AD AD9725

14-Bit, 600+ MSPS
D/A Converter
AD9725
Preliminary Technical Data
FUNCTIONAL BLOCK DIAGRAM
FEATURES
600+ MSPS DAC update rate
16/14/12/10-bit resolution family
LVDS interface with built-in 100-termination resistors
Single data rate and double data rate capability
Excellent dynamic performance
SFDR = 63 dBc at 140 MHz
IMD = 73 dBc at 140 MHz
Differential current outputs: 2 mA to 20 mA
–40°C to +85°C temperature range operation
On-chip 1.20 V reference
Package: 80-lead thermally-enhanced TQFP
Versatile clock and data interface
CALIBRATION
REFERENCE
FSADJ
REFIO
IOUTA
DB[13:0]+
DB[13:0]–
DATA
FORMATTER
DATA SYNC.
14-BIT
DAC
IOUTB
DDR
SDIO
DATACLK_IN+
SDO/SYNC_ALRM
SPI
DATACLK_IN–
REXT
DATA CLOCK
FORMATTER
CLOCK DISTRIBUTION
AND CONTROL
CSB
SCLK/SYNC_UPD
RESET
DATACLK_OUT+
DATACLK_OUT–
APPLICATIONS
CLK+
04540-0-001
Instrumentation and test
Wideband communications systems
Point-to-point wireless
LMDS
PA linearization
High resolution displays
CLK–
Figure 1
PRODUCT DESCRIPTION
PRODUCT HIGHLIGHTS
The AD9725 is a 14-bit digital-to-analog converter (DAC) that
utilizes an LVDS interface to achieve conversion rates in excess
of 600 MSPS. It is in a family of pin compatible converters that
offers selection of 10-bit, 12-bit, 14-bit, and 16-bit resolution
grades. All of the devices share the same interface options, small
outline package, and pinout, providing an upward or downward
component selection path based on performance, resolution
and cost.
Ultralow noise and intermodulation distortion (IMD) enable
high quality waveform synthesis at intermediate frequencies up
to 200 MHz.
LVDS receivers support SDR or DDR modes, with the maximum conversion rate exceeding 600 MSPS.
Manufactured on a CMOS process, the AD9725 uses a proprietary switching technique that enhances dynamic performance.
The current output of the AD9725 can be easily configured for
various single-ended or differential circuit topologies.
Rev. PrA
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.
AD9725
Preliminary Technical Data
TABLE OF CONTENTS
Specifications..................................................................................... 3
Data Synchronization Circuitry ............................................... 13
DC Specifications ......................................................................... 3
Internal Reference and Full-Scale Output Current................ 13
AC Specifications.......................................................................... 4
Analog Output ............................................................................ 14
Digital Specifications ................................................................... 5
SPI Port Control ......................................................................... 14
Digital Timing Information ........................................................ 5
General Operation of the Serial Port Interface ...................... 14
Absolute Maximum Ratings............................................................ 6
Instruction Byte .......................................................................... 14
Pin Configuration and Function Description .............................. 7
Serial Port Interface Pin Description....................................... 14
Serial Port Interface Register Maps ................................................ 9
Notes on Serial Port Operation ................................................ 15
Definitions ....................................................................................... 11
Outline Dimension......................................................................... 16
Typical Performance Curves ......................................................... 12
Ordering Guide .......................................................................... 16
Theory of Operation ...................................................................... 13
LVDS Inputs ................................................................................ 13
Rev. PrA | Page 2 of 16
AD9725
Preliminary Technical Data
SPECIFICATIONS
DC SPECIFICATIONS
Table 1. TMIN to TMAX, AVDD1, AVDD2, DBVDD = 3.3 V, ADVDD, ACVDD, CLKVDD, DVDD = 2.5 V, IOUTFS = 20 mA, unless
otherwise noted. Specifications subject to change without notice
Parameter
Resolution
DC Accuracy
Integral Nonlinearity
Differential Nonlinearity
Analog Output
Offset Error
Gain Error
Full Scale Output Current
Output Compliance Range
Output Resistance
Output Capacitance
Reference Output
Reference Voltage
Reference Output Current
Reference Input
Reference Input Compliance Range
Reference Input Resistance
Small Signal Bandwidth
Temperature Coefficients
Offset Drift
Gain Drift (With Internal Reference)
Reference Voltage Drift
Power Supply1
AVDD1, AVDD2
Voltage Range
Analog Supply Current (IAVDD1 + IAVDD2)
ADVDD
Voltage Range
ACVDD
Voltage Range
Analog Supply Current ( IADVDD + IACVDD)
CLKVDD
Voltage Range
Clock Supply Current (ICLKVDD)
DVDD
Voltage Range
Digital Supply Current (IDVDD)
DBVDD
Voltage Range
Digital Supply Current (IDBVDD)
Nominal Power Dissipation (PDIS)2
Nominal Power Dissipation (PDIS)3
Min
14
Typ
Max
±1.5
±0.75
–1
LSB
LSB
1
20
1.26
TBD
TBD
1.25
1.14
0.1
1
Rev. PrA | Page 3 of 16
%FSR
%FSR
mA
V
kW
pF
1.2
100
V
nA
5
0.5
V
kW
MHz
TBD
TBD
TBD
ppm of FSR/ºC
ppm of FSR/ºC
ppm/ºC
3.3
51
V
mA
2.5
2.5
9
V
mA
V
mA
2.5
20
V
mA
2.5
69
V
mA
3.3
20
479
1000
V
mA
mW
mW
Supply currents measured under the following conditions: fDAC = 200 MSPS, fOUT = 11 MHz, nominal power supply voltages
Power dissipation measured under the following conditions: fDAC = 200 MSPS, fOUT = 11 MHz, nominal power supply voltages
3
Power dissipation measured under the following conditions: fDAC = 600 MSPS, fOUT = 111 MHz, nominal power supply voltages
2
Unit
Bits
AD9725
Preliminary Technical Data
AC SPECIFICATIONS
Table 2. TMIN to TMAZ, AVDD1, AVDD2, DBVDD = 3.3 V, ADVDD, ACVDD, CLKVDD, DVDD = 2.5 V, IOUTFS = 20 mA, unless
otherwise noted. Specifications subject to change without notice.
