 5.5 V; AGND = DGND = 0 V
Parameter
DYNAMIC PERFORMANCE
Output Voltage Settling Time
Slew Rate2
Digital-to-Analog Glitch Energy
Glitch Impulse Peak Amplitude
Channel-to-Channel Isolation
DAC-to-DAC Crosstalk
Digital Crosstalk
Digital Feedthrough
Output Noise 0.1 Hz to 10 Hz
Output Noise Spectral Density
@ 1 kHz
@ 10 kHz
1
2
All
Unit
Test Conditions/Comments
6
8
2
3
12
15
100
1
0.8
0.1
15
40
µs typ
µs max
V/µs typ
V/µs typ
nV-s typ
mV typ
dB typ
nV-s typ
nV-s typ
nV-s typ
µV p-p typ
µV p-p typ
150
100
nV/√Hz typ
nV/√Hz typ
1/4 scale to 3/4 scale change settling to ±1 LSB.
Boost mode off, CR9 = 0
Boost mode on, CR9 = 1
See Terminology section
See Terminology section
Effect of input bus activity on DAC output under test
External reference, midscale loaded to DAC
Internal reference, midscale loaded to DAC
Guaranteed by design and characterization, not production tested.
Slew rate can be programmed via the current boost control bit in the AD5381 control register.
Rev. A | Page 7 of 36
AD5381
TIMING CHARACTERISTICS
SERIAL INTERFACE TIMING
Table 6. DVDD= 2.7 V to 5.5 V; AVDD = 4.5 V to 5.5 V or 2.7 V to 3.6 V; AGND = DGND = 0 V; all specifications
TMIN to TMAX, unless otherwise noted
Parameter1, 2, 3
t1
t2
t3
t4
t5 4
t6 4
t7
t7A
t8
t9
t104
t11
t124
t13
t14
t15
t16
t17
t18
t19
t205
t215
t225
t23
Limit at TMIN, TMAX
33
13
13
13
13
33
10
50
5
4.5
30
670
20
20
100
0
100
8
20
12
20
5
8
20
Unit
ns min
ns min
ns min
ns min
ns min
ns min
ns min
ns min
ns min
ns min
ns max
ns max
ns min
ns min
ns max
ns min
ns min
µs typ
ns min
µs max
ns max
ns min
ns min
ns min
Description
SCLK cycle time
SCLK high time
SCLK low time
SYNC falling edge to SCLK falling edge setup time
24th SCLK falling edge to SYNC falling edge
Minimum SYNC low time
Minimum SYNC high time
Minimum SYNC high time in Readback mode
Data setup time
Data hold time
24th SCLK falling edge to BUSY falling edge
BUSY pulse width low (single channel update)
24th SCLK falling edge to LDAC falling edge
LDAC pulse width low
BUSY rising edge to DAC output response time
BUSY rising edge to LDAC falling edge
LDAC falling edge to DAC output response time
DAC output settling time
CLR pulse width low
CLR pulse activation time
SCLK rising edge to SDO valid
SCLK falling edge to SYNC rising edge
SYNC rising edge to SCLK rising edge
SYNC rising edge to LDAC falling edge
1
Guaranteed by design and characterization, not production tested.
All input signals are specified with tr = tf = 5 ns (10% to 90% of VCC) and are timed from a voltage level of 1.2 V.
See Figure 2, Figure 3, Figure 4, and Figure 5.
4
Standalone mode only.
5
Daisy-chain mode only.
2
3
IOL
VOH (MIN) OR
VOL (MAX)
TO OUTPUT PIN
CL
50pF
200µA
IOH
Figure 2. Load Circuit for Digital Output Timing
Rev. A | Page 8 of 36
03731-0-003
200µA
AD5381
t1
24
SCLK
t3
t4
t2
24
t5
t6
SYNC
t7
t8 t9
DB0
DIN
DB23
t10
BUSY
t11
t13
t12
t17
LDAC1
t14
VOUT1
t15
t13
LDAC2
t17
t16
VOUT2
t18
CLR
03731-0-004
VOUT
t19
1LDAC ACTIVE DURING BUSY
2LDAC ACTIVE AFTER BUSY
Figure 3. Serial Interface Timing Diagram (Standalone Mode)
SCLK
24
48
t7A
SYNC
DB23
DIN
DB0
DB23
DB0
INPUT WORD SPECIFIES
REGISTER TO BE READ
NOP CONDITION
DB0
UNDEFINED
03731-0-005
DB23
SDO
SELECTED REGISTER
DATA CLOCKED OUT
Figure 4. Serial Interface Timing Diagram (Data Readback Mode)
t1
SCLK
24
t7
t3
48
t2
t21
t22
t4
SYNC
t8 t9
DIN
DB23
DB0
DB23
INPUT WORD FOR DAC N
DB0
INPUT WORD FOR DAC N+1
t20
UNDEFINED
DB0
INPUT WORD FOR DAC N
t23
LDAC
Figure 5. Serial Interface Timing Diagram (Daisy-Chain Mode)
Rev. A | Page 9 of 36
t13
03731-0-006
DB23
SDO
AD5381
I2C SERIAL INTERFACE TIMING
Table 7. DVDD = 2.7 V to 5.5 V; AVDD = 4.5 V to 5.5 V or 2.7 V to 3.6 V; AGND = DGND = 0 V; all specifications
TMIN to TMAX, unless otherwise noted
Parameter1, 2
FSCL
t1
t2
t3
t4
t5
t63
t7
t8
t9
t10
t11
Cb
Limit at TMIN, TMAX
400
2.5
0.6
1.3
0.6
100
0.9
0
0.6
0.6
1.3
300
0
300
0
300
20 + 0.1Cb 4
400
Unit
kHz max
µs min
µs min
µs min
µs min
ns min
µs max
µs min
µs min
µs min
µs min
ns max
ns min
ns max
ns min
ns max
ns min
pF max
Description
SCL clock frequency
SCL cycle time
tHIGH, SCL high time
tLOW, SCL low time
tHD,STA, start/repeated start condition hold time
tSU,DAT, data setup time
tHD,DAT, data hold time
tHD,DAT, data hold time
tSU,STA, setup time for repeated start
tSU,STO, stop condition setup time
tBUF, bus free time between a STOP and a START condition
tR, rise time of SCL and SDA when receiving
tR, rise time of SCL and SDA when receiving (CMOS compatible)
tF, fall time of SDA when transmitting
tF, fall time of SDA when receiving (CMOS compatible)
tF, fall time of SCL and SDA when receiving
tF, fall time of SCL and SDA when transmitting
Capacitive load for each bus line
1
Guaranteed by design and characterization, not production tested.
See Figure 6.
3
A master device must provide a hold time of at least 300 ns for the SDA signal (referred to the VIH min of the SCL signal) in order to bridge the undefined region of
SCL’s falling edge.
4
Cb is the total capacitance, in pF, of one bus line. tR and tF are measured between 0.3DVDD and 0.7DVDD.
2
SDA
t9
t3
t10
t11
t4
SCL
t6
t2
t1
t5
START
CONDITION
REPEATED
START
CONDITION
Figure 6. I2C Compatible Serial Interface Timing Diagram
Rev. A | Page 10 of 36
t8
t7
STOP
CONDITION
03731-0-007
t4
AD5381
PARALLEL INTERFACE TIMING
Table 8. DVDD = 2.7 V to 5.5 V; AVDD = 4.5 V to 5.5 V or 2.7 V to 3.6 V; AGND = DGND = 0 V; all specifications
TMIN to TMAX, unless otherwise noted
Parameter1,2,3
t0
t1
t2
t3
t4
t5
t6
t7
t8
t94
t104
t114, 5
t12
t13
t14
t15
t16
t17
t18
t19
t20
Limit at TMIN, TMAX
4.5
4.5
20
20
0
0
4.5
4.5
20
700
30
670
30
20
100
20
0
100
8
20
12
Unit
ns min
ns min
ns min
ns min
ns min
ns min
ns min
ns min
ns min
ns min
ns max
ns max
ns min
ns min
ns max
ns min
ns min
ns min
µs typ
ns min
µsmax
Description
REG0, REG1, address to WR rising edge setup time
REG0, REG1, address to WR rising edge hold time
CS pulse width low
WR pulse width low
CS to WR falling edge setup time
WR to CS rising edge hold time
Data to WR rising edge setup time
Data to WR rising edge hold time
WR pulse width high
Minimum WR cycle time (single-channel write)
WR rising edge to BUSY falling edge
BUSY pulse width low (single-channel update)
WR rising edge to LDAC falling edge
LDAC pulse width low
BUSY rising edge to DAC output response time
LDAC rising edge to WR rising edge
BUSY rising edge to LDAC falling edge
LDAC falling edge to DAC output response time
DAC output settling time, boost mode off
CLR pulse width low
CLR pulse activation time
1
Guaranteed by design and characterization, not production tested.
All input signals are specified with tR = tR = 5 ns (10% to 90% of DVDD) and timed from a voltage level of 1.2 V.
See Figure 7.
4
See Figure 29.
5
Measured with the load circuit of Figure 2.
2
3
Rev. A | Page 11 of 36
AD5381
t0
t1
REG0, REG1, A5..A0
t4
t5
t2
CS
t9
t3
WR
t8
t6
t15
t7
DB11..DB0
t10
t11
BUSY
t12
t13
t18
LDAC1
t14
VOUT1
t16
LDAC2
t13
t18
t17
VOUT2
CLR
t19
1LDAC
2LDAC
ACTIVE DURING BUSY
ACTIVE AFTER BUSY
Figure 7. Parallel Interface Timing Diagram
Rev. A | Page 12 of 36
03731-0-008
t20
VOUT
AD5381
ABSOLUTE MAXIMUM RATINGS
Table 9. TA = 25°C, unless otherwise noted1
Parameter
AVDD to AGND
DVDD to DGND
Digital Inputs to DGND
SDA/SCL to DGND
Digital Outputs to DGND
REFIN/REFOUT to AGND
AGND to DGND
VOUTx to AGND
Analog Inputs to AGND
Operating Temperature Range
Commercial (B Version)
Storage Temperature Range
JunctionTemperature (TJ Max)
100-lead LQFP Package
θJAThermal Impedance
Reflow Soldering
Peak Temperature
1
Rating
–0.3 V to +7 V
–0.3 V to +7 V
–0.3 V to DVDD + 0.3 V
–0.3 V to + 7 V
–0.3 V to DVDD + 0.3 V
–0.3 V to AVDD + 0.3 V
–0.3 V to +0.3 V
–0.3 V to AVDD + 0.3 V
–0.3 V to AVDD + 0.3 V
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 listed in the operational sections
of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
–40°C to +85°C
–65°C to +150°C
150°C
44°C/W
230°C
Transient currents of up to 100 mA will not cause SCR latch-up
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.
