FEATURES
On-Chip Reference and Track/Hold
On-Chip Input Buffer
850 mW Typical Power Dissipation at 105 MSPS
500 MHz Analog Bandwidth
SNR = 67 dB @ 49 MHz AIN at 105 MSPS
SFDR = 80 dB @ 49 MHz AIN at 105 MSPS
2.0 V p-p Differential Analog Input Range
Single 5.0 V Supply Operation
3.3 V CMOS/TTL Outputs
Two’s Complement Output Format
APPLICATIONS
Communications
Basestations and ‘Zero-IF’ Subsystems
Wireless Local Loop (WLL)
Local Multipoint Distribution Service (LMDS)
HDTV Broadcast Cameras and Film Scanners
GENERAL INTRODUCTION
The AD9432 is a 12-bit monolithic sampling analog-to-digital
converter with an on-chip track-and-hold circuit and is optimized
for high-speed conversion and ease of use. The product operates
at a 105 MSPS conversion rate with outstanding dynamic performance over its full operating range.
The ADC requires only a single 5.0 V power supply and a
105 MHz encode clock for full-performance operation. No
A/D Converter
AD9432
FUNCTIONAL BLOCK DIAGRAM
external reference or driver components are required for many
applications. The digital outputs are TTL/CMOS compatible
and a separate output power supply pin supports interfacing
with 3.3 V logic. The encode input supports either differential
or single-ended and is TTL/CMOS-compatible.
Fabricated on an advanced BiCMOS process, the AD9432 is
available in a 52-lead plastic quad flatpack package (LQFP)
specified over the industrial temperature range (–40°C to +85°C).
REV. E
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. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices.
Logic “1” Voltage (VDD = 3.3 V)FullVIVDD – 0.05VDD – 0.05V
Logic “0” Voltage (V
= 3.3 V)FullVI0.050.05V
DD
Output Coding Two’s Complement Two’s Complement
POWER SUPPLY
Power Dissipation
3
FullVI79010008501100mW
Power Supply Rejection Ratio (PSRR) 25°CI–5+0.5+5–5+0.5+5mV/V
I
I
VCC
VDD
FullVI158200170220mA
FullVI9.512.212.516mA
–2–
REV. E
AD9432
TestAD9432BST/BSQ-80AD9432BST/BSQ-105
ParameterTempLevelMinTypMaxMinTypMaxUnit
DYNAMIC PERFORMANCE
Signal-to-Noise Ratio (SNR)
(Without Harmonics)
f
= 10.3 MHz25°CI65.567.565.567.5dB
IN
= 40 MHz25°CI6567.267.2dB
f
IN
f
= 49 MHz25°CI67.06467.0dB
IN
f
= 70 MHz25°CV66.166.1dB
IN
Signal-to-Noise Ratio (SINAD)
(With Harmonics)
= 10.3 MHz25°CI6567.26567.2dB
f
IN
= 40 MHz25°CI64.566.966.9dB
f
IN
f
= 49 MHz25°CI66.76366.7dB
IN
f
= 70 MHz25°CV65.865.8dB
IN
Effective Number of Bits
= 10 MHz25°CV11.011.0Bits
f
IN
f
= 40 MHz25°CV10.910.9Bits
IN
= 49 MHz25°CV10.910.9Bits
f
IN
f
= 70 MHz25°CV10.710.7Bits
IN
Second and Third Harmonic Distortion
= 10 MHz25°CI–75–85–75–85dBc
f
IN
f
= 40 MHz25°CI–73–85–83dBc
IN
f
= 49 MHz25°CI–83–72–80dBc
IN
= 70 MHz25°CV–80–78dBc
f
IN
Worst Harmonic or Spur
(Excluding Second and Third)
= 10 MHz25°CI–80–90–80–90dBc
f
IN
f
= 40 MHz25°CI–80–90–90dBc
IN
f
= 49 MHz25°CI–90–80–90dBc
IN
= 70 MHz25°CV–90–90dBc
f
IN
Two-Tone Intermod Distortion (IMD)
f
= 29.3 MHz; f
IN1
f
= 70.3 MHz; f
IN1
NOTES
1
Gain error and gain temperature coefficients are based on the ADC only (with a fixed 2.5 V external reference and a 2 V p-p differential analog input).