Parameter
Dynamic Performance
Max DAC Output Update Rate (DDR)
Max DAC Output Update Rate (SDR)
AC Linearity
Spurious Free Dynamic Range (SFDR) to Nyquist (fOUT = 0 dBFS)
fDATA = 260 MSPS, fOUT = 20 MHz
fDATA = 260 MSPS, fOUT = 70 MHz
fDATA = 260 MSPS, fOUT = 120 MHz
fDATA = 400 MSPS, fOUT = 20 MHz
fDATA = 400 MSPS, fOUT = 70 MHz
fDATA = 400 MSPS, fOUT = 140 MHz
fDATA = 600 MSPS, fOUT = 20 MHz
fDATA = 600 MSPS, fOUT = 125 MHz
fDATA = 600 MSPS, fOUT = 250 MHz
Two Tone IMD to Nyquist (fOUT1 = fOUT2 = –6 dBFS)
fDATA = 300 MSPS, fOUT1 = 26 MHz, fOUT2 = 27 MHz
fDATA = 300 MSPS, fOUT1 = 100 MHz, fOUT2 = 101 MHz
fDATA = 300 MSPS, fOUT1 = 126 MHz, fOUT2 = 127 MHz
fDATA = 500 MSPS, fOUT1 = 26 MHz, fOUT2 = 27 MHz
fDATA = 500 MSPS, fOUT1 = 100 MHz, fOUT2 = 101 MHz
fDATA = 500 MSPS, fOUT1 = 126 MHz, fOUT2 = 127 MHz
fDATA = 600 MSPS, fOUT1 = 26 MHz, fOUT2 = 27 MHz
fDATA = 600 MSPS, fOUT1 = 126 MHz, fOUT2 = 127 MHz
fDATA = 600 MSPS, fOUT1 = 250 MHz, fOUT2 = 251 MHz
Noise Spectral Density (NSD)
fDATA = 500 MSPS, fOUT = 20 MHz, 0 dBFS
fDATA = 500 MSPS, fOUT = 20 MHz, –12 dBFS
fDATA = 500 MSPS, fOUT = 120 MHz, 0 dBFS
fDATA = 500 MSPS, fOUT = 120 MHz, –12 dBFS
CDMA2000 Adjacent Channel Leakage Ratio (ACLR)
fDATA = 245.76 MSPS, IF = 61.44 MHz
fDATA = 491.52 MSPS, IF = 122.88 MHz
fDATA = 491.52 MSPS, IF = 190 MHz
WCDMA Adjacent Channel Leakage Ratio (ACLR), Single Carrier
fDATA = 184.32 MSPS, IF = 61.44 MHz
fDATA = 245.76 MSPS, IF= 61.44 MHz
fDATA = 491.52 MSPS, IF = 122.88 MHz
fDATA = 491.52 MSPS, IF = 190 MHz
WCDMA Adjacent Channel Leakage Ratio (ACLR), Four Carrier
fDATA = 184.32 MSPS, IF = 61.44 MHz,
fDATA = 368.64 MSPS, IF = 92.16 MHz
Rev. PrA | Page 4 of 16
Typ
Unit
600
440
MSPS
MSPS
71
68
68
72
66
60
TBD
TBD
TBD
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
89
80
80
90
78
76
TBD
TBD
TBD
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
–162
–165
–151
–161
dBm/Hz
dBm/Hz
dBm/Hz
dBm/Hz
TBD
TBD
TBD
dBc
dBc
dBc
79
79
76
74
dBc
dBc
dBc
dBc
69
67
dBc
dBc
AD9725
Preliminary Technical Data
DIGITAL SPECIFICATIONS
Table 3. TMIN to TMAX, AVDD1, AVDD2, DBVDD = 3.3 V, ADVDD, ACVDD, CLKVDD, DVDD = 2.5 V , IOUTFS = 20 mA, unless
otherwise noted. Specifications subject to change without notice.