Rev. A | Page 13 of 36
AD5381
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
1
75 RESET
74 DB5
PIN 1
IDENTIFIER
2
3
4
73 DB4
72 DB3
5
71 DB2
6
70 DB1
69 DB0
7
8
68 NC
67 NC
9
10
66 REG0
65 REG1
11
AD5381
12
13
64 VOUT23
63 VOUT22
TOP VIEW
(Not to Scale)
14
62 VOUT21
15
61 VOUT20
60 AVDD3
16
17
59 AGND3
58 DAC_GND3
18
19
03732-0-002
50
49
48
47
46
45
44
43
42
41
40
38
39
37
36
SIGNAL_GND5
DAC_GND5
AGND5
AVDD5
VOUT5
VOUT6
VOUT7
VOUT32
VOUT33
VOUT34
VOUT35
VOUT36
VOUT37
VOUT38
VOUT39/MON_OUT
VOUT8
VOUT9
VOUT10
VOUT11
VOUT12
DAC_GND2
SIGNAL_GND2
VOUT13
VOUT14
VOUT15
35
51 AGND2
34
25
33
53 VOUT16
52 AVDD2
32
24
31
23
30
55 VOUT18
54 VOUT17
29
21
22
28
57 SIGNAL_GND3
56 VOUT19
27
20
26
FIFO EN
CLR
VOUT24
VOUT25
VOUT26
VOUT27
SIGNAL_GND4
DAC_GND4
AGND4
AVDD4
VOUT28
VOUT29
VOUT30
VOUT31
REF GND
REFOUT/REFIN
SIGNAL_GND1
DAC_GND1
AVDD1
VOUT0
VOUT1
VOUT2
VOUT3
VOUT4
AGND1
99
100
CS/(SYNC/AD0)
DB11/(DIN/SDA)
DB10/(SCLK/SCL)
DB9/(SPI/I2C)
DB8
DB7
DB6
SDO(A/B)
DVDD
DGND
DGND
A5
A4
A3
A2
A1
A0
DVDD
DVDD
DGND
SER/PAR
PD
WR (DCEN/AD1)
LDAC
BUSY
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
Figure 8. 100-Lead LQFP Pin Configuration
Table 10. Pin Function Descriptions
Mnemonic
VOUTx
SIGNAL_GND(1–5)
DAC_GND(1–5)
AGND(1–5)
AVDD(1–5)
DGND
DVDD
REFGND
REFOUT/REFIN
Function
Buffered Analog Outputs for Channel x. Each analog output is driven by a rail-to-rail output amplifier operating at a
gain of 2. Each output is capable of driving an output load of 5 kΩ to ground. Typical output impedance is 0.5 Ω.
Analog Ground Reference Points for Each Group of Eight Output Channels. All SIGNAL_GND pins are tied together
internally and should be connected to the AGND plane as close as possible to the AD5381.
Each group of eight channels contains a DAC_GND pin. This is the ground reference point for the internal 12-bit DAC.
These pins shound be connected to the AGND plane.
Analog Ground Reference Point. Each group of eight channels contains an AGND pin. All AGND pins should be
connected externally to the AGND plane.
Analog Supply Pins. Each group of eight channels has a separate AVDD pin. These pins are shorted internally and
should be decoupled with a 0.1 µF ceramic capacitor and 10 µF tantalum capacitor. Operating range for the
AD5381-5 is 4.5 V to 5.5 V; operating range for the AD5381-3 is 2.7 V to 3.6 V.
Ground for All Digital Circuitry.
Logic Power Supply. Guaranteed operating range is 2.7 V to 5.5 V. It is recommended that these pins be decoupled
with a 0.1 µF ceramic and a 10 µF tantalum capacitors to DGND.
Ground Reference Point for the Internal Reference.
The AD5381 contains a common REFOUT/REFIN pin. When the internal reference is selected, this pin is the reference
output. If the application requires an external reference, it can be applied to this pin and the internal reference can
be disabled via the control register. The default for this pin is a reference input.
Rev. A | Page 14 of 36
AD5381
Mnemonic
VOUT39/MON_OUT
SER/PAR
CS/(SYNC/AD0)
WR/(DCEN/ AD1)
DB11–DB0
A5–A0
REG1, REG0
SDO/(A/B)
BUSY
LDAC
CLR
RESET
PD
Function
This pin has a dual function. It acts a a buffered output for Channel 39 in default mode. But when the monitor
function is enabled, this pin acts as the output of a 39-to-1 channel multiplexer that can be programmed to
multiplex one of Channels 0 to 38 to the MON_OUT pin. The MON_OUT pin’s output impedance is typically 500 Ω
and is intended to drive a high input impedance like that exhibited by SAR ADC inputs.
Interface Select Input. This pin allows the user to select whether the serial or parallel interface is used. If it is tied high,
the serial interface mode is selected and Pin 97 (SPI/I2C) is used to determine if the interface mode is SPI or I2C.
Parallel interface mode is selected when SER/PAR is low.
In parallel interface mode, this pin acts as chip select input (level sensitive, active low). When low, the AD5381
is selected.
Serial Interface Mode. This is the frame synchronization input signal for the serial clock and data.
I2C Mode. This pin acts as a hardware address pin used in conjunction with AD1 to determine the software address
for the device on the I2C bus.
Multifunction Pin. In parallel interface mode, this pin acts as write enable. In serial interface mode, this pin acts as a
daisy-chain enable in SPI mode and as a hardware address pin in I2C mode.
Parallel Interface Write Input (edge sensitive). The rising edge of WR is used in conjunction with CS low, and the
address bus inputs to write to the selected device registers.
Serial Interface. Daisy-chain select input (level sensitive, active high). When high, this signal is used in conjunction
with SER/PAR high to enable the SPI serial interface daisy-chain mode.
I2C Mode. This pin acts as a hardware address pin used in conjunction with AD0 to determine the software address
for this device on the I2C bus.
Parallel Data Bus. DB11 is the MSB and DB0 is the LSB of the input data-word on the AD5381.
Parallel Address Inputs. A5 to A0 are decoded to address one of the AD5381’s 40 input channels. Used in conjunction
with the REG1 and REG0 pins to determine the destination register for the input data.
In parallel interface mode, REG1 and REG0 are used in decoding the destination registers for the input data. REG1
and REG0 are decoded to address the input data register, offset register, or gain register for the selected channel and
are also used to decide the special function registers.
Serial Data Output in Serial Interface Mode. Three-stateable CMOS output. SDO can be used for daisy-chaining a
number of devices together. Data is clocked out on SDO on the rising edge of SCLK, and is valid on the falling edge
of SCLK.
When operating in parallel interface mode, this pin acts as the A or B data register select when writing data to the
AD5381’s data registers with toggle mode selected (see the Toggle Mode Function section). In toggle mode, the
LDAC is used to switch the output between the data contained in the A and B data registers. All DAC channels
contain two data registers. In normal mode, Data Register A is the default for data transfers.
Digital CMOS Output. BUSY goes low during internal calculations of the data (x2) loaded to the DAC data register.
During this time, the user can continue writing new data to the x1, c, and m registers, but no further updates to the
DAC registers and DAC outputs can take place. If LDAC is taken low while BUSY is low, this event is stored. BUSY also
goes low during power-on reset, and when the RESET pin is low. During this time, the interface is disabled and any
events on LDAC are ignored. A CLR operation also brings BUSY low.
Load DAC Logic Input (Active Low). If LDAC is taken low while BUSY is inactive (high), the contents of the input
registers are transferred to the DAC registers and the DAC outputs are updated. If LDAC is taken low while BUSY is
active and internal calculations are taking place, the LDAC event is stored and the DAC registers are updated when
BUSY goes inactive. However any events on LDAC during power-on reset or on RESET are ignored.
Asynchronous Clear Input. The CLR input is falling edge sensitive. When CLR is activated, all channels are updated
with the data contained in the CLR code register. BUSY is low for a duration of 35 µs while all channels are being
updated with the CLR code.
Asynchronous Digital Reset Input (Falling Edge Sensitive). The function of this pin is equivalent to that of the poweron reset generator. When this pin is taken low, the state machine initiates a reset sequence to digitally reset the x1,
m, c, and x2 registers to their default power-on values. This sequence typically takes 270 µs. The falling edge of RESET
initiates the RESET process and BUSY goes low for the duration, returning high when RESET is complete. While BUSY
is low, all interfaces are disabled and all LDAC pulses are ignored. When BUSY returns high, the part resumes normal
operation and the status of the RESET pin is ignored until the next falling edge is detected.
Power Down (Level Sensitive, Active High). PD is used to place the device in low power mode, where the analog
current consumption is reduced to 2 µA and the digital current consumption is reduced to 20 µA. In power-down
mode, all internal analog circuitry is placed in low power mode, and the analog output is configured as a high
impedance output or provides a 100 kΩ load to ground, depending on how the power-down mode is configured.
The serial interface remains active during power-down.
Rev. A | Page 15 of 36
AD5381
Mnemonic
FIFOEN
DB9 (SPI/I2C)
DB10 (SCLK/SCL)
DB11/(DIN/SDA)
Function
FIFO Enable (Level Sensitive, Active High). When connected to DVDD, the internal FIFO is enabled, allowing the user
to write to the device at full speed. FIFO is only available in parallel interface mode. The status of the FIFO_EN pin is
sampled on power-up, and also following a CLEAR or RESET, to determine if the FIFO is enabled. In either serial or I2C
interface modes, the FIFO_EN pin should be tied low.