2
tV and tPD are measured from the transition points of the ENCODE input to the 50%/50% levels of the digital outputs swing. The digital output load during test is
not to exceed an ac load of 10 pF or a dc current of ± 40 µA. Rise and fall times measured from 10% to 90%.
3
Power dissipation measured with encode at rated speed and a dc analog input. (Outputs Static, I
4
SNR/harmonics based on an analog input voltage of –0.5 dBFS referenced to a 2 V full-scale input range.
Maximum Junction Temperature . . . . . . . . . . . . . . . . 150°C
Maximum Case Temperature . . . . . . . . . . . . . . . . . . . 150°C
*Stresses above those listed under Absolute Maximum Ratings may cause perma-
nent damage to the device. This is a stress rating only; functional operation of the
device at these or any other conditions outside of those indicated in the operation
sections of this specification is not implied. Exposure to absolute maximum
ratings for extended periods may affect device reliability.
EXPLANATION OF TEST LEVELS
Test Level
I100% production tested.
II100% production tested at 25°C and sample tested at
specified temperatures.
III Sample tested only.
IV Parameter is guaranteed by design and characterization
testing.
VParameter is a typical value only.
VI 100% production tested at 25°C; guaranteed by design and
characterization testing for industrial temperature range.
THERMAL CHARACTERISTICS
52-Lead Plastic LQFP (ST-52)
= 50°C/W, No Airflow
JA
52-lead PowerQuad
= 25°C/W, Soldered Exposed Heat Sink, No Airflow
JA
= 33°C/W, Unsoldered Exposed Heat Sink, No Airflow
JA
= 2°C/W, Bottom of package (Exposed Heat Sink)
JC
®
4 LQFP (SQ-52)
Simulated Typical performance for 4-layer JEDEC board,
horizontal orientation.
ORDERING GUIDE
TemperaturePackagePackage
ModelRangesDescriptionsOption
AD9432BSQ–40°C to +85°C 52-Lead ThermallySQ-52
-80, -105Enhanced Plastic
Quad Flatpack
AD9432BST–40°C to +85° C 52-Lead Plastic Quad ST-52
-80, -105Flatpack (LQFP)
AD9432/PCB 25°CEvaluation Board
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 the AD9432 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.
PowerQuad is a registered trademark of AMkor Technology, Inc.
7ENCODEEncode Clock for ADC–Complementary
8ENCODEEncode Clock for ADC–True (ADC samples on rising edge of ENCODE)
14OROut of Range Output
15–20, 25–30D11–D6, D5–D0 Digital Output
12, 21, 24, 31DGNDDigital Output Ground
13, 22, 23, 32V
DD
Digital Output Power Supply (2.7 V to 3.6 V)
41DNCDo Not Connect
45VREFINReference Input for ADC (2.5 V Typical); Bypass with 0.1 µF to Ground.
46VREFOUTInternal Reference Output (2.5 V Typical)
49AINAnalog Input–True
50AINAnalog Input–Complementary
DEFINITION OF SPECIFICATIONS
Analog Bandwidth (Small Signal)
The analog input frequency at which the spectral power of the
fundamental frequency (as determined by the FFT analysis) is
reduced by 3 dB.
Aperture Delay
The delay between a differential crossing of ENCODE and
ENCODE and the instant at which the analog input is sampled.
Aperture Uncertainty (Jitter)
The sample-to-sample variation in aperture delay.
Differential Nonlinearity
The deviation of any code from an ideal 1 LSB step.
Encode Pulsewidth/Duty Cycle
Pulsewidth high is the minimum amount of time that the ENCODE
pulse should be left in Logic “1” state to achieve rated performance;
pulsewidth low is the minimum time ENCODE pulse should be left
in low state. At a given clock rate, these specs define an acceptable
Encode duty cycle.