Parameter
Digital Inputs
Differential Logic ‘1’
Conditions
VCM = 0.875 V to 1.575 V
(put into footnote, and delete
column?)
Differential Logic ‘0’
Logic ‘1’ current
Logic ‘0’ current
Differential Input Resistance
Differential Input Capacitance
Data Setup Time (tDS)
Data Hold Time (tDH)
Data Clock Output Delay ( tDCO)
Serial Control Bus
Maximum SCLK Frequency (fSCLK)
Minimum Clock Pulse Width High (tPWH)
Minimum Clock Pulse Width Low (tPWL)
Maximum Clock Rise/Fall Time
Minimum Data/Chip Select Set Up Time (tDS)
Minimum Data Hold Time (tDH)
Maximum Data Valid Time (tDV)
RESET Pulse Width
Inputs (SDI, SDIO, SCLK, CSB)
Logic ‘1’ Voltage
Logic ‘0’ Voltage
Logic ‘1’ Current
Logic ‘0’ Current
Input Capacitance
SDIO Output
Logic ‘1’ Voltage
Logic ‘0’ Voltage
Logic ‘1’ Current
Logic ‘0’ Current
Min
Typ
0.1
–0.6
Max
Unit
0.6
V
–0.1
V
mA
mA
W
pF
ns
ns
ns
3.5
3.5
100
3
0.9
–0.3
2.4
15
30
30
1
25
0
30
1.5
2.1
3
0
0.9
+10
+10
–10
–10
5
DRVDD–0.6
0.4
50
50
30
30
MHz
ns
ns
ms
ns
ns
ns
ns
V
V
µA
µA
pF
V
V
mA
mA
DIGITAL TIMING INFORMATION
tDCO
CLK
CLK
DATACLK_OUT
DATACLK_OUT
DB[15:0]
DB[15:0]
DATACLK_IN
tDH
04540-0-002
DATACLK_IN
tDS
tDS
tDH
tDS
tDH
Figure 3. Double Datarate (DDR) Mode
Figure 2. Single Datarate (SDR) Mode
Rev. PrA | Page 5 of 16
04540-0-003
tDCO
AD9725
Preliminary Technical Data
ABSOLUTE MAXIMUM RATINGS
Parameter
AVDD1, AVDD2, DBVDD
ADVDD, ACVDD, CLKVDD, DVDD
ACOM1, ACOM2, DBCOM
ADCOM, ACCOM, CLKCOM, DCOM
REFIO, FSDAJ
IOUTA, IOUTB
DB0-DB15, DB0-DB15
DATACLKOUT, DATACLKOUT
REXT, CLK+, CLKSDO/SYNC_ALRM, SDIO, CSB
SCLK/SYNC, RESET
DDR, SPI_DIS
With Respect to
ACOM1, ACOM2, DBCOM
ADCOM, ACCOM, CLKCOM,
DCOM
ACOM1, ACOM2, DBCOM
ADCOM, ACCOM, CLKCOM,
DCOM
ACOM1
ACOM1
DBCOM
DBCOM
CLKCOM
DBCOM
DBCOM
ADCOM
Min
–0.3
–0.3
Max
TBD
TBD
Unit
V
V
–0.3
–0.3
+0.3
+0.3
V
V
–0.3
–1
–0.3
–0.3
–0.3
–0.3
–0.3
–0.3
AVDD1 + 0.3
AVDD1 + 0.3
DBVDD + 0.3
DBVDD + 0.3
CLKVDD + 0.3
DBVDD + 0.3
DBVDD + 0.3
ADVDD + 0.3
V
V
V
V
V
V
V
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.
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. PrA | Page 6 of 16
AD9725
Preliminary Technical Data
SPI_DIS
ADVDD
ADGND
ACVDD
ACGND
AVDD2
AGND2
AVDD1
AGND1
IOUTA
IOUTB
AGND1
AVDD1
AGND2
AVDD2
ACGND
ACVDD
ADGND
ADVDD
DDR
PIN CONFIGURATION AND FUNCTION DESCRIPTION
80 79 78 77 76 75 74 73 72 71 70 69 68 67 66 65 64 63 62 61
CLKVDD
REXT
CLKVDD
CLKGND
CLK+
CLK–
CLKGND
DGND
DVDD
DB13+
DB13–
DB12+
DB12–
DB11+
DB11–
DB10+
DB10–
DB9+
DB9–
DBVDD
1
60
2
59
3
4
PIN 1
IDENTIFIER
58
57
5
56
6
55
7
54
8
53
9
10
11
12
52
AD9725
51
TOP VIEW
(Not to Scale)
50
49
13
48
14
47
15
46
16
45
17
44
18
43
19
42
20
41
FSADJ
REFIO
RESET
CSB
SCLK/SYNC_UPD
SDIO
SDO/SYNC_ALRM
DGND
DVDD
NC
NC
NC
NC
DB0–
DB0+
DB1–
DB1+
DB2–
DB2+
DBGND
04540-0-012
DBGND
DB8+
DB8–
DB7+
DB7–
DB6+
DB6–
DATACLK_OUT+
DATACLK_OUT–
DBVDD
DBGND
DATACLK_IN+
DATACLK_IN–
DB5+
DB5–
DB4+
DB4–
DB3+
DB3–
DBVDD
21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
Figure 4. Pin Configuration
Table 4. Pin Function Description
Pin
No.
