SLDU040A November   2022  – August 2024 LP5891

 

  1.   1
  2.   Description
  3.   Features
  4.   Applications
  5.   5
  6. 1Evaluation Module Overview
    1. 1.1 Introduction
    2. 1.2 Kit Contents
    3. 1.3 Specification
    4. 1.4 Device Information
  7. 2Hardware
    1. 2.1 Function Descriptions
    2. 2.2 Test Setup
      1. 2.2.1 System/Tool Requirements
      2. 2.2.2 Hardware Setup for Single Device
      3. 2.2.3 Hardware Setup for Dual Cascaded Devices
  8. 3Software
    1. 3.1 Software Setup
  9. 4Hardware Design Files
    1. 4.1 Schematic
    2. 4.2 PCB Layout
    3. 4.3 Bill of Materials
  10. 5Additional Information
    1. 5.1 Additional Resources
    2. 5.2 Trademarks
  11. 6Revision History

2.2.3 Hardware Setup for Dual Cascaded Devices

The LP5891EVM can be cascaded in a daisy chain. In such case, each LP5891 works in the independent mode (compared to the stackable mode). The host TMS320F280039C LaunchPad sends the serial data to the first LP5891 through the 40-pin BoosterPack Header. Then the first LP5891 transmits the serial data through board-to-board connector (J3 and J4) to the second LP5891. The second LP5891 can transmit the serial data to the host with an additional 1-pin cable. The serial data are transmitted through the daisy chain, while the clock signal is shared between multiple devices.

When multiple LP5891EVM are cascaded in a daisy chain, using an external power supply is recommended due to the large current consumption. Also, an additional digital buffer for SCLK is needed if the drive strength of the controller is not enough.

Dual cascaded LP5891EVM in independent mode can be quickly set up and tested by following these steps:

  1. Download the code to the TMS320F280039C LaunchPad with TI Code Composer Studio software.
  2. For the first LP5891EVM, put the J5 jumper on TP1 5V and EX 5V. Then put the J6 jumper on EX5V and the middle. Set the switch S1 towards SOUT1TO2. These setups are marked with red boxes on the First Device in Figure 2-4.
  3. For the second LP5891EVM, put the J5 jumper on J3 5V and EX 5V. Then put the J6 jumper on EX5V and the middle. Set the switch S1 towards SOUTHOST. These setups are marked with red boxes on the Second Device in Figure 2-4.
  4. Connect BoosterPack connectors (J1, J2) on the first LP5891EVM with the TMS320F280039C LaunchPad, the connection method is shown in Figure 2-4.
  5. Connect the J4 connector of the first LP5891EVM to the J3 connector of the second LP5891EVM. The direction is shown in Figure 2-4.
  6. (Optional) Connect the SOUT pin of connector J2 on the second LP5891EVM to the IO.17 pin of connector J2 on the TMS320F280039C LaunchPad through an additional 1-pin cable that is marked as the bottom blue line in Figure 2-4. This step enables LP5891EVM to report LOD (LED Open Detection), and LSD (LED Short Detection) out to the host TMS320F280039C LaunchPad.
  7. Power the TMS320F280039C LaunchPad through the USB cable.
  8. Connect TP1 and TP2 on the first LP5891EVM to 5V/GND power source.
  9. Power on 5V/GND power supply.
LP5891EVM Dual Cascaded LP5891EVM Connected with the TMS320F280039C LaunchPad Figure 2-4 Dual Cascaded LP5891EVM Connected with the TMS320F280039C LaunchPad