SBAU202 Datasheet, PDF (13/47 Pages) Texas Instruments – Performance Demonstration Kit for the ADS130E08

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ADS130E08EVM Daughter-Card Hardware Overview
3.2 Clock
The ADS130E08 has an on-chip oscillator circuit that generates a 2.048-MHz clock (nominal). This clock
can vary by ±5% over temperature. For applications that require higher accuracy, the ADS130E08 can
also accept an external clock signal. The ADS130E08 provides an option to test both internal and external
clock configurations. It also provides an option to generate the external clock from either the onboard
oscillator or from an external clock source.
The onboard oscillator is powered by the DVDD supply of the ADS130E08. Care must be taken to ensure
that the external oscillator can operate either with +1.8 V or +3.3 V, depending on the DVDD supply
configuration. Table 4 shows the jumper settings for the three options for the ADS130E08 clocks.
ADS130E08 Clock
JP5
JP6
J4 - pin 10
Table 4. CLK Jumper Options
Internal Clock
Not installed
Don't care
Don't care
External OSC Clock
2-3
1-2 (disable)
Don't care
External Clock
1-2
Don't care
Clock source
A 2.048-MHz oscillator available for the +3.3-V DVDD supply is the FXO-HC735-2.048MHz. For a +1.8-V
DVDD supply, use the SiT8002AC-34-18E-2.048. The EVM is shipped with the external oscillator enabled.
3.3 Reference
The ADS130E08 has an on-chip internal reference circuit that provides reference voltages to the device.
Alternatively, the internal reference can be powered down and VREFP can be applied externally. This
configuration is achieved with the external reference generators (U2 and U3) and driver buffer. These
components (U2, U3, and U4) must be installed by the user; they are not installed at the factory. The
external reference voltage can be set to either 4.096 V or 2.5 V, depending on the analog supply voltage.
Measure TP3 to make sure the external reference is correct and stable. The settings for the external
reference is described in Table 5. This table assumes REF5025 is installed at U2 and REF5040 at U3. A
low-noise amplifier like the OPA350 can be installed at U4.
ADS130E08 Reference
JP12
JP2
Table 5. External Reference Jumper Options
Internal Reference
VREF = 2.5 V
Don't care
Not installed
External Reference
VREF = 4.096 V
VREF = 2.5 V
2-3
1-2
Installed
Installed
3.3.1 Accessing ADS130E08 Analog Supplies
Some ADS130E08 output signals are provided as test points for probing purposes using J4 (not installed
on the board). Table 6 lists the various test signals with the corresponding test points.
Signal
Not connected
Not connected
PWDN
Dasiy in
AGND
Table 6. Auxiliary Connector Test Signals and Test Points
J4 Pin Number
1
2
3
4
5
6
7
8
9
10
Signal
GPIO1
GPIO2
GPIO3
GPIO4
Not connected
SBAU202 – June 2012
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Performance Demonstration Kit for the ADS130E08
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Copyright © 2012, Texas Instruments Incorporated