DC2903A no-OS Example Project

Supported Evaluation Boards

Overview

The DC2903A evaluation board is designed to assess the LTC2672, a five-channel DAC with low dropout current source output. It features five programmable DAC output channels capable of sourcing currents up to 3.125 mA per channel. These channels allow configuration through a software interface, supporting operations such as toggling outlined channels (e.g., OUT3) to switch between preset currents. Communication is established via SPI, with parameters like device ID and baud rate set in the software. The board also allows reference settings configuration for VREF measurement, ensuring precise control. This setup facilitates efficient interaction and monitoring in various applications.

Applications

  • Tunable lasers

  • Semiconductor optical amplifier biasing

  • Resistive heaters

  • Current mode biasing

Hardware Specifications

Power Supply Requirements

The DC2903A evaluation board requires a positive supply voltage at the VCC (E6) input and a ground connection at E7, supporting a voltage range from 2.1V to 5.5V DC. Stability within these voltage limits is necessary for optimal operation. The board is integrated with the LTC2672 DAC, providing five channels of current output and interfaces with the DC2026C controller board via a ribbon cable at the J1 connector. Ensure all channels are grounded and can handle the maximum current output specified. The board also allows monitoring of output voltages and internal die temperature through a multiplexer pin for operational diagnostics.

Connections

Connector

Function

J1

SPI/I2C interface pin header connector

JP1

REF select

JP2

FSADJ select

JP3 to JP7

Internal or external VDDx voltage select

E1

CLR

E2, E5, E12 to E14, E16, E18, E22, E29

GND connections

E3

Toggle enable (TGP)

E4

LDAC

E6

VCC positive voltage supply

E7

GND for power supply

E8

V− negative voltage supply

E9

Channel 1 output pin (OUT1)

E10

External reference connection (REF)

E11

Channel 0 output pin (OUT0)

E15

Channel 2 output pin (OUT2)

E17

Channel 3 output pin (OUT3)

E19

Channel 4 output pin (OUT4)

E20

Multiplexer output (MUX)

E23, E25 to E28

External supplies for VDDx pins

No-OS Supported Examples

The initialization data used in the examples is taken out from the Project Source Data Path.

Basic example

The basic example code for the DC2903A evaluation board demonstrates the configuration of the LTC2672 DAC’s output channels via SPI communication. The user must configure SPI communication parameters and define settings for DAC channels to output desired current levels up to 3.125 mA. The example also includes monitoring the board’s outputs and internal diagnostics like the die temperature via the multiplexer. Essential steps include powering the board with a voltage between 2.1 V and 5.5 V, ensuring all connections via specified J1 and E connectors, and verifying the reference settings through JP connectors.

This is the only example in this project, so it builds by default. See the Build Command section below for the build instructions.

No-OS Supported Platforms

Maxim

Hardware Used

  • DC2903A

  • MAX32666FTHR

Connections

Description

DC2903A Connection

MAX32666 Connection

Power Connection (VCC)

E6 (VCC)

Connect to the power source providing 2.1V to 5.5V

Ground Connection

E7 (GND)

Connect to Ground

Negative Voltage Supply

E8 (V−)

Connect to Ground or a negative supply if required

SPI Chip Select

J1 Pin 6 (CS)

Chip select signal from MAX32666

SPI Clock Signal

J1 Pin 4 (SCL/SCK)

Serial clock signal from MAX32666

SPI Master-Out Slave-In

J1 Pin 7 (SDA/MOSI)

Data from MAX32666 to DC2903A

SPI Master-In Slave-Out

J1 Pin 5 (MISO)

Data to MAX32666 from DC2903A

EEPROM Data Connection

J1 Pin 9 (EEDA)

Connect for data transfer with EEPROM

EEPROM VCC Connection

J1 Pin 10 (EEVCC)

Power supply for EEPROM

EEPROM Ground

J1 Pin 12 (EEGND)

Ground for EEPROM

Build Command

For toolchain setup and prerequisites, see the Maxim CMake build guide.

Available variants: basic. Available boards: max32666fthr. Replace --variant / --board accordingly.

export MAXIM_LIBRARIES=</path/to/MaximSDK/Libraries>
# Windows (PowerShell): $env:MAXIM_LIBRARIES = "C:\MaximSDK\Libraries"

cd no-OS

# build the project (basic example on the max32666fthr board)
python tools/scripts/no_os_build.py build \
   --project dc2903a --variant basic --board max32666fthr

# build and flash (requires a connected debug probe)
python tools/scripts/no_os_build.py build \
   --project dc2903a --variant basic --board max32666fthr \
   --probe openocd --flash