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Copyright 2003, Texas Instruments Incorporated
EVM IMPORTANT NOTICE
Texas Instruments (TI) provides the enclosed product(s) under the following conditions:
This evaluation kit being sold by TI is intended for use for ENGINEERING DEVELOPMENT OR EVALUATION
PURPOSES ONLY and is not considered by TI to be fit for commercial use. As such, the goods being provided
may not be complete in terms of required design-, marketing-, and/or manufacturing-related protective
considerations, including product safety measures typically found in the end product incorporating the goods.
As a prototype, this product does not fall within the scope of the European Union directive on electromagnetic
compatibility and therefore may not meet the technical requirements of the directive.
Should this evaluation kit not meet the specifications indicated in the EVM User’s Guide, the kit may be returned
within 30 days from the date of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE
WARRANTY MADE BY SELLER TO BUYER AND IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED,
IMPLIED, OR S TATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR ANY
PARTICULAR PURPOSE.
The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user
indemnifies TI from all claims arising from the handling or use of the goods. Please be aware that the products
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discharge.
EXCEPT TO THE EXTENT OF THE INDEMNITY SET FORTH ABOVE, NEITHER PARTY SHALL BE LIABLE
TO THE OTHER FOR ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.
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TI assumes no liability for applications assistance, customer product design, software performance, orinfringement of patents or services described herein.
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Post Office Box 655303
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Copyright 2003, Texas Instruments Incorporated
EVM WARNINGS AND RESTRICTIONS
It is important to operate this EVM within an input voltage range of 0 V to 3.3 V.
Exceeding the specified input range may cause unexpected operation and/or irreversible
damage to the EVM. If there are questions concerning the input range, please contact a TI
field representative prior to connecting the input power.
Applying loads outside of the specified output range may result in unintended operation and/or
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connecting any load to the EVM output. If there is uncertainty as to the load specification,
please contact a TI field representative.
During normal operation, some circuit components may have case temperatures greater than
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as the input and output ranges are maintained. These components include but are not limited
to linear regulators, switching transistors, pass transistors, and current sense resistors. These
types of devices can be identified using the EVM schematic located in the EVM User’s Guide.
When placing measurement probes near these devices during operation, please be aware
that these devices may be very warm to the touch.
Mailing Address:
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Post Office Box 655303
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This user’s guide document gives a general overview of the DAC5674
evaluation module (EVM) and provides a general description of the features
and functions to be considered while using this module.
The DAC5674 EVM provides a platform for evaluating the DAC5674
digital-to-analog converter (DAC) under various signal, reference, and supply
conditions. This document should be used in combination with the EVM
schematic diagram supplied.
1.2EVM Basic Functions
Digital inputs to the DAC can be provided with CMOS level signals up to
200 MSPS through a 40-pin header. This enables the user to provide
high-speed digital data to the DAC5674.
The analog output from the DAC is available via SMA connectors. Because
of its flexible design, the analog output of the DAC5674 can be configured to
drive a 50- Ω terminated cable using a 4:1 or 1:1 impedance ratio transformer,
or single-ended referred to GND.
The EVM allows for different clock configurations. The user can input a
differential ECL/PECL or TTL/CMOS level signal, to be used to generate a
single-ended or differential clock source. See the clock section for proper
configuration and operation.
Power connections to the EVM are via banana jack sockets. Separate sockets
are provided for the analog, digital, PLL, and I/O supply.
In addition to the internal bandgap reference provided by the DAC5674 device,
options on the EVM allow external reference to be provided to the DAC.
1.3Power Requirements
The demonstration board has four power inputs. The first, +3.3VA, is required
to be +3.3 Vdc at banana jack J9 with the return going to J11. This is the analog
supply for the DAC5674. The second, +1.8 VD, is required to be +1.8 Vdc at
banana jack J14 with the return to J16. This is the digital +1.8-V supply for the
DAC5674. The third, +3.3VCLK, is required to be +3.3 Vdc at banana jack J10
with the return at J13. This is the digital supply for the internal PLL circuitry. The
fourth, +1.8/3.3VD_IO, is required to be either +1.8 or +3.3 Vdc at banana jack
J12 with the return at J15. This is the supply for the digital I/Os. The EVM can
be powered using only two supplies, but powering from four separate supplies
provides higher performance.
