Analog Interface; Connectors For Signal Source; Adc Differential Input Signal Driver; J2 To J5 Sma Analog Interface Connections - Texas Instruments ADS9224REVM-PDK User Manual

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2

Analog Interface

The ADS9224R is a dual-channel, simultaneous-sampling ADC that supports fully-differential inputs. Each
channel of the ADS9224R uses a
of the ADC. This section covers driver details and board connections for a differential signal source.
2.1

Connectors for Signal Source

The ADS9224REVM is designed for easy interfacing to multiple analog sources. SMA connectors allow
the EVM to have input signals connected through coaxial cables. In addition, header connectors JP1
through JP4 provide a convenient way to connect input signals. All analog inputs are buffered by the
THS4551 high-speed FDA in order to properly drive the ADS9224R ADC inputs.
Pin Number
J2
J3
J4
J5
Pin Number
JP1.1
JP2.1
JP3.1
JP4.1
2.2

ADC Differential Input Signal Driver

The analog inputs of the ADS9224R SAR ADC are not high-impedance but rather present a dynamic load
as the sample-and-hold switches open and close. The current demand of the SAR ADC input increases as
a function of the sampling rate. Thus, the evaluation board provides the THS4551 FDA driver that
maintains ADC performance with maximum loading at the full device throughput of 3 MSPS.
SBAU315A – July 2018 – Revised June 2019
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THS4551 fully-differential amplifier (FDA) to drive the differential inputs
Table 1. J2 to J5 SMA Analog Interface Connections
Signal
CHA negative differential input. This SMA connector can be grounded by
AIN-_A installing a shunt on JP1 for single-ended signals.
1-kΩ input impedance
CHA positive differential input or input for single-ended signals.
AIN+_A
1-kΩ input impedance
CHB positive differential input or input for single-ended signals.
AIN+_B
1-kΩ input impedance
CHB negative differential input. This SMA connector can be grounded by
AIN-_B installing a shunt on JP4 for single-ended signals.
1-kΩ input impedance
Table 2. JP1 to JP4 Header Descriptions
Signal
CHA negative differential input. This SMA connector can be grounded by
AIN-_A installing a shunt on JP1 for single-ended signals.
1-kΩ input impedance.
CHA positive differential input or input for single-ended signals.
AIN+_A
1-kΩ input impedance.
CHB positive differential input or input for single-ended signals.
AIN+_B
1-kΩ input impedance.
CHB negative differential input. This SMA connector can be grounded by
AIN-_B installing a shunt on JP4 for single-ended signals.
1-kΩ input impedance.
Copyright © 2018–2019, Texas Instruments Incorporated
Description
Description
Analog Interface
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ADS9224REVM-PDK