AD AD9246-125EB 14-bit, 80 msps/105 msps/125 msps, 1.8 v analog-to-digital converter Datasheet

14-Bit, 80 MSPS/105 MSPS/125 MSPS,
1.8 V Analog-to-Digital Converter
AD9246
FEATURES
FUNCTIONAL BLOCK DIAGRAM
AVDD
DRVDD
AD9246
VIN+
VIN–
8-STAGE
1 1/2-BIT PIPELINE
MDAC1
SHA
8
4
A/D
3
A/D
REFT
REFB
CORRECTION LOGIC
OR
15
OUTPUT BUFFERS
DCO
D13 (MSB)
VREF
D0 (LSB)
SENSE
0.5V
REF
SELECT
AGND
CLOCK
DUTY CYCLE
STABILIZER
CLK+
CLK–
SCLK/DFS
MODE
SELECT
PDWN
SDIO/DCS
CSB
DRGND
APPLICATIONS
Ultrasound equipment
IF sampling in communications receivers
IS-95, CDMA-One, IMT-2000
Battery-powered instruments
Hand-held scopemeters
Low cost digital oscilloscopes
GENERAL DESCRIPTION
05491-001
1.8 V analog supply operation
1.8 V to 3.3 V output supply
SNR = 71.7 dBc (72.7 dBFS) to 70 MHz input
SFDR = 85 dBc to 70 MHz input
Low power: 395 mW @ 125 MSPS
Differential input with 650 MHz bandwidth
On-chip voltage reference and sample-and-hold amplifier
DNL = ±0.4 LSB
Flexible analog input: 1 V p-p to 2 V p-p range
Offset binary, Gray code, or twos complement data format
Clock duty cycle stabilizer
Data output clock
Serial port control
Built-in selectable digital test pattern generation
Programmable clock and data alignment
Figure 1.
The digital output data is presented in offset binary, Gray code, or
twos complement formats. A data output clock (DCO) is provided
to ensure proper latch timing with receiving logic.
The AD9246 is a monolithic, single 1.8 V supply, 14-bit, 80 MSPS/
105 MSPS/125 MSPS analog-to-digital converter (ADC), featuring
a high performance sample-and-hold amplifier (SHA) and on-chip
voltage reference. The product uses a multistage differential
pipeline architecture with output error correction logic to
provide 14-bit accuracy at 125 MSPS data rates and guarantees
no missing codes over the full operating temperature range.
The AD9246 is available in a 48-lead LFCSP_VQ and is specified
over the industrial temperature range (−40°C to +85°C).
1.
The AD9246 operates from a single 1.8 V power supply
and features a separate digital output driver supply to
accommodate 1.8 V to 3.3 V logic families.
The wide bandwidth, truly differential SHA allows a variety of
user-selectable input ranges and offsets, including single-ended
applications. It is suitable for multiplexed systems that switch
full-scale voltage levels in successive channels and for sampling
single-channel inputs at frequencies well beyond the Nyquist rate.
Combined with power and cost savings over previously available
ADCs, the AD9246 is suitable for applications in communications,
imaging, and medical ultrasound.
2.
The patented SHA input maintains excellent performance
for input frequencies up to 225 MHz.
3.
The clock DCS maintains overall ADC performance over a
wide range of clock pulse widths.
4.
A standard serial port interface supports various product
features and functions, such as data formatting (offset
binary, twos complement, or Gray coding), enabling the
clock DCS, power-down, and voltage reference mode.
5.
The AD9246 is pin-compatible with the AD9233, allowing
a simple migration from 12 bits to 14 bits.
A differential clock input controls all internal conversion cycles.
A duty cycle stabilizer (DCS) compensates for wide variations in
the clock duty cycle while maintaining excellent overall ADC
performance.
PRODUCT HIGHLIGHTS
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: 781.461.3113
©2006 Analog Devices, Inc. All rights reserved.
AD9246
TABLE OF CONTENTS
Features .............................................................................................. 1
Timing ......................................................................................... 22
Applications....................................................................................... 1
Serial Port Interface (SPI).............................................................. 23
General Description ......................................................................... 1
Configuration Using the SPI..................................................... 23
Functional Block Diagram .............................................................. 1
Hardware Interface..................................................................... 23
Product Highlights ........................................................................... 1
Configuration Without the SPI ................................................ 23
Revision History ............................................................................... 3
Memory Map .................................................................................. 24
Specifications..................................................................................... 4
Reading the Memory Map Register Table............................... 24
DC Specifications ......................................................................... 4
Memory Map Register Table..................................................... 25
AC Specifications.......................................................................... 5
Layout Considerations................................................................... 27
Digital Specifications ................................................................... 6
Power and Ground Recommendations ................................... 27
Switching Specifications .............................................................. 7
CML ............................................................................................. 27
Timing Diagram ........................................................................... 7
RBIAS........................................................................................... 27
Absolute Maximum Ratings............................................................ 8
Reference Decoupling................................................................ 27
Thermal Resistance ...................................................................... 8
Evaluation Board ............................................................................ 28
ESD Caution.................................................................................. 8
Power Supplies ............................................................................ 28
Pin Configuration and Function Descriptions............................. 9
Input Signals................................................................................ 28
Equivalent Circuits ......................................................................... 10
Output Signals ............................................................................ 28
Typical Performance Characteristics ........................................... 11
Default Operation and Jumper Selection Settings................. 29
Theory of Operation ...................................................................... 15
Alternative Clock Configurations............................................ 29
Analog Input Considerations.................................................... 15
Alternative Analog Input Drive Configuration...................... 29
Voltage Reference ....................................................................... 17
Schematics................................................................................... 31
Clock Input Considerations ...................................................... 18
Evaluation Board Layouts ......................................................... 36
Jitter Considerations .................................................................. 20
Bill of Materials........................................................................... 39
Power Dissipation and Standby Mode..................................... 20
Outline Dimensions ....................................................................... 42
Digital Outputs ........................................................................... 21
Ordering Guide .......................................................................... 42
Rev. A | Page 2 of 44
AD9246
REVISION HISTORY
8/06—Rev. 0 to Rev. A
Added 80 MSPS .................................................................. Universal
Changes to Features ..........................................................................1
Deleted Figures 19, 20, 22, 23 ........................................................11
Deleted Figures 24, 25, 27 to 29.....................................................12
Deleted Figures 31, 34.....................................................................13
Deleted Figures 37, 38, 40, 41 ........................................................14
Deleted Figure 46 ............................................................................15
Deleted Figure 52 ............................................................................16
Changes to Figure 41 ......................................................................17
Changes to Figure 46 ......................................................................19
Inserted Figure 54 ...........................................................................21
Added Data Clock Output (DCO) Section .................................22
Changes to Table 15 ........................................................................25
Changes to Table 16 ........................................................................39
Changes to the Ordering Guide ....................................................42
4/06—Revision 0: Initial Version
Rev. A | Page 3 of 44
AD9246
SPECIFICATIONS
DC SPECIFICATIONS
AVDD = 1.8 V; DRVDD = 2.5 V, maximum sample rate, 2 V p-p differential input, 1.0 V internal reference; AIN = −1.0 dBFS, DCS
enabled, unless otherwise noted.
Table 1.
Parameter
RESOLUTION
ACCURACY
No Missing Codes
Offset Error
Gain Error
Differential Nonlinearity (DNL) 1
Integral Nonlinearity (INL)1
TEMPERATURE DRIFT
Offset Error
Gain Error
INTERNAL VOLTAGE REFERENCE
Output Voltage Error (1 V Mode)
Load Regulation @ 1.0 mA
INPUT REFERRED NOISE
VREF = 1.0 V
ANALOG INPUT
Input Span, VREF = 1.0 V
Input Capacitance 2
REFERENCE INPUT RESISTANCE
POWER SUPPLIES
Supply Voltage
AVDD
DRVDD
Supply Current
IAVDD1
IDRVDD1 (DRVDD = 1.8 V)
IDRVDD1 (DRVDD = 3.3 V)
POWER CONSUMPTION
DC Input
Sine Wave Input1 (DRVDD = 1.8 V)
Sine Wave Input1 (DRVDD = 3.3 V)
Standby Power 3
Power-Down Power
Temp
Full
AD9246BCPZ-80
Min
Typ
Max
14
AD9246BCPZ-105
Min
Typ
Max
14
AD9246BCPZ-125
Min
Typ
Max
14
Guaranteed
±0.3
±0.5
±0.6
±4.7
±1.0
±0.4
±5.0
±1.5
Guaranteed
±0.3
±0.8
±0.6
±5.0
±1.0
±0.4
±5.0
±1.3
Guaranteed
±0.3
±0.8
±0.6
±4.2
±1.0
±0.4
±5.0
±1.5
Full
Full
Full
Full
25°C
Full
25°C
±15
±95
Full
Full
±5
7
25°C
1.3
1.3
1.3
LSB rms
Full
Full
Full
2
8
6
2
8
6
2
8
6
V p-p
pF
kΩ
±20
1.8
2.5
1.9
3.6
Full
Full
Full
138
7
12
Full
Full
Full
Full
Full
248
261
288
40
1.8
Full
Full
±5
7
1.7
1.7
±15
±95
% FSR
% FSR
LSB
LSB
LSB
LSB
Full
Full
1.7
1.7
±15
±95
Unit
Bits
±35
1.8
2.5
1.9
3.6
155
178
9
16
279
320
337
373
40
1.8
1
±5
7
1.7
1.7
ppm/°C
ppm/°C
±35
mV
mV
1.8
2.5
1.9
3.6
V
V
194
220
11
19
236
mA
mA
mA
350
395
415
458
40
1.8
425
mW
mW
mW
mW
mW
Measured with a low input frequency, full-scale sine wave, with approximately 5 pF loading on each output bit.
Input capacitance refers to the effective capacitance between one differential input pin and AGND. Refer to Figure 4 for the equivalent analog input structure.
3
Standby power is measured with a dc input, the CLK pin inactive (set to AVDD or AGND).
2
Rev. A | Page 4 of 44
AD9246
AC SPECIFICATIONS
AVDD = 1.8 V; DRVDD = 2.5 V, maximum sample rate, 2 V p-p differential input, 1.0 V internal reference;AIN = −1.0 dBFS, DCS
enabled, unless otherwise noted.
Table 2.
Parameter 1
SIGNAL-TO-NOISE-RATIO (SNR)
fIN = 2.4 MHz
fIN = 70 MHz
fIN = 100 MHz
fIN = 170 MHz
SIGNAL-TO-NOISE AND DISTORTION
(SINAD)
fIN = 2.4 MHz
fIN = 70 MHz
fIN = 100 MHz
fIN = 170 MHz
EFFECTIVE NUMBER OF BITS (ENOB)
fIN = 2.4 MHz
fIN = 70 MHz
fIN = 100 MHz
fIN = 170 MHz
WORST SECOND OR THIRD HARMONIC
fIN = 2.4 MHz
fIN = 70 MHz
fIN = 100 MHz
fIN = 170 MHz
SPURIOUS-FREE DYNAMIC RANGE (SFDR)
fIN = 2.4 MHz
fIN = 70 MHz
fIN = 100 MHz
fIN = 170 MHz
WORST OTHER HARMONIC OR SPUR
fIN = 2.4 MHz
fIN = 70 MHz
fIN = 100 MHz
fIN = 170 MHz
TWO-TONE SFDR
fIN = 29 MHz (−7 dBFS), 32 MHz
(−7 dBFS)
fIN = 169 MHz (−7 dBFS), 172 MHz
(−7 dBFS)
ANALOG INPUT BANDWIDTH
1
Temp
25°C
25°C
Full
25°C
25°C
25°C
25°C
Full
25°C
25°C
AD9246BCPZ-80
Min
Typ
Max
AD9246BCPZ-105
Min
Typ
Max
AD9246BCPZ-125
Min
Typ
Max
71.9
71.9
71.9
71.9
71.9
71.7
70.8
69.5
dBc
dBc
dBc
dBc
dBc
69.5
71.6
70.9
71.6
70.9
71.6
70.8
71.1
71.5
71.1
70.8
71.1
70.6
Unit
70.6
69.9
70.6
69.9
70.6
69.8
dBc
dBc
dBc
dBc
dBc
25°C
25°C
25°C
25°C
11.7
11.6
11.6
11.5
11.7
11.6
11.6
11.5
11.7
11.6
11.6
11.5
Bits
Bits
Bits
Bits
25°C
25°C
Full
25°C
25°C
−90
−85
−90
−85
−90
−85
dBc
dBc
dBc
dBc
dBc
25°C
25°C
Full
25°C
25°C
70.4
68.5
68.5
−76
−73
−73
−85
−83.5
−85
−83.5
−85
−83
90
85
90
85
90
85
76
73
dBc
dBc
dBc
dBc
dBc
73
85
83.5
85
83.5
85
83
25°C
25°C
Full
25°C
25°C
−90
−90
−90
−90
−90
−90
−90
−90
−90
−90
−90
−90
dBc
dBc
dBc
dBc
dBc
25°C
87
87
85
dBc
25°C
83
83
84
dBc
25°C
650
650
650
MHz
−85
See AN-835, Understanding High Speed ADC Testing and Evaluation, for a complete set of definitions.
Rev. A | Page 5 of 44
−80
−80
AD9246
DIGITAL SPECIFICATIONS
AVDD = 1.8 V; DRVDD = 2.5 V, maximum sample rate, 2 V p-p differential input, 1.0 V internal reference; AIN = −1.0 dBFS, DCS
enabled, unless otherwise noted.
Table 3.