Multifunction Input Pin. In parallel interface mode, this pin acts as DB9 of the parallel input data-word. In serial
interface mode, this pin acts as serial interface mode select. When serial interface mode is selected (SER/PAR = 1) and
this input is low, SPI mode is selected. In SPI mode, DB12 is the serial clock (SCLK) input and DB11 is the serial data
(DIN) input.
When serial interface mode is selected (SER/PAR = 1) and this input is high I2C Mode is selected.
In this mode, DB12 is the serial clock (SCL) input and DB11 is the serial data (SDA) input.
Multifunction Input Pin. In parallel interface mode, this pin acts as DB10 of the parallel input data-word. In serial
interface mode, this pin acts as a serial clock input.
Serial Interface Mode. In serial interface mode, data is clocked into the shift register on the falling edge of SCLK. This
operates at clock speeds up to 50 MHz.
I2C Mode. In I2C mode, this pin performs the SCL function, clocking data into the device. The data transfer rate in I2C
mode is compatible with both 100 kHz and 400 kHz operating modes.
Multifunction Data Input Pin. In parallel interface mode, this pin acts as DB11 of the parallel input data-word.
Serial Interface Mode. In serial interface mode, this pin acts as the serial data input. Data must be valid on the falling
edge of SCLK.
I2C Mode. In I2C mode, this pin is the serial data pin (SDA) operating as an open-drain input/output.
Rev. A | Page 16 of 36
AD5381
TERMINOLOGY
Relative Accuracy
DC Output Impedance
Relative accuracy or endpoint linearity is a measure of the
maximum deviation from a straight line passing through the
endpoints of the DAC transfer function. It is measured after
adjusting for zero-scale error and full-scale error, and is
expressed in LSB.
This is the effective output source resistance. It is dominated by
package lead resistance.
Differential Nonlinearity
Differential nonlinearity 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.
Zero-Scale Error
Zero-scale error is the error in the DAC output voltage when all
0s are loaded into the DAC register. Ideally, with all 0s loaded to
the DAC and m = all 1s, c = 2n – 1
VOUT(Zero-Scale) = 0 V
Zero-scale error is a measure of the difference between VOUT
(actual) and VOUT (ideal), expressed in mV. It is mainly due to
offsets in the output amplifier.
Output Voltage Settling Time
This is the amount of time it takes for the output of a DAC to
settle to a specified level for a ¼ to ¾ full-scale input change,
and is measured from the BUSY rising edge.
Digital-to-Analog Glitch Energy
This is the amount of energy injected into the analog output at
the major code transition. It is specified as the area of the glitch
in nV-s. It is measured by toggling the DAC register data
between 0x7FF and 0x800.
DAC-to-DAC Crosstalk
DAC-to-DAC crosstalk is the glitch impulse that appears at the
output of one DAC due to both the digital change and to the
subsequent analog output change at another DAC. The victim
channel is loaded with midscale. DAC-to-DAC crosstalk is
specified in nV-s.
Digital Crosstalk
Offset Error
Offset error is a measure of the difference between VOUT
(actual) and VOUT (ideal) in the linear region of the transfer
function, expressed in mV. Offset error is measured on the
AD5381-5 with Code 32 loaded into the DAC register, and on
the AD5381-3 with Code 64.
Gain Error
Gain Error is specified in the linear region of the output range
between VOUT = 10 mV and VOUT = AVDD – 50 mV. It is the
deviation in slope of the DAC transfer characteristic from the
ideal and is expressed in %FSR with the DAC output unloaded.
DC Crosstalk
This is the dc change in the output level of one DAC at midscale
in response to a full-scale code (all 0s to all 1s, and vice versa)
and output change of all other DACs. It is expressed in LSB.
The glitch impulse transferred to the output of one converter
due to a change in the DAC register code of another converter
is defined as the digital crosstalk and is specified in nV-s.
Digital Feedthrough
When the device is not selected, high frequency logic activity on
the device’s digital inputs can be capacitively coupled both
across and through the device to show up as noise on the
VOUT pins. It can also be coupled along the supply and ground
lines. This noise is digital feedthrough.
Output Noise Spectral Density
This is a measure of internally generated random noise.
Random noise is characterized as a spectral density (voltage per
√Hertz). It is measured by loading all DACs to midscale and
measuring noise at the output. It is measured in nV/√Hz in a
1 Hz bandwidth at 10 kHz.
Rev. A | Page 17 of 36
AD5381
TYPICAL PERFORMANCE CHARACTERISTICS
1.00
1.00
AVDD = 5V
REFIN = 2.5V
TA = 25°C
0.75
0.50
0.25
0
–0.25
0.25
0
–0.25
–0.50
–0.75
–0.75
–1.00
0
512
1024
1536
2048
2560
INPUT CODE
3072
3584
4096
03732-0-017
–0.50
–1.00
0
512
2.539
2.538
2.537
2.536
2.535
2.534
2.533
2.532
2.531
2.530
2.529
2.528
2.527
2.526
2.525
2.524
2.523
1536
2048
2560
INPUT CODE
3072
3584
4096
Figure 12. Typical AD5381-3 INL Plot
1.254
AVDD = DVDD = 5V
VREF = 2.5V
TA = 25°C
14ns/SAMPLE NUMBER
1 LSB CHANGE AROUND MIDSCALE
GLITCH IMPULSE = 10nV-s
AVDD = DVDD = 3V
VREF = 1.25V
TA = 25°C
14ns/SAMPLE NUMBER
1 LSB CHANGE AROUND MIDSCALE
GLITCH IMPULSE = 5nV-s
1.253
1.252
AMPLITUDE (V)
1.251
1.250
1.249
1.248
1.247
100
150
200 250 300 350
SAMPLE NUMBER
400
450
500
550
Figure 10. AD5381-5 Glitch Impulse
1.245
0
50
100
150
200 250 300 350
SAMPLE NUMBER
400
450
500
550
Figure 13. AD5381-3 Glitch Impulse
AVDD = DVDD = 5V
VREF = 2.5V
TA = 25°C
AVDD = DVDD = 5V
VREF = 2.5V
TA = 25°C
VOUT
VOUT
Figure 11. Slew Rate with Boost Off
Figure 14. Slew Rate with Boost On
Rev. A | Page 18 of 36
03731-0-036
50
03732-0-004
0
03731-0-034
1.246
03732-0-003
AMPLITUDE (V)
Figure 9. Typical AD5381-5 INL Plot
1024
03732-0-018
INL ERROR (LSB)
0.50
INL ERROR (LSB)
AVDD = 3V
REFIN = 1.25V
TA = 25°C
0.75
AD5381
AVDD = 5.5V
VREF = 2.5V
TA = 25°C
14
PERCENTAGE OF UNITS (%)
12
AVDD = DVDD = 5V
VREF = 2.5V
TA = 25°C
POWER SUPPLY RAMP RATE = 10ms
10
VOUT
8
6
4
AVDD
9
10
AIDD (mA)
11
03731-0-011
8
04598-0-049
2
Figure 15. AIDD Histogram with Boost Off
Figure 18. AD5381 Power-Up Transient
40
DVDD = 5.5V
VIH = DVDD
VIL = DGND
TA = 25°C
10
35
30
FREQUENCY
6
4
25
20
15
10
2
0
0.4
0.5
0.6
0.7
DIDD (mA)
0.8
0.9
Figure 16. DIDD Histogram
0
–5.0 –4.0 –3.0 –2.0 –1.0
0
1.0 2.0 3.0 4.0 5.0
–4.5 –3.5 –2.5 –1.5 –0.5 0.5 1.5 2.5 3.5 4.5
REFERENCE DRIFT (ppm/°C)
Figure 19. AD5381 REFOUT Temperature Coefficient
WR
PD
BUSY
AVDD = DVDD = 5V
VREF = 2.5V
TA = 25°C
EXITS SOFT PD
TO MIDSCALE
VOUT
VOUT
03731-0-038
AVDD = DVDD = 5V
VREF = 2.5V
TA = 25°C
EXITS HARDWARE PD
TO MIDSCALE
Figure 17. Exiting Soft Power Down
Figure 20. Exiting Hardware Power Down
Rev. A | Page 19 of 36
03731-0-048
04598-0-050
5
03731-0-045
NUMBER OF UNITS
8
AD5381
6
6
AVDD = DVDD = 3V
VREF = 1.25V
TA = 25°C
FULLSCALE
5
5
AVDD = DVDD = 5V
VREF = 2.5V
TA = 25°C
3/4 SCALE
4
4
MIDSCALE
3
2
VOUT (V)
VOUT (V)
3/4 SCALE
1/4 SCALE
1
3
FULL-SCALE
MIDSCALE
2
1
ZEROSCALE
0
–20
–10
–5
–2
0
2
CURRENT (mA)
5
10
20
40
ZERO-SCALE
03731-0-039
–1
–40
–1
–40
Figure 21. AD5381-5 Output Amplifier Source and Sink Capability
0.20
5
10
20
–40
AVDD = DVDD = 5V
VREF = 2.5V
TA = 25°C
14ns/SAMPLE NUMBER
2.454
ERROR AT ZERO SINKING CURRENT
0.05
AMPLITUDE (V)
0
–0.05
2.453
2.452
2.451
(VDD–VOUT) AT FULL-SCALE SOURCING CURRENT
0
0.25
0.50
0.75
1.00
1.25
ISOURCE/ISINK (mA)
1.50
1.75
2.00
03731-0-047
–0.20
50
100
150
200 250 300 350
SAMPLE NUMBER
400
450
500
550
AVDD = DVDD = 5V
TA = 25°C
DAC LOADED WITH MIDSCALE
EXTERNAL REFERENCE
Y AXIS = 5µV/DIV
X AXIS = 100ms/DIV
AVDD = 5V
TA = 25°C
REFOUT DECOUPLED
WITH 100nF CAPACITOR
500
0
Figure 25. Adjacent Channel DAC-to-DAC Crosstalk
Figure 22. Headroom at Rails vs. Source/Sink Current
600
2.449
400
300
REFOUT = 2.5V
200
0
100
REFOUT = 1.25V
1k
10k
FREQUENCY (Hz)
100k
03731-0-047
100
AVDD = DVDD = 5V
VREF = 2.5V
TA = 25°C
EXITS SOFT PD
TO MIDSCALE
Figure 23. REFOUT Noise Spectral Density
Rev. A | Page 20 of 36
Figure 26. 0.1 Hz to 10 Hz Noise Plot
03731-0-041
2.450
03731-0-046
ERROR VOLTAGE (V)
1/4 SCALE
–2
0
2
CURRENT (mA)
2.455
–0.15
OUTPUT NOISE (nV/ Hz)
–5
2.456
0.10
–0.10
–10
Figure 24. AD5381-3 Output Amplifier Source and Sink Capability
AVDD = 5V
VREF = 2.5V
TA = 25°C
0.15
–20
03731-0-040
0
AD5381
FUNCTIONAL DESCRIPTION
DAC ARCHITECTURE—GENERAL
The AD5381 is a complete, single-supply, 40-channel voltage
output DAC that offers 12-bit resolution. The part is available in
a 100-lead LQFP package and features both a parallel and a
serial interface. This product includes an internal, software
selectable, 1.25 V/2.5 V, 10 ppm/°C reference that can be used to
drive the buffered reference inputs; alternatively, an external
reference can be used to drive these inputs. Internal/external
reference selection is via the CR8 bit in the control register;
CR10 selects the reference magnitude if the internal reference is
selected. All channels have an on-chip output amplifier with
rail-to-rail output capable of driving 5 kΩ in parallel with a
200 pF load.
