Texas Instruments ADS1610EVM User Manual page 4

Digital Interface
For more information on the reference generation circuitry, see sheet 6 of the ADS1610EVM schematic, at
the end of this user's guide.
2.1.3 Clock Source
The ADS1610 uses the external clock signal applied to the CLK input pin as the modulator clock. Input
sampling is controlled by this clock signal. As with any high-speed data converter, a high-quality clock is
essential for achieving optimum performance. In order to maximize SNR performance of the converter,
keep the jitter on this clock source below those recommended in the ADS1610 data sheet.
The modulator clock can be fed into the ADS1610 from two sources. It can be applied via SMA connector
(J4) or from the onboard source. The onboard source is the 60-MHz oscillator installed at X1. The
factory-set condition applies the onboard 60-MHz oscillator to the CLK pin of the ADS1610. The
user-supplied external clock must be fed to the board through the SMA connector, J4. The board has a
footprint at R9 for a 50 -Ω termination on this line. It can be installed at the user's discretion. If R9 is not
installed by the user and the user clock is generated from a 50-Ω source, then be sure to reduce the clock
amplitude to half.
To switch from the onboard oscillator to the user clock applied at J4, change the position of jumper of W3
from pins 1–2 to 2–3.
The performance of the ADS1610 is sensitive to clock jitter; see the data sheet for the requirements.
Reference
Designator
W1
W2
W3
(1)
Factory installed
3 Digital Interface
This section describes the digital sections and pinout of the ADS1610EVM.
3.1 Board-Level Control
3.1.1 DIP Switch Options
Optional settings for the ADS1610 are set and controlled manually via a DIP switch – SW1. The functions
controlled by this switch are summarized in
Switch, SW1
Position
1
2
3
4
5
6
4 ADS1610EVM
Table 2. Jumper Setting
1-2 2-3
(1)
Installed Not installed
Not installed Installed
(1)
Installed Not installed
Not installed Installed
(1)
Installed Not installed
Not installed Installed
Table
Table 3. Switch Function Control, SW1
Function
Mode 0 pin
Mode 1 pin
Power-down bit
Not used
Not used
Not used
Set voltage on AVDD1 as source for the reference generation circuitry.
Set voltage REF02 as the source for the reference generation circuitry.
Enable 60-MHz oscillator
Disable 60-MHz oscillator
Set modulator clock to onboard 60-MHz oscillator
Set modulator clock to user-supplied clock via J4.
3.
ON(LO)
Set M0 to 0
Set M1 to 0
Device is powered down
SLAU180A – May 2006 – Revised August 2006
www.ti.com
Description
OFF(HI)
Set M0 to 1
Set M0 to 1
Device is not powered down
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