Parameter
DIFFERENTIAL CLOCK INPUTS (CLK+, CLK−)
Logic Compliance
Internal Common-Mode Bias
Differential Input Voltage
Input Voltage Range
Input Common-Mode Range
High Level Input Voltage (VIH)
Low Level Input Voltage (VIL)
High Level Input Current (IIH)
Low Level Input Current (IIL)
Input Resistance
Input Capacitance
LOGIC INPUTS (SCLK/DFS, OEB, PWDN)
High Level Input Voltage (VIH)
Low Level Input Voltage (VIL)
High Level Input Current (IIH)
Low Level Input Current (IIL)
Input Resistance
Input Capacitance
LOGIC INPUTS (CSB)
High Level Input Voltage (VIH)
Low Level Input Voltage (VIL)
High Level Input Current (IIH)
Low Level Input Current (IIL)
Input Resistance
Input Capacitance
LOGIC INPUTS (SDIO/DCS)
High Level Input Voltage (VIH)
Low Level Input Voltage (VIL)
High Level Input Current (IIH)
Low Level Input Current (IIL)
Input Resistance
Input Capacitance
DIGITAL OUTPUTS
DRVDD = 3.3 V
High Level Output Voltage (VOH, IOH = 50 μA)
High Level Output Voltage (VOH , IOH = 0.5 mA)
Low Level Output Voltage (VOL, IOL = 1.6 mA)
Low Level Output Voltage (VOL, IOL = 50 μA)
DRVDD = 1.8 V
High Level Output Voltage (VOH, IOH = 50 μA)
High Level Output Voltage (VOH, IOH = 0.5 mA)
Low Level Output Voltage (VOL, IOL = 1.6 mA)
Low Level Output Voltage (VOL, IOL = 50 μA)
Temp
Full
Full
Full
Full
Full
Full
Full
Full
Full
Full
Min
0.2
AVDD − 0.3
1.1
1.2
0
−10
−10
8
Full
Full
Full
Full
Full
Full
1.2
0
−50
−10
Full
Full
Full
Full
Full
Full
1.2
0
−10
+40
Full
Full
Full
Full
Full
Full
1.2
0
−10
+40
Full
Full
Full
Full
3.29
3.25
Full
Full
Full
Full
1.79
1.75
Rev. A | Page 6 of 44
AD9246BCPZ-80/105/125
Typ
Max
CMOS/LVDS/LVPECL
1.2
6
AVDD + 1.6
AVDD
3.6
0.8
+10
+10
10
12
4
Unit
V
V p-p
V
V
V
V
μA
μA
kΩ
pF
3.6
0.8
−75
+10
V
V
μA
μA
kΩ
pF
3.6
0.8
+10
+135
V
V
μA
μA
kΩ
pF
DRVDD + 0.3
0.8
+10
+130
V
V
μA
μA
kΩ
pF
30
2
26
2
26
5
0.2
0.05
V
V
V
V
0.2
0.05
V
V
V
V
AD9246
SWITCHING SPECIFICATIONS
AVDD = 1.8 V, DRVDD = 2.5 V, unless otherwise noted.
Table 4.
Parameter 1
CLOCK INPUT PARAMETERS
Conversion Rate, DCS Enabled
Conversion Rate, DCS Disabled
CLK Period
CLK Pulse Width High, DCS Enabled
CLK Pulse Width High, DCS Disabled
DATA OUTPUT PARAMETERS
Data Propagation Delay (tPD) 2
DCO Propagation Delay (tDCO)
Setup Time (tS)
Hold Time (tH)
Pipeline Delay (Latency)
Aperture Delay (tA)
Aperture Uncertainty (Jitter, tJ)
Wake-Up Time 3
OUT-OF-RANGE RECOVERY TIME
SERIAL PORT INTERFACE 4
SCLK Period (tCLK)
SCLK Pulse Width High Time (tHI)
SCLK Pulse Width Low Time (tLO)
SDIO to SCLK Setup Time (tDS)
SDIO to SCLK Hold Time (tDH)
CSB to SCLK Setup Time (tS)
CSB to SCLK Hold Time (tH)
Temp
AD9246BCPZ-80
Min
Typ
Max
AD9246BCPZ-105
Min
Typ
Max
AD9246BCPZ-125
Min
Typ
Max
Unit
Full
Full
Full
Full
Full
20
10
12.5
3.75
5.63
MSPS
MSPS
ns
ns
ns
Full
Full
Full
Full
Full
Full
Full
Full
Full
3.1
80
80
4.9
5.9
Full
Full
Full
Full
Full
Full
Full
6.25
6.25
8.75
6.88
20
10
9.5
2.85
4.28
3.9
4.4
5.7
6.8
12
0.8
0.1
350
2
4.8
3.1
3.4
4.4
40
16
16
5
2
5
2
105
105
4.75
4.75
6.65
5.23
20
10
8
2.4
3.6
3.9
4.4
4.3
5.3
12
0.8
0.1
350
2
4.8
3.1
125
125
2.6
3.7
40
16
16
5
2
5
2
40
16
16
5
2
5
2
See AN-835, Understanding High Speed ADC Testing and Evaluation, for a complete set of definitions.
Output propagation delay is measured from CLK 50% transition to DATA 50% transition, with 5 pF load.
Wake-up time is dependent on the value of the decoupling capacitors, values shown with 0.1 μF capacitor across REFT and REFB.
4
See Figure 57 and the Serial Port Interface (SPI) section.
2
3
TIMING DIAGRAM
N+2
N+3
N
N+4
tA
N+8
N+5
N+6
N+7
N–7
N–6
tCLK
CLK+
CLK–
tPD
N – 13
tS
N – 12
N – 11
tH
N – 10
N–9
N–8
tDCO
DCO
Figure 2. Timing Diagram
Rev. A | Page 7 of 44
tCLK
N–5
N–4
05491-002
DATA
5.6
4.4
3.9
4.4
3.5
4.5
12
0.8
0.1
350
3
4.8
ns
ns
ns
ns
cycles
ns
ps rms
μs
Cycles
ns
ns
ns
ns
ns
ns
ns
1
N+1
4
4
AD9246
ABSOLUTE MAXIMUM RATINGS
Table 5.
Parameter
ELECTRICAL
AVDD to AGND
DRVDD to DGND
AGND to DGND
AVDD to DRVDD
D0 through D13 to DGND
DCO to DGND
OR to DGND
CLK+ to AGND
CLK− to AGND
VIN+ to AGND
VIN− to AGND
VREF to AGND
SENSE to AGND
REFT to AGND
REFB to AGND
SDIO/DCS to DGND
PDWN to AGND
CSB to AGND
SCLK/DFS to AGND
OEB to AGND
ENVIRONMENTAL
Storage Temperature Range
Operating Temperature Range
Lead Temperature
(Soldering 10 Sec)
Junction Temperature
Rating
−0.3 V to +2.0 V
−0.3 V to +3.9 V
−0.3 V to +0.3 V
−3.9 V to +2.0 V
−0.3 V to DRVDD + 0.3 V
−0.3 V to DRVDD + 0.3 V
−0.3 V to DRVDD + 0.3 V
−0.3 V to +3.9 V
−0.3 V to +3.9 V
−0.3 V to AVDD + 0.2 V
−0.3 V to AVDD + 0.2 V
−0.3 V to AVDD + 0.2 V
−0.3 V to AVDD + 0.2 V
−0.3 V to AVDD + 0.2 V
−0.3 V to AVDD + 0.2 V
−0.3 V to DRVDD + 0.3 V
−0.3 V to +3.9 V
−0.3 V to +3.9 V
−0.3 V to +3.9 V
−0.3 V to +3.9 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 indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
THERMAL RESISTANCE
The exposed paddle must be soldered to the ground plane for
the LFCSP_VQ package. Soldering the exposed paddle to the
customer board increases the reliability of the solder joints,
maximizing the thermal capability of the package.
Table 6. Thermal Resistance
Package Type
48-lead LFCSP_VQ (CP-48-3)
θJA
26.4
θJC
2.4
Unit
°C/W
Typical θJA and θJC are specified for a 4-layer board in still air.
Airflow increases heat dissipation effectively reducing θJA. In
addition, metal in direct contact with the package leads from
metal traces, and through holes, ground, and power planes,
reduces the θJA.
–65°C to +125°C
–40°C to +85°C
+300°C
+150°C
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 8 of 44
AD9246
48
47
46
45
44
43
42
41
40
39
38
37
DRVDD
DRGND
D1
D0 (LSB)
DCO
OEB
AVDD
AGND
AVDD
CLK–
CLK+
AGND
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
D2
D3
1
2
PIN 1
INDICATOR
D4 3
D5 4
D6 5
D7 6
DRGND 7
DRVDD 8
D8 9
D9 10
D10 11
D11 12
AD9246
PDWN
RBIAS
CML
AVDD
AGND
VIN–
VIN+
AGND
REFT
REFB
VREF
SENSE
05491-003
D12
D13 (MSB)
OR
DRGND
DRVDD
SDIO/DCS
SCLK/DFS
CSB
AGND
AVDD
AGND
AVDD
13
14
15
16
17
18
19
20
21
22
23
24
TOP VIEW
(Not to Scale)
36
35
34
33
32
31
30
29
28
27
26
25
Figure 3. Pin Configuration
Table 7. Pin Function Description
Pin No.
0, 21, 23, 29, 32,
37, 41
45, 46, 1 to 6,
9 to 14
7, 16, 47
8, 17, 48
15
18
Mnemonic
AGND
Description
Analog Ground. (Pin 0 is the exposed thermal pad on the bottom of the package.)
D0 (LSB) to D13 (MSB)
Data Output Bits.
DRGND
DRVDD
OR
SDIO/DCS
Digital Output Ground.
Digital Output Driver Supply (1.8 V to 3.3 V).
Out-of-Range Indicator.
Serial Port Interface (SPI)® Data Input/Output (Serial Port Mode); Duty Cycle Stabilizer Select
(External Pin Mode). See Table 10.
Serial Port Interface Clock (Serial Port Mode); Data Format Select Pin (External Pin Mode).
Serial Port Interface Chip Select (Active Low). See Table 10.
Analog Power Supply.
Reference Mode Selection. See Table 9.
Voltage Reference Input/Output.
Differential Reference (−).
Differential Reference (+).
Analog Input Pin (+).
Analog Input Pin (−).
Common-Mode Level Bias Output.
External Bias Resistor Connection. A 10 kΩ resistor must be connected between this pin and
analog ground (AGND).
Power-Down Function Select.
Clock Input (+).
Clock Input (−).
Output Enable (Active Low).
Data Clock Output.
19
20
22, 24, 33, 40, 42
25
26
27
28
30
31
34
35
SCLK/DFS
CSB
AVDD
SENSE
VREF
REFB
REFT
VIN+
VIN–
CML
RBIAS
36
38
39
43
44
PDWN
CLK+
CLK–
OEB
DCO
Rev. A | Page 9 of 44
AD9246
EQUIVALENT CIRCUITS
1kΩ
SCLK/DFS
OEB
PDWN
05491-004
05491-008
VIN
30kΩ
Figure 4. Equivalent Analog Input Circuit
Figure 8. Equivalent SCLK/DFS, OEB, PDWN Input Circuit
AVDD
AVDD
26kΩ
1.2V
1kΩ
CLK–
05491-005
CLK+
CSB
10kΩ
05491-010
10kΩ
Figure 9. Equivalent CSB Input Circuit
Figure 5. Equivalent Clock Input Circuit
DRVDD
SENSE
1kΩ
1kΩ
05491-006
05491-011
SDIO/DCS
Figure 10. Equivalent Sense Circuit
Figure 6. Equivalent SDIO/DCS Input Circuit
DRVDD
AVDD
6kΩ
05491-007
DRGND
05491-012
VREF
Figure 11. Equivalent VREF Circuit
Figure 7. Equivalent Digital Output Circuit
Rev. A | Page 10 of 44
AD9246
TYPICAL PERFORMANCE CHARACTERISTICS
AVDD = 1.8 V; DRVDD = 2.5 V; maximum sample rate, DCS enabled, 1 V internal reference; 2 V p-p differential input;
AIN = −1.0 dBFS; 64k sample; TA = 25°C, unless otherwise noted. All figures show typical performance for all speed grades.