Integral Nonlinearity
The deviation of the transfer function from a reference line
measured in fractions of 1 LSB using a “best straight line”
determined by a least square curve fit.
REV. E
–5–
Minimum Conversion Rate
The encode rate at which the SNR of the lowest analog signal
frequency drops by no more than 3 dB below the guaranteed limit.
Maximum Conversion Rate
The encode rate at which parametric testing is performed.
Output Propagation Delay
The delay between a differential crossing of ENCODE and
ENCODE and the time when all output data bits are within
valid logic levels.
Power Supply Rejection Ratio
The ratio of a change in input offset voltage to a change in
power supply voltage.
Signal-to-Noise Plus Distortion (SINAD)
The ratio of the rms signal amplitude (set at 1 dB below full
scale) to the rms value of the sum of all other spectral components, including harmonics but excluding dc.
Signal-to-Noise Ratio (SNR)
The ratio of the rms signal amplitude (set at 1 dB below full
scale) to the rms value of the sum of all other spectral components, excluding the first five harmonics and dc.
AD9432
V
DD
DIGITAL
OUTPUT
DIGITAL OUTPUT
Spurious-Free Dynamic Range (SFDR)
The ratio of the rms signal amplitude to the rms value of the
peak spurious spectral component. The peak spurious component may or may not be a harmonic. May be reported in dBc
(i.e., degrades as signal level is lowered), or in dBFS (always
related back to converter full scale).
Two-Tone Intermodulation Distortion Rejection
The ratio of the rms value of either input tone to the rms value
of the worst third order intermodulation product; reported in dBc.
SAMPLE N–1
AIN
ENCODE
ENCODE
D11–D0
SAMPLE N
t
A
t
EH
DATA N–11DATA N–10N–9DATA N–1DATA NDATA N + 1
SAMPLE N+1
t
EL
N–2
Figure 1. Timing Diagram
V
CC
Two-Tone SFDR
The ratio of the rms value of either input tone to the rms value
of the peak spurious component. The peak spurious component
may or may not be an IMD product. May be reported in dBc
(i.e., degrades as signal level is lowered), or in dBFS (always
related back to converter full scale).
Worst Harmonic
The ratio of the rms signal amplitude to the rms value of the
worst harmonic component, reported in dBc.
SAMPLE N+10SAMPLE N+11
SAMPLE N+9
1/f
S
t
PD
t
V
V
CC
VREFIN
Figure 2. Equivalent Voltage Reference Input Circuit
V
CC
Q1
NPN
VREFOUT
OUTPUT
V
REF
Figure 3. Equivalent Voltage Reference Output Circuit
V
CC
AIN
AIN
5k⍀
7k⍀
17k⍀
ENCODEENCODE
100⍀
8k⍀
17k⍀
100⍀
8k⍀
Figure 4. Equivalent Encode Input Circuit
Figure 5. Equivalent Digital Output Circuit
5k⍀
7k⍀
ANALOG INPUT
Figure 6. Equivalent Analog Input Circuit
–6–
REV. E
AIN INPUT FREQUENCY – MHz (–0.5dBFS)
70
0
SNR – dB
50100150200
250
65
60
55
50
ANALOG INPUT FREQUENCY – MHz
0100
dBc
20120401406016080
50
40
60
70
80
90
100
180
2nd or 3rd (–3.0dBFS)
2nd or 3rd (–6.0dBFS)
2nd or 3rd (–0.5dBFS)
200
ENCODE = 105MSPS
Typical Performance Characteristics–
AD9432
90
85
80
75
dB
70
AIN = 10.3MHz
SFDR
SNR
65
SINAD
60
020
406080100120140160
ENCODE – MSPS
TPC 1. SNR/SINAD/SFDR vs. fS: fIN = 10.3 MHz
–50
–55
–60
–65
–70
–75
dBc
–80
–85
–90
–95
–100
020
3rd
2nd
406080100120140160
ENCODE – MSPS
AIN = 10.3MHz
TPC 2. Harmonics vs. fS: fIN = 10.3 MHz
TPC 4. SNR vs. AIN Input Frequency,
Encode = 105 MSPS
TPC 5. Harmonics vs. fIN: fS = 105 MSPS
REV. E
70
65
60
SINAD (–3.0dBFS)
55
dB
50
45
40
020
SINAD (–6.0dBFS)
SINAD (–0.5dBFS)
406080 100 120 140 160
ANALOG INPUT FREQUENCY – MHz
TPC 3. SINAD vs. fIN: fS = 105 MSPS
ENCODE = 105MSPS
180
200
–7–
100
ENCODE = 105MSPS
90
80
WORST OTHER (–6.0dBFS)
70
dBc
60
WORST OTHER (–0.5dBFS)
WORST OTHER (–3.0dBFS)
50
40
020
406080 100 120 140 160
ANALOG INPUT FREQUENCY – MHz
180 200
TPC 6. Worst-Case Spur (Other than Second and
Third) vs. f
The AD9432 is a multibit pipeline converter that uses a switched
capacitor architecture. Optimized for high speed, this converter
provides flat dynamic performance up to frequencies near Nyquist.
