Evm Operation - Texas Instruments ADS794x EVM Series User Manual

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5

EVM Operation

This section provides information on the analog input, digital control, and general operating conditions of
the ADS794xEVM without the MMB0 motherboard. Software operation is presented in
5.1 Analog Input
The ADS794xEVM offers three different analog input modes, selectable with jumper J6 and the type of
input signal. Note that the ADS794x converter by itself only allows dc-coupled unipolar signals. The two
additional input modes are available because OPA836 operational amplifiers drive the analog inputs. It is
preferable for external signal drivers or filters to have low output impedance to reduce gain errors.
Mode 1: DC-Coupled Unipolar Inputs (J6 Closed)
DC-coupled unipolar signals are typically produced by single-supply signal drivers. To allow dc-coupled
unipolar signals, J6 should be closed. This mode allows an input signal range from 0 V to V
analog inputs. In this mode, the voltage read at the ADC is equal to (V
Mode 2: DC-Coupled Bipolar Inputs (J6 Open)
DC-coupled bipolar signals are typically produced by dual-supply signal drivers. To allow dc-coupled
bipolar signals, J6 should be open. This mode allows an input signal range from –V
EVM analog inputs. In this mode, the voltage read at the ADC is equal to (V
Mode 3: AC-Coupled Inputs (J6 Closed)
AC-coupled signals are typically produced by high-pass filters. To allow ac-coupled bipolar signals, J6
should be closed. This mode allows an input signal range from –V
inputs. In this mode, the voltage read at the ADC is equal to (V
5.2 Digital Control
The digital control signals can be applied directly to the P1 header (top or bottom side). The modular
ADS794xEVM can also be connected directly to a DSP or microcontroller interface board, such as the
5-6K Interface or HPA-MCU Interface
as part of the ADS794xEVM-PDK. For a list of compatible interface and/or accessory boards for the EVM
or the ADS794x, see the relevant product folder on the TI web site.
SBAU194 – August 2011
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boards available from Texas Instruments, or the MMB0 if purchased
Copyright © 2011, Texas Instruments Incorporated
Section
– V ).
REF IN
/2 to +V
REF
/2 – V ).
REF IN
/2 to +V /2 for all EVM analog
REF REF
/2 – V ).
REF IN
ADS794xEVM and ADS794xEVM-PDK
EVM Operation
7.
for all EVM
REF
/2 for all
REF
9