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DC919A-C

P1-P3P4-P6P7-P8
4
dc919af
DEMO MANUAL DC919A
If the transformer input is required, C4 and C6 should be
0.1μF X5R 0402, R9 and R13 should be 10Ω 0402 resistors.
Note that this transformer (ETC1-1T) is poor below 1MHz.
Reduced amplitude signals can be applied to 300kHz.
Applications below 300kHz must be driven directly via
DC inputs.
As there are a significant number of these boards that
are customized, please confirm the population of your
board. The schematic below shows the default population,
the photograph shows the population of a transformer
coupled version. This board may also be populated with
LTC2204-2207 for DC drive applications, in which case,
R33 is a 0.1μF capacitor.
Apply the analog input signal of interest to the SMA con-
nector on the DC919A demonstration circuit board marked
“J2 ANALOG INPUT”. These inputs are capacitive coupled
to a Flux coupled transformers ETC1-1T. In some cases,
where these devices are to be used in undersampling
scenarios, this transformer should be replaced with an
ETC1-1-13 Balun.
The DC919A can be modified for direct DC drive from a
suitable differential signal source.
This may be done by yourself or at special request when
you order the demo board.
If the DC input paths are populated with low value (5.1Ω)
resistors at both ends of these transmission lines, you
must provide a reasonably well balanced differential drive
with 1.25V common mode.
The spacing of these SMA connectors (0.8") allows them
to be mated directly with demo boards for devices such
as the LT1993, LT1994, LT5514 and others.
It is not recommended to drive this ADC in a single-ended
fashion into a single DC input.
An internally generated conversion clock output is available
on pin 3 of J1 and the data samples are available on Pins
7 to 37 of J1 which can be collected via a logic analyzer,
cabled to a development system through a SHORT 2 to 4
inch long 40-pin ribbon cable or collected by the DC718
QuikEval II Data Acquisition Board using the PScope™
System Software provided or down loaded from the Linear
Technology website at http://www.linear.com/software/.
If a DC718 was provided, follow the DC718 Quick Start
Guide and the instructions below.
If data is to be collected by a logic analyzer, pin 40 must
be strapped to OVDD or 2.5V.
(Please see schematic.)
To start the data collection software if PScope.exe is in-
stalled (by default) in \Program Files\LTC\PScope\, double
click the PScope Icon or bring up the run window under
the start menu and browse to the PScope directory and
select PScope.
If the DC919A demonstration circuit is properly connected
to the DC718, PScope should automatically detect the
DC919A, and configure itself accordingly. If necessary,
the procedure below explains how to manually configure
PScope.
Under the configure menu, go to ADC Configuration.
Check the Config Manually box and use the following
configuration options:
User configure
16-Bit (or 14-Bit if using -14 versions)
Alignment: Left-16
Bipolar (2’s complement)
Positive clock edge
Type: CMOS
If everything is hooked up properly, powered and a suit-
able convert clock is present, clicking the Collect button
should result in time and frequency plots displayed in
the PScope window. Additional information and help for
PScope is available in the DC718 Quick Start Guide and in
the online help available within the PScope program itself.
Analog Input Network
For optimal distortion and noise performance the RC
network on the analog inputs should be optimized for
different analog input frequencies. At this point in time,
the circuit in Figure 3 for input frequencies below 70MHz.
For input frequencies from 70MHz to 140MHz, the circuit
in Figure 2 is used. These two input networks cover a
QUICK START PROCEDURE
5
dc919af
DEMO MANUAL DC919A
broad bandwidth and are not optimized for operation at a
specific input frequency.
In almost all cases, filters will be required on both analog
input and encode clock to provide data sheet SNR.
Narrow band high-Q filters may produce poor SNR results
with Dither enabled. 10% bandpass would be preferred
over 5% bandpass on the analog input. The filters should
be located close to the inputs to avoid reflections from