VREF
AVDD
×1 INPUT
REG
×2
DAC
REG
12-BIT
DAC
c REG
VOUT
R
VOUT = 2 × VREF × x2/2n
where:
x2 is the data-word loaded to the resistor string DAC. VREF is the
internal reference voltage or the reference voltage externally
applied to the DAC REFOUT/REFIN pin. For specified
performance, an external reference voltage of 2.5 V is
recommended for the AD5381-5, and 1.25 V for the AD5381-3.
Data Decoding
The AD5381 contains a 12-bit data bus, DB11–DB0. Depending
on the value of REG1 and REG0 (see Table 11), this data is
loaded into the addressed DAC input registers, offset (c)
registers, or gain (m) registers. The format data, offset (c), and
gain (m) register contents are shown in Table 12 to Table 14.
Table 11. Register Selection
R
03732-0-005
INPUT DATA m REG
The complete transfer function for these devices can be
represented as
Figure 27. Single-Channel Architecture
The architecture of a single DAC channel consists of a 12-bit
resistor-string DAC followed by an output buffer amplifier
operating at a gain of 2. This resistor-string architecture
guarantees DAC monotonicity. The 12-bit binary digital code
loaded to the DAC register determines at what node on the
string the voltage is tapped off before being fed to the output
amplifier. Each channel on these devices contains independent
offset and gain control registers that allow the user to digitally
trim offset and gain. These registers give the user the ability to
calibrate out errors in the complete signal chain, including the
DAC, using the internal m and c registers, which hold the
correction factors. All channels are double buffered, allowing
synchronous updating of all channels using the LDAC pin.
Figure 27 shows a block diagram of a single channel on the
AD5381. The digital input transfer function for each DAC can
be represented as
x2 = [(m + 2)/ 2n × x1] + (c – 2n – 1)
where:
x2 = the data-word loaded to the resistor string DAC
x1 = the 12-bit data-word written to the DAC input register
m = the gain coefficient (default is 0xFFE). The gain coefficient
is written to the 11 most significant bits (DB11–DB1), the LSB
(DB0) of the data-word is a 0.
n = DAC resolution (n = 12 for AD5381)
c is the12-bit offset coefficient (default is 0x800).
REG1
1
1
0
0
REG0
1
0
1
0
Register Selected
Input Data Register (x1)
Offset Register (c)
Gain Register (m)
Special Function Registers (SFRs)
Table 12. DAC Data Format (REG1 = 1, REG0 = 1)
1111
1111
1000
1000
0111
0000
0000
DB11 to DB0
1111
1111
1111
1110
0000
0001
0000
0000
1111
1111
0000
0001
0000
0000
DAC Output (V)
2 VREF × (4095/4096)
2 VREF × (4094/4096)
2 VREF × (2049/4096)
2 VREF × (2048/4096)
2 VREF × (2047/4096)
2 VREF × (1/4096)
0
Table 13. Offset Data Format (REG1 = 1, REG0 = 0)
1111
1111
1000
1000
0111
0000
0000
DB11 to DB0
1111
1111
0000
0000
1111
0000
0000
1111
1110
0001
0000
1111
0001
0000
Offset (LSB)
+2048
+2047
+1
0
–1
–2047
–2048
Table 14. Gain Data Format (REG1 = 0, REG0 = 1)
1111
1011
0111
0011
0000
Rev. A | Page 21 of 36
DB11 to DB0
1111
1111
1111
1111
0000
1110
1110
1110
1110
0000
Gain Factor
1
0.75
0.5
0.25
0
AD5381
ON-CHIP SPECIAL FUNCTION REGISTERS (SFR)
Soft CLR
The AD5381 contains a number of special function registers
(SFRs), as outlined in Table 15. SFRs are addressed with
REG1 = REG0 = 0 and are decoded using address bits A5 to A0.
REG1 = REG0 = 0, A5–A0 = 000010
DB11–DB0 = Don’t Care
Table 15. SFR Register Functions (REG1 = 0, REG0 = 0)
R/W
A5
A4
A3
A2
A1
A0
Function
X
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
0
0
0
0
0
1
1
0
1
0
0
1
0
0
0
0
1
1
0
1
0
0
1
0
0
0
1
NOP (No Operation)
Write CLR Code
Soft CLR
Soft Power-Down
Soft Power-Up
Control Register Write
Control Register Read
Monitor Channel
Soft Reset
SFR COMMANDS
NOP (No Operation)
REG1 = REG0 = 0, A5–A0 = 000000
Performs no operation but is useful in serial readback mode to
clock out data on DOUT for diagnostic purposes. BUSY pulses
low during a NOP operation.
Write CLR Code
REG1 = REG0 = 0, A5–A0 = 000001
DB11–DB0 = Contain the CLR data
Bringing the CLR line low or exercising the soft clear function
will load the contents of the DAC registers with the data contained in the user configurable CLR register, and will set
VOUT0 to VOUT39 accordingly. This can be very useful for
setting up a specific output voltage in a clear condition. It is also
beneficial for calibration purposes; the user can load full scale
or zero scale to the clear code register and then issue a hardware or software clear to load this code to all DACs, removing
the need for individual writes to each DAC. Default on powerup is all zeros.
Executing this instruction performs the CLR, which is functionally the same as that provided by the external CLR pin. The
DAC outputs are loaded with the data in the CLR code register.
It takes 35 µs to fully execute the SOFT CLR, as indicated by the
BUSY low time.
Soft Power-Down
REG1 = REG0 = 0, A5–A0 = 001000
DB11–DB0 = Don’t Care
Executing this instruction performs a global power-down
feature that puts all channels into a low power mode that
reduces the analog supply current to 2 µA max and the digital
current to 20 µA max. In power-down mode, the output
amplifier can be configured as a high impedance output or
provide a 100 kΩ load to ground. The contents of all internal
registers are retained in power-down mode. No register can be
written to while in power-down.
Soft Power-Up
REG1 = REG0 = 0, A5–A0 = 001001
DB11–DB0 = Don’t Care
This instruction is used to power up the output amplifiers and
the internal reference. The time to exit power–down is 8 µs. The
hardware power-down and software function are internally
combined in a digital OR function.
Soft RESET
REG1 = REG0 = 0, A5–A0 = 001111
DB11–DB0 = Don’t Care
This instruction is used to implement a software reset. All
internal registers are reset to their default values, which
correspond to m at full scale and c at zero. The contents of the
DAC registers are cleared, setting all analog outputs to 0 V. The
soft reset activation time is 135 µs.
Rev. A | Page 22 of 36
AD5381
Table 16. Control Register Contents
MSB
CR11
CR10
CR9
CR8
CR7
CR6
CR5
CR4
CR3
CR2
CR1
LSB
CR0
Control Register Write/Read
REG1 = REG0 = 0, A5–A0 = 001100, R/W status determines if
the operation is a write (R/W = 0) or a read (R/W = 1). DB11 to
DB0 contains the control register data.
CR7 = 0: Monitor Disabled (default on power-up). When the
monitor is disabled, the MON_OUT pin assumes its normal
DAC output function.
CR6: Thermal Monitor Function. This function is used to
monitor the AD5381’s internal die temperature when enabled.
The thermal monitor powers down the output amplifiers when
the temperature exceeds 130°C. This function can be used to
protect the device in cases where power dissipation may be
exceeded if a number of output channels are simultaneously
short-circuited. A soft power-up will re-enable the output
amplifiers if the die temperature has dropped below 130°C.
Control Register Contents
CR11: Power-Down Status. This bit is used to configure the
output amplifier state in power down.
CR11 = 1. Amplifier output is high impedance (default on
power-up).
CR11 = 0. Amplifier output is 100 kΩ to ground.
CR6 = 1: Thermal Monitor Enabled.
CR10: REF Select. This bit selects the operating internal
reference for the AD5381. CR10 is programmed as follows:
CR6 = 0: Thermal Monitor Disabled (default on power- up).
CR10 = 1: Internal reference is 2.5 V (AD5381-5 default), the
recommended operating reference for AD5381-5.
CR10 = 0: Internal reference is 1.25 V (AD5381-3 default),
the recommended operating reference for AD5381-3.
CR9: Current Boost Control. This bit is used to boost the
current in the output amplifier, thereby altering its slew rate.
This bit is configured as follows:
CR9 = 1: Boost Mode On. This maximizes the bias current in
the output amplifier, optimizing its slew rate but increasing
the power dissipation.