0
–20
–40
–60
–80
–100
–120
15.625
31.250
46.875
62.500
0
0
15.625
31.250
46.875
62.500
Figure 15. AD9246-125 Single-Tone FFT with fIN = 100.3 MHz
0
125MSPS
140.3MHz @ –1dBFS
SNR = 71dB (72dBFS)
ENOB = 11.4 BITS
SFDR = 85dBc
–20
–40
AMPLITUDE (dBFS)
–60
–80
–100
–60
–80
–100
–120
15.625
31.250
46.875
62.500
FREQUENCY (MHz)
–140
05491-014
0
31.250
46.875
62.500
Figure 16. AD9246-125 Single-Tone FFT with fIN = 140.3 MHz
0
125MSPS
70.3MHz @ –1dBFS
SNR = 71.7dB (72.7dBFS)
ENOB = 11.5 BITS
SFDR = 85dBc
–20
15.625
FREQUENCY (MHz)
Figure 13. AD9246-125 Single-Tone FFT with fIN = 30.3 MHz
0
0
05491-017
–120
–40
125MSPS
170.3MHz @ –1dBFS
SNR = 70.8dB (71.8dBFS)
ENOB = 11.4 BITS
SFDR = 83.4dBc
–20
AMPLITUDE (dBFS)
–40
–60
–80
–100
–60
–80
–100
–120
0
15.625
31.250
46.875
62.500
FREQUENCY (MHz)
05491-015
–120
–40
Figure 14. AD9246-125 Single-Tone FFT with fIN = 70.3 MHz
–140
0
15.625
31.250
46.875
62.500
FREQUENCY (MHz)
Figure 17. AD9246-125 Single-Tone FFT with fIN = 170.3 MHz
Rev. A | Page 11 of 44
05491-018
AMPLITUDE (dBFS)
–100
FREQUENCY (MHz)
125MSPS
30.3MHz @ –1dBFS
SNR = 71.9dBc (72.9dBFS)
ENOB = 11.6 BITS
SFDR = 88.8dBc
–20
AMPLITUDE (dBFS)
–80
–140
Figure 12. AD9246-125 Single-Tone FFT with fIN = 2.3 MHz
–140
–60
05491-016
0
FREQUENCY (MHz)
–140
–40
–120
05491-013
–140
125MSPS
100.3MHz @ –1dBFS
SNR = 71.6dBc (72.6dBFS)
ENOB = 11.5 BITS
SFDR = 85dBc
–20
AMPLITUDE (dBFS)
AMPLITUDE (dBFS)
0
125MSPS
2.3MHz @ –1dBFS
SNR = 71.9dB (72.9dBFS)
ENOB = 11.7 BITS
SFDR = 90dBc
AD9246
0
–20
SFDR = +25°C
90
–60
–80
85
SFDR = +85°C
80
SNR = +85°C
SNR = +25°C
75
SNR = –40°C
–100
0
15.625
31.250
62.500
46.875
FREQUENCY (MHz)
Figure 18. AD9246-125 Single-Tone FFT with fIN = 225.3 MHz
0
65
05491-019
–140
50
100
150
200
250
INPUT FREQUENCY (MHz)
Figure 21. AD9246 Single-Tone SNR/SFDR vs. Input Frequency (fIN) and
Temperature with 2 V p-p Full Scale
95
125MSPS
300.3MHz @ –1dBFS
SNR = 69.3dB (70.3dBFS)
ENOB = 11 BITS
SFDR = 77.5dBc
–20
0
05491-022
70
–120
SFDR = +85°C
90
–40
SNR/SFDR (dBc)
–60
–80
85
SFDR = –40°C
SFDR = +25°C
80
75
–100
SNR = +85°C
70
–120
0
15.625
31.250
62.500
46.875
65
05491-020
–140
FREQUENCY (MHz)
SNR = –40°C
SNR = +25°C
0
50
100
150
200
250
INPUT FREQUENCY (MHz)
05491-023
AMPLITUDE (dBFS)
SFDR = –40°C
–40
SNR/SFDR (dBc)
AMPLITUDE (dBFS)
95
125MSPS
225.3MHz @ –1dBFS
SNR = 70.3dB (71.3dBFS)
ENOB = 11.3 BITS
SFDR = 80.4dBc
Figure 22. AD9246 Single-Tone SNR/SFDR vs. Input Frequency (fIN) and
Temperature with 1 V p-p Full Scale
Figure 19. AD9246-125 Single-Tone FFT with fIN = 300.3 MHz
0
120
SFDR (dBFS)
GAIN/OFFSET ERROR (%FSR)
SNR/SFDR (dBc and dBFS)
100
SNR (dBFS)
80
60
40
SFDR (dBc)
85dB REFERENCE LINE
OFFSET ERROR
–0.25
–0.50
GAIN ERROR
–0.75
20
–70
–60
–50
–40
–30
INPUT AMPLITUDE (dBFS)
–20
–10
0
–1.00
–40
–20
0
20
40
60
TEMPERATURE (°C)
Figure 23. AD9246 Gain and Offset vs. Temperature
Figure 20. AD9246 Single-Tone SNR/SFDR vs. Input Amplitude (AIN)
with fIN = 2.4 MHz
Rev. A | Page 12 of 44
80
05491-035
–80
05491-040
SNR (dBc)
0
–90
AD9246
0
SFDR (dBc)
–20
SFDR/IMD3 (dBc and dBFS)
–20
AMPLITUDE (dBFS)
0
125MSPS
29.1MHz @ –7dBFS
32.1MHz @ –7dBFS
SFDR = 85dBc (92dBFS)
–40
–60
–80
–100
–40
IMD3 (dBc)
–60
–80
SFDR (dBFS)
–100
–120
15.625
31.250
46.875
62.500
FREQUENCY (MHz)
05491-025
0
–120
–90
–42
–30
–6
–18
0
SFDR (dBFS)
–20
SFDR/IMD3 (dBc and dBFS)
AMPLITUDE (dBFS)
–54
Figure 27. AD9246 Two-Tone SFDR/IMD vs. Input Amplitude (AIN)
with FIN1 = 29.1 MHz, FIN2 = 32.1 MHz
125MSPS
169.1MHz @ –7dBFS
172.1MHz @ –7dBFS
SFDR = 84dBc (91dBFS)
–20
–66
INPUT AMPLITUDE (dBFS)
Figure 24. AD9246-125 Two-Tone FFT with fIN1 = 29.1 MHz, fIN2 = 32.1 MHz
0
–78
05491-028
IMD3 (dBFS)
–140
–40
–60
–80
–100
–40
IMD3 (dBFS)
–60
–80
SFDR (dBc)
–100
–120
15.625
31.250
46.875
62.500
FREQUENCY (MHz)
–120
–90
05491-026
0
–54
–42
–30
–6
–18
Figure 28. AD9246 Two-Tone SFDR/IMD vs. Input Amplitude (AIN)
with FIN1 = 169.1 MHz, FIN2 = 172.11 MHz
0
0
–20
NPR = 62.9dBc
NOTCH @ 18.5MHz
NOTCH WIDTH = 3MHz
–20
AMPLITUDE (dBFS)
–40
–60
–80
–100
–40
–60
–80
0
15.36
30.72
46.08
FREQUENCY (MHz)
61.44
Figure 26. AD9246-125 Two 64k WCDMA Carriers
with fIN = 215.04 MHz, fS = 122.88 MSPS
–120
0
15.625
31.250
46.875
FREQUENCY (MHz)
Figure 29. AD9246 Noise Power Ratio (NPR)
Rev. A | Page 13 of 44
62.500
05491-089
–100
05491-085
AMPLITUDE (dBFS)
–66
INPUT AMPLITUDE (dBFS)
Figure 25. AD9246-125 Two-Tone FFT with fIN1 = 169.1 MHz, fIN2 = 172.1 MHz
–120
–78
05491-029
IMD3 (dBc)
–140
AD9246
10
100
1.3 LSB rms
95
8
NUMBER OF HITS (1M)
90
85
80
4
2
75
SNR
5
25
45
65
85
105
125
CLOCK FREQUENCY (MSPS)
0
N–4 N–3 N–2
N–1
N
N+1 N+2 N+3
OUTPUT CODE
Figure 30. AD9246 Single-Tone SNR/SFDR vs. Clock Frequency (fS)
with fIN = 2.4 MHz
N+4
05491-084
70
6
05491-030
SNR/SFDR (dBc)
SFDR
Figure 33. AD9246 Grounded Input Histogram
2.0
100
1.5
95
SFDR DCS ON
1.0
85
INL ERROR (LSB)
SNR/SFDR (dBc)
90
SFDR DCS OFF
80
SNR DCS ON
75
0.5
0
–0.5
–1.0
70
–1.5
60
DUTY CYCLE (%)
0
2048
4096
6144
8192
10240
12288
14336
16384
05491-024
40
80
05491-027
–2.0
60
20
16384
05491-021
SNR DCS OFF
65
OUTPUT CODE
Figure 34. AD9246 INL with fIN = 10.3 MHz
Figure 31. AD9246 SNR/SFDR vs. Duty Cycle with fIN = 10.3 MHz
0.5
90
0.4
SFDR
0.3
DNL ERROR (LSB)
80
0.2
0.1
0
–0.1
–0.2
75
–0.3
SNR
70
0.5
0.6
–0.4
0.7
0.8
0.9
1.0
1.1
1.2
1.3
INPUT COMMON-MODE VOLTAGE (V)
05491-031
SNR/SFDR (dBc)
85
–0.5
0
2048
4096
6144
8192
10240
12288
14336
OUTPUT CODE
Figure 35. AD9246 DNL with fIN = 10.3 MHz
Figure 32. AD9246 SNR/SFDR vs. Input Common Mode (VCM)
with fIN = 30 MHz
Rev. A | Page 14 of 44
AD9246
THEORY OF OPERATION
The AD9246 architecture consists of a front-end sample-andhold amplifier (SHA) followed by a pipelined switched capacitor
ADC. The quantized outputs from each stage are combined into
a final 14-bit result in the digital correction logic. The pipeline
architecture permits the first stage to operate on a new input
sample, while the remaining stages operate on preceding
samples. Sampling occurs on the rising edge of the clock.
For more information, see Application Notes AN-742, Frequency
Domain Response of Switched-Capacitor ADCs; and AN-827,
A Resonant Approach to Interfacing Amplifiers to SwitchedCapacitor ADCs, and the Analog Dialogue article, “TransformerCoupled Front-End for Wideband A/D Converters.”
S
Each stage of the pipeline, excluding the last, consists of a low
resolution flash ADC connected to a switched capacitor DAC
and interstage residue amplifier (MDAC). The residue amplifier
magnifies the difference between the reconstructed DAC output
and the flash input for the next stage in the pipeline. One bit of
redundancy is used in each stage to facilitate digital correction
of flash errors. The last stage simply consists of a flash ADC.
ANALOG INPUT CONSIDERATIONS
The analog input to the AD9246 is a differential switched
capacitor SHA that has been designed for optimum
performance while processing a differential input signal.
The clock signal alternately switches the SHA between sample
mode and hold mode (see Figure 36). When the SHA is
switched into sample mode, the signal source must be capable
of charging the sample capacitors and settling within one-half
of a clock cycle. A small resistor in series with each input can
help reduce the peak transient current required from the output
stage of the driving source.
A shunt capacitor can be placed across the inputs to provide
dynamic charging currents. This passive network creates a lowpass filter at the ADC input; therefore, the precise values are
dependent on the application.
In IF undersampling applications, any shunt capacitors should
be reduced. In combination with the driving source impedance,
these capacitors would limit the input bandwidth.
CS
VIN+
CPIN, PAR
S
H
CS
VIN–
CH
CPIN, PAR
S
05491-037
The input stage contains a differential SHA that can be ac- or
dc-coupled in differential or single-ended modes. The output
staging block aligns the data, carries out the error correction,
and passes the data to the output buffers. The output buffers are
powered from a separate supply, allowing adjustment of the
output voltage swing. During power down, the output buffers
go into a high impedance state.
CH
S
Figure 36. Switched Capacitor SHA Input
For best dynamic performance, the source impedances driving
VIN+ and VIN− should match such that common-mode
settling errors are symmetrical. These errors are reduced by the
common-mode rejection of the ADC.
An internal differential reference buffer creates two reference
voltages used to define the input span of the ADC core. The
span of the ADC core is set by the buffer to be 2 × VREF. The
reference voltages are not available to the user. Two bypass
points, REFT and REFB, are brought out for decoupling to
reduce the noise contributed by the internal reference buffer.
It is recommended that REFT be decoupled to REFB by a 0.1 μF
capacitor, as described in the Layout Considerations section.
Input Common Mode
The analog inputs of the AD9246 are not internally dc-biased.
In ac-coupled applications, the user must provide this bias
externally. Setting the device such that VCM = 0.55 × AVDD is
recommended for optimum performance; however, the device
functions over a wider range with reasonable performance (see
Figure 32). An on-board, common-mode voltage reference is
included in the design and is available from the CML pin.
Optimum performance is achieved when the common-mode
voltage of the analog input is set by the CML pin voltage
(typically 0.55 × AVDD). The CML pin must be decoupled to
ground by a 0.1 μF capacitor, as described in the Layout
Considerations section.
Rev. A | Page 15 of 44
AD9246
At input frequencies in the second Nyquist zone and above, the
noise performance of most amplifiers is not adequate to achieve
the true SNR performance of the AD9246. For applications where
SNR is a key parameter, transformer coupling is the recommended input.
DIFFERENTIAL INPUT CONFIGURATIONS
Optimum performance is achieved by driving the AD9246 in
a differential input configuration. For baseband applications,
the AD8138 differential driver provides excellent performance
and a flexible interface to the ADC. The output common-mode
voltage of the AD8138 is easily set with the CML pin of the
AD9246 (see Figure 37), and the driver can be configured in
a Sallen-Key filter topology to provide band limiting of the
input signal.
49.9Ω
499Ω
R
VIN+
499Ω
523Ω
AVDD
In any configuration, the value of the shunt capacitor, C, is
dependent on the input frequency and source impedance and
may need to be reduced or removed. Table 8 displays recommended values to set the RC network. However, these values are
dependent on the input signal and should only be used as a
starting guide.
AD9246
C
AD8138
0.1µF
As an alternative to using a transformer-coupled input at
frequencies in the second Nyquist zone, the AD8352 differential
driver can be used (see Figure 41).
R
CML
VIN–
05491-038
499Ω
Figure 37. Differential Input Configuration Using the AD8138
Table 8. RC Network Recommended Values
For baseband applications where SNR is a key parameter,
differential transformer coupling is the recommended input
configuration (see Figure 38). The CML voltage can be
connected to the center tap of the secondary winding of the
transformer to bias the analog input.
Frequency Range (MHz)
0 to 70
70 to 200
200 to 300
>300
The signal characteristics must be considered when selecting
a transformer. Most RF transformers saturate at frequencies
below a few MHz, and excessive signal power can cause core
saturation, which leads to distortion.
R
49.9Ω
VIN+
AD9246
C
R
In this configuration, SFDR and distortion performance
degrade due to the large input common-mode swing. If the
source impedances on each input are matched, there should be
little effect on SNR performance. Figure 39 details a typical
single-ended input configuration.