impedance discontinuities at the driven end of a long
transmission line. Most filters do not present 50Ω outside
the passband.
In cases with long transmission lines, 3dB to 10dB pads
may be required to obtain low distortion.
If your generator cannot deliver full-scale signals without
distortion, you may benefit from a medium power amplifier
QUICK START PROCEDURE
based on a Gallium Arsenide Gain block prior to the final
filter. This is particularly true at higher frequencies where
IC based operational amplifiers may be unable to deliver
the combination of low noise figure and High IP3 point
required. A high order filter can be used prior to this final
amplifier, and a relatively lower Q filter used between the
amplifier and the demo circuit.
For advice on drive circuits or for input frequencies greater
than 70MHz contact the factory for support.
For input frequencies less than 5MHz, or greater than
150MHz, other input networks may be more appropriate.
Please consult the factory for suggestions on drivers
and networks if your signal sources extend outside these
ranges, or if you experience difficulties driving these sug-
gested networks.
0.1μF
A
IN
+
A
IN
–
4.7pF
2.2μF
V
CM
ANALOG
INPUT
0.1μF
0.1μF
T1
1:1
T1 = MA/COM ETC1-1-13.
RESISTORS, CAPACITORS
ARE 0402 PACKAGE SIZE,
EXCEPT 2.2μF
dc919a F02
25Ω
5Ω
5Ω
10Ω
50Ω
10Ω
25Ω
LTC2203/
LTC2202
Figure 2. Analog Front End Circuit For 70MHz+
Figure 3. Analog Front End Circuit for 1MHz < A
IN
< 70MHz
0.1μF
A
IN
+
A
IN
–
8.2pF
2.2μF
V
CM
ANALOG
INPUT
0.1μF
T1
1:1
T1 = COILCRAFT WBCI-IT OR
MA/COM ETC1-1T RESISTORS,
CAPACITORS ARE 0402 PACKAGE
SIZE EXCEPT 2.2μF
dc919a F03
25Ω
5Ω
5Ω
10Ω
50Ω
10Ω
25Ω
LTC2203/
LTC2202
6
dc919af
DEMO MANUAL DC919A
PARTS LIST
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 5 C1, C13, C14, C25, C26 CAP., X7R, 0.1μF, 25V, 10% 0603 TDK, C1608X7R1E104K
2 0 C4, C6 (OPEN) CAP., 0603
3 2 C8, C2 CAP., X5R, 2.2μF, 6.3V, 10% 0603 TDK, C1608X5R0J225K
4 3 C3, C5, C7 CAP., C0G, 8.2pF, 50V, 5% 0402 AVX, 04025A8R2JAT
5 7 C9, C15-C19, C28 CAP., X5R, 0.1μF, 10V, 10% 0402 TDK, C1005X5R1A104K
6 1 C20 CAP., X5R, 10μF, 6.3V, 10% 0805 TDK, C2012X5R0J106K
7 1 C21 CAP., X7R, 0.01μF, 50V, 10% 0603 TDK, C1608X7R1H103K
8 1 C22 CAP., X7R, 1.0μF, 16V, 10% 0603 TDK, C1608X7R1C105K
9 1 C23 CAP., X5R, 4.7μF, 10V, 10% 0805 TDK, C2012X5R1A475K
10 0 C27 (OPT) CAP., 100μF, 6.3V 6032
11 3 E1, E3, E4 TESTPOINT, TURRET, 0.061" MILL-MAX, 2308-2-00-44
12 6 JP1-JP6 0.079 SINGLE ROW HEADER, 3-PIN SAMTEC, TMM103-02-L-S
13 6 JP1-JP6 SHUNT SAMTEC, 2SN-BK-G
14 1 J1
CON, HDR, 0.1 × 0.1 CNTRS, 40-PIN
SAMTEC, TSW-120-07-L-D
15 3 J2, J3, J4 CON., SMA 50Ω EDGE-LANCH CONNEX, 132357
16 0 OSC1 (OPT)
17 4 RN1, RN2, RN3, RN4 RES ARRAY, 33Ω, 5%, 0402 VISHAY, CRA04S0803330JRT7
18 4 R1, R2, R20, R21 RES., CHIP, 10k, 1/16W, 5% 0402 AAC, CR05-103JM
19 2 R3, R7 RES., CHIP, 1k, 1/16W, 5% 0603 AAC, CR16-102JM
20 0 R4, R6, R9, R11-R13, R24, R30 (OPEN) RES., CHIP, 0603
21 2 R26, R27 RES., CHIP, 10Ω, 1/16W, 5% 0603 AAC, CR16-100JM
22 2 R5, R28 RES., CHIP, 33Ω, 1/16W, 5% 0402 VISHAY, CRCW0402330JRT6
23 1 R8 RES., CHIP, 51Ω, 1/16W, 5% 0402 AAC, CR05-510JM
24 1 R29 RES., CHIP, 1k, 1/16W, 5% 0402 AAC, CR05-102JM
25 2 R10, R14 RES., CHIP, 5.1Ω, 1/16W, 5% 0402 AAC, CR05-5R1JM
26 2 R31, R32 RES., CHIP, 0Ω, 1/16W, 0402 AAC, CJ05-000M
28 2 R12, R11 RES., CHIP, 24.9Ω, 1/16W, 1% 0603 VISHAY, CRCW060324R9FRT6
29 3 R17, R18, R19 RES., CHIP, 10k, 1/16W, 5% 0603 AAC, CR16-103JM
30 1 R22 RES., CHIP, 105k, 1/16W, 1% 0603 AAC, CR16-1053FM
31 1 R23 RES., CHIP, 100k, 1/16W, 5% 0603 AAC, CR16-104JM
32 1 R25 RES., CHIP, 1Ω, 1/8W, 5% 0805 AAC, CR10-1R0JM
33 1 T1 TRANSFORMER, 1:1, ETC1-1T M/A-COM, ETC1-1T
34 2 U3, U2 I.C., 74VCX245BQX, DQFN20 FAIRCHILD, 74VCX245BQX
35 2 U4, U5 I.C., NC7SV86 SC70-5 FAIRCHILD, NC7SV86P5X
36 1 U6 I.C., 24LC025, TSSOP-8 MICROCHIP, 24LC025 I /ST
37 1 U7 I.C., LT1763, SO8 LINEAR TECH., LT1763CS8
38 4 (STAND-OFF) STAND-OFF, NYLON 0.25" tall KEYSTONE, 8831(SNAP ON)
P1-P3P4-P6P7-P8

DC919A-C

Mfr. #:
Buy DC919A-C
Manufacturer:
Analog Devices Inc.
Description:
Data Conversion IC Development Tools LTC2205 - CMOS OUT, DC INPUT, 65Msps 16
Lifecycle:
New from this manufacturer.
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