DNL transitional errors are calibrated at final test to a typical
accuracy of 0.25 LSB or less.
USING THE AD9432
Analog Input
The analog input to the AD9432 is a differential buffer. The input
buffer is self-biased by an on-chip resistor divider that sets the
dc common-mode voltage to a nominal 3 V (see Equivalent
Circuits section). Rated performance is achieved by driving the
input differentially. Minimum input offset voltage is obtained when
driving from a source with a low differential source impedance
such as a transformer in ac applications. Capacitive coupling at the
inputs will increase the input offset voltage by as much as ±25 mV.
Driving the ADC single-endedly will degrade performance.
For best dynamic performance, impedances at AIN and AIN
should match.
Special care was taken in the design of the analog input section
of the AD9432 to prevent damage and corruption of data when
the input is overdriven. The nominal input range is 2 V p-p.
Each analog input will be 1 V p-p when driven differentially.
4.0
3.5
AIN
AD9432
ENCODE
ENCODE
PECL
GATE
510⍀
GND
510⍀
0.1F
0.1F
Figure 8. AC Coupling to ENCODE Inputs
ENCODE Voltage Level Definition
The voltage level definitions for driving ENCODE and ENCODE
in single-ended and differential mode are shown in Figure 9.
High Differential Input Voltage (V
Low Differential Input Voltage (V
Common-Mode Input (V
) . . . . . . . 1.25 V min, 1.6 V nom
ICM
High Single-Ended Voltage (V
Low Single-Ended Voltage (V
ENCODE
ENCODE
ENCODE
0.1F
ILS
V
IHD
V
ICM
V
ILD
V
IHS
V
ILS
) . . . . . . . . . . 3.5 V max
IHD
) . . . . . . . . . . . . . 0 V min
ILD
) . . . . . 2 V min to 3.5 V max
IHS
) . . . . . 0 V min to 0.8 V max
V
ID
3.0
2.5
2.0
AIN
Figure 7. Full-Scale Analog Input Range
ENCODE Input
Any high speed A/D converter is extremely sensitive to the quality of the sampling clock provided by the user. A track/hold
circuit is essentially a mixer, and any noise, distortion, or timing
jitter on the clock will be combined with the desired signal at the
A/D output. For that reason, considerable care has been taken
in the design of the ENCODE input of the AD9432, and the
user is advised to give commensurate thought to the clock source.
The ENCODE input supports either differential or single-ended
and is fully TTL/CMOS compatible.
Note that the ENCODE inputs cannot be driven directly from
PECL level signals (V
is 3.5 V max). PECL level signals can
IHD
easily be accommodated by ac coupling as shown in Figure 8.
Good performance is obtained using an MC10EL16 in the
circuit to drive the encode inputs.
