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5.1 Reference Voltages
6 EVM Operation
6.1 Default Jumper Locations
EVM Operation
Table 4. JP1 Pinout
Signal Pin Number Signal
+VA (positive input buffer supply) 1 2 -VA (negative input buffer supply)
+5VA (+Va to the ADS7864) 3 4 -5VA (Unused)
DGND 5 6 AGND
+1.8VD (Unused) 7 8 +VD1 (Unused)
+3.3VD (used with W5 for support circuitry) 9 10 +5VD (+Vd to the ADS7864)
Alternate power sources can be applied through various test points located on the EVM. See the
schematic at the end of this document for details. Note – although filters are provided for all power supply
inputs, optimal performance of the EVM requires a clean, well-regulated power source.
The ADS7864MEVM is configured to use its internal reference through jumper W3 (see schematic for
details). If an external reference is desired, the shunt jumper on W3 should be moved to cover pins 1-2;
the external reference source then can be applied to the test point labeled TP10 referenced to TP12. The
internal +2.5-V reference is still connected to the input buffer U1 in this case to ensure proper mid-point
biasing to channel A1.
The analog input swing is 5 Vpp, centered on a +2.5-V internal or external reference. The installed device
accepts bipolar input ranges when a level shift circuit is used in the analog front-end circuitry. See section
3.2 of this document or section 12 of Op Amps for Everyone (SLOD006 ) for information on various circuit
configurations. Channel B1 is factory configured for bipolar operation and is ready to accept inputs in the
rage of ± 10V (see section 3.3 of this document).
Once power is applied to the EVM, the analog input source can be connected directly to J3 or J4 (top or
bottom side) or through optional amplifier and signal-conditioning modules using the 5-6K and HPA-MCU
Interface Boards. The analog input level (at the ADC) should not exceed 5 Vpp. The analog input range is
from ± Vref (typically 2.5 VDC) centered at +2.5 V.
The digital control signals can be applied directly to J1 and J5 (top or bottom side). The ADS7864MEVM
also can be connected directly to the 5-6K Interface Board for use with a variety of C5000™ and C6000™
series DSP Starter Kits (DSK), or the HPA-MCU Interface Board for use with C2000™ Series DSPs or
TMS470™ Series controllers. The Control and Data connectors are designed to allow pattern generators
and/or logic analyzers to be connected to the EVM using standard ribbon-type cables on 0.1-inch centers.
The BYTE signal, which controls the output of the ADS7864 when used with 8-bit controllers, can be
manipulated with jumper W7. By default, W7 is closed and the BYTE pin is held low, providing data in
16-bit format. Removing the shunt on jumper at W7 asserts BYTE high by means of pullup resistor R23.
The conversion clock can be applied to J7, a BNC connector with a 50- Ω terminator, or J5 as mentioned
previously. Jumper W8 allows the EVM user to select the clock source. In normal operation (factory
default) the shunt on jumper W8 is covering pins 2-3. To use a clock source applied to the BNC connector
J7, move the shunt at jumper W8 to cover pins 1-2. In either mode, the clock source can be monitored at
TP21.
Table 5 provides a list of jumpers found on the EVM and their factory default conditions.
ADS7864MEVM 6 SLAU188 – September 2006
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