LT3960

Demonstration circuit 2686A is a 1.3A 8-switch matrix LED dimmer system with an I²C to CAN-physical transceiver featuring the LT3967 and LT3960. This demonstration circuit connects directly to a LED string and LED driver demonstration circuit to allow for independent dimming control of up to 8 channels of LEDs. A Linduino^® One demonstration circuit is used to interface with the board and can connect in one of two different ways:

1. Connect directly to a Linduino One demonstration circuit with a QuikEval^™ ribbon cable.
2. Connect using the LT3960 break-off board to connect to the I²C master device, but pass data over two twisted pair lines to the LT3960 on the main PCB.

The LT3967 matrix dimmer features 8 individually con-trolled 1.3A rated floating NMOS switch channels and can support up to 56V of LEDs per device. The channels of the LT3967 can be configured for series connections, or non-series connections. Additional DC2686A demo circuits can be connected in series for higher number of LEDs, or in parallel to allow for higher current operation. Resistors are used to configure both the I²C slave address as well as the default start-up state. The default configuration for DC2686A sets the I²C address as 0000 with all LEDs off. See the LT3967 data sheet for details.

The LT3960 I²C to CAN-Physical transceiver is used to send and receive I²C data through harsh or noisy environments at up to 400kb/s using the CAN-Physical layer for differential signaling over twisted pair connections. Both SDA and SCL data lines are converted to differential signals and are shared between devices connected to the bus. This allows for physical separation of the I²C source with the LT3960 transceiver board and the LT3967 main PCB along with the LED driver.

This demo circuit is designed to be easily configured and interfaced with a compatible low output capacitance LED driver and LED string. It can easily be directly attached to a buck LED driver or a floating buck-mode LED driver. More sophisticated setups with series matrix dimmers for higher number of LEDs such as 12 or 16 is possible. Please consult factory applications for details or look for more details on analog.com.

The LT3967 and LT3960 data sheets give complete description of the parts, their operation and applications information. The data sheets must be read in conjunction with the demo manual for demonstration circuit DC2686A. The LT3967EFE is assembled in a thermally enhanced 28-lead TSSOP package. The LT3960EMSE is assembled in a 10-lead MSOP package.

評価用回路EVAL-LT3960-AZは、10ピン・プラスチックMSOPパッケージにLT3960、I²C to CAN物理トランシーバーを搭載しています。EVAL-LT3960-AZは、選択可能なJP1とJP3ジャンパを使ってマスタ・モードとスレーブ・モードで設定された2つのICで構成されています。ボードは中央で簡単に分離され、2つの回路に分かれる設計になっています。

LT3960 I²C-to-CAN物理トランシーバーは、ツイスト・ペア接続を介した差動伝送を行うためのCAN物理層を使用して、過酷でノイズの多い環境でも最高400kbpsでのI²Cデータ送受信を実現します。SDAおよびSCLデータ・ラインの両方を差動信号に変換して、バスに接続されたデバイス間で共有します。これにより、I²CソースとI²Cレシーバーを物理的に分離できます。

1つ目のLT3960がI²Cマスタ（I²C互換のマイクロコントローラ）に接続されます。2つ目のLT3960は、2つのツイスト・ペアで1つ目のLT3960に接続する必要があります。1つまたはそれ以上のI²Cスレーブ・デバイスを使うにはローカルにI²Cバスが必要です。LT3960デバイスは、マスタからスレーブへの一方向のみにクロック信号を送信します。データ信号は常に双方向に通信できます。

LT3960のデータシートには、部品、動作、およびアプリケーションの詳細が記載されています。評価用回路EVAL-LT3960-AZを使用する際は、ユーザー・ガイドと併せてデータシートを参照してください。LT3960EMSEは10ピンMSOPパッケージで組み立てられています。