Figure 9. Differential and Single-Ended Input Levels
Often, the cleanest clock source is a crystal oscillator producing
a pure sine wave. In this configuration, or with any roughly
symmetrical clock input, the input can be ac-coupled and biased
to a reference voltage that also provides the ENCODE. This
ensures that the reference voltage is centered on the encode signal.
Digital Outputs
The digital outputs are 3.3 V (2.7 V to 3.6 V) TTL/CMOScompatible for lower power consumption. The output data
format is Two’s Complement, illustrated in Table I. The out of
range (OR) output (logic LOW for normal operation) will be
HIGH during any clock cycle when the ADC output data (Dx)
reach positive or negative full scale (–2048 or +2047). The OR
is internally generated each clock cycle, has the same pipeline latency and propagation delay as the ADC output data, and
will remain HIGH until the output data reflect an in-range
condition. The ADC output bits (Dx) will not roll over, and
will therefore remain at positive or negative full scale (+2048 or
–2047) while the OR output is HIGH.
–10–
REV. E
AD9432
AIN – MHz
0
dB
2060
64
40
63
62
61
60
SNR
SINAD
65
66
Table I. Output Coding (VREF = 2.5 V) (Two’s Complement)
CodeAIN–AIN (V)Digital Output
+20471.0000111 1111 1111
The dc common-mode voltage for the AD8138 outputs can be
adjusted via input V
to provide the 3 V common-mode voltage
OCM
the AD9432 inputs require.
500⍀
•••
•••
10pF
AD9432
000000 0000 0000
–1–0.000491111 1111 1111
•••
•••
–2048–1.0001000 0000 0000
Voltage Reference
A stable and accurate 2.5 V voltage reference is built into the
VIN
50⍀
500⍀
AD8138
V
OCM
500⍀
50⍀
22pF
50⍀
AIN
AIN
5V
2k⍀
AD9432 (VREFOUT). In normal operation the internal reference is used by strapping Pin 45 to Pin 46 and placing a 0.1 µF
decoupling capacitor at VREFIN.
25⍀
500⍀
10pF
3k⍀
0.1F
The input range can be adjusted by varying the reference voltage
applied to the AD9432. No appreciable degradation in performance occurs when the reference is adjusted ±5%. The full-scale
Figure 10. AD8138/AD9432 Schematic
range of the ADC tracks reference voltage changes linearly.
Timing
The AD9432 provides latched data outputs, with 10 pipeline
delays. Data outputs are included or available one propagation
delay (t
) after the rising edge of the encode command
PD
(see Figure 1). The length of the output data lines and loads
placed on them should be minimized to reduce transients within
the AD9432; these transients can detract from the converter’s
dynamic performance.
The minimum guaranteed conversion rate of the AD9432 is
1 MSPS. At internal clock rates below 1 MSPS, dynamic
performance may degrade. Therefore, input clock rates below
1 MHz should be avoided.
During initial power-up, or whenever the clock to the AD9432
is interrupted, the output data will not be accurate data for 200 ns
or 10 clock cycles, whichever is longer.
Figure 11. Measured SNR and SINAD (Encode = 105 MSPS)
Using the AD8138 to Drive the AD9432
A new differential output op amp from Analog Devices, Inc.,
–70
the AD8138, can be used to drive the AD9432 in dc-coupled
applications. The AD8138 was specifically designed for ADC
driver applications. Superior SNR performance is maintained up
to analog frequencies of 30 MHz. The AD8138 op amp provides
–80
H2
single-ended-to-differential conversion, providing for a low-cost
option to transformer coupling for ac applications as well.
dB
H3
The circuit in Figure 10 was breadboarded and the measured
performance is shown in Figures 11 and 12. The figures shown
–90
are for ± 5 V supplies at the AD8138—performance dropped by
about 1 dB–2 dB with a single 5 V supply at the AD8138.
Figure 11 shows SNR and SINAD for a –1 dBFS analog input
frequency varied from 2 MHz to 40 MHz with an encode rate of
105 MSPS. The measurements are for nominal conditions at
room temperature. Figure 12 shows the second and third harmonic distortion performance under the same conditions.