CML
VIN–
0.1µF
Figure 38. Differential Transformer-Coupled Configuration
10µF
AVDD
1kΩ
R
1V p-p
49.9Ω
0.1µF
1kΩ
0.1µF
VIN+
1kΩ
AVDD
10µF
C Differential (pF)
15
5
5
Open
Although not recommended, it is possible to operate the
AD9246 in a single-ended input configuration, as long as the
input voltage swing is within the AVDD supply. Single-ended
operation can provide adequate performance in cost-sensitive
applications.
05491-039
2V p-p
R Series (Ω)
33
33
15
15
Single-Ended Input Configuration
C
R
AD9246
VIN–
1kΩ
Figure 39. Single-Ended Input Configuration
Rev. A | Page 16 of 44
05491-042
1V p-p
For applications where SFDR is a key parameter, differential
double balun coupling is the recommended input configuration
(see Figure 40).
AD9246
0.1µF
0.1µF
R
VIN+
2V p-p
25Ω
S
S
P
0.1µF
25Ω
AD9246
C
0.1µF
R
VIN–
05491-080
PA
CML
Figure 40. Differential Double Balun Input Configuration
VCC
0.1µF
0Ω
ANALOG INPUT
16
8, 13
1
11
0.1µF
R
2
VIN+
200Ω
CD
RD
AD8352
RG
3
10
0.1µF
200Ω
C
R
4
5
ANALOG INPUT
0.1µF
AD9246
VIN–
CML
14
0Ω
0.1µF
0.1µF
05491-081
0.1µF
Figure 41. Differential Input Configuration Using the AD8352
Table 9. Reference Configuration Summary
Selected Mode
External Reference
Internal Fixed Reference
Programmable Reference
SENSE Voltage
AVDD
VREF
0.2 V to VREF
Resulting VREF (V)
N/A
0.5
Internal Fixed Reference
AGND to 0.2 V
1.0
R2 ⎞
0.5 × ⎛⎜1 +
⎟ (see Figure 43)
⎝ R1 ⎠
VOLTAGE REFERENCE
A stable and accurate voltage reference is built into the AD9246.
The input range is adjustable by varying the reference voltage
applied to the AD9246, using either the internal reference or an
externally applied reference voltage. The input span of the ADC
tracks reference voltage changes linearly. The various reference
modes are summarized in the following sections. The Reference
Decoupling section describes the best practices and requirements for PCB layout of the reference.
Internal Reference Connection
A comparator within the AD9246 detects the potential at the
SENSE pin and configures the reference into four possible
states, as summarized in Table 9. If SENSE is grounded, the
reference amplifier switch is connected to the internal resistor
divider (see Figure 42), setting VREF to 1 V.
Resulting Differential
Span (V p-p)
2 × External Reference
1.0
2 × VREF
2.0
If a resistor divider is connected external to the chip as shown
in Figure 43, the switch sets to the SENSE pin. This puts the
reference amplifier in a noninverting mode with the VREF
output defined as
R2 ⎞
VREF = 0.5 ⎛⎜1 +
⎟
R1 ⎠
⎝
If the SENSE pin is connected to AVDD, the reference amplifier
is disabled, and an external reference voltage can be applied to
the VREF pin (see the External Reference Operation section).
The input range of the ADC always equals twice the voltage at
the reference pin for either an internal or an external reference.
Connecting the SENSE pin to VREF switches the reference
amplifier input to the SENSE pin, completing the loop and
providing a 0.5 V reference output.
Rev. A | Page 17 of 44
AD9246
External Reference Operation
–
The use of an external reference may be necessary to enhance
the gain accuracy of the ADC or improve thermal drift characteristics. Figure 45 shows the typical drift characteristics of the
internal reference in both 1 V and 0.5 V modes.
REFT
0.1µF
REFB
0.1µF
0.1µF
10
REFERENCE VOLTAGE ERROR (mV)
VREF
SELECT
LOGIC
SENSE
05491-043
0.5V
AD9246
ADC
CORE
VIN–
4
2
0
–40
–
VIN+
VREF = 0.5V
6
–
Figure 42. Internal Reference Configuration
VREF = 1V
8
REFT
–20
0
20
40
TEMPERATURE (°C)
0.1µF
When the SENSE pin is tied to AVDD, the internal reference is
disabled, allowing the use of an external reference. An internal
resistor divider loads the external reference with an equivalent
6 kΩ load (see Figure 11). In addition, an internal buffer
generates the positive and negative full-scale references for the
ADC core. Therefore, the external reference must be limited to
a maximum of 1 V.
REFB
R2
SENSE
SELECT
LOGIC
0.5V
R1
AD9246
05491-044
0.1µF
CLOCK INPUT CONSIDERATIONS
Figure 43. Programmable Reference Configuration
If the internal reference of the AD9246 is used to drive multiple
converters to improve gain matching, the loading of the reference
by the other converters must be considered. Figure 44 depicts
how the internal reference voltage is affected by loading.
0
VREF = 1V
–0.50
–0.75
–1.00
0.5
1.0
1.5
LOAD CURRENT (mA)
Figure 44. VREF Accuracy vs. Load
2.0
05491-033
REFERENCE VOLTAGE ERROR (%)
–0.25
0
For optimum performance, the AD9246 sample clock inputs
(CLK+ and CLK−) should be clocked with a differential signal.
The signal is typically ac-coupled into the CLK+ pin and the
CLK− pin via a transformer or capacitors. These pins are biased
internally (see Figure 5) and require no external bias.
Clock Input Options
The AD9246 has a very flexible clock input structure. The clock
input can be a CMOS, LVDS, LVPECL, or sine wave signal.
Regardless of the type of signal used, the jitter of the clock
source is of the most concern (see the Jitter Considerations
section).
VREF = 0.5V
–1.25
80
Figure 45. Typical VREF Drift
0.1µF
VREF
60
05491-036
ADC
CORE
VIN–
–
VIN+
Figure 46 shows one preferred method for clocking the
AD9246. A low jitter clock source is converted from singleended to a differential signal using an RF transformer. The
back-to-back Schottky diodes across the transformer secondary
limit clock excursions into the AD9246 to approximately
0.8 V p-p differential. This helps prevent the large voltage
swings of the clock from feeding through to other portions of
the AD9246, while preserving the fast rise and fall times of the
signal, which are critical to a low jitter performance.
Rev. A | Page 18 of 44
AD9246
50Ω
0.1µF
CLOCK
INPUT
CLK+
ADC
AD9246
100Ω
0.1µF
1kΩ
OPTIONAL
0.1µF
100Ω
AD951x
CMOS DRIVER
ADC
AD9246
CLK–
CLK–
05491-048
SCHOTTKY
DIODES:
HSMS2812
0.1µF
CLK+
1kΩ
50Ω1
0.1µF
150Ω
Figure 46. Transformer Coupled Differential Clock
39kΩ
05491-051
0.1µF
CLOCK
INPUT
VCC
MIN-CIRCUITS
ADT1–1WT, 1:1Z
0.1µF
XFMR
RESISTOR IS OPTIONAL
Figure 49. Single-Ended 1.8 V CMOS Sample Clock
If a low jitter clock source is not available, another option is to
ac-couple a differential PECL signal to the sample clock input
pins, as shown in Figure 47. The AD9510/AD9511/AD9512/
AD9513/AD9514/AD9515 family of clock drivers offers excellent jitter performance.
VCC
50Ω1
1kΩ
AD951x
CMOS DRIVER
OPTIONAL 0.1µF
100Ω
1kΩ
0.1µF
CLK+
ADC
AD9246
CLK–
0.1µF
CLOCK
INPUT
CLK+
100Ω
AD951x
0.1µF PECL DRIVER
0.1µF
CLK
50Ω1
150Ω
240Ω
50Ω1
Figure 50. Single-Ended 3.3 V CMOS Sample Clock
ADC
AD9246
Clock Duty Cycle
CLK–
240Ω
05491-049
CLOCK
INPUT
150Ω RESISTOR IS OPTIONAL
0.1µF
CLK
RESISTORS ARE OPTIONAL
Figure 47. Differential PECL Sample Clock
A third option is to ac-couple a differential LVDS signal to the
sample clock input pins, as shown in Figure 48. The AD9510/
AD9511/AD9512/AD9513/AD9514/AD9515 family of clock
drivers offers excellent jitter performance.
0.1µF
CLOCK
INPUT
AD951x
0.1µF LVDS DRIVER
0.1µF
CLK
50Ω1
ADC
AD9246
CLK–
50Ω1
150Ω RESISTORS ARE OPTIONAL
05491-050
CLOCK
INPUT
CLK+
100Ω
Typical high speed ADCs use both clock edges to generate a
variety of internal timing signals. As a result, these ADCs may
be sensitive to clock duty cycle. Commonly, a ±5% tolerance is
required on the clock duty cycle to maintain dynamic
performance characteristics.
The AD9246 contains a duty cycle stabilizer (DCS) that retimes
the nonsampling, or falling edge, providing an internal clock
signal with a nominal 50% duty cycle. This allows a wide range
of clock input duty cycles without affecting the performance of
the AD9246. Noise and distortion performance are nearly flat
for a wide range of duty cycles when the DCS is on, as shown in
Figure 31.
0.1µF
CLK
05491-052
CLOCK
INPUT
0.1µF
Figure 48. Differential LVDS Sample Clock
In some applications, it is acceptable to drive the sample clock
inputs with a single-ended CMOS signal. In such applications,
directly drive CLK+ from a CMOS gate, while bypassing the
CLK− pin to ground using a 0.1 μF capacitor in parallel with a
39 kΩ resistor (see Figure 49). CLK+ may be directly driven
from a CMOS gate. This input is designed to withstand input
voltages up to 3.6 V, making the selection of the drive logic
voltage very flexible. When driving CLK+ with a 1.8 V CMOS
signal, biasing the CLK− pin with a 0.1 μF capacitor in parallel
with a 39 kΩ resistor (see Figure 49) is required. The 39 kΩ
resistor is not required when driving CLK+ with a 3.3 V CMOS
signal (see Figure 50).
Jitter in the rising edge of the input is still of paramount
concern and is not reduced by the internal stabilization circuit.
The duty cycle control loop does not function for clock rates
less than 20 MHz nominally. The loop has a time constant
associated with it that needs to be considered in applications
where the clock rate can change dynamically. This requires a
wait time of 1.5 μs to 5 μs after a dynamic clock frequency
increase (or decrease) before the DCS loop is relocked to the
input signal. During the time period the loop is not locked, the
DCS loop is bypassed, and the internal device timing is
dependent on the duty cycle of the input clock signal. In such
an application, it may be appropriate to disable the duty cycle
stabilizer. In all other applications, enabling the DCS circuit is
recommended to maximize ac performance.
Rev. A | Page 19 of 44
AD9246
The DCS can be enabled or disabled by setting the SDIO/DCS
pin when operating in the external pin mode (see Table 10), or
via the SPI, as described in Table 13.
Table 10. Mode Selection (External Pin Mode)
Voltage at Pin
AGND
AVDD
SCLK/DFS
Binary (default)
Twos complement
SDIO/DCS
DCS disabled
DCS enabled
(default)
High speed, high resolution ADCs are sensitive to the quality of
the clock input. The degradation in SNR at a given input
frequency (fIN) due to jitter (tJ) is calculated as follows:
SNR = −20 log (2π × fIN × tJ)
In the equation, the rms aperture jitter represents the root mean
square of all jitter sources, which include the clock input, analog
input signal, and ADC aperture jitter specification. IF undersampling applications are particularly sensitive to jitter, as
illustrated in Figure 51.
75
0.05ps
fCLK
×N
2
where N is the number of output bits, 14 in the case of the
AD9246.
This maximum current occurs when every output bit switches
on every clock cycle, that is, a full-scale square wave at the
Nyquist frequency, fCLK/2. In practice, the DRVDD current is
established by the average number of output bits switching,
which is determined by the sample rate and the characteristics
of the analog input signal. Reducing the capacitive load
presented to the output drivers can minimize digital power
consumption. The data in Figure 52 and Figure 53 was taken
under the same operating conditions as the data for the Typical
Performance Characteristics section, with a 5 pF load on each
output driver.
MEASURED
PERFORMANCE
65
475
250
0.20ps
450
60
IAVDD
200
425
10
100
INPUT FREQUENCY (MHz)
100
375
2.50ps
3.00ps
1
TOTAL POWER
1000
IDRVDD
Figure 51. SNR vs. Input Frequency and Jitter
325
0
25
50
75
100
0
125
CLOCK FREQUENCY (MSPS)
Figure 52. AD9246-125 Power and Current vs. Clock Frequency fIN = 30 MHz
410
200
180
390
IAVDD
160
370
140
POWER (mW)
Treat the clock input as an analog signal in cases where aperture
jitter may affect the dynamic range of the AD9246. Power supplies
for clock drivers should be separated from the ADC output driver
supplies to avoid modulating the clock signal with digital noise.
The power supplies should also not be shared with analog input
circuits, such as buffers, to avoid the clock modulating onto the
input signal or vice versa. Low jitter, crystal-controlled oscillators
make the best clock sources. If the clock is generated from
another type of source (by gating, dividing, or other methods),
it should be retimed by the original clock at the last step.
50
350
05491-034
2.00ps
45
400
Refer to Application Notes AN-501, Aperture Uncertainty and
ADC System Performance, and AN-756, Sampled Systems and
the Effects of Clock Phase Noise and Jitter, for more in-depth
information about jitter performance as it relates to ADCs.