1
2
Name
Description
Name
Description
DBGND
DB2+
Digital Data Supply Common
Digital Input Bit 2–True
CLKVDD
CLKGND
CLK+
CLK–
CLKGND
DGND
DVDD
DB13+
DB13–
DB12+
DB12–
DB11+
Clock Supply Voltage
Bias Resistor. Sets DATACLK_OUT drive
strength. Nominally 1 kΩ to DBGND
Clock Supply Voltage
Clock Supply Common
Clock Input–True
Clock Input–Complement
Clock Supply Common
Digital Common
Digital Supply Voltage
Digital Input Bit 13–True
Digital Input Bit 13–Complement
Digital Input Bit 12–True
Digital Input Bit 12–Complement
Digital Input Bit 11–True
Pin
No.
41
42
CLKVDD
REXT
3
4
5
6
7
8
9
10
11
12
13
14
43
44
45
46
47
48
49
50
51
52
53
54
DB2–
DB1+
DB1–
DB0+
DB0–
NC
NC
NC
NC
DVDD
DGND
SDO/SYNC_ALRM
15
16
DB11–
DB10+
Digital Input Bit 11–Complement
Digital Input Bit 10–True
55
56
SDIO
SCLK/SYNC_UPD
17
18
19
20
DB10–
DB9+
DB9–
DBVDD
Digital Input Bit 10–Complement
Digital Input Bit 9–True
Digital Input Bit 9–Complement
Digital Data Supply Voltage
57
58
59
60
CSB
RESET
REFIO
FSADJ
Digital Input Bit 2–Complement
Digital Input Bit 1–True
Digital Input Bit 1–Complement
Digital Input Bit 0–True
Digital Input Bit 0–Complement
No Connect
No Connect
No Connect
No Connect
Digital Supply Voltage
Digital Common
SPI_DIS = 1: Data/Clock
Synchronization Alarm
SPI Serial Data Input/Output
SPI_DIS = 1: Data/Clock
Synchronization Update Required
SPI Chip Select (Active Low)
Hardware Reset
Reference Output, 1.2 V Nominal
Full-Scale Current Adjust
Rev. PrA | Page 7 of 16
AD9725
Preliminary Technical Data
Pin
No.
21
Name
Description
Name
Description
Digital Data Supply Common
Pin
No.
61
DBGND
DDR
Digital Input Bit 8–True
Digital Input Bit 8–Complement
Digital Input Bit 7–True
Digital Input Bit 7–Complement
Digital Input Bit 6–True
Digital Input Bit 6–Complement
Data Clock Output–True
Data Clock Output–Complement
Digital Data Supply Voltage
Digital Data Supply Common
Data Clock Input–True
Data Clock Input–Complement
Digital Input Bit 5–True
Digital Input Bit 5–Complement
Digital Input Bit 4–True
Digital Input Bit 4–Complement
Digital Input Bit 3–True
Digital Input Bit 3–Complement
Digital Data Supply Voltage
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
ADVDD
ADGND
ACVDD
ACGND
AVDD2
AGND2
AVDD1
AGND1
IOUTB
IOUTA
AGND1
AVDD1
AGND2
AVDD2
ACGND
ACVDD
ADGND
ADVDD
SPI_DIS
SPI_DIS = 1: Double Data Rate Mode
(Active High)
Analog Supply Voltage
Analog Supply Common
Analog Supply Voltage
Analog Supply Common
Analog Supply Voltage
Analog Supply Common
Analog Supply Voltage
Analog Supply Common
DAC Current Output–Complement
DAC Current Output–True
Analog Supply Common
Analog Supply Voltage
Analog Supply Common
Analog Supply Voltage
Analog Supply Common
Analog Supply Voltage
Analog Supply Common
Analog Supply Voltage
SPI Disable (Active High)
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
DB8+
DB8–
DB7+
DB7–
DB6+
DB6–
DATACLK_OUT+
DATACLK_OUT–
DBVDD
DBGND
DATACLK_IN+
DATACLK_IN–
DB5+
DB5–
DB4+
DB4–
DB3+
DB3–
DBVDD
Rev. PrA | Page 8 of 16
AD9725
Preliminary Technical Data
SERIAL PORT INTERFACE REGISTER MAPS
Table 5. Mode Control via SPI Port
Address
COMMS
DATA
VERSION
CALMEMCK
MEMRDWR
MEMADDR
MEMDATA
1
00
01
02
03
04
05
06
07
08
09
0A
0B
0C
0D
0E
0F
10
11
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
SDIODIR
DATADIR
SWRST
PDN
RESERVED1
RESERVED
EXREF
DATAFMT
DDR
DCLKPOLI
DISDCLKO
SYNCMAN
SYNCUPD
SYNCALRM
RESERVED
RESERVED
CALSTAT
MEMADDR[7]
RESERVED
RESERVED
RESERVED
CALEN
MEMADDR[6]
RESERVED
RESERVED
CALMEM[1]
XFERSTAT
MEMADDR[5]
MEMDATA[5]
SLEEP
RESERVED
DCLKPOLO
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
CALMEM[0]
XFEREN
MEMADDR[4]
MEMDATA[4]
VERSION[3]
RESERVED
SMEMWR
MEMADDR[3]
MEMDATA[3]
VERSION[2]
CALCKDIV[2]
SMEMRD
MEMADDR[2]
MEMDATA[2]
VERSION[1]
CALCKDIV[1]
FMEMRD
MEMADDR[1]
MEMDATA[1]
VERSION[0]
CALCKDIV[0]
UNCAL
MEMADDR[0]
MEMDATA[0]
Reserved registers should be set to Logic 0 (low state) during a write operation, and masked (ignored) during a read operation.
