SLDU040 November   2022 LP5891

 

  1.   Abstract
  2.   Trademarks
  3. 1Introduction
    1. 1.1 Features
    2. 1.2 Applications
  4. 2Function Descriptions
  5. 3Test Setup
    1. 3.1 System/Tool Requirements
    2. 3.2 Software Setup
    3. 3.3 Hardware Setup for Single Device
    4. 3.4 Hardware Setup for Dual Cascaded Devices
  6. 4Additional Resources
  7. 5Schematic
  8. 6Layout
  9. 7Bill of Materials

3.4 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 MSP430F5529 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 may be 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 MSP430F5529 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 3-3.
  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 3-3.
  4. Connect BoosterPack connectors (J1, J2) on the first LP5891EVM with the MSP430F5529 LaunchPad, the connection method is shown in Figure 3-3.

  5. Connect the J4 connector of the first LP5891EVM to the J3 connector of the second LP5891EVM. The direction is shown in Figure 3-3.

  6. (Optional) Connect the SOUT pin of connector J2 on the second LP5891EVM to the P3.1 pin of connector J4 on the MSP430F5529 LaunchPad through an additional 1-pin cable that is marked as the bottom blue line in Figure 3-3. This step enables LP5891EVM to report LOD (LED Open Detection), and LSD (LED Short Detection) out to the host MSP430F5529 LaunchPad.

  7. Power the MSP430F5529 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.
Figure 3-3 Dual Cascaded LP5891EVM Connected with the MSP430F5529 LaunchPad