350
120
330
100
TOTAL POWER
80
310
CURRENT (mA)
1.50ps
150
60
290
40
270
250
20
IDRVDD
0
25
50
75
CLOCK FREQUENCY (MSPS)
100
0
05491-068
1.0ps
50
40
POWER (mW)
55
CURRENT (mA)
0.5ps
05491-083
SNR (dBc)
As shown in Figure 52 and Figure 53, the power dissipated by
the AD9246 is proportional to its sample rate. The digital power
dissipation is determined primarily by the strength of the digital
drivers and the load on each output bit. The maximum DRVDD
current (IDRVDD) can be calculated as:
I DRVDD = VDRVDD × CLOAD ×
JITTER CONSIDERATIONS
70
POWER DISSIPATION AND STANDBY MODE
Figure 53. AD9246-105 Power and Current vs. Clock Frequency fIN = 30 MHz
Rev. A | Page 20 of 44
AD9246
290
150
As detailed in the Interfacing to High Speed ADCs via SPI User
Manual, the data format can be selected for either offset binary,
twos complement, or Gray code when using the SPI control.
IAVDD
120
275
245
60
230
30
An out-of-range condition exists when the analog input voltage
is beyond the input range of the ADC. OR is a digital output
that is updated along with the data output corresponding to the
particular sampled input voltage. Thus, OR has the same pipeline
latency as the digital data.
OR DATA OUTPUTS
1 11 1111 1111 1111
0 11 1111 1111 1111
0 11 1111 1111 1110
215
0
20
40
CLOCK FREQUENCY (MSPS)
60
0
80
05491-091
IDRVDD
–FS + 1/2 LSB
Figure 54. AD9246-80 Power and Current vs. Clock Frequency fIN = 30 MHz
0
0
1
Power-Down Mode
By asserting the PDWN pin high, the AD9246 is placed in
power-down mode. In this state, the ADC typically dissipates
1.8 mW. During power-down, the output drivers are placed in
a high impedance state. Reasserting the PDWN pin low returns
the AD9246 to its normal operational mode. This pin is both
1.8 V and 3.3 V tolerant.
Low power dissipation in power-down mode is achieved by
shutting down the reference, reference buffer, biasing networks,
and clock. The decoupling capacitors on REFT and REFB are
discharged when entering power-down mode and then must be
recharged when returning to normal operation. As a result, the
wake-up time is related to the time spent in power-down mode;
and shorter power-down cycles result in proportionally shorter
wake-up times. With the recommended 0.1 μF decoupling
capacitors on REFT and REFB, it takes approximately 0.25 ms
to fully discharge the reference buffer decoupling capacitors and
0.35 ms to restore full operation.
Standby Mode
When using the SPI port interface, the user can place the ADC
in power-down mode or standby mode. Standby mode allows the
user to keep the internal reference circuitry powered when
faster wake-up times are required (see the Memory Map section).
+FS – 1 LSB
OR
00 0000 0000 0001
00 0000 0000 0000
00 0000 0000 0000
–FS
–FS – 1/2 LSB
+FS
+FS – 1/2 LSB
05491-088
TOTAL POWER
Figure 55. OR Relation to Input Voltage and Output Data
OR is low when the analog input voltage is within the analog
input range and high when the analog input voltage exceeds the
input range, as shown in Figure 55. OR remains high until the
analog input returns to within the input range, and another conversion is completed. By logically AND’ing the OR bit with the MSB
and its complement, overrange high or underrange low conditions
can be detected. Table 11 is a truth table for the overrange/
underrange circuit in Figure 56, which uses NAND gates.
MSB
OVER = 1
OR
UNDER = 1
MSB
05491-087
90
260
CURRENT (mA)
POWER (mW)
Out-of-Range (OR) Condition
Figure 56. Overrange/Underrange Logic
Table 11. Overrange/Underrange Truth Table
OR
0
0
1
1
MSB
0
1
0
1
Analog Input Is:
Within range
Within range
Underrange
Overrange
Digital Output Enable Function (OEB)
DIGITAL OUTPUTS
The AD9246 output drivers can be configured to interface with
1.8 V to 3.3 V logic families by matching DRVDD to the digital
supply of the interfaced logic. The output drivers are sized to
provide sufficient output current to drive a wide variety of logic
families. However, large drive currents tend to cause current
glitches on the supplies that may affect converter performance.
Applications requiring the ADC to drive large capacitive loads
or large fan-outs may require external buffers or latches.
The AD9246 has three-state ability. If the OEB pin is low, the
output data drivers are enabled. If the OEB pin is high, the
output data drivers are placed in a high impedance state. This is
not intended for rapid access to the data bus. Note that OEB is
referenced to the digital supplies (DRVDD) and should not
exceed that supply voltage.
The output data format can be selected for either offset binary
or twos complement by setting the SCLK/DFS pin when operating in the external pin mode (see Table 10).
Rev. A | Page 21 of 44
AD9246
TIMING
Data Clock Output (DCO)
The lowest typical conversion rate of the AD9246 is 10 MSPS.
At clock rates below 10 MSPS, dynamic performance can degrade.
The AD9246 provides a data clock output (DCO) intended for
capturing the data in an external register. The data outputs are valid
on the rising edge of DCO, unless the DCO clock polarity has
been changed via the SPI. See Figure 2 for a graphical timing
description.
The AD9246 provides latched data outputs with a pipeline delay
of 12 clock cycles. Data outputs are available one propagation
delay (tPD) after the rising edge of the clock signal.
The length of the output data lines and the loads placed on
them should be minimized to reduce transients within the
AD9246. These transients can degrade the dynamic performance
of the converter.
Table 12. Output Data Format
Input (V)
VIN+ – VIN–
VIN+ – VIN–
VIN+ – VIN–
VIN+ – VIN–
VIN+ – VIN–
Condition (V)
< –VREF – 0.5 LSB
= –VREF
=0
= +VREF – 1.0 LSB
> +VREF – 0.5 LSB
Binary Output Mode
00 0000 0000 0000
00 0000 0000 0000
10 0000 0000 0000
11 1111 1111 1111
11 1111 1111 1111
Twos Complement Mode
10 0000 0000 0000
10 0000 0000 0000
00 0000 0000 0000
01 1111 1111 1111
01 1111 1111 1111
Rev. A | Page 22 of 44
Gray Code Mode
(SPI accessible)
11 0000 0000 0000
11 0000 0000 0000
00 0000 0000 0000
10 0000 0000 0000
10 0000 0000 0000
OR
1
0
0
0
1
AD9246
SERIAL PORT INTERFACE (SPI)
The AD9246 serial port interface (SPI) allows the user to
configure the converter for specific functions or operations
through a structured register space provided inside the ADC.
This provides the user added flexibility and customization,
depending on the application. Addresses are accessed via the
serial port and can be written to or read from via the port.
Memory is organized into bytes that are further divided into
fields, as documented in the Memory Map section. For detailed
operational information, see the Interfacing to High Speed ADCs
via SPI User Manual.
CONFIGURATION USING THE SPI
As summarized in Table 13, three pins define the SPI of this ADC.
The SCLK/DFS pin synchronizes the read and write data
presented to the ADC. The SDIO/DCS dual purpose pin allows
data to be sent and read from the internal ADC memory map
registers. The CSB pin is an active low control that enables or
disables the read and write cycles.
Table 13. Serial Port Interface Pins
Pin Name
SCLK/DFS
SDIO/DCS
CSB
Function
SCLK (serial clock) is the serial shift clock in. SCLK
synchronizes serial interface reads and writes.
SDIO (serial data input/output) is a dual purpose
pin. The typical role for this pin is an input and
output, depending on the instruction being sent
and the relative position in the timing frame.
CSB (chip select bar) is an active low control that
gates the read and write cycles.
The falling edge of the CSB, in conjunction with the rising edge
of the SCLK, determines the start of the framing. Figure 57 and
Table 14 provide examples of the serial timing and its definitions.
Other modes involving the CSB are available. The CSB can be
held low indefinitely to permanently enable the device (this is
called streaming). The CSB can stall high between bytes to allow
for additional external timing. When CSB is tied high, SPI
functions are placed in a high impedance mode. This mode
turns on any SPI pin secondary functions.
During an instruction phase, a 16-bit instruction is transmitted.
Data follows the instruction phase, and the length is determined
by the W0 bit and the W1 bit. All data is composed of 8-bit
words. The first bit of each individual byte of serial data
indicates whether a read or write command is issued. This
allows the serial data input/output (SDIO) pin to change
direction from an input to an output.
In addition to word length, the instruction phase determines if
the serial frame is a read or write operation, allowing the serial
port to be used to both program the chip as well as read the
contents of the on-chip memory. If the instruction is a readback
operation, performing a readback causes the serial data input/
output (SDIO) pin to change direction from an input to an
output at the appropriate point in the serial frame.
Data can be sent in MSB- or in LSB-first mode. MSB first is the
default on power up and can be changed via the configuration
register. For more information, see the Interfacing to High Speed
ADCs via SPI User Manual.
Table 14. SPI Timing Diagram Specifications
Name
tDS
tDH
tCLK
tS
tH
tHI
tLO
Description
Setup time between data and rising edge of SCLK
Hold time between data and rising edge of SCLK
Period of the clock
Setup time between CSB and SCLK
Hold time between CSB and SCLK
Minimum period that SCLK should be in a logic
high state
Minimum period that SCLK should be in a logic
low state
HARDWARE INTERFACE
The pins described in Table 13 comprise the physical interface
between the user’s programming device and the serial port of
the AD9246. The SCLK and CSB pins function as inputs when
using the SPI interface. The SDIO pin is bidirectional, functioning
as an input during write phases and as an output during readback.
The SPI interface is flexible enough to be controlled by either
PROM or PIC microcontrollers. This provides the user with the
ability to use an alternate method to program the ADC. One
method is described in detail in the Application Note AN-812,
Microcontroller-based Serial Port Interface Boot Circuit.
When the SPI interface is not used, some pins serve a dual
function. When strapped to AVDD or ground during device
power-on, the pins are associated with a specific function.
CONFIGURATION WITHOUT THE SPI
In applications that do not interface to the SPI control registers,
the SDIO/DCS and SCLK/DFS pins serve as stand-alone
CMOS-compatible control pins. When the device is powered
up, it is assumed that the user intends to use the pins as static
control lines for the output data format and duty cycle stabilizer
(see Table 10). In this mode, the CSB chip select should be
connected to AVDD, which disables the serial port interface.
For more information, see the Interfacing to High Speed ADCs
via SPI User Manual.
Rev. A | Page 23 of 44
AD9246
Default Values
MEMORY MAP
Coming out of reset, critical registers are loaded with default
values. The default values for the registers are shown in Table 15.
READING THE MEMORY MAP REGISTER TABLE
Each row in the memory map register table has eight address
locations. The memory map is roughly divided into three
sections: the chip configuration registers map (Address 0x00 to
Address 0x02), the device index and transfer registers map
(Address 0xFF), and the ADC functions map (Address 0x08 to
Address 0x18).
Logic Levels
An explanation of two registers follows:
•
“Bit is set” is synonymous with “Bit is set to Logic 1” or
“Writing Logic 1 for the bit.”
•
“Clear a bit” is synonymous with “Bit is set to Logic 0” or
“Writing Logic 0 for the bit.”
Table 15 displays the register address number in hexadecimal in
the first column. The last column displays the default value for
each hexadecimal address. The Bit 7 (MSB) column is the start
of the default hexadecimal value given. For example, Hexadecimal
Address 0x14, output_phase, has a hexadecimal default value of
0x00. This means Bit 3 = 0, Bit 2 = 0, Bit 1 = 1, and Bit 0 = 1 or
0011 in binary. This setting is the default output clock or DCO
phase adjust option. The default value adjusts the DCO phase
90° relative to the nominal DCO edge and 180° relative to the
data edge. For more information on this function, consult the
Interfacing to High Speed ADCs via SPI User Manual.
•
Modes: Set either power-down or standby mode.
•
Clock: Access the DCS via the SPI.
Open Locations
•
Offset: Digitally adjust the converter offset.
•
Test I/O: Set test modes to have known data on output bits.
•
Output Mode: Set up outputs; vary the strength of the
output drivers.
•
Output Phase: Set the output clock polarity.
•
VREF: Set the reference voltage.
SPI-Accessible Features
A list of features accessible via the SPI and a brief description of
what the user can do with these features follow. These features
are described in detail in the Interfacing to High Speed ADCs via
SPI User Manual.
Locations marked as open are currently not supported for this
device. When required, these locations should be written with
0s. Writing to these locations is required only when part of an
address location is open (for example, Address 0x14). If the
entire address location is open (Address 0x13), then the address
location does not need to be written.
tDS
tS
tHI
tCLK
tDH
tH
tLO
CSB
SCLK DON’T CARE
R/W
W1
W0
A12
A11
A10
A9
A8
A7
D5
D4
D3
D2
D1
D0
DON’T CARE
05491-056
SDIO DON’T CARE
DON’T CARE
Figure 57. Serial Port Interface Timing Diagram
Rev. A | Page 24 of 44
AD9246
MEMORY MAP REGISTER TABLE
Table 15. Memory Map Register
Addr.
Bit 7
(Hex) Parameter Name (MSB)
Chip Configuration Registers
00
chip_port_config 0
01
chip_id
02
chip_grade
Bit 6
Bit 5
Bit 4
Bit 3
LSB first
0 = Off
(Default)
1 = On
Soft reset
0 = Off
(Default)
1 = On
1
1
Bit 2
Soft reset
0 = Off
(Default)
1 = On
Bit 1
LSB first
0 = Off
(Default)
1 = On
Bit 0
(LSB)
Default
Value
(Hex)
0
0x18
8-bit Chip ID Bits 7:0
(AD9246 = 0x00), (default)
Read
only
Default Notes/
Comments
The nibbles
should be
mirrored. See the
Interfacing to
High Speed ADCs
via SPI User
Manual.
