Datasheet
www.ti.com
1 EVM Overview
1.1 Features
2 Analog Interface
EVM Overview
• Full-featured evaluation board for the ADS8402 (1.25 MHz), ADS8406 (1.25 MHz), and ADS8412
(2 MHz) high-speed 16-bit, single channel, parallel interface SAR-type analog-to-digital converters.
• Onboard Signal Conditioning
• Onboard Reference
• Input and Output Digital Buffers
• Onboard Decoding for Stacking Multiple EVMs
The ADS8402/ADS8406/ADS8412EVM analog-to-digital converter has pseudo-bipolar differential input. A
pseudo-bipolar differential input is a differential signal (inverting and noninverting input is 180 degrees out
of phase) that is level shifted such that the signals levels are always equal to or above zero volts. The
peak-to-peak amplitude on each input pin can be as large as the reference voltage. See the respective
product data sheet for more information.
The ADS8402/ADS8406/ADS8412EVM comes installed with the unity gain buffer (U2) wired for
single-ended into differential-out configuration. The common-mode voltage is derived from REF3040
reference IC and adjustable using a potentiometer (R9). The common mode voltage pin of the THS4503 is
set to 2.0 V on the evaluation module. A single-ended input signal can be applied at pin-connector P1 or
via SMA connectors J2 (noninverting input). The buffer circuit can be reconfigured for a differential input
by installing resistor R6 and R8 and removing R1. The inverting leg of the differential signal should be
applied
to
either
connector
P1
pin
1
or
SMA
connector
J4
(inverting
input).
See
Table
1 for
pinout
of
analog
connector,
P1.
See
Section
8 for
the
EVM
schematic.
Table 1. Analog Input Connector
Description Signal Name Connector.pin# Signal Name Description
Inverting Input (–) P1.1 P1.2 (+) Noninverting Input
Reserved N/A P1.3 P1.4 N/A Reserved
Reserved N/A P1.5 P1.6 N/A Reserved
Reserved N/A P1.7 P1.8 N/A Reserved
Pin tied to Ground AGND P1.9 P1.10 N/A Reserved
Pin tied to Ground AGND P1.11 P1.12 N/A Reserved
Reserved N/A P1.13 P1.14 N/A Reserved
Pin tied to Ground AGND P1.15 P1.16 N/A Reserved
Pin tied to Ground AGND P1.17 P1.18 N/A Reserved
Reserved N/A P1.19 P1.20 REF+ External Reference Input
ADS8402/ADS8406/ADS8412 EVM User's Guide2 SLAU126A – December 2003 – Revised September 2004