Table 6. SPI Register Definitions
Register
COMMCTRL(00)
SDIODIR
Bit
Direction
Default
Description
7
1
0
DATADIR
6
1
0
SWRST
SLEEP
PDN
5
4
3
1
1
1
0
0
0
2
1
0
0
0
1
0
0
0
0: SDIO pin configured for input only during data
transfer
1: SDIO pin configured for input or output during data
transfer
0: Serial data uses MSB first format
1: Serial data uses LSB first format
1: Default all serial register bits, except address 00h
1: DAC output current off
1: All analog and digital circuitry, except serial
interface, off
RESERVED
RESERVED
0: Internal bandgap reference
7
1
0
DDR
6
1
0
DCLKPOLI
5
1
0
DCLKPOLO
4
1
0
DISDCLKO
3
1
0
SYNCMAN
2
1
0
RESERVED
RESERVED
EXREF
DATACTRL(02)
DATAFMT
Rev. PrA | Page 9 of 16
0: Twos complement input data format
1: Unsigned binary input data format
0: Single Data Rate mode
1: Double Data Rate mode
0: Data latched on DATACLKIN rising edge
1: Data latched on DATACLKIN falling edge
0: Data latched on DATACLKOUT rising edge
1: Data latched on DATACLKOUT falling edge
0: DATACLKOUT enabled
1: DATACLKOUT disabled
0: Automatic synchronization initiated following a
SYNCALRM
1: Manual synchronization needed following a
SYNCALRM
AD9725
Preliminary Technical Data
SYNCUPD
1
1
0
SYNCALRM
0
0
0
[3:0]
0
–
Hardware version identifier
[5:4]
0
00
[2:0]
1
000
Calibration memory
00: Uncalibrated
01: Self calibration
10: Factory calibration
11: User input
Calibration clock divide ratio from channel data rate
000:/32
001:/64
110:/2048
111:/4096
MEMRDWR(0F)
CALSTAT
7
0
0
CALEN
XFERSTAT
6
5
1
0
0
0
XFEREN
SMEMWR
SMEMRD
FMEMRD
UNCAL
MEMADDR(10)
MEMADDR
MEMDATA(11)
MEMDATA
4
3
2
1
0
1
1
1
1
1
0
0
0
0
0
0: Self Calibration cycle not complete
1: Self Calibration cycle complete
1: Self Calibration in progress
0: Factory memory transfer not complete
1: Factory memory transfer complete
1: Factory memory transfer in progress
1: Write static memory data from external port
1: Read static memory to external port
1: Read factory memory data to external port
1: Use uncalibrated
[7:0]
I/O
00000000
Address of factory or static memory to be accessed
[5:0]
I/O
000000
Data for factory or static memory access
VERSION(0D)
VERSION[3:0]
CALMEMCK(0E)
CALMEM
CALCKDIV
1: External reference
Rev. PrA | Page 10 of 16
0: Data synchronization complete
1: Initiate data synchronization
0: Data synchronizer does not require updating
1: Data synchronizer requires updating
AD9725
Preliminary Technical Data
DEFINITIONS
Linearity Error (Also Called Integral Nonlinearity or INL)
Power Supply Rejection
Linearity error is defined as the maximum deviation of the
actual analog output from the ideal output, determined by a
straight line drawn from zero-scale to full-scale.
The maximum change in the full-scale output as the supplies
are varied from minimum to maximum specified voltages.
Differential Nonlinearity ( DNL)
The time required for the output to reach and remain within a
specified error band about its final value, measured from the
start of the output transition.
DNL is the measure of the variation in analog value, normalized
to full-scale, and associated with a 1 LSB change in digital input
code.
Monotonicity
Settling Time
Glitch Impulse
A D/A converter is monotonic if the output either increases or
remains constant as the digital input increases.
Asymmetrical switching times in a DAC give rise to undesired
output transients that are quantified by a glitch impulse. It is
specified as the net area of the glitch in pV-s.
Offset Error
Spurious-Free Dynamic Range
The deviation of the output current from the ideal of zero is
called offset error. For IOUTA, 0 mA output is expected when the
inputs are all 0s. For IOUTB, 0 mA output is expected when all
inputs are set to 1s.
The difference, in decibels, between the rms amplitude of the
output signal and the peak spurious signal over the specified
bandwidth.