Default is unique
chip ID, different
for each device.
Child ID used to
differentiate
speed grades.
Open
Open
Open
Child ID
0 = 125
MSPS,
1 = 105
MSPS
Open
Open
Open
Read
only
Device Index and Transfer Registers
FF
device_update
Open
Open
Open
Open
Open
Open
Open
SW transfer
0x00
Synchronously
transfers data
from the master
shift register to
the slave.
PDWN
0—full
(Default)
1—standby
Open
Open
Internal power-down mode
000—normal (power-up, Default)
001—full power-down
010—standby
011—normal (power-up)
Note: External PDWN pin overrides
this setting.
0x00
Determines
various generic
modes of chip
operation. See
the Power
Open
0x01
Global ADC Functions
08
modes
Open
Open
Open
Dissipation
and Standby
Mode section
and the SPIAccessible
Features
section.
09
clock
Open
Open
Open
Open
Open
Open
Duty cycle
stabilizer
0—disabled
1— enabled
(Default)
See the Clock
Duty Cycle
section and the
SPI-Accessible
Features
section.
Rev. A | Page 25 of 44
AD9246
Addr.
Bit 7
(Hex) Parameter Name (MSB)
Flexible ADC Functions
10
offset
Bit 6
Bit 5
test_io
14
output_mode
Output Driver
Configuration
00 for DRVDD = 2.5 V to
3.3 V (Default)
10 for DRVDD = 1.8 V
Open
16
output_phase
Open
Output Clock
Polarity
1 = inverted
0 = normal
(Default)
Internal Reference
Resistor Divider
00—VREF = 1.25 V
01—VREF = 1.5 V
10—VREF = 1.75 V
11—VREF = 2.00 V
(Default)
Open
1
VREF
Bit 3
Digital Offset Adjust<5:0>
011111
011110
011101
…
000010
000001
000000
111111
111110
111101
...
100001
100000
PN9
PN23
0=
0=
normal
normal
(Default) (Default)
1 = reset 1 =
reset
0D
18
Bit 4
Output
Disable
1—
disabled
0—
enabled 1
Open
Open
Open
Bit 2
Bit 1
Bit 0
(LSB)
Default
Value
(Hex)
0x00
Offset in LSBs
+31
+30
+29
Default Notes/
Comments
Adjustable for
offset inherent
in the converter.
See the SPI-
Accessible
Features
+2
+1
0 (Default)
1
−2
−3
section.
−31
−32
Global Output Test Options
000—off (Default)
001—midscale short
010—+FS short
011—−FS short
100—checker board output
101—PN 23 sequence
110—PN 9
111—one/zero word toggle
Data Format Select
Output
00—offset binary
Data
(default)
Invert
01—twos
1=
complement
invert
10—Gray Code
Open
Open
Open
0x00
See the
Interfacing to
High Speed
ADCs via SPI
User Manual.
0x00
Configures the
outputs and
the format of
the data.
0x00
See the SPIAccessible
Features
section.
Open
Open
Open
Open
Open
Open
0xC0
See the SPIAccessible
Features
section.
External output enable (OEB) pin must be high.
Rev. A | Page 26 of 44
AD9246
LAYOUT CONSIDERATIONS
SILKSCREEN PARTITION
PIN 1 INDICATOR
When connecting power to the AD9246, it is recommended
that two separate supplies be used: one for analog (AVDD, 1.8 V
nominal) and one for digital (DRVDD, 1.8 V to 3.3 V nominal).
If only a single 1.8 V supply is available, it is routed to AVDD
first, then tapped off and isolated with a ferrite bead or filter
choke with decoupling capacitors proceeding connection to
DRVDD. The user can employ several different decoupling
capacitors to cover both high and low frequencies. These should
be located close to the point of entry at the PC board level and
close to the parts with minimal trace length.
A single PC board ground plane is sufficient when using the
AD9246. With proper decoupling and smart partitioning of
analog, digital, and clock sections of the PC board, optimum
performance is easily achieved.
Exposed Paddle Thermal Heat Slug Recommendations
It is required that the exposed paddle on the underside of the
ADC be connected to analog ground (AGND) to achieve the
best electrical and thermal performance of the AD9246. An
exposed, continuous copper plane on the PCB should mate to
the AD9246 exposed paddle, Pin 0. The copper plane should
have several vias to achieve the lowest possible resistive thermal
path for heat dissipation to flow through the bottom of the PCB.
These vias should be solder-filled or plugged.
To maximize the coverage and adhesion between the ADC and
PCB, partition the continuous plane by overlaying a silkscreen
on the PCB into several uniform sections. This provides several
tie points between the two during the reflow process. Using one
continuous plane with no partitions guarantees only one tie
point between the ADC and PCB. See Figure 58 for a PCB layout
example. For detailed information on packaging and the PCB
layout of chip scale packages, see Application Note AN-772,
A Design and Manufacturing Guide for the Lead Frame Chip
Scale Package.
05491-057
POWER AND GROUND RECOMMENDATIONS
Figure 58. Typical PCB Layout
CML
The CML pin should be decoupled to ground with a 0.1 μF
capacitor, as shown in Figure 38.
RBIAS
The AD9246 requires the user to place a 10 kΩ resistor between
the RBIAS pin and ground. This resistor sets the master current
reference of the ADC core and should have at least a 1% tolerance.
REFERENCE DECOUPLING
The VREF pin should be externally decoupled to ground with
a low ESR 1.0 μF capacitor in parallel with a 0.1 μF ceramic low
ESR capacitor. In all reference configurations, REFT and REFB
are bypass points provided for reducing the noise contributed
by the internal reference buffer. It is recommended that an external
0.1 μF ceramic capacitor be placed across REFT/REFB. While
placement of this 0.1 μF capacitor is not required, the SNR
performance degrades by approximately 0.1 dB without it. All
reference decoupling capacitors should be placed as close to the
ADC as possible with minimal trace lengths.
Rev. A | Page 27 of 44
AD9246
EVALUATION BOARD
The AD9246 evaluation board provides all of the support
circuitry required to operate the ADC in its various modes and
configurations. The converter can be driven differentially through
a double balun configuration (default) or through the AD8352
differential driver. The ADC can also be driven in a single-ended
fashion. Separate power pins are provided to isolate the DUT
from the AD8352 drive circuitry. Each input configuration can
be selected by proper connection of various components (see
Figure 60 to Figure 70). Figure 59 shows the typical bench
characterization setup used to evaluate the ac performance of
the AD9246.
When operating the evaluation board in a nondefault condition,
L501, L503, L504, L508, and L509 can be removed to disconnect
the switching power supply. This enables the user to individually
bias each section of the board. Use P501 to connect a different
supply for each section. At least one 1.8 V supply is needed with
a 1 A current capability for AVDD_DUT and DRVDD_DUT;
however, it is recommended that separate supplies be used for
analog and digital. To operate the evaluation board using the
AD8352 option, a separate 5.0 V supply (AMP_VDD) with a
1 A current capability is needed. To operate the evaluation board
using the alternate SPI options, a separate 3.3 V analog supply
is needed, in addition to the other supplies. The 3.3 V supply
(AVDD_3.3V) should have a 1 A current capability, as well.
Solder Jumpers J501, J502, and J505 allow the user to combine
these supplies (see Figure 64 for more details).
It is critical that the signal sources used for the analog input and
clock have very low phase noise (<1 ps rms jitter) to realize the
optimum performance of the converter. Proper filtering of the
analog input signal to remove harmonics and lower the integrated
or broadband noise at the input is also necessary to achieve the
specified noise performance.
INPUT SIGNALS
When connecting the clock and analog source, use clean signal
generators with low phase noise, such as Rohde & Schwarz SMHU
or Agilent HP8644 signal generators or the equivalent. Use
1-meter long, shielded, RG-58, 50 Ω coaxial cable for making
connections to the evaluation board. Enter the desired frequency
and amplitude for the ADC. Typically, most evaluation boards
from Analog Devices, Inc. can accept a ~2.8 V p-p or 13 dBm
sine wave input for the clock. When connecting the analog
input source, it is recommended to use a multipole, narrowband, band-pass filter with 50 Ω terminations. Analog Devices
uses TTE®, Allen Avionics, and K&L® types of band-pass filters.
Connect the filter directly to the evaluation board, if possible.
See Figure 60 to Figure 64 for the complete schematics and
layout diagrams that demonstrate the routing and grounding
techniques that should be applied at the system level.
POWER SUPPLIES
This evaluation board comes with a wall-mountable switching
power supply that provides a 6 V, 2 A maximum output. Connect
the supply to the rated 100 V ac to 240 V ac wall outlet at 47 Hz
to 63 Hz. The other end is a 2.1 mm inner diameter jack that
connects to the PCB at P500. Once on the PC board, the 6 V
supply is fused and conditioned before connecting to five low
dropout linear regulators that supply the proper bias to each of
the various sections on the board.
OUTPUT SIGNALS
The parallel CMOS outputs interface directly with the Analog
Devices standard single-channel FIFO data capture board
(HSC-ADC-EVALB-SC). For more information on the FIFO
boards and their optional settings, visit www.analog.com/FIFO.
WALL OUTLET
100V TO 240V AC
47Hz TO 63Hz
AIN
3.3V
+
–
+
–
+
VDL
GND
AVDD_3.3V
GND
VCC
3.3V
–
GND
3.3V
+
DRVDD_DUT
GND
2.5V
–
GND
–
AD9246
EVALUATION BOARD
CLK
14-BIT
PARALLEL
CMOS
SPI
Figure 59. Evaluation Board Connection
Rev. A | Page 28 of 44
HSC-ADC-EVALB-SC
FIFO DATA
CAPTURE
BOARD
USB
CONNECTION
SPI
PC
RUNNING
ADC
ANALYZER
AND SPI
USER
SOFTWARE
SPI
05491-082
ROHDE & SCHWARZ,
SMHU,
2V p-p SIGNAL
SYNTHESIZER
BAND-PASS
FILTER
+
AMP_VDD
ROHDE & SCHWARZ,
SMHU,
2V p-p SIGNAL
SYNTHESIZER
1.8V
+
–
GND
5.0V
SWITCHING
POWER
SUPPLY
AVDD_DUT
6V DC
2A MAX
AD9246
DEFAULT OPERATION AND JUMPER SELECTION
SETTINGS
The following is a list of the default and optional settings or
modes allowed on the AD9246 Rev. A evaluation board.
POWER
Connect the switching power supply that is supplied in the
evaluation kit between a rated 100 V ac to 240 V ac wall outlet
at 47 Hz to 63 Hz and P500.
VIN
The evaluation board is set up for a double balun configuration
analog input with optimum 50 Ω impedance matching out to
70 MHz. For more bandwidth response, the differential
capacitor across the analog inputs can be changed or removed
(see Table 8). The common mode of the analog inputs is
developed from the center tap of the transformer via the CML
pin of the ADC (see the Analog Input Considerations section).
VREF
VREF is set to 1.0 V by tying the SENSE pin to ground via
JP507 (Pin 1 and Pin 2). This causes the ADC to operate in
2.0 V p-p full-scale range. A separate external reference option
is also included on the evaluation board. Connect JP507
between Pin 2 and Pin 3, connect JP501, and provide an
external reference at E500. Proper use of the VREF options is
detailed in the Voltage Reference section.
RBIAS
RBIAS requires a 10 kΩ resistor (R503) to ground and is used to
set the ADC core bias current.
CLOCK
The default clock input circuitry is derived from a simple
transformer-coupled circuit using a high bandwidth 1:1 impedance
ratio transformer (T503) that adds a very low amount of jitter to
the clock path. The clock input is 50 Ω terminated and ac-coupled
to handle single-ended sine wave inputs. The transformer converts
the single-ended input to a differential signal that is clipped
before entering the ADC clock inputs.
PDWN
To enable the power-down feature, connect JP506, shorting the
PDWN pin to AVDD.
CSB
The CSB pin is internally pulled up, setting the chip into
external pin mode, to ignore the SDIO and SCLK information.
To connect the control of the CSB pin to the SPI circuitry on the
evaluation board, connect JP1 Pin 1 and Pin 2. To set the chip
into serial pin mode and enable the SPI information on the
SDIO and SCLK pins, tie JP1 low (connect Pin 2 and Pin 3) in
the always enabled mode.
SCLK/DFS
If the SPI port is in external pin mode, the SCLK/DFS pin sets the
data format of the outputs. If the pin is left floating, the pin is
internally pulled down, setting the default condition to binary.
Connecting JP2 Pin 2 and Pin 3 sets the format to twos complement. If the SPI port is in serial pin mode, connecting JP2 Pin 1
and Pin 2 connects the SCLK pin to the on-board SPI circuitry
(see the Serial Port Interface (SPI) section).
SDIO/DCS
If the SPI port is in external pin mode, the SDIO/DCS pin acts
to set the duty cycle stabilizer. If the pin is left floating, the pin is
internally pulled up, setting the default condition to DCS enabled.
To disable the DCS, connect JP3 Pin 2 and Pin 3. If the SPI port
is in serial pin mode, connecting JP3 Pin 1 and Pin 2 connects the
SDIO pin to the on-board SPI circuitry (see the Serial Port
Interface (SPI) section).
ALTERNATIVE CLOCK CONFIGURATIONS
A differential LVPECL clock can also be used to clock the ADC
input using the AD9515 (U500). When using this drive option,
the components listed in Table 16 need to be populated.
Consult the AD9515 data sheet for more information.
To configure the analog input to drive the AD9515 instead of
the default transformer option, the following components need
to be added, removed, and/or changed.
1.
Remove R507, R508, C532, and C533 in the default
clock path.
2.