–100
0204060
AIN – MHz
Figure 12. Measured Second and Third Order Harmonic
Distortion (Encode = 105 MSPS)
REV. E
–11–
AD9432
[T]
86 ACQS
STOP:
TEK5.00GS/s
T
2
CH2
CH1 1.00V1.00VM 5.00ns CH11.20V
C1 MAX
2.33V
C1 MIN
810mV
C1 FREQ
106.3167MHz
LOW
SIGNAL
AMPLITUDE
EVALUATION BOARD
The AD9432 evaluation board offers an easy way to test the
AD9432. It requires an analog signal, encode clock, and power
supplies as inputs. The clock is buffered on the board to provide
the clocks for an on-board DAC and latches. The digital outputs
and output clock are available at a standard 37-pin connector P7.
Power Connector
Power is supplied to the board via two detachable 4-pin power
strips P30, P40.
P5No Connect
P6No Connect
P7VD3.3 V /105 mA Latch, ADC Digital Output Supply
P8GND
Analog Inputs
The evaluation board accepts a 2 V p-p analog input signal at
SMB connector P2. This single-ended signal is ac-coupled by
capacitor C11 and drives a wideband RF transformer T1 (MiniCircuits ADT1-1WT) that converts the single-ended signal to a
differential signal. (The AD9432 should be driven differentially toprovide optimum performance.) The evaluation board is shipped
with termination resistors R4, R5, which provide the effective
50 Ω termination impedance; input termination resistor R10 is
optional. Note: The second harmonic distortion that some RF
transformers tend to introduce at high frequencies can be reduced
by coupling two transformers in series as shown in Figure 13.
(Improvements on the order of 3 dB–4 dB can be realized.)
C1
0.1F
TO AIN+
TO AIN–
C2
0.1F
IN
T2T1
R1
25⍀
R2
25⍀
Figure 13. Improving Second Harmonic Distortion
Performance
TEK5.00GS/s
STOP:
2
CH1
500mV
CH3
2.00V
14 ACQS
[T]
T
500mVM 5.00ns CH13.00V
CH2
C1 MAX
3.4V
C1 MIN
2.5mV
C1 FREQ
49.995MHz
LOW SIGNAL
AMPLITUDE
Figure 14. Analog Input Levels
The full-scale analog inputs to the ADC should be two 1 V p-p
signals 180 degrees out of phase with each other, as shown in
Figure 14. The analog inputs are dc biased by two on-chip
resistor dividers that set the common-mode voltage to approximately 0.6 × VCC (0.6 × 5 = 3 V). AIN+ and AIN– each vary
between 2.5 V and 3.5 V as shown in the two upper traces in Figure 14. The lower trace is the input at SMB P2 (on a 2 V/div scale).
Encode
The encode input to the board is at SMB connector P3. The
(>1 V p-p) input is ac-coupled and drives two high-speed differential line receivers (MC10EL16). These receivers provide
subnanosecond rise times at their outputs—a requirement for
the ADC clock inputs for optimum performance. The EL16
outputs are PECL levels and must be ac-coupled to meet the
common-mode dc levels required at the AD9432 encode inputs.
A PECL/TTL translator (MC100ELT23), provides the clocks
required at the output latches, DAC, and 37-pin connector.
Note: Jitter performance on the clock source is critical at this
performance level; a stable, crystal-controlled signal generator is
used to generate all of the ADC performance plots. Figure 15
shows the Encode+ clock at the ADC. The 3 V latch clock
generated on the card is also shown in the plot.
–12–
Figure 15. Encode+ Clock and Latch Clock
REV. E
AD9432
DATA OUTPUTS
The ADC digital outputs are latched on the board by two 574s;
the latch outputs are available at the 37-pin connector at Pins
25–36. A latch output clock (data ready) is available at Pin 21,
with the complement at Pin 2. There are series termination
resistors on the data and clock outputs. These can be changed if
required to accommodate different loading situations. Figure
16 shows a data bit switching and output clock (DR) at the
connector.