CR9 = 0: Boost Mode Off (default on power-up). This
reduces the bias current in the output amplifier and reduces
the overall power consumption.
CR8: Internal/External Reference. This bit determines if the
DAC uses its internal reference or an externally applied
reference.
CR5: Don’t Care.
CR4 to CR0: Toggle Function Enable. This function allows the
user to toggle the output between two codes loaded to the A and
B register for each DAC. Control register bits CR4 to CR0 are
used to enable individual groups of eight channels for operation in toggle mode. A Logic 1 written to any bit enables a group
of channels; a Logic 0 disables a group. LDAC is used to toggle
between the two registers.
Table 17.
CR Bit
CR4
CR3
CR2
CR1
CR0
Group
4
3
2
1
0
Channels
32–39
24–31
16–23
8–15
0–7
Channel Monitor Function
CR8 = 1: Internal Reference Enabled. The reference output
depends on data loaded to CR10.
CR8 = 0: External Reference Selected (default on power up).
CR7: Channel Monitor Enable (see Channel Monitor Function)
CR7= 1: Monitor Enabled. This enables the channel monitor
function. After a write to the monitor channel in the SFR
register, the selected channel output is routed to the
MON_OUT pin. VOUT 39 operates at the MON_OUT pin.
REG1 = REG0 = 0, A5–A0 = 001010
DB11–DB6 = Contain data to address the monitored channel.
A channel monitor function is provided on the AD5381. This
feature, which consists of a multiplexer addressed via the
interface, allows any channel output to be routed to the
MON_OUT pin for monitoring using an external ADC. In
channel monitor mode, VOUT 39 becomes the MON_OUT pin,
to which all monitored pins are routed. The channel monitor
function must be enabled in the control register before any
channels are routed to MON_OUT. On the AD5381, DB11 to
DB6 contain the channel address for the monitored channel.
Selecting channel address 63 three-states MON_OUT.
Rev. A | Page 23 of 36
AD5381
Table 18. AD5381 Channel Monitor Decoding
REG1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
•
REG0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
•
A5
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
•
A4
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
•
A3
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
•
A2
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
•
A1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
•
A0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
•
DB11
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
•
DB10
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
•
DB9
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
•
DB8
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
•
DB8
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
•
DB6
0
1
0
1
0
1
0
0
1
0
1
0
1
0
0
1
0
1
0
1
0
0
1
0
1
0
1
0
0
1
0
1
0
1
0
1
0
1
0
1
•
DB5–DB0
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
•
MON_OUT
VOUT 0
VOUT 1
VOUT 2
VOUT 3
VOUT 4
VOUT 5
VOUT 6
VOUT 7
VOUT 8
VOUT 9
VOUT 10
VOUT 11
VOUT 12
VOUT 13
VOUT 14
VOUT 15
VOUT 16
VOUT 17
VOUT 18
VOUT 19
VOUT 20
VOUT 21
VOUT 22
VOUT 23
VOUT 24
VOUT 25
VOUT 26
VOUT 27
VOUT 28
VOUT 29
VOUT 30
VOUT 31
VOUT 32
VOUT 33
VOUT 34
VOUT 35
VOUT 36
VOUT 37
VOUT 38
Undefined
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
0
0
0
0
0
0
0
0
1
1
0
0
1
1
0
0
1
1
1
1
1
1
1
1
1
1
0
1
X
X
Undefined
Three-State
REG1 REG0 A5 A4 A3 A2 A1 A0
0
0
0
0
1
0
1
0
VOUT0
VOUT1
AD5381
CHANNEL
MONITOR
DECODING
VOUT39/MON_OUT
CHANNEL ADDRESS
DB11–DB6
Figure 28. Channel Monitor Decoding
Rev. A | Page 24 of 36
03732-0-006
VOUT37
VOUT38
AD5381
HARDWARE FUNCTIONS
RESET FUNCTION
FIFO OPERATION IN PARALLEL MODE
Bringing the RESET line low resets the contents of all internal
registers to their power-on reset state. Reset is a negative edgesensitive input. The default corresponds to m at full-scale and to
c at zero. The contents of the DAC registers are cleared, setting
VOUT 0 to VOUT 39 to 0 V. This sequence takes 270 µs. The
falling edge of RESET initiates the reset process; BUSY goes low
for the duration, returning high when RESET is complete. While
BUSY is low, all interfaces are disabled and all LDAC pulses are
ignored. When BUSY returns high, the part resumes normal
operation and the status of the RESET pin is ignored until the
next falling edge is detected.
The AD5381 contains a FIFO to optimize operation when
operating in parallel interface mode. The FIFO Enable (level
sensitive, active high) is used to enable the internal FIFO. When
connected to DVDD, the internal FIFO is enabled, allowing the
user to write to the device at full speed. FIFO is only available in
parallel interface mode. The status of the FIFO_EN pin is
sampled on power-up, and after a CLR or RESET, to deter-mine
if the FIFO is enabled. In either serial or I2C interface modes,
FIFO_EN should be tied low. Up to 128 successive instructions
can be written to the FIFO at maximum speed in parallel mode.
When the FIFO is full, any further writes to the device are
ignored. Figure 29 shows a comparison between FIFO mode
and non-FIFO mode in terms of channel update time. Figure 29
also outlines digital loading time.
ASYNCHRONOUS CLEAR FUNCTION
Bringing the CLR line low clears the contents of the DAC
registers to the data contained in the user configurable CLR
register and sets VOUT 0 to VOUT 39 accordingly. This function can be used in system calibration to load zero-scale and
full-scale to all channels. The execution time for a CLR is 35 µs.
25
WITHOUT FIFO
(CHANNEL UPDATE TIME)
20
BUSY AND LDAC FUNCTIONS
TIME (µs)
15
10
WITH FIFO
(CHANNEL UPDATE TIME)
5
WITH FIFO
(DIGITAL LOADING TIME)
0
1
4
7
10
13 16 19 22 25 28
NUMBER OF WRITES
31
34
37
40
03731-0-018
BUSY is a digital CMOS output that indicates the status of the
AD5381. The value of x2, the internal data loaded to the DAC
data register, is calculated each time the user writes new data to
the corresponding x1, c, or m registers. During the calculation
of x2, the BUSY output goes low. While BUSY is low, the user
can continue writing new data to the x1, m, or c registers, but no
DAC output updates can take place. The DAC outputs are
updated by taking the LDAC input low. If LDAC goes low while
BUSY is active, the LDAC event is stored and the DAC outputs
update immediately after BUSY goes high. The user may hold
the LDAC input permanently low, in which case the DAC
outputs update immediately after BUSY goes high. BUSY also
goes low during power-on reset and when a falling edge is
detected on the RESET pin. During this time, all interfaces are
disabled and any events on LDAC are ignored. The AD5381
contains an extra feature whereby a DAC register is not updated
unless its x2 register has been written to since the last time
LDAC was brought low. Normally, when LDAC is brought low,
the DAC registers are filled with the contents of the x2 registers.
However, the AD5381 will only update the DAC register if the
x2 data has changed, thereby removing unnecessary digital
crosstalk.
Figure 29. Channel Update Rate (FIFO vs. NON-FIFO)
POWER-ON RESET
The AD5381 contains a power-on reset generator and state
machine. The power-on reset resets all registers to a predefined
state and configures the analog outputs as high impedance. The
BUSY pin goes low during the power-on reset sequencing,
preventing data writes to the device.
POWER-DOWN
The AD5381 contains a global power-down feature that puts all
channels into a low power mode and reduces the analog power
consumption to 2 µA max and digital power consumption to
20 µA max. In power-down mode, the output amplifier can be
configured as a high impedance output or can provide a 100 kΩ
load to ground. The contents of all internal registers are
retained in power-down mode. When exiting power-down, the
settling time of the amplifier will elapse before the outputs settle
to their correct values.
Rev. A | Page 25 of 36
AD5381
AD5381 INTERFACES
The AD5381 contains both parallel and serial interfaces.
Furthermore, the serial interface can be programmed to be
either SPI, DSP, MICROWIRE, or I2C compatible. The SER/PAR
pin selects parallel and serial interface modes. In serial mode,
the SPI/I2C pin is used to select DSP, SPI, MICROWIRE, or I2C
interface mode.
The devices use an internal FIFO memory to allow high speed
successive writes in parallel interface mode. The user can continue writing new data to the device while write instructions are
being executed. The BUSY signal indicates the current status of
the device, going low while instructions in the FIFO are being
executed. In parallel mode, up to 128 successive instructions can
be written to the FIFO at maximum speed. When the FIFO is
full, any further writes to the device are ignored.
To minimize both the power consumption of the device and the
on-chip digital noise, the active interface only powers up fully
when the device is being written to, i.e., on the falling edge of
WR or the falling edge of SYNC.
DSP, SPI, MICROWIRE COMPATIBLE SERIAL
INTERFACES
The serial interface can be operated with a minimum of three
wires in standalone mode or four wires in daisy-chain mode.
Daisy chaining allows many devices to be cascaded together to
increase system channel count. The SER/PAR pin must be tied
high and the SPI/I2C pin (Pin 97) should be tied low to enable
the DSP/SPI/MICROWIRE compatible serial interface. In serial
interface mode, the user does not need to drive the parallel
input data pins. The serial interface’s control pins are
Figure 3 and Figure 5 show timing diagrams for a serial write to
the AD5381 in standalone and daisy-chain modes. The 24-bit
data-word format for the serial interface is shown in Table 19
A/B. When toggle mode is enabled, this pin selects whether the
data write is to the A or B register. With toggle disabled, this bit
should be set to zero to select the A data register.
R/W is the read or write control bit.
A5–A0 are used to address the input channels.
REG1 and REG0 select the register to which data is written, as
shown in Table 11.
DB11–DB0 contain the input data-word.
X is a don’t care condition.
Standalone Mode
By connecting the DCEN (Daisy-Chain Enable) pin low, standalone mode is enabled. The serial interface works with both a
continuous and a noncontinuous serial clock. The first falling
edge of SYNC starts the write cycle and resets a counter that
counts the number of serial clocks to ensure that the correct
number of bits are shifted into the serial shift register. Any
further edges on SYNC except for a falling edge are ignored
until 24 bits are clocked in. Once 24 bits have been shifted in,
the SCLK is ignored. In order for another serial transfer to take
place, the counter must be reset by the falling edge of SYNC.