Populate R505 with a 0 Ω resistor and C531 in the default
clock path.
3.
Populate R511, R512, R513, R515 to R524, U500, R580,
R582, R583, R584, C536, C537, and R586.
If using an oscillator, two oscillator footprint options are also
available (OSC500) to check the performance of the ADC.
JP508 gives the user flexibility in using the enable pin, which is
common on most oscillators. Populate OSC500, R575, R587,
and R588 to use this option.
ALTERNATIVE ANALOG INPUT DRIVE
CONFIGURATION
This section provides a brief description of the alternative
analog input drive configuration using the AD8352. When
using this particular drive option, some components need to be
populated, as listed in Table 16. For more details on the AD8352
differential driver, including how it works and its optional pin
settings, consult the AD8352 data sheet.
To configure the analog input to drive the AD8352 instead of
the default transformer option, the following components need
to be added, removed and/or changed.
Rev. A | Page 29 of 44
AD9246
1.
Remove C1 and C2 in the default analog input path.
4.
2.
Populate R3 and R4 with 200 Ω resistors in the analog
input path.
3.
Populate the optional amplifier input path with all
components except R594, R595, and C502. Note that
to terminate the input path, only one of the following
components should be populated: R9, R592, or the
combination of R590 and R591.
Currently, R561 and R562 are populated with 0 Ω resistors to
allow signal connection. This area allows the user to design a
filter, if additional requirements are necessary.
Rev. A | Page 30 of 44
Populate C529 with a 5 pF capacitor in the analog input path.
S504
Rev. A | Page 31 of 44
Figure 60. Evaluation Board Schematic, DUT Analog Inputs
DNI
Ampin/
S505
DNI
R8
DNI
R502
50
DNI
GND;3,4,5
SMA200UP
R7
DNI
R560
0
2
RC0603
2
RC0603
C528
0.1UF
C3
DNI
CML
RC0402
R6
DNI
RC0402
R2
0
R11
0
DNI
R9
DNI
1
1
RC0603
2
R12
0
DNI
RC0603
2
R10
DNI
0
C4
0
C5
0
C509
.1UF
4
5
T500
S
T1
4
5
DNI
5
S
4
2
3
6
1
P
T502
DNI
ETC1-1-13
P
3
2
1
3
2
1
CML
RC0402
For amplifier (AD8352):
Install all optional Amp input components.
R590/R591,R9,R592 Only one should be installed at a time.
Remove C1, C2.
Set R3=R4=200 OHM.
DNI
DNI
When using T502, remove T500, T501.
Repalce C1, C2 with 0 ohm resistors.
Remove R3, R4. Place R6, R502,.
1
1
GND;3,4,5
SMA200UP
GND;3,4,5
SMAEDGE
GND;3,4,5
RC060 3
Ampin
Ain/
S503
Ain
SMAEDGE
CC0402
CC0402
S500
RC060 3
CC0402
R590
25
DNI
R591
25
DNI
R1
DNI
RC0402
R592
DNI
S
T501
P
5
C503
.1UF
DNI
C500
.1UF
DNI
R5
0
C2
.1UF
AMPOUT-
R565
DNI
AMPOUT+
RC0402
R597
4.3K
DNI
R596
0
DNI
DNI
2
1
4
RDP
VIN
RDN
5
16
VIP
2
15
U511
VCM
14
6
7
GND
AMPVDD
GND
VON
VCC
8
GND
VOP
VCC
13
AMPVDD
AD8352
DNI
SIGNAL=GND;17
ENB
3
disable
R594
10K
DNI
J500
enable
1
RGP
R598
100
RGN
DNI 3
AMPVDD
C501
0.3PF
R593
0
DNI
R4
25
R3
25
C510
.1UF
9
10
11
12
RC0402
R571
0
R595
10K
DNI
OPTIONAL AMP INPUT
When using R1, remove R3, R4,R6.
Replace R5 with 0.1UF cap
Replace C1, C2 with 0 ohm resistors.
3 ETC1-1-13 4
2
1
C1
.1UF
RC040 2
CC0402
RC040 2
RC0402
RC0402
RC0402
R536
R535
C502
.1UF
DNI
R562
0
CML
R561
0
0
0
RC0402
DNI
RC0402
DNI
1
D500
DNI
R567
33
R566
33
3
VIN+
R574
DNI
HSMS281 2
DOUBLE BALUN / XFMR INPUT
RC0402
C505
.1UF
DNI
C504
.1UF
DNI
DUTAVDD
2
RC0402
RC0402
R563
DNI
HSMS281 2
AMPOUT-
2
VIN-
DUTAVDD
C529
20PF
D501
DNI
AMPOUT+
1
3
VIN-
CC0402
VIN+
AD9246
SCHEMATICS
RC060 3
RC060 3
05491-072
C556
0.1UF
CML
R503
10K
TP500
TP504
D1
Rev. A | Page 32 of 44
E500
48
47
CC0402
E X T _V R E F
45
D0
46
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
DCO
JP502
DNI
CLK
CLK
JP506
DNI
VIN-
VIN+
CC0402
C554
0.1UF
VREF
SENSE
DUTDRVDD
DUTAVDD
CC0603
RC060 3
chip corners
AVDD
AGND
AVDD
AGND
CSB
SCLK/DFS
SDIO/DCS
DRVDD
DRGND
OR
D13 (MSB)
D12
C555
0.1UF
DNI
JP501
CC0805
DNI
JP500
C553
1.0UF
DUTAVDD
3
2
JP507
1
Figure 61. Evaluation Board Schematic, DUT, VREF, and Digital Output Interface
R0402
DNI
R501
VREF
R0402
DNI
R500
SEN SE
AD9246LFCSP
AGND
D11
CLK+
D10
EPAD
D9
CLKD8
AVDD
DRVDD
AGND
DRGND
AVDD
OEB
D7
DCO
D6
D0 (LSB)
D5
U510
D1
D4
DRGND
D3
DRVDD
D2
SENSE
VREF
REFB
REFT
AGND
VIN+
VINAGND
AVDD
CML
RBIAS
PDWN
1
2
3
4
5
6
7
8
9
10
11
12
D2
D3
D4
D5
D6
D7
D8
D9
D10
D11
D12
D13
13
DOR
14
TP502
TP501
TP503
DUTDRVDD
DUTAVDD
15
16
17
18
19
20
21
22
23
24
8
10
9
9
RP500 22
RP501 22
RP501 22
RP502 22
1
7
8
8
DCO
D0
D1
D2
D3
D4
D5
D6
D7
D8
D9
D10
D11
D12
D13
DOR
7
6
5
16
15
14
13
12
11
16
15
14
13
12
11
10
RP500 22
RP500 22
RP500 22
RP501 22
RP501 22
RP501 22
RP501 22
RP501 22
RP501 22
RP502 22
RP502 22
RP502 22
RP502 22
RP502 22
RP502 22
RP502 22
CSB_DUT
2
3
4
1
2
3
4
5
6
1
2
3
4
5
6
7
1
JP1
VDL
2
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
3
2
JP2
O10
O7
O6
I7
I6
OUTPUT BUFFER
OE1
O0
I0
OE2
O1
I1
GND1
O2
GND8
O3
I2
VCC1
O4
O5
I3
VCC4
I4
I5
GND2
O8
GND7
O9
I9
I8
GND3
I10
GND6
O11
I11
VCC2
O12
I12
VCC3
O13
GND4
I13
GND5
O14
OE4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
SDIO_ODM
O15
3
DUTAVDD
I14
U509
74VCX16224
1
I15
OE3
SCLK_DTP
1
JP3
3
FDOR
FD0
FD1
FD2
FD3
FD4
FD5
FD6
FD7
FD8
FD9
FD10
FD11
FD12
FD13
FIFOCLK
FIFOCLK
FD0
FD1
FD2
FD3
FD4
FD5
FD6
FD7
FD8
FD9
FD10
FD11
FD12
FD13
FDOR
2
J503
B1
B2
B3
B4
B5
B6
B7
B8
B9
B10
B11
B12
B13
B14
B15
B16
B17
B18
B19
B20
SCLK_CHA
SDO_CHA
CSB1_CHA
SDI_CHA
C1
C2
C3
C4
C5
C6
C7
C8
C9
C10
C11
C12
C13
C14
C15
C16
C17
C18
C19
C20
J503
OUTPUT CONNECTOR
J503
A1
A2
A3
A4
A5
A6
A7
A8
A9
A10
A11
A12
A13
A14
A15
A16
A17
A18
A19
A20
05491-073
DUT
AD9246
GND;3,4,5
CLK/
SMAEDGE
S502
GND;3,4,5
CLK
SMAEDGE
S501
R505
49.9
DNI
C530
0.1UF
C531
0.1UF
DNI
CC0402
RC0402
OPT_CLK
1
1
OPT_CLK
OPT_CLK
OPT_CLK
R504
49.9
CC0402
VCC
R511
DNI
2
RC0603
2
RC0603
R579
DNI
R510
DNI
R512
0
RC0603
RC0603
R576
DNI
R507
0
DNI
0
OE
OE
GND
GND
CB3LV-3C
OUT
R508
8
10
OUT
12 VCC
RC0402
RC0402
14
C511
.1UF
R578
DNI
R577
DNI
R509
0
R506
0
RC0603
RC0603
D502
HSMS2812
2
1
3
C533
0.1UF
C532
0.1UF
CLK
CLK
E501
5
3
2
AD9515
RC0402
DNI
OUT0B
OUT0
NC=27,28
OUT1B
OUT1
AVDD_3P3V;1,4,17,20,21,24,26,29,30
SYNCB
CLKB
CLK
DNI
U500
R586
4.12K
18
19
22
23
R584
240
DNI
R585
100
DNI
R583
240
DNI
R582
100
DNI
C536
0.1UF
DNI
C537
0.1UF
DNI
RC060 3
C534
0.1UF
DNI
C535
0.1UF
DNI
E503
E502
CLK
CLK
To use AD9515 (OPT _CLK), remove R507, R508, C533, C532.
Place C531,R505=0.
4
3
6
5
R580
10K
DNI
T503
R588
10K
DNI
2
1
AVDD_3P3V
R581
DNI
7
5
3
1
RC0402
R575
0
DNI
1
RC0402
2
S6
DNI
S7
OSC500
S8
DISABLE
S9
ENABLE
S10
DNI JP508
VREF
6
S0
7
S1
8
S2
9
S3
10
S4
11
S5
12
Figure 62. Evaluation Board Schematic, DUT Clock Input
13
RC060 3
14
RC060 3
15
3
RSET
16
RC0402
RC0402
CC0402
CC0402
RC0402
10K
DNI
RC0402
R587
GN D
25
CC0402
RC0402
RC0402
RC0402
AVDD_3P3V
GND_PAD
RC0402
32
CC0402
31
CC0402
Rev. A | Page 33 of 44
33
S0
S1
S2
S3
S4
S5
S6
S7
S8
S9
S10
CC0402
XFMR/AD9515
Clock Circuitry
S10
S9
S8
S7
S6
S5
S4
S3
S2
S1
S0
R532
DNI
R533
DNI
R534
DNI
R529
DNI
R528
DNI
R530
DNI
R531
DNI
R526
DNI
R527
DNI
R525
DNI
0
0
0
0
0
0
0
0
0
0
0
RC0603
RC0603
RC0603
RC0603
RC0603
RC0603
RC0603
RC0603
RC0603
RC0603
RC0603
R522
R523
R524
R519
R518
R520
R521
R516
R517
R515
R513
0
0
0
0
0
0
0
0
0
0
0
RC0603
DNI
RC0603
DNI
RC0603
DNI
RC0603
DNI
RC0603
DNI
RC0603
DNI
RC0603
DNI
RC0603
DNI
RC0603
DNI
RC0603
DNI
RC0603
DNI
AD9515 LOGIC SETUP
AVDD_3P3V R514
DNI
AD9246
05491-071
2
1
S1
DNI
4
3
1
2
JP509
1
SOIC8
DNI
GP1
GP0
VSS
RC0603
2
2
1
GP1
3
GP0
5
MCLR-GP3
7
9
HEADER UP MALE
DNI
J504
E504
5
6
7
8
DNI
GP2
MCLR
PIC12F629
GP4
GP5
VDD
U506
A M P VD D
R559
D505
261
Optional
DNI
4
3
2
1
DNI
3
PICVCC 1
Rev. A | Page 34 of 44
2
4
6
8
10
PICVCC
GP1
GP0
MCLR-GP3
Figure 63. Evaluation Board Schematic, SPI Circuitry
R547
4.7K
DNI
When using PICSPI controlled port, populate R545, R546, R547.
When using PICSPI controlled port, remove R555, R556, R557.
For FIFO controlled port, populate R555, R556, R557.
PIC-HEADER
DNI
C557 CC0603
0.1UF
DNI
R558
4.7K
A V D D _ 3P 3V
+5V=PROGRAMMING ONLY=AMPVDD
+3.3V=NORMAL OPERATION=AVDD_3P3V
RC060 3
SPI CIRCUITRY
R545
4.7K
RC0603
DNI
R546
4.7 K
RC0603
DNI
RC0603
R555
0
R557
0
R556
0
R549
10K
AVDD_3P3V
R554
0
RC0603
RC0603
RC0603
RC0603
SCLK_CHA
RC0603
SDI_CHA
R548
10K
R550
10K
RC0603
RC0603
CSB1_CHA
U508
6
Y1
5
VCC
4
Y2
6
Y1
5
VCC
4
Y2
NC7WZ16
1
A1
2
GND
3
A2
U507
NC7WZ07
1
A1
2
GND
3
A2
R552
1K
R551
1K
R553
1K
DUTAVDD AVDD_3P3V
RC0603
SDO_CHA
RC0603
REMOVE WHEN USING OR PROGRAMMING PIC (U506)
CSB_DUT
SCLK_DTP
SDIO_ODM
AD9246
RC0603
05491-070
Rev. A | Page 35 of 44
10
P10
9
P9
8
P8
7
P7
6
P6
J502
J501
J505
LC1210
L500
10UH
LC1210
L506
10UH
LC1210
L502
10UH
LC1210
L507
10UH
LC1210
L505
10UH
D504
S2A_RECT
2A
DO-214AA
ACASE
ACASE
ACASE
ACASE
ACASE
Remove L501,L503,L504,L508,L509.