CH2
265 ACQS
[T]
T
C1 MAX
3.06V
C1 MIN
–390mV
C1 FREQ
105.4562MHz
TEK5.00GS/s
STOP:
2
CH1 1.00V1.00VM 5.00ns CH11.20V
Figure 16. Data Bit and Clock at 37-Pin Connector
REFERENCE
The AD9432 has an on-chip reference of 2.5 V available at
VREFOUT (Pin 46). Most applications will simply tie this
output to the VREFIN input (Pin 45). This is accomplished
jumping E4 to E6 on the board. An external voltage reference
can drive the VREFIN pin if desired by strapping E4 to E3 and
placing an AD780 voltage reference on the board (not supplied).
DAC
The evaluation board has an on-board reconstruction DAC
(AD9752). This is placed only to facilitate testing and debug of
the board. It should not be used to measure the performance of
the ADC, as it will not accurately indicate the ADC performance.
The DAC output is available at SMB P1. It will drive a 50 Ω
load. Provision to power down the DAC is at Pin 15 at the DAC.
PCB LAYOUT
The PCB is designed on a four-layer (1 oz. Cu) board. Components and routing are on the top layer with a ground flood for
additional isolation. Test and ground points were judiciously
placed to facilitate high-speed probing. A common ground plane
exists on the second layer. The third layer has three split power
planes, two for the ADC and one for support logic. The DAC,
components, and routing are located on the bottom layer.
TROUBLESHOOTING
If the board does not seem to be working correctly, try the
following:
• Verify power at IC pins.
• Check that all jumpers are in the correct position for the
desired mode of operation.
• Verify VREF is at 2.5 V.
• Try running encode clock and analog inputs at low speeds
(10 MSPS/1 MHz) and monitor 574 outputs, DAC output,
and ADC outputs for toggling.
The AD9432 Evaluation Board is provided as a design example
for customers of Analog Devices, Inc. ADI makes no warranties,
express, statutory, or implied, regarding merchantability or fitness
for a particular purpose.
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS
ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR REFERENCE
ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN
0.057 (1.45)
0.053 (1.35)
1
0.026 (0.65)
BSC
0.015 (0.38)
0.009 (0.22)
14
13
THERMALLY ENHANCED
52-Lead Power Thin Plastic Quad Flatpack (LQFP_ED)
(SQ-52)
0.093 (2.35)
0.472 (12.00) SQ
0.307 (7.80)
1
TOP VIEW
(PINS DOWN)
13
14
SEATING
PLANE
0.015 (0.38)
0.013 (0.32)
0.009 (0.22)
0.026 (0.65)
0.063
(1.60)
MAX
0.030 (0.75)
0.024 (0.60)
0.018 (0.45)
NOTES
1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS ARE ROUNDED-OFF MILLIMETER
EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.
2. ALTHOUGH NOT REQUIRED IN ALL APPLICATIONS, THE AD9432 HAS AN EXPOSED METALLIC PAD ON THE
PACKAGE BOTTOM WHICH IS INTENDED TO ENHANCE THE HEAT REMOVAL PATH. TO MAXIMIZE THE REMOVAL
OF HEAT, A LAND PATTERN WITH CLOSELY SPACED THERMAL VIAS TO THE GROUND PLANE(S) SHOULD
BE INCORPORATED ON THE PCB WITHIN THE FOOTPRINT OF THE PACKAGE CORRESPONDING TO THE
EXPOSED METAL PAD DIMENSIONS OF THE PACKAGE. THE SOLDERABLE LAND AREA SHOULD BE SOLDER
MASK DEFINED AND BE AT LEAST THE SAME SIZE AND SHAPE AS THE EXPOSED PAD AREA ON THE
PACKAGE. AT LEAST 0.25 MM CLEARANCE BETWEEN THE OUTER EDGES OF THE LAND PATTERN AND THE
INNER EDGES OF THE PAD PATTERN SHOULD BE MAINTAINED TO AVOID ANY SHORTS.