Gain Error
THD is the ratio of the rms sum of the first six harmonic components to the rms value of the measured fundamental. It is
expressed as a percentage or in decibels (dB).
The difference between the actual and ideal output span. The
actual span is determined by the output when all inputs are set
to 1s, minus the output when all inputs are set to 0s.
Output Compliance Range
The range of allowable voltage at the output of a current-output
DAC. Operation beyond the maximum compliance limits may
cause either output stage saturation or breakdown, resulting in
nonlinear performance.
Temperature Drift
Temperature drift is specified as the maximum change from the
ambient (25°C) value to the value at either TMIN or TMAX. For
offset and gain drift, the drift is reported in ppm of full-scale
range (FSR) per degree celsius. For reference drift, the drift is
reported in ppm per degree celsius.
Total Harmonic Distortion
Signal-to-Noise Ratio (SNR)
S/N is the ratio of the rms value of the measured output signal
to the rms sum of all other spectral components below the
Nyquist frequency, excluding the first six harmonics and dc. The
value for SNR is expressed in decibels.
Adjacent Channel Power Ratio (or ACPR)
A ratio in dBc between the measured power within a channel
relative to its adjacent channel.
LVDS
Low voltage differential signaling. A differential logic specification that defines logic levels as approximately ±350 mV
(differential) over a common mode range of 0.875 V to 1.575 V.
LVDS is designed to achieve clock rates of up to 840 MHz.
Rev. PrA | Page 11 of 16
AD9725
Preliminary Technical Data
TYPICAL PERFORMANCE CURVES
Figure 7. Noise Spectral Density vs. fOUT at fDAC = 500 MSPS
Figure 5. SFDR vs. fOUT at fDAC = 400 MSPS
Figure 8. WCDMA ACLR at Select Intermediate Frequencies
and Sample Rates
Figure 6. IMD vs. fOUT at fDAC = 500 MSPS
Rev. PrA | Page 12 of 16
AD9725
Preliminary Technical Data
THEORY OF OPERATION
LVDS INPUTS
The AD9725 uses LVDS (Low Voltage Differential Signaling)
digital inputs to enable high speed digital signaling. LVDS
allows the use of a differential signal for optimum noise rejecttion, and has small signal amplitude for fast speed and lower
power dissipation. Each differential digital input on the AD9725
has an internal 100 Ω resistor for proper load termination. The
LVDS digital data inputs on the AD9725 meet the IEEE reduced
range (RR) specs for common mode input range (875 mV to
1575 mV) with an input differential threshold of ±350 mV.
Once synchronization is established, the AD9725 needs to be
reoptimized only if operating conditions change enough to
affect the relative phase of the DAC and data clocks by more
than one clock cycle. The AD9725 detects when a synchronization update is necessary, and indicates this need by asserting
SYNCALRM (02h[0]) or SYNC_ALRM high. If SYNCALRM
(02h[0]) or SYNC_ALRM have been asserted, resynchronization can be accomplished as follows:
1.
If the synchronization logic is in automatic mode
(SYNCMAN (02h[2]) = 0), the synchronization logic will
optimize the internal timing as necessary. Two data words
will typically be lost or repeated when an optimization
occurs. If that possibility could cause serious problems,
manual operation may be required.
2.
If the synchronization logic is in manual mode
(SYNCMAN (02h[2]) = 1), the logic will indicate the need
for an update by asserting SYNCALRM (02h[0]) high. In
normal operation, a logic high on SYNCALRM (02h[0])
does not mean that data is being lost, but that conditions
are close to the point where data may be lost. Optimization
should be initiated by setting SYNCUPD (02h[1]) high at a
convenient time.
3.
Monitoring the synchronization logic state and initiating
an update can be done via package pins by setting SPI_DIS
high and using the SYNC_ALRM and SYNC_UPD pins in
the same way the manual synchronization operation is
described in step 2.
DATA SYNCHRONIZATION CIRCUITRY
The high speeds at which the LVDS digital interface is designed
to operate require maintaining synchronization of the data
(DB[15:0]+, DB[15:0]–) and data clock (DATACLK_IN+,
DATACLK_IN–) with the DAC clock (CLK+, CLK–). Since the
DAC clock input is not LVDS, the phase relationship between
that clock and the data can vary, and, unless precautions are
taken, data can be corrupted.
The input data must be provided at the same frequency as the
DAC clock from an LVDS source with an accompanying LVDS
data clock. Since the DAC and data clocks are different types,
their phase relationship is difficult to specify.
The AD9725 provides internal circuitry to keep the data from
being corrupted over a wide variation in relative phase. Once
the DAC and data clocks have been established and synchronization has been initiated, the phase between the two clocks can
vary by at least one full clock cycle without loss of data. If the
phase relationship between the clocks varies enough to cause a
possible loss of data, the AD9725 can be resynchronized in
several different ways.
The internal synchronization circuitry in the AD9725 eases this
problem by allowing the phase to vary by at least one full clock
cycle, once synchronization has been established. It does this by
demultiplexing the incoming data stream into four channels,
each containing every fourth data word. Each of these words is
present for four DAC clock cycles. The data is then remultiplexed by sampling each channel with the appropriate DAC
clock cycle.