To use optional power connection
GND
AVDD_3P3VIN
GND
VDLIN
GND
DUTDRVDDIN
GND
AMPVDDIN
DUTAVDDIN
5
P5
C527
10UF
SMDC110F
3
C548
1OUF
6.3V
C552
1OUF
6.3V
C551
1OUF
6.3V
C550
1OUF
6.3V
C549
1OUF
6.3V
C512
0.1UF
AVDD_3P3V
C517
0.1UF
DUTDRVDD
C516
0.1UF
DUTAVDD
C515
0.1UF
VDL
C514
0.1UF
AMPVDD
OPTIONAL POWER CONNECTION
4
P4
2
3
P3
3
GND
1
2
P2
P501
1
P1
7.5V POWER
CON005
2.5MM JACK
P500
4
FER500
CHOKE_COIL
DUTDRVDD
DUTAVDD
VDL
AMPVDD
PWR_IN
CC0603
CC0603
CC0603
CC0603
C573
0.1UF
C569
0.1UF
C564
0.1UF
C567
0.1UF
R589
261
C572
0.1UF
C575
0.1UF
C565
0.1UF
CC0603
CC0603
CC0603
CC0603
C524
1UF
PWR_IN
C521
1UF
PWR_IN
C519
1UF
PWR_IN
CC0603
C599
0.1UF
CC0603
0.1UF
C570
0.1UF
4
4
4
CC0603
2
O UTP U T1
OUTPUT4
CC0603
C559
CC0603
C566
0.1UF
IN P U T
C558
CC0603
2
O UTP U T1
OUTPUT4
U504
ADP3339AKC-3.3
IN P U T
U503
ADP3339AKC-2.5
2
O UTP U T1
OUTPUT4
U502
ADP3339AKC-1.8
IN P U T
0.1UF
C568
0.1UF
3
3
3
GND
1
GND
1
GND
1
C574
0.1UF
CC0402
C540
0.1UF
CC0402
C545
0.1UF
VDLIN
CC0402
CC0402
C513
1UF
PWR_IN
C523
1UF
PWR_IN
DUTDRVDDIN
DUTAVDDIN
TP508
TP505
AVDD_3P3V
LC1210
L508
10UH
LC1210
L503
10UH
AVDD_3P3V
C526
1UF
C520
1UF
C518
1UF
L504
10UH
LC1210
TP506
C539
0.1UF
C544
0.1UF
3
3
O U TP U T1
OUTPUT4
CC0402
CC0402
IN P U T
C542
0.1UF
C546
0.1UF
CC0402
CC0402
C538
0.1UF
C543
0.1UF
O UT PUT 1
OUTPUT4
U505
ADP3339AKC-3.3
IN P U T
U501
ADP3339AKC-5
DUTAVDD=1.8V
DUTDRVDD=2.5V
VDL=3.3V
AMPVDD=5V
AVDD_3.3V=3.3V
GND
1
GND
1
F500
D503
3A
SHOT_RECT
DO-214AB
2
2
LC1210
L509
10UH
LC1210
L501
10UH
C525
1UF
C522
1UF
TEST POINTS
GROUND
4
4
TP510
Figure 64. Evaluation Board Schematic, Power Supply Inputs
TP512
2
TP511
CR500
TP509
1
H503
H502
Connected to Ground
Mounting Holes
H500
H501
AVDD_3P3V
AMPVDDIN
TP513
TP507
05491-069
Power Supply Input
6V, 2A max
AD9246
AD9246
05491-077
EVALUATION BOARD LAYOUTS
05491-076
Figure 65. Evaluation Board Layout, Primary Side
Figure 66. Evaluation Board Layout, Secondary Side (Mirrored Image)
Rev. A | Page 36 of 44
05491-079
AD9246
05491-078
Figure 67. Evaluation Board Layout, Ground Plane
Figure 68. Evaluation Board Layout, Power Plane
Rev. A | Page 37 of 44
05491-075
AD9246
05491-074
Figure 69. Evaluation Board Layout, Silkscreen Primary Side
Figure 70. Evaluation Board Layout, Silkscreen Secondary Side (Mirrored Image)
Rev. A | Page 38 of 44
AD9246
BILL OF MATERIALS
Table 16. Evaluation Board Bill of Materials (BOM)
Item
1
2
Qty.
1
24
Omit
(DNP)
12
1
2
Reference Designator
AD9246CE_REVA
C1, C2, C509, C510, C511, C512,
C514, C515, C516, C517, C528,
C530, C532, C533, C538, C539,
C540, C542, C543, C544, C545,
C546, C554, C555
C3, C500, C502, C503, C504,
C505, C531, C534, C535, C536,
C537, C557
C501
C4, C5
C513, C518, C519, C520, C521,
C522, C523, C524, C525, C526
Device
PCB
Capacitor
Package
0402
Description
PCB
0.1 μF
Capacitor
Resistor
Capacitor
0402
0402
0402
0.3 pF
0Ω
1.0 μF
3
4
5
10
6
7
8
9
10
1
1
5
1
15
C527
C529
C548, C549, C550, C551, C552
C553
C556, C558, C559, C564, C565,
C566, C567, C568, C569, C570,
C572, C573, C574, C575, C599
Capacitor
Capacitor
Capacitor
Capacitor
Capacitor
1206
0402
ACASE
0805
0603
10 μF
20 pF
10 μF
1.0 μF
0.1 μF
11
1
CR500
LED
0603
green
12
1
Diode
SOT-23
30 V, 20 mA,
dual Schottky
Diode
DO-214AB
3 A, 30 V, SMC
13
1
D502
D500, D501
D503
14
1
D504
Diode
DO-214AA
2 A, 50 V, SMC
15
16
1
D505
F500
LED
Fuse
LN1461C
1210
AMB
6.0 V, 2.2 A
trip current
resettable fuse
17
1
FER500
Choke
2020
J500
J501, J502, J505
J503
J504
JP1, JP2, JP3
JP500, JP501, JP502, JP506
JP507
JP508, JP509
L500, L501, L502, L503, L504,
L505, L506, L507, L508, L509
Jumper
Jumper
Connector
Connector
Jumper
Jumper
Jumper
1
OSC500
Oscillator
3.2 mm ×
2.5 mm ×
1.6 mm
SMT
1
P500
P501
Connector
Connector
PJ-102A
10 pin
2
18
19
20
21
22
23
24
1
1
3
1
1
3
4
1
2
25
10
26
27
28
1
Ferrite Bead
Rev. A | Page 39 of 44
120 pin
10 pin
3 pin
2 pin
3-pin
jumper
Supplier/Part Number
ADI
Panasonic
LNJ314G8TRA
HSMS2812
Micro Commercial
Group SK33-TPMSCT-ND
Micro Commercial
Group S2A-TPMSTR-ND
Amber LED
Tyco, Raychem
NANOSMDC110F-2
Murata
DLW5BSN191SQ2
Solder jumper
Solder jumper
Male header
Male, 2 × 5
Male, straight
Male, straight
Male, straight
Samtec TSW-140-08-G-T-RA
Samtec
Samtec TSW-103-07-G-S
Samtec TSW-102-07-G-S
Samtec TSW-103-07-G-S
Digikey P9811CT-ND
125 MHz or
105 MHz
DC power jack
Male, straight
CTS Reeves CB3LV-3C
Digikey CP-102A-ND
PTMICRO10
AD9246
Item
29
30
Qty.
Omit
(DNP)
6
5
6
31
32
33
2
34
35
4
1
36
9
6
6
1
23
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
1
54
2
2
1
2
2
1
1
2
1
1
1
1
58
Resistor
Resistor
Resistor
0402
0603
0402
25 Ω
DNI
DNI
Resistor
Resistor
0603
0603
10 kΩ
49.9 Ω
Resistor
0603
0Ω
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Switch
0603
0603
0603
0402
0402
0402
0402
0402
0603
0402
0402
0402
0402
0402
RCA74204
RCA74208
Connector
SMAEDGE
4.7 kΩ
1 kΩ
261 Ω
33 Ω
100 Ω
240 Ω
4.12 kΩ
10 kΩ
261 Ω
25 Ω
DNI
0Ω
10 kΩ
4.3 kΩ
22 Ω
22 Ω
Momentary
(normally open)
SMA edge
right angle
Connector
SMA200UP
T500, T501
T1
T503
T502
U500
Transformer
SM-22
M/A-Com ETC1-1-13
Transformer
CD542
Mini-Circuits ADT1-1WT
IC
S500, S501
S502, S503
S504, S505
3
2
1
3
57
Description
DNI
0Ω
2
2
1
2
2
Package
0402
0402
1
3
56
Device
Resistor
Resistor
R507, R514, R513, R515, R516,
R517, R518, R519, R520, R521,
R522, R523, R524, R525, R526,
R527, R528, R529, R530, R531,
R532, R533, R534,
R545, R546, R547, R558
R551, R552, R553
R559
R566, R567
R582, R585, R598
R583, R584
R586
R580, R587, R588
R589
R590, R591
R592
R593, R596
R594, R595
R597
RP500
RP501, RP502
S1
4
55
Reference Designator
R1, R6, R563, R565, R574, R577
R2, R5, R561, R562, R571
R10, R11, R12, R535, R536, R575
R3, R4
R7, R8, R9, R502, R510, R511
R500, R501, R576, R578, R579,
R581
R503, R548, R549, R550
R504
R505
R506, R508, R509, R512, R554,
R555, R556, R557, R560
59
1
U501
IC
32-pin
LFCSP
SOT-223
60
1
U502
IC
SOT-223
Rev. A | Page 40 of 44
Supplier/Part Number
Panasonic EVQ-PLDA15
SMA RF 5-pin
upright
Clock
distribution
Voltage
regulator
Voltage
regulator
ADI AD9515BCPZ
ADI ADP3339AKCZ-5
ADI ADP3339AKCZ-1.8
AD9246
Item
61
Qty.
1
62
2
63
Omit
(DNP)
1
Reference Designator
U503
Device
IC
Package
SOT-223
U504, U505
IC
SOT-223
U506
IC
8-pin SOIC
SC70
SC70
48-pin
TSSOP
48-pin
LFCSP_VQ
16-pin
LFCSP_VQ
64
65
66
1
1
1
U507
U508
U509
IC
IC
IC
67
1
U510
DUT
(AD9246)
IC
68
Total
1
128
U511 (or Z500)
107
Rev. A | Page 41 of 44
Description
Voltage
regulator
Voltage
regulator
8-bit
microcontroller
Dual buffer
Dual buffer
Buffer/line
driver
ADC
Supplier/Part Number
ADI ADP3339AKCZ-2.5
Differential
amplifier
ADI AD8352ACPZ
ADI ADP3339AKCZ-3.3
Microchip PIC12F629
Fairchild NC7WZ16
Fairchild NC7WZ07
Fairchild 74VCX162244
ADI AD9246BCPZ
AD9246
OUTLINE DIMENSIONS
7.00
BSC SQ
0.60 MAX
37
36
PIN 1
INDICATOR
TOP
VIEW
12° MAX
48
PIN 1
INDICATOR
1
EXPOSED
PAD
6.75
BSC SQ
4.25
4.10 SQ
3.95
(BOTTOM VIEW)
0.50
0.40
0.30
1.00
0.85
0.80
0.30
0.23
0.18
0.60 MAX
25
24
12
13
0.25 MIN
5.50
REF
0.80 MAX
0.65 TYP
0.05 MAX
0.02 NOM
0.50 BSC
SEATING
PLANE
0.20 REF
COPLANARITY
0.08
COMPLIANT TO JEDEC STANDARDS MO-220-VKKD-2
Figure 71. 48-Lead Lead Frame Chip Scale Package [LFCSP_VQ]
7 mm × 7 mm Body, Very Thin Quad (CP-48-3)
Dimensions shown in millimeters
ORDERING GUIDE
Model
AD9246BCPZ-125 2
AD9246BCPZRL7-1252
AD9246BCPZ-1052
AD9246BCPZRL7-1052
AD9246BCPZ-802
AD9246BCPZRL7-802
AD9246-125EB
AD9246-105EB
AD9246-80EB
1
2
Temperature Range
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
Package Description
48-Lead Lead Frame Chip Scale Package (LFCSP_VQ)
48-Lead Lead Frame Chip Scale Package (LFCSP_VQ)
48-Lead Lead Frame Chip Scale Package (LFCSP_VQ)
48-Lead Lead Frame Chip Scale Package (LFCSP_VQ)
48-Lead Lead Frame Chip Scale Package (LFCSP_VQ)
48-Lead Lead Frame Chip Scale Package (LFCSP_VQ)
Evaluation Board
Evaluation Board
Evaluation Board
It is required that the exposed paddle be soldered to the AGND plane to achieve the best electrical and thermal performance.
Z = Pb-free part.
Rev. A | Page 42 of 44
Package Option 1
CP-48-3
CP-48-3
CP-48-3
CP-48-3
CP-48-3
CP-48-3
AD9246
NOTES
Rev. A | Page 43 of 44
AD9246
NOTES
©2006 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D05491-0-8/06(A)
Rev. A | Page 44 of 44