Texas Instruments ADS9110EVM-PDK, User Manual, Page: 5 / 37

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Analog Interface
2 Analog Interface
As an analog interface, the evaluation board uses operational amplifiers in a variety of configurations to
drive the ADS9110 signal and reference inputs. This section covers driver details including jumper
configuration for different input signal common modes and board connectors for a differential signal
source.
2.1 Connectors for Differential Signal Source
The ADS9110EVM is designed for easy interfacing to external analog differential source via SMA
connector or 100-mil headers. J7 and J3 are SMA connectors that allow analog source connectivity
through coaxial cables. Also, 100-mil jumper cables or mini-grabbers can be used to connect analog
sources to J4:2 and J6:2 pins.
NOTE: The input does not support single-ended signals. The external source must be differential or
balanced keeping the negative and positive inputs to the board symmetric such that Vs(+) =
–Vs(–) at any given time.
Table 1. J7 and J3 SMA Connectors Description
Pin Number Signal Description
Negative Differential Board Input
J3 Vs(–)
1-k Ω Input Impedance
Positive Differential Board Input
J7 Vs(+)
1-k Ω Input Impedance
Table 2. J4 and J6 Headers Description
Pin Number Signal Description
J4 : 3 TEST 0.2V DO NOT USE: Diagnostic use only
Negative Differential Board Input
J4 : 2 Vs(–)
1-k Ω Input Impedance
J4 : 1 AGND Analog ground
J6 : 3 AGND Analog ground
Positive Differential Board Input
J6 : 2 Vs(+)
1-k Ω Input Impedance
J6 : 1 TEST 4.3V DO NOT USE: Diagnostic use only
2.2 ADC Differential Input Signal Driver
The differential signal inputs of the ADS9110 are not dynamically high impedance. SAR ADC inputs
terminate in switched-capacitor networks that create large instantaneous current loads when the switches
are closed that effectively make the ADC inputs dynamically low impedance. Thus, the evaluation board
has low impedance on board drivers that maintain ADC performance with maximum loading at the full
device throughput of 2 MSPS for signal and reference inputs.
5 SBAU249 – October 2015 ADS9110EVM-PDK
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