Initial synchronization is established in one of the following
ways:
1.
When the RESET pin is asserted, the synchronization logic
is initiated to provide optimal internal timing.
2.
If SPI_DIS is not asserted, the synchronization is optimized
by writing setting SYNC_UPD (02h[1]) high.
3.
Note that SYNCUPD (02h[1]) or SYNC_UPD can be asserted
at any time to optimize the synchronization, even if
SYNCALRM (02h[0]) or SYNC_ALRM have not indicated that
it is necessary.
If either the data clock or the DAC clock is interrupted for any
reason, a SYNCUPD or SYNC_UPD should be executed to
insure that no subsequent data is lost.
INTERNAL REFERENCE AND FULL-SCALE OUTPUT
CURRENT
The AD9725 contains an internal band gap reference of 1.2 V.
The reference voltage is applied to an external resistor at FSADJ,
and the resultant current is amplified by the reference buffer to
provide the full-scale current for the DAC output. The gain
equation from the internal reference to the DAC output
(assuming the digital inputs are at full scale) is as follows:
IOUTFS = 1.2 × 32/FSADJ
Taking into account the state of the digital inputs, the output
current of IOUTA and IOUTB at any instant in time is:
If SPI_DIS is asserted, the synchronization is optimized by
asserting the SYNC_UPD pin.
Rev. PrA | Page 13 of 16
IOUTA = IOUTFS × (DB15:DB0)/65536
IOUTB = IOUTFS × (1 − DB15:DB0)/65536
AD9725
Preliminary Technical Data
ANALOG OUTPUT
INSTRUCTION BYTE
The analog output of the AD9725 is based around a high dynamic range CMOS DAC core. The output consists of a differenttial current source capable of up to 20 mA full-scale. The output
devices are PMOS and are capable of sourcing current into an
output termination within a compliance voltage range of ±1 V.
Excellent distortion, noise, and ACLR perfor-mance is achievable to Nyquist at sample rates of 600 MSPS+.
The instruction byte contains the information shown in Table 7
Table 7
N1
0
0
1
1
N0
0
1
0
1
Description
Transfer 1 byte
Transfer 2 byte
Transfer 3 byte
Transfer 4 byte
SPI PORT CONTROL
The AD9725 serial port is a flexible, synchronous serial communications port allowing easy interface to many industry
standard microcontrollers and microprocessors. The serial I/O
is compatible with most synchronous transfer formats, including both the Motorola SPI and Intel SSR protocols. The interface allows read/write access to all registers that configure the
AD9725. Single or multiple byte transfers are supported as well
as MSB first or LSB first transfer formats. The AD9725 serial
interface port can be configured as a single pin I/O (SDIO) or
two unidirectional pins for in/out (SDIO/SDO).
GENERAL OPERATION OF THE SERIAL PORT
INTERFACE
There are two phases to a communication cycle with the
AD9725. Phase 1 is the instruction cycle, which is the writing of
an instruction byte into the AD9725, and coincident with the
first eight SCLK rising edges. The instruction byte provides the
AD9725 serial port controller with information regarding the
data transfer cycle, which is Phase 2 of the communication
cycle. The Phase 1 instruction byte defines the number of bytes
in the data transfer, the starting register address for the first byte
of the data transfer, and whether the upcoming data transfer is
read or write. The first eight SCLK rising edges of each communication cycle are used to write the instruction byte into the
AD9725.
A Logic 1 on the CS pin followed by a Logic 0 will reset the SPI
port timing to the initial state of the instruction cycle. This is
true regardless of the present state of the internal registers or
the other signal levels present at the inputs to the SPI port. If the
SPI port is in the midst of an instruction cycle or a data transfer
cycle, none of the present data will be written.
The remaining SCLK edges are for Phase 2 of the communication cycle. Phase 2 is the actual data transfer between the
AD9777 and the system controller. Phase 2 of the communication cycle is a transfer of 1, 2, 3, or 4 data bytes as determined
by the instruction byte. Normally, using one multibyte transfer
is the preferred method. However, single byte data transfers are
useful to reduce CPU overhead when register access requires
1 byte only. Registers change immediately upon writing to the
last bit of each transfer byte.
R/W
Bit 7 of the instruction byte determines whether a read or a
write data transfer will occur after the instruction byte write.
Logic high indicates a read operation. Logic 0 indicates a write
operation. N1, N0 -Bits 6 and 5 of the instruction byte
determine the number of bytes to be transferred during the data
transfer cycle. The bit decodes are shown in the following table:
Table 8
MSB
I7
R/W
I6
N1
I5
N0
I4
A4
I3
A3
I2
A2
I1
A1
LSB
I0
A0
A4, A3, A2, A1, A0
Bits 4, 3, 2, 1, 0 of the instruction byte determine which register
is accessed during the data transfer portion of the communications cycle. For multibyte transfers, this address is the starting
byte address. The remaining register addresses are generated by
the AD9725.