SYNC, DIN, SCLK—Standard 3-Wire Interface Pins.
DCEN—Selects Standalone Mode or Daisy-Chain Mode.
SDO—Data Out Pin for Daisy-Chain Mode.
Table 19. 40-Channel, 12-bit DAC Serial Input Register Configuration
MSB
A/B
R/W
A5
A4
A3
A2
A1
A0
REG1
REG0
DB11
DB10
DB9
DB8
Rev. A | Page 26 of 36
DB7
DB6
DB5
DB4
DB3
DB2
DB1
DB0
X
LSB
X
AD5381
Daisy-Chain Mode
Readback Mode
For systems that contain several devices, the SDO pin may be
used to daisy-chain several devices together. This daisy-chain
mode can be useful in system diagnostics and in reducing the
number of serial interface lines.
Readback mode is invoked by setting the R/W bit = 1 in the
serial input register write. With R/W = 1, Bits A5 to A0, in
association with Bits REG1 and REG0, select the register to be
read. The remaining data bits in the write sequence are don’t
cares. During the next SPI write, the data appearing on the SDO
output will contain the data from the previously addressed
register. For a read of a single register, the NOP command can
be used in clocking out the data from the selected register on
SDO. Figure 30 shows the readback sequence. For example, to
read back the M register of Channel 0 on the AD5381, the
following sequence should be implemented. First, write
0x404XXX to the AD5381 input register. This configures the
AD5381 for read mode with the m register of Channel 0
selected. Note that data bits DB11 to DB0 are don’t cares. Follow
this with a second write, a NOP condition, 0x000000. During
this write, the data from the m register is clocked out on the
DOUT line, i.e., data clocked out will contain the data from the
m register in Bits DB11 to DB0, and the top 10 bits contain the
address information as previously written. In readback mode,
the SYNC signal must frame the data. Data is clocked out on the
rising edge of SCLK and is valid on the falling edge of the SCLK
signal. If the SCLK idles high between the write and read
operations of a readback operation, the first bit of data is
clocked out on the falling edge of SYNC.
By connecting the DCEN (Daisy-Chain Enable) pin high, daisychain mode is enabled. The first falling edge of SYNC starts the
write cycle. The SCLK is continuously applied to the input shift
register when SYNC is low. If more than 24 clock pulses are
applied, the data ripples out of the shift register and appears on
the SDO line. This data is clocked out on the rising edge of
SCLK and is valid on the falling edge. By connecting the SDO of
the first device to the DIN input on the next device in the chain,
a multidevice interface is constructed. Twenty-four clock pulses
are required for each device in the system. Therefore, the total
number of clock cycles must equal 24N, where N is the total
number of AD538x devices in the chain.
When the serial transfer to all devices is complete, SYNC is
taken high. This latches the input data in each device in the
daisy-chain and prevents any further data from being clocked
into the input shift register.
If the SYNC is taken high before 24 clocks are clocked into the
part, this is considered a bad frame and the data is discarded.
The serial clock may be either a continuous or a gated clock. A
continuous SCLK source can only be used if it can be arranged
that SYNC is held low for the correct number of clock cycles. In
gated clock mode, a burst clock containing the exact number of
clock cycles must be used and SYNC must be taken high after
the final clock to latch the data.
SCLK
24
48
SYNC
DB23
DB0
DB23
INPUT WORD SPECIFIES REGISTER TO BE READ
SDO
DB23
DB0
UNDEFINED
DB0
NOP CONDITION
DB23
SELECTED REGISTER DATA CLOCKED OUT
Figure 30. Serial Readback Operation
Rev. A | Page 27 of 36
DB0
03731-0-019
DIN
AD5381
I2C SERIAL INTERFACE
The AD5381 features an I2C compatible 2-wire interface
consisting of a serial data line (SDA) and a serial clock line
(SCL). SDA and SCL facilitate communication between the
AD5381 and the master at rates up to 400 kHz. Figure 6 shows
the 2-wire interface timing diagrams that incorporate three
different modes of operation. In selecting the I2C operating
mode, first configure serial operating mode (SER/PAR = 1) and
then select I2C mode by configuring the SPI/I2C pin to a Logic
1. The device is connected to the I2C bus as a slave device (i.e.,
no clock is generated by the AD5381). The AD5381 has a 7-bit
slave address 1010 1(AD1)(AD0). The 5 MSB are hard-coded
and the 2 LSB are determined by the state of the AD1 and AD0
pins. The facility to hardware configure AD1 and AD0 allows
four of these devices to be configured on the bus.
2
I C Data Transfer
One data bit is transferred during each SCL clock cycle. The
data on SDA must remain stable during the high period of the
SCL clock pulse. Changes in SDA while SCL is high are control
signals that configure START and STOP conditions. Both SDA
and SCL are pulled high by the external pull-up resistors when
the I2C bus is not busy.
START and STOP Conditions
A master device initiates communication by issuing a START
condition. A START condition is a high-to-low transition on
SDA with SCL high. A STOP condition is a low-to-high
transition on SDA while SCL is high. A START condition from
the master signals the beginning of a transmission to the
AD5381. The STOP condition frees the bus. If a repeated
START condition (Sr) is generated instead of a STOP condition,
the bus remains active.
Repeated START Conditions
A repeated START (Sr) condition may indicate a change of data
direction on the bus. Sr may be used when the bus master is
writing to several I2C devices and wants to maintain control of
the bus.
Acknowledge Bit (ACK)
The acknowledge bit (ACK) is the ninth bit attached to any
8-bit data-word. ACK is always generated by the receiving
device. The AD5381 devices generate an ACK when receiving
an address or data by pulling SDA low during the ninth clock
period. Monitoring ACK allows for detection of unsuccessful
data transfers. An unsuccessful data transfer occurs if a
receiving device is busy or if a system fault has occurred. In the
event of an unsuccessful data transfer, the bus master should
reattempt communication.
AD5381 Slave Addresses
A bus master initiates communication with a slave device by
issuing a START condition followed by the 7-bit slave address.
When idle, the AD5381 waits for a START condition followed
by its slave address. The LSB of the address word is the Read/
Write (R/W) bit. The AD5381 is a receive only device; when
communicating with the AD5381, R/W = 0. After receiving the
proper address 1010 1(AD1)(AD0), the AD5381 issues an ACK
by pulling SDA low for one clock cycle.
The AD5381 has four different user programmable addresses
determined by the AD1 and AD0 bits.
Write Operation
There are three specific modes in which data can be written to
the AD5381 DAC.
4-Byte Mode
When writing to the AD5381 DACs, the user must begin with
an address byte (R/W = 0) after which the DAC acknowledges
that it is prepared to receive data by pulling SDA low. The
address byte is followed by the pointer byte; this addresses the
specific channel in the DAC to be addressed and is also
acknowledged by the DAC. Two bytes of data are then written
to the DAC, as shown in Figure 31. A STOP condition follows.
This allows the user to update a single channel within the
AD5381 at any time and requires four bytes of data to be
transferred from the master.
3-Byte Mode
In 3-byte mode, the user can update more than one channel in a
write sequence without having to write the device address byte
each time. The device address byte is only required once; subsequent channel updates require the pointer byte and the data
bytes. In 3-byte mode, the user begins with an address byte
(R/W = 0), after which the DAC will acknowledge that it is
prepared to receive data by pulling SDA low. The address byte is
followed by the pointer byte. This addresses the specific channel
in the DAC to be addressed and is also acknowledged by the
DAC. This is then followed by the two data bytes. REG1 and
REG0 determine the register to be updated.
If a STOP condition does not follow the data bytes, another
channel can be updated by sending a new pointer byte followed
by the data bytes. This mode only requires three bytes to be sent
to update any channel once the device has been initially
addressed, and reduces the software overhead in updating the
AD5381 channels. A STOP condition at any time exits this
mode. Figure 32 shows a typical configuration.
Rev. A | Page 28 of 36
AD5381
SCL
1
SDA
0
1
0
1
AD1
AD0
START COND
BY MASTER
R/W
0
ACK BY
AD538x
MSB
0
A5
A4
A3
A2
A1
A0
ACK BY
AD538x
ADDRESS BYTE
POINTER BYTE
SCL
REG1
REG0
MSB
LSB
MSB
LSB
ACK BY
AD538x
ACK BY
AD538x
MOST SIGNIFICANT BYTE
LEAST SIGNIFICANT BYTE
STOP
COND
BY
MASTER
03731-0-020
SDA
Figure 31. 4-Byte AD5381, I2C Write Operation
SCL
SDA
1
0
1
0
1
AD1
AD0
START COND
BY MASTER
R/W
0
ACK BY
AD538x
MSB
0
ADDRESS BYTE
A5
A4
A3
A2
A1
A0
ACK BY
AD538x
POINTER BYTE FOR CHANNEL "N"
SCL
SDA
REG1
REG0
MSB
LSB
MSB
LSB
ACK BY
AD538x
ACK BY
AD538x
MOST SIGNIFICANT DATA BYTE
LEAST SIGNIFICANT DATA BYTE
DATA FOR CHANNEL "N"
SCL
SDA
0
0
A5
A4
A3
A2
A1
A0
MSB
ACK BY
AD538x
POINTER BYTE FOR CHANNEL "NEXT CHANNEL"
SCL
REG1
REG0
MSB
LSB
MSB
LSB
ACK BY
AD538x
MOST SIGNIFICANT DATA BYTE
ACK BY
AD538x
LEAST SIGNIFICANT DATA BYTE
DATA FOR CHANNEL "NEXT CHANNEL"
Figure 32. 3-Byte AD5381, I2C Write Operation
Rev. A | Page 29 of 36
STOP COND
BY MASTER
03731-0-021
SDA
AD5381
2-Byte Mode
PARALLEL INTERFACE
Following initialization of 2-byte mode, the user can update
channels sequentially. The device address byte is only required
once and the pointer address pointer is configured for autoincrement or burst mode.
