BOOSTXL-ADS7841-Q1 EVM Overview
5
SNAU229 – December 2017
Copyright © 2017, Texas Instruments Incorporated
BOOSTXL-ADS7841-Q1 BoosterPack™ User's Guide
The analog input range is from GND to +VREF when configured as single-ended inputs. A maximum of
four single-ended inputs may be applied to J10, using pins J10:1 to J10:4. When configured for differential
mode operation, the positive analog input level has a range of -0.2V to VCC + 0.2V. The voltage on the
negative analog input is limited between -0.2V and 1.25V. A maximum of two pseudo-differential inputs
may be applied to J10, using pins J10:1 - J10:2, and J10:3 - J10:4.
The input to channel 0 can be optionally configured to use the OPA2320 buffer through 100ohm resistor
with an 560pF capacitor to GND. Jumper J8 can be placed on pins 1-2 to select this unity gain buffer
configuration of the OPA2320 and in this case channel 0 input is provided via SMA connector J7. A similar
configuration is available for channel 2 input as well by using Jumper J12 pins 1-2 and via SMA connector
J11.
By default, AIN3 is factory configured by Jumper J15 pins 1-2 and J15 pins 3-4 on the BOOSTXL-
ADS7841-Q1 EVM to measure a fraction of the 5V supply voltage using simple resistor divider circuit
formed by R35/R36 (see schematic in
). Please ensure Jumper J15 shunts are disconnected
when using J10.3 as AIN3 input.
2.2
Voltage Reference
The BOOSTXL-ADS7841-Q1 EVM has two sources for the reference voltage. Jumper J13 can select the
VREF voltage from either the REF5045A (U9) or from 5V VCC. The EVM is factory configured for use with
the REF5045A 4.5V reference (J13 pins 2-3).
2.3
Digital Interface
As noted in
, the BOOSTXL-ADS7841-Q1 EVM interfaces with the TM4C1294 LaunchPad™,
which in turn communicates with the computer over USB. The two devices on the booster pack that the
TM4C1294 communicates with are the ADS7841-Q1 ADC (over SPI) and the EEPROM (over I
2
C). The
EEPROM comes preprogrammed with the information required to configure and initialize the BOOSTXL-
ADS7841-Q1 EVM platform every time on power up.
2.4
ADS7841-Q1EVM Digital I/O Interface
The BOOSTXL-ADS7841-Q1 EVM supports the SPI digital interface and functional modes as detailed in
the ADS7841-Q1EVM device data sheet (
). The TM4C1294 LaunchPad™ is operating at a 3.3-V
logic level and is connected to the 5.0-V digital I/O lines of the ADC through level shifter
(SN74LVC2T45QDCURQ1).
2.5
Power Supplies
The device supports a single supply with a wide range of operation. The VCC can operate from 2.7 V to
5.0 V. TI’s TPS79901 adjustable voltage regulator available onboard is configured to supply 5.0 V to
ADS7841-Q1 VCC pin on the BOOSTXL-ADS7841-Q1 EVM.