Note: Voltage Limits
Exceeding the maximum input voltages can damage EVM components.
Undervoltage may cause improper operation of some or all of the EVM
components.
1-2
1.4DAC5674 EVM Operational Procedure
The DAC5674 EVM can be set up in a variety of configurations to
accommodate a specific mode of operation. Before starting evaluation, the
user should decide on the configuration and make the appropriate
connections or changes. The demonstration board comes with the following
factory-set configuration:
- Differential clock mode using transformer T2 and a clock input at J4
- Transformer coupled output using transformer T1
- The converter is set to operate with internal reference. Jumper W2 is
installed between pins 1 and 2.
DAC5674 EVM Operational Procedure
- Full-scale output current set to 20 mA through R
- The DAC5674 output is enabled (sleep mode disabled). Jumper W3 is
resistor R1
BIAS
installed between pins 1 and 2.
- Reset operation controlled through S1. Jumper W5 is installed between
pins 2 and 3.
- Internal PLL is disabled. Jumper W4 is installed between pins 1 and 2.
Overview
1-3
1-4
Chapter 2
PCB Layout and Parts List
This chapter describes the physical characteristics and PCB layout of the EVM
and lists the components used on the module.
The EVM is constructed on a 4-layer, 3.3-inch × 5.75-inch, 0.062-inch thick
PCB using FR-4 material. Figure 2−1 through Figure 2−4 show the PCB layout
for the EVM.
2-2
Figure 2−2.Layer 2, Ground Plane
PCB Layout
Figure 2−3.Layer 3, Power Plane
PCB Layout and Parts List
2-3
PCB Layout
Figure 2−4.Bottom Layer
2-4
Parts List
2.2Parts List
Table 2−1 lists the parts used in constructing the EVM.
SW-PB switch1EVQ-PJX04MPanasonicS1
Switch1SD05HOSKCKS2
SMA connectors3713-4339
(901-144-8RFX)
SN74LVC04A1SN74LVC04APWTIU2
Standoff, hex (1/4 × 1”)4219-2063Allied
Black test point35001KKeystoneTP3, TP4, TP5
Red test point35000KKeystoneTP1, TP2, TP6
Transformer1T1-1T-KK8Mini-CircuitsT1
Transformer1TCM4-1Mini-Circuits T2
AlliedJ2, J4, J7J1, J3, J5, J6
InstalledNot Installed
Ref. Des.
2-6
Chapter 3
Circuit Description
This chapter provides descriptions of the primary functional circuits on the
DAC5674 EVM.
The following paragraphs describe the EVM circuits.
3.1.1Input Clock
The DAC5674 EVM default operation setting is with a differential input clock
sent to the DAC5674. A 500-mV p-p, 0-V offset, 50% duty-cycle external
sinewave is applied to SMA connector J4 and converted to a d i fferential clock
input to the DAC5674 by transformer T2. This input represents a 50-Ω load to
the source. In order to preserve the specified performance of the DAC5674
converter, the clock source should feature very low jitter. Using a clock with a
50% duty cycle gives optimum dynamic performance.
3.1.1.1 Differential ECL/PECL Input Clock
The EVM can be configured for differential ECL/PECL input clock mode by
configuring the board per Table 3−1 and applying the appropriate ECL/PECL
common mode voltage at terminal E1 (VTT). Use J3 and J5 to input the
external differential ECL/PECL clock signals.
3.1.1.2 Single-Ended Input Clock
The EVM can be configured for single-ended input clock mode by configuring
the board per T able 3−1. SMA connector J3 or header J8 can be used to input
the external TTL/CMOS clock signal.
Single ended TTL/CMOS from J3R9, C55R10, R12, R25, R34, R35, R37,
Single ended TTL/CMOS from J8R34, R37, C55R9, R10, R12, R35, T2, C56
†
All component values are per the schematic except where shown in parentheses.
