ADS7038Q1EVM-PDK

ADC7038-Q1 8-CHANNEL, 1-MSPS, 12

The ADS7038-Q1 Evaluation Module (EVM) Performance Demonstration Kit (PDK) allows users to evaluate the functionality of Texas Instruments' ADS7038-Q1 12-bit, eight-channel programmable successive approximation register (SAR) analog-to-digital converter (ADC). The ADS7038-Q1 device showcases eight inputs, each configurable to an analog input, digital output, or digital input. This user’s guide describes both the hardware platform showcasing the ADS7038-Q1 device and the graphical user interface (GUI) software used to configure the various modes of operation of this device. It includes complete circuit descriptions, schematic diagrams, and a bill of materials. The EVM-PDK eases the evaluation of the ADS7038-Q1 device with hardware, software, and computer connectivity through the universal serial bus (USB) interface. The following figure shows the ADS7038Q1EVM-PDK.

Trademarks

Firefox™ is a trademark of Mozilla Foundation.

Google Chrome™ is a trademark of Google LLC..

All other trademarks are the property of their respective owners.

1 Introduction

The ADS7038-Q1 EVM is a fully-assembled evaluation platform designed to highlight the ADS7038-Q1 features and various modes of operation that make this device suitable for ultra-low-power, small-size sensor monitor applications. The accompanying Precision ADC Motherboard (PAMBoard) development kit is used as a USB-toPC GUI communication bridge. This kit also serves as an example implementation of a master microcontroller (MCU) to communicate with the ADS7038-Q1 device through a serial-peripheral interface (SPI).

The PAMBoard is controlled by commands received from the ADS7038-Q1 GUI, and returns data to the GUI for display and analysis. If the PAMBoard is not used, the EVM plug-in module format allows for an alternative external host to communicate with the ADS7038-Q1 by easily connecting through a pin header. The ADS7038- Q1 device incorporates all required circuitry and components with the following features:

• ADS7038-Q1 small general purpose, feature integrated, eight-channel ADC

• Buffered analog input drive circuit available on channel 0

• External power-supply connection available to provide DVDD power supply instead of the USB power

• Adjustable linear regulator, TPS78001, to generate stable output voltage to AVDD from the 5-V USB power from the PAMBoard

• SPI for communication and configuration of modes

Figure 1-1 shows the ADS7038-Q1EVM input circuity for the analog inputs.

2 ADS7038Q1EVM-PDK Overview

This section describes various onboard components that are used to interface the analog input, general purpose inputs/outputs (GPIOs), digital interface, and provide power supply to the ADS7038-Q1 device.

Figure 2-1 shows an ADS7038Q1EVM-PDK board overview.

2.1 Connections to Input ChannelsThe ADS7038Q1EVM-PDK is designed for easy interface to an external, analog single-ended source, or to GPIOs through a 100-mil header. Connector J5 provides a connection to the device channels. Table 2-1 lists the channel connections. The AIN0 channel features an operational amplifier, TLV9061, to drive the analog input. This is further explained in Section 4. Channels AIN1 through AIN6 have a resistor and capacitor filter circuit to condition the analog input, as Figure 1-1 shows. Channel 7 is hardware configured to demonstrate GPIO functionality. GPIO7 has a resistor and light-emitting diode (LED) to visibly demonstrate and monitor digital output channel state. The LED illuminates when the GPIO7 is logic LOW.

2.2 Digital Interface

As noted in Section 1, the ADS7038Q1EVM interfaces with the PAMBoard, which in turn communicates with the computer over the USB. The two devices on the EVM that communicate over SPI are the ADS7038-Q1 ADC (U3) and the electrically erasable programmable read-only memory (EEPROM) (U4). The EEPROM is preprogrammed with the information required to configure and initialize the ADS7038 platform. Once the hardware is initialized, the EEPROM is no longer used.

2.3 ADS7038Q1EVM-PDK PAMBoard Interface

The ADS7038Q1EVM-PDK supports the digital SPI and functional modes as detailed in the ADS7038 Small, 8- Channel, 12-bit ADC with SPI Interface, GPIOs, and CRC data sheet. The PAMBoard is capable of operating at a 3.3-V logic level and is directly connected to the digital I/O lines of the ADC.

2.4 Power Supplies

The device supports a wide range of operation on its analog supply. The AVDD can operate from 3 V to 5.5 V. The DVDD operates from 1.65 V to 5.5 V, independent of the AVDD supply. A voltage regulator available on the PAMBoard is used to create a regulated 5-V supply for the EVM. AVDD is created from this supply using a lowdropout (LDO) voltage regulator to create a clean +3.3 V. DVDD is provided directly from the PAMBoard at 3.3 V. There is an option to use an external power supply for DVDD through J2.

3 ADS7038Q1EVM-PDK Initial Setup

The instructions to set up the ADS7038Q1EVM-PDK are described in the following sections.

3.1 EVM Plug-In Hardware Setup Instructions

The EVM and PAMboard should come packaged together. If they are not, for correct functionality, the boards need to be installed together properly

To install the EVM to the PAMboard, stack the ADS7038Q1EVM board on the PAMBoard. Make sure the 20-pin connector (J1, J3) on the ADS7038Q1EVM is mapped to left connector on the PAMBoard, and the EVM connector (J4, J2) is mapped to right connector on the PAMBoard. The silk screen on the ADS7038-Q1 must match with the PAMBoard. Figure 3-1 shows the correct installation. The board headers must be flush. Make sure the USB is not plugged in during board connections. After matching the boards together, connect the PAMBoard micro USB data port to an available USB port on the PC.

3.2 The ADS7038 GUI Online and TI Cloud Agent Application Installation

The following steps describe the ADS7038 GUI software installation:

1. Plug in the included micro USB to USB cable to the PAMBoard and a USB port on the computer, respectively.

2. On the ADS7038Q1EVM-PDK landing page, the software is available through a web-based GUI. Connecting to the GUI may require login to a user account for access.

3. First-time users may be prompted to download and install the browser extension for Firefox™ or Google Chrome™ and the TI Cloud Agent Application as Figure 3-2 shows. Do so if need be, this is a one time download.