SERIAL PORT INTERFACE PIN DESCRIPTION
SCLK (Serial Clock)
The serial clock pin is used to synchronize data to and from the
AD9725, and to run the internal state machines. The SCLK
maximum frequency is 15 MHz. All data input to the AD9725 is
registered on the rising edge of SCLK. All data is driven out of
the AD9725 on the falling edge of SCLK.
CSB (Chip Select)
Active low input starts and gates a communication cycle. It
allows more than one device to be used on the same serial
communications line. The SDO and SDIO pins will go to a high
impedance state when this input is high. Chip select should stay
low during the entire communication cycle.
SDIO
Serial data I/O. Data is always written into the AD9725 on this
pin. This pin, however, can be used as a bidirectional data line.
The configuration of this pin is controlled by Bit 7 of register
address 00h. The default is Logic 0, which configures the SDIO
pin as unidirectional.
Rev. PrA | Page 14 of 16
AD9725
Preliminary Technical Data
SDO
NOTES ON SERIAL PORT OPERATION
Serial data out. Data is read from this pin for protocols that use
separate lines for transmitting and receiving data. In the case
where the AD9725 operates in a single bidirectional I/O mode,
this pin does not output data and is set to a high impedance
state.
The AD9725 serial port configuration bits reside in Bit 6 and
Bit 7 of register address 00h. It is important to note that the
configuration changes immediately upon writing to the last bit
of the register. For multibyte transfers, writing to this register
may occur during the middle of communication cycle. Care
must be taken to compensate for this new configuration for the
remaining bytes of the current communication cycle.
The AD9725 serial port controller address will increment from
1Fh to 00h for multibyte I/O operations if the MSB first mode is
active. The serial port controller address will decrement from
00h to 1Fh for multibyte I/O operations if the LSB first mode is
active.
INSTRUCTION CYCLE
DATA TRANSFER CYCLE
SCLK
SDIO
10
11
12
13
14 15(n) 16(n) R/W D00 D10 D20
D6n D7n
D00 D10 D20
D6n D7n
SDO
04540-0-009
CS
Figure 10. Serial Register Interface Timing LSB First
CS
tDS
tSCLK
tPWH
tPWL
SCLK
tDS
SDIO
tDH
INSTRUCTION BIT 7
INSTRUCTION BIT 6
04540-0-010
The AD9725 serial port can support both MSB first and LSB
first data formats. This functionality is controlled by register
address 00h Bit 6. The default is MSB first. When this bit is set
to active high, the AD9725 serial port is in LSB first format.
That is, if the AD9725 is in LSB first mode, the instruction byte
must be written from least significant bit to most significant bit.
Multibyte data transfers in MSB format can be completed by
writing an instruction byte that includes the register address of
the most significant byte. In MSB first mode, the serial port
internal byte address generator decrements for each byte
required of the multibyte communication cycle. Multibyte data
transfers in LSB first format can be completed by writing an
instruction byte that includes the register address of the least
significant byte. In LSB first mode, the serial port internal byte
address generator increments for each byte required of the
multibyte communication cycle.
Figure 11. Timing Diagram for Register Write to AD9725
CS
SCLK
tDV
SDIO
SDO
DATA BIT n
DATA BIT n– 1
04540-0-011
MSB/LSB Transfers
Figure 12. Timing Diagram for Register READ to AD9725
INSTRUCTION CYCLE
The same considerations apply to setting the reset bit in register
address 00h. All other registers are set to their default values, but
the software reset doesn’t affect the bits in register address 00h.
DATA TRANSFER CYCLE
CS
SCLK
SDO
R/W 16(n) 15(n) 14
13
12
11
10
D7n D6n
D20 D10
D00
D7n D6n
D20 D10
D00
04540-0-008
SDIO
It is recommended to use only single byte transfers when
changing serial port configurations or initiating a software
reset.
Figure 9. Serial Register Interface Timing MSB First
Rev. PrA | Page 15 of 16
AD9725
Preliminary Technical Data
OUTLINE DIMENSION
14.00 SQ
1.20
MAX
0.75
0.60
0.45
12.00 SQ
80
61
SEATING
PLANE
80
61
60
1
60
1
PIN 1
TOP VIEW
(PINS DOWN)
BOTTOM
VIEW
20
41
21
6.00
SQ
20
41
40
40
21
0.15
0.05
1.05
1.00
0.95
7°
3.5°
0°
0.20
0.09
COPLANARITY
0.08
0.50 BSC
0.27
0.22
0.17
GAGE PLANE
0.25
COMPLIANT TO JEDEC STANDARDS MS-026-ADD-HD
Figure 13. 80-Lead Thin Plastic Quad Flat Package, Exposed Pad [TQFP/ED]
(SV-80)
Dimensions shown in millimeters
ORDERING GUIDE
Model
AD9725BSV
Temperature Range
-40°C to +85°C
Package Description
80 Lead TQFP
THERMAL CHARACTERISTICS
Thermal Resistance
80-Lead Thermally Enhanced
TQFP Package θJA = 23.5°C/W*
*With thermal pad soldered to PCB.
© 2004 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
PR04682-0-1/04(PrA)
Rev. PrA | Page 16 of 16
Package Option
SV-80