†
Components Not Installed
C55, C56
R36, R12, R34, R35, R37, T2,
C55, C56
T2, C56
3.1.2Input Data
The DAC5674 EVM can accept 3.3-V CMOS logic level data inputs through
the 40-pin header J8 per Table 3−2. The board provides 50-Ω termination to
ground and series dampening resistors to minimize digital ringing and
switching noise. J8 also provides a path for an input clock (see Table 3−1 for
proper board configuration).
1CMOS data bit 13 (MSB)15CMOS data bit 629Reset
2GND16GND30GND
3CMOS data bit 1217CMOS data bit 531
4GND18GND32GND
5CMOS data bit 1119CMOS data bit 433
6GND20GND34GND
7CMOS data bit 1021CMOS data bit 335
8GND22GND36GND
9CMOS data bit 923CMOS data bit 237
10GND24GND38GND
11CMOS data bit 825CMOS data bit 139SCLK_IN
12GND26GND40GND
13CMOS data bit 727CMOS data bit 0 (LSB)
14GND28GND
3.1.3Output Data
The DAC5674 EVM can be configured to drive a doubly terminated 50-Ω cable
or provide unbuffered differential outputs.
3.1.3.1 Transformer Coupled Signal Output
The factory-set configuration of the demonstration board provides the user
with a single-ended output signal at SMA connector J7. The DAC5674 is
configured to drive a doubly terminated 50-Ω cable using a 1:1 impedance
ratio transformer, a 100-Ω terminating resistor R2, and the center tap of T1
connected to ground per Table 3−3. When using a 4:1 impedance ratio
transformer, configure the EVM per Table 3−3. The common mode input
voltage of T1 can be adjusted by using the resistor divider network R5 and R6.
All component values are per the schematic except where shown in parenthesis.
3.1.3.2 Unbuffered Differential Output
†
Components Not Installed
R2, R5, R7, R8, C20, C21
To provide unbuffered differential outputs, the EVM must be configured as
follows: remove R2, C20, C21, and T1; Install R3, R4, R7, R8, J1 and J6.
Circuit Description
3-3
Circuit Function
3.1.4Internal Reference Operation
The full-scale output current is set by applying an external resistor (R1)
between the BIASJ pin of the DAC5674 and ground. The full-scale output
current can be adjusted from 20 mA down to 2 mA by varying R1 or changing
the externally applied reference voltage. The full-scale output current,
IOUT
, is defined as follows:
FS
IOUT
= 32 × (V
FS
EXTIO
/R1)
where V
is the voltage at pin EXTIO. This voltage is 1.2 V typical when
EXTIO
using the internally provided bandgap reference voltage source.
3.1.5External Reference Operation
The internal reference can be disabled and overridden by an external
reference by connecting a voltage source to terminal TP2 (EXT_I/O) and
connecting EXTLO to AVDD. The specified range for external reference
voltages should be observed (see the DAC5674 data sheet (SLWS148) for
details).
3.1.6Sleep Mode
The DAC5674 EVM provides a means of placing the DAC5674 into a
power-down mode. This mode is activated by placing jumper W3 between pins
2 and 3.
3.1.7Filter Control
The DAC5674 has two inputs, HP1 and HP2, which control the internal
interpolation filters (FIR1 and FIR2) mode of operation. When these inputs are
set to a logic high, the filters are configured for high-pass response. When set
to a logic low, the filters are configured for low-pass response. A third input,
X4, allows the user to bypass Interpolation Filter 1. When X4 is set to a logic
low, Filter 1 is bypassed. See the data sheet (SL WS148) for more information.
3.1.8PLL Divider Control
The DAC5674 has two inputs, DIV0 and DIV1, which control the internal PLL
prescaler divide ratio setting. These two signals, along with the three filter
control signals, are all controlled by DIP switch S2 on the EVM. All control
signals are in the logic low level when the DIP switch is in the closed position.
See the data sheet (SLWS148) for more information.