The SER/PAR pin must be tied low to enable the parallel
interface and disable the serial interfaces. Figure 7 shows the
timing diagram for a parallel write. The parallel interface is
controlled by the following pins:
The user must begin with an address byte (R/W = 0), after
which the DAC acknowledges that it is prepared to receive data
by pulling SDA low. The address byte is followed by a specific
pointer byte (0xFF) that initiates the burst mode of operation.
The address pointer initializes to Channel 0, the data following
the pointer is loaded to Channel 0, and the address pointer
automatically increments to the next address.
CS Pin
Active Low Device Select Pin.
WR Pin
On the rising edge of WR, with CS low, the addresses on Pins
A5 to A0 are latched; data present on the data bus is loaded into
the selected input registers.
REG0, REG1 Pins
The REG0 and REG1 bits in the data byte determine which
register will be updated. In this mode, following the initialization, only the two data bytes are required to update a channel.
The channel address automatically increments from Address 0
to Channel 39 and then returns to the normal 3-byte mode of
operation. This mode allows transmission of data to all
channels in one block and reduces the software overhead in
configuring all channels. A STOP condition at any time exits
this mode. Toggle mode is not supported in 2-byte mode.
Figure 33 shows a typical configuration.
The REG0 and REG1 pins determine the destination register of
the data being written to the AD5381. See Table 11.
Pins A5 to A0
Each of the 40 DAC channels can be addressed individually.
Pins DB11 to DB0
The AD5381 accepts a straight 12-bit parallel word on DB11 to
DB0, where DB11 is the MSB and DB0 is the LSB.
SCL
SDA
1
0
1
0
1
AD1
START COND
BY MASTER
AD0
R/W
A7 = 1
ACK BY
CONVERTER
MSB
A6 = 1 A5 = 1
A4 = 1 A3 = 1 A2 = 1
A1 = 1 A0 = 1
ACK BY
CONVERTER
ADDRESS BYTE
POINTER BYTE
SCL
SDA
REG1
REG0
MSB
LSB
MSB
LSB
ACK BY
AD538x
ACK BY
AD538x
MOST SIGNIFICANT DATA BYTE
LEAST SIGNIFICANT DATA BYTE
CHANNEL 0 DATA
SCL
SDA
REG1
REG0
MSB
LSB
MSB
LSB
ACK BY
CONVERTER
ACK BY
CONVERTER
MOST SIGNIFICANT DATA BYTE
LEAST SIGNIFICANT DATA BYTE
CHANNEL 1 DATA
SCL
REG1
REG0
MSB
LSB
MSB
LSB
ACK BY
CONVERTER
MOST SIGNIFICANT DATA BYTE
LEAST SIGNIFICANT DATA BYTE
CHANNEL N DATA FOLLOWED BY STOP
Figure 33. 2-Byte, 12C Write Operation
Rev. A | Page 30 of 36
ACK BY
STOP
CONVERTER COND
BY
MASTER
03731-0-022
SDA
AD5381
MICROPROCESSOR INTERFACING
The AD5381 can be interfaced to a variety of 16-bit microcontrollers or DSP processors. Figure 35 shows the AD5381 family
interfaced to a generic 16-bit microcontroller/DSP processor.
The lower address lines from the processor are connected to
A0–A5 on the AD5381. The upper address lines are decoded to
provide a CS, LDAC signal for the AD5381. The fast interface
timing of the AD5381 allows direct interface to a wide variety of
microcontrollers and DSPs, as shown in Figure 35.
being transmitted to the AD5381, the SYNC line is taken low
(PC7). Data appearing on the MOSI output is valid on the
falling edge of SCK. Serial data from the 68HC11 is transmitted
in 8-bit bytes with only eight falling clock edges occurring in
the transmit cycle.
DVDD
MC68HC11
RESET
AD5381 to MC68HC11
The serial peripheral interface (SPI) on the MC68HC11 is
configured for Master mode (MSTR = 1), Clock Polarity bit
(CPOL) = 0, and the Clock Phase bit (CPHA) = 1. The SPI is
configured by writing to the SPI control register (SPCR)—see
the 68HC11 User Manual. SCK of the 68HC11 drives the SCLK
of the AD5381, the MOSI output drives the serial data line (DIN)
of the AD5381, and the MISO input is driven from DOUT. The
SYNC signal is derived from a port line (PC7). When data is
MISO
SDO
MOSI
DIN
SCK
SCLK
PC7
SYNC
SPI/I2C
Figure 34. AD5381-to-MC68HC11 Interface
µCONTROLLER/
DSP PROCESSOR*
AD5381
D15
REG1
REG0
D11
DATA
BUS
D0
D0
ADDRESS
DECODE
CS
LDAC
A5
A5
A4
A4
A3
A3
A2
A2
A1
A1
A0
A0
R/W
WR
*ADDITIONAL PINS OMITTED FOR CLARITY
Figure 35. AD5381-to-Parallel Interface
Rev. A | Page 31 of 36
03732-0-008
UPPER BITS OF
ADDRESS BUS
AD5381
SER/PAR
03731-0-024
Parallel Interface
AD5381
AD5381 to PIC16C6x/7x
DVDD
AD5381
SER/PAR
SDO
SDO/RC5
DIN
SCK/RC3
SCLK
RA1
SYNC
SPI/I2C
03732-0-009
RESET
SDI/RC4
Figure 36. AD5381-to-PIC16C6x/7x Interface
RESET
RxD
SDO
DIN
TxD
SCLK
P1.1
SYNC
SPI/I2C
Figure 37. AD5381-to-8051 Interface
AD5381 to ADSP-2101/ADSP-2103
Figure 38 shows a serial interface between the AD5381 and the
ADSP-2101/ADSP-2103. The ADSP-2101/ADSP-2103 should
be set up to operate in SPORT transmit alternate framing mode.
The ADSP-2101/ADSP-2103 SPORT is 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.
ADSP-2101/
ADSP-2103
AD5381 to 8051
AD5381
SER/PAR
03732-0-010
The PIC16C6x/7x synchronous serial port (SSP) is configured
as an SPI master with the Clock Polarity bit = 0. This is done by
writing to the synchronous serial port control register
(SSPCON). See the PIC16/17 Microcontroller User Manual. In
this example I/O, port RA1 is being used to pulse SYNC and
enable the serial port of the AD5381. This microcontroller
transfers only eight bits of data during each serial transfer
operation; therefore, three consecutive read/write operations
may be needed depending on the mode. Figure 36 shows the
connection diagram.
PIC16C6X/7X
DVDD
8XC51
DVDD
AD5381
SER/PAR
RESET
Rev. A | Page 32 of 36
DR
SDO
DT
DIN
SCK
TFS
RFS
SCLK
SYNC
SPI/I2C
Figure 38. AD5381-to-ADSP-2101/ADSP-2103 Interface
03732-0-011
The AD5381 requires a clock synchronized to the serial data.
The 8051 serial interface must therefore be operated in Mode 0.
In this mode, serial data enters and exits through RxD, and a
shift clock is output on TxD. Figure 37 shows how the 8051 is
connected to the AD5381. Because the AD5381 shifts data out
on the rising edge of the shift clock and latches data in on the
falling edge, the shift clock must be inverted. The AD5381
requires its data to be MSB first. Since the 8051 outputs the LSB
first, the transmit routine must take this into account.
AD5381
APPLICATION INFORMATION
In any circuit where accuracy is important, careful consideration of the power supply and ground return layout helps to
ensure the rated performance. The printed circuit board on
which the AD5381 is mounted should be designed so that the
analog and digital sections are separated and confined to
certain areas of the board. If the AD5381 is in a system where
multiple devices require an AGND-to-DGND connection, the
connection should be made at one point only, a star ground
point established as close to the device as possible.
For supplies with multiple pins (AVDD, DVDD), these pins should
be tied together. The AD5381 should have ample supply bypassing of 10 µF in parallel with 0.1 µF on each supply, located as
close to the package as possible and ideally right up against the
device. The 10 µF capacitors are the tantalum bead type. The
0.1 µF capacitor should have low effective series resistance
(ESR) and effective series inductance (ESI), like the common
ceramic types that provide a low impedance path to ground at
high frequencies, to handle transient currents due to internal
logic switching.
The power supply lines of the AD5381 should use as large a
trace as possible to provide low impedance paths and reduce the
effects of glitches on the power supply line. Fast switching
signals such as clocks should be shielded with digital ground to
avoid radiating noise to other parts of the board, and should
never be run near the reference inputs. A ground line routed
between the DIN and SCLK lines will help reduce crosstalk
between them (this is not required on a multilayer board
because there will be a separate ground plane, but separating the
lines will help). It is essential to minimize noise on the VIN and
REFIN lines.
an ADR421 or ADR431 2.5 V reference. Suitable external
references for the AD5381-3 include the ADR280 1.2 V
reference. The reference should be decoupled at the
REFOUT/REFIN pin of the device with a 0.1 µF capacitor.
AVDD
DVDD
0.1µF
10µF
ADR431/
ADR421
0.1µF
AVDD
DVDD
VOUT0
REFOUT/REFIN
0.1µF
AD5381-5
REFGND
VOUT39
DAC
GND
SIGNAL
GND
AGND
DGND
03732-0-012
POWER SUPPLY DECOUPLING
Figure 39. Typical Configuration with External Reference
Figure 40 shows a typical configuration when using the internal
reference. On power-up, the AD5381 defaults to an external
reference; therefore, the internal reference needs to be
configured and turned on via a write to the AD5381 control
register. Control Register Bit CR10 allows the user choose the
reference value; Bit CR8 is used to select the internal reference.
It is recommended to use the 2.5 V reference when AVDD = 5 V,
and the 1.25 V reference when AVDD = 3 V.
AVDD
DVDD
0.1µF
10µF
Avoid crossover of digital and analog signals. Traces on opposite
sides of the board should run at right angles to each other. This
reduces the effects of feedthrough through the board. A microstrip technique is by far the best, but is not always possible with
a double-sided board. In this technique, the component side of
the board is dedicated to the ground plane while signal traces
are placed on the solder side.
0.1µF
AVDD
DVDD
REFOUT/REFIN
0.1µF
VOUT0
AD5381
REFGND
VOUT39
SIGNAL
GND
AGND
DGND
03732-0-013
DAC
GND
TYPICAL CONFIGURATION CIRCUIT
Figure 39 shows a typical configuration for the AD5381-5 when
configured for use with an external reference. In the circuit
shown, all AGND, SIGNAL_GND, and DAC_GND pins are tied
together to a common AGND. AGND and DGND are
connected together at the AD5381 device. On power-up, the
AD5381 defaults to external reference operation. All AVDD lines
are connected together and driven from the same 5 V source. It
is recommended to decouple close to the device with a 0.1 µF
ceramic and a 10 µF tantalum capacitor. In this application, the
reference for the AD5381-5 is provided externally from either
Figure 40. Typical Configuration with Internal Reference
Digital connections have been omitted for clarity. The AD5381
contains an internal power- on reset circuit with a 10 ms
brownout time. If the power supply ramp rate exceeds 10 ms,
the user should reset the AD5381 as part of the initialization
process to ensure the calibration data gets loaded correctly into
the device.
Rev. A | Page 33 of 36
AD5381
AD5381 MONITOR FUNCTION
The AD5381 contains a channel monitor function that consists
of a multiplexer addressed via the interface, allowing any channel output to be routed to this pin for monitoring using an
external ADC. In channel monitor mode, VOUT 39 becomes
the MON_OUT pin, to which all monitored signals are routed.
The channel monitor function must be enabled in the control
register before any channels are routed to MON_OUT. Table 18
contains the decoding information required to route any channel to MON_OUT. Selecting Channel Address 63 three-states
MON_OUT. Figure 41 shows a typical monitoring circuit implemented using a 12-bit SAR ADC in a 6-lead SOT-23 package.
The controller output port selects the channel to be monitored,
and the input port reads the converted data from the ADC.
AVDD
DIN
SYNC
SCLK
OUTPUT PORT
VDD
AD5381
CS
SCLK
VIN
INPUT PORT
SDATA
GND
DAC_GND SIGNAL_GND
03732-0-014
VOUT38
LDAC is used to switch between the A and B registers in
determining the analog output. The first LDAC configures the
output to reflect data in the A registers. This mode offers significant advantages if the user wants to generate a square wave at
the output of all 40 channels, as might be required to drive a
liquid crystal based variable optical attenuator. In this case, the
user writes to the control register and enables the toggle function by setting CR4 to CR2 = 0, thus enabling the five groups of
eight for toggle mode operation. The user must then load data
to all 40 A and B registers. Toggling LDAC sets the output
values to reflect the data in the A and B registers. The LDAC’s
frequency determines the frequency of the square wave output.
THERMAL MONITOR FUNCTION
CONTROLLER
AGND
2.
3.
4.
Enable toggle mode for the required channels via the
control register.
Load data to A registers.
Load data to B registers.
Apply LDAC.
Toggle mode is disabled via the control register. The first LDAC
following the disabling of the toggle mode will update the
outputs with the data contained in the A registers.
AD7476
VOUT39/MON_OUT
1.
Figure 41. Typical Channel Monitoring Circuit
TOGGLE MODE FUNCTION
The toggle mode function allows an output signal to be generated using the LDAC control signal that switches between two
DAC data registers. This function is configured using the SFR
control register as follows. A write with REG1 = REG0 = 0 and
A5–A0 = 001100 specifies a control register write. The toggle
mode function is enabled in groups of eight channels using Bits
CR4 to CR0 in the control register. See the AD5381 control
register description. Figure 42 shows a block diagram of toggle
mode implementation. Each of the 40 DAC channels on the
AD5381 contain an A and B data register. Note that B registers
The AD5381 contains a temperature shutdown function to
protect the chip in case multiple outputs are shorted. The short
circuit current of each output amplifier is typically 40 mA.
Operating the AD5381 at 5 V leads to a power dissipation of
200 mW per shorted amplifier. With five channels shorted, this
leads to an extra watt of power dissipation. For the 100-lead
LQFP, the θJA is typically 44°C/W.
The thermal monitor is enabled by the user via CR6 in the
control register. The output amplifiers on the AD5381 are
automatically powered down if the die temperature exceeds
approximately 130°C. After a thermal shutdown has occurred,
the user can re-enable the part by executing a soft power-up if
the temperature has dropped below 130°C or by turning off the
thermal monitor function via the control register.
DATA
REGISTER
A
DAC
REGISTER
INPUT
INPUT
DATA REGISTER
12-BIT DAC
VOUT
DATA
REGISTER
B
LDAC
CONTROL INPUT
A/B
Figure 42. Toggle Mode Function
Rev. A | Page 34 of 36
03732-0-015
VOUT0
can only be loaded when toggle mode is enabled. The sequence
of events when configuring the AD5381 for toggle mode is
AD5381
OPTICAL ATTENUATORS
UTILIZING THE AD5381 FIFO
Based on its high channel count, high resolution, monotonic
behavior, and high level of integration, the AD5381 is ideally
targeted at optical attenuation applications used in dynamic
gain equalizers, variable optical attenuators (VOA), and optical
add-drop multiplexers (OADM). In these applications, each
wavelength is individually extracted using an arrayed wave
guide; its power is monitored using a photodiode, transimpedance amplifier and ADC in a closed-loop control system. The
AD5381 controls the optical attenuator for each wavelength,
ensuring that the power is equalized in all wavelengths before
being multiplexed onto the fiber. This prevents information loss
and saturation from occurring at amplification stages further
along the fiber.
The AD5381 FIFO mode optimizes total system update rates in
applications where a large number of channels need to be
updated. FIFO mode is only available when parallel interface
mode is selected. The FIFO_EN pin is used to enable the FIFO.
The status of FIFO_EN is sampled during the initialization
sequence. Therefore, the FIFO status can only be changed by
resetting the device. In a telescope that provides for the cancellation of atmospheric distortion, for example, a large number of
channels need to be updated in a short period of time. In such
systems, as many as 400 channels need to be updated within
40 µs. Four-hundred channels requires the use of 10 AD5381s.
With FIFO mode enabled, the data write cycle time is 40 ns;
therefore, each group consisting of 40 channels can be fully
loaded in 1.6 µs. In FIFO mode, a complete group of 40 channels will update in 14.4 µs. The time taken to update all 400
channels is 14.4 µs + 9 × 1.6 µs = 28.8 µs. Figure 44 shows the
FIFO operation scheme.
ADD
PORTS
DROP
PORTS
OPTICAL
SWITCH
PHOTODIODES
11
ATTENUATOR
12
DWDM
IN
DWDM
OUT
ATTENUATOR
FIBRE AWG
AWG FIBRE
1n–1
ATTENUATOR
1n
ATTENUATOR
TIA/LOG AMP
(AD8304/AD8305)
N:1 MULTIPLEXER
CONTROLLER
16-BIT ADC
ADG731
(40:1 MUX)
AD7671
(0-5V, 1MSPS)
03732-0-016
AD5381,
40-CHANNEL,
12-BIT DAC
Figure 43. OADM Using the AD5381 as Part of an Optical Attenuator
GROUP B
CHNLS 40-79
FIFO DATA LOAD
GROUP A
1.6µs
1.6µs
14.4µs
GROUP C
CHNLS
80-119
GROUP D
CHNLS
120-159
GROUP E
CHNLS
160-199
GROUP F
CHNLS
200-239
GROUP G
CHNLS
240-279
FIFO DATA LOAD
GROUP B
GROUP I
CHNLS
320-359
FIFO DATA LOAD
GROUP J
OUTPUT UPDATE
TIME FOR GROUP A
14.4µs
GROUP H
CHNLS
280-319
OUTPUT UPDATE
TIME FOR GROUP J
OUTPUT UPDATE
TIME FOR GROUP B
TIME TO UPDATE 400 CHANNELS = 28.8µs
Figure 44. Using FIFO Mode 400 Channels Updated in Under 30 µs
Rev. A | Page 35 of 36
GROUP J
CHNLS
360-399
1.6µs
14.4µs
03731-0-032
GROUP A
CHNLS 0-39
AD5381
OUTLINE DIMENSIONS
16.00 BSC SQ
1.60 MAX
0.75
0.60
0.45
SEATING
PLANE
14.00 BSC SQ
12°
TYP
100
1
76
75
PIN 1
12.00
REF
TOP VIEW
(PINS DOWN)
10°
6°
2°
1.45
1.40
1.35
0.15
0.05
0.20
0.09
VIEW A
7°
3.5°
0°
0.08 MAX
COPLANARITY
SEATING
PLANE
25
51
50
26
0.27
0.22
0.17
0.50 BSC
VIEW A
ROTATED 90° CCW
COMPLIANT TO JEDEC STANDARDS MS-026BED
Figure 45. 100-Lead Low Profile Quad Flat Package [LQFP]
(ST-100)
Dimensions shown in millimeters
ORDERING GUIDE
Model
AD5381BST-3
AD5381BST-3-REEL
AD5381BST-5
AD5381BST-5-REEL
EVAL-AD5381EB
Resolution
12 Bits
12 Bits
12 Bits
12 Bits
Temperature
Range
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
AVDD
Range
2.7 V to 3.6 V
2.7 V to 3.6 V
4.5 V to 5.5 V
4.5 V to 5.5 V
Output
Channels
40
40
40
40
Linearity
Error (LSB)
±1
±1
±1
±1
Package
Description
100-Lead LQFP
100-Lead LQFP
100-Lead LQFP
100-Lead LQFP
Evaluation Kit
Package
Option
ST-100
ST-100
ST-100
ST-100
Purchase of licensed I2C components of Analog Devices or one of its sublicensed Associated Companies conveys a license for the purchaser under the Philips I2C Patent
Rights to use these components in an I2C system, provided that the system conforms to the I2C Standard Specification as defined by Philips.
© 2004 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D03732–0–6/04(A)
Rev. A | Page 36 of 36