Texas Instruments LP8864 User manual

User’s Guide
LP8864 Evaluation Module
ABSTRACT
The Texas Instruments LP8864EVM evaluation module helps designers to evaluate the operation and
performance of the LP8864-Q1 device. This document includes a hardware setup instructions, software
instructions, a complete schematic diagram, printed-circuit board (PCB) layout, and bill of materials (BOM) of the
LP8864EVM.
Table of Contents
1 Introduction.............................................................................................................................................................................2
1.1 Features............................................................................................................................................................................. 2
1.2 Applications........................................................................................................................................................................2
2 Test Setup................................................................................................................................................................................3
2.1 LP8864EVM Kit..................................................................................................................................................................3
2.2 System and Equipment Requirements...............................................................................................................................3
2.3 Hardware Setup................................................................................................................................................................. 4
2.4 Software Installation...........................................................................................................................................................4
2.5 Quick Start-Up Procedure.................................................................................................................................................. 5
2.6 Additional GUI Functions................................................................................................................................................... 7
2.7 Instructions for Standalone Evaluation...............................................................................................................................9
3 LP8864EVM Board Layout................................................................................................................................................... 10
4 LP8864EVM Schematic.........................................................................................................................................................11
5 LP8864EVM Bill of Materials................................................................................................................................................12
6 LED Load Board....................................................................................................................................................................14
Trademarks
All trademarks are the property of their respective owners.
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1 Introduction
The LP8864EVM helps designers to evaluate the characteristics, operation, and use of the LP8864-Q1 device, a
high-performance LED driver for automotive lighting. The LP8864-Q1 device is a high-efficiency LED driver with
boost controller. The four 200-mA high-precision current sinks support phase shifting that is automatically
adjusted based on the number of channels in use. LED brightness can be controlled globally through the I2C
interface or PWM input.
1.1 Features
The EVM has the following features:
• Up to 48-V VOUT boost controller
• Four high-precision current sinks
• Supports built-in phase-shift PWM dimming, hybrid dimming, current dimming and direct PWM dimming
mode
• LED brightness controlled globally through I2C interface or PWM input
• Extensive fault diagnostics
1.2 Applications
Backlight for:
• Automotive infotainment
• Automotive instrument clusters
• Smart mirrors
• Heads-Up Displays (HUD)
• Central Information Displays (CID)
• Audio-Video Navigation (AVN)
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2 Test Setup
This section describes how to properly connect and setup the LP8864EVM.
2.1 LP8864EVM Kit
The LP8864EVM kit contains (see Figure 2-1):
• USB2ANY
– Ribbon cable
– USB cable
• LP8864EVM
• LP886X-LEDLOAD-EVM
Figure 2-1. LP8864EVM Kit
2.2 System and Equipment Requirements
• DC power supply: 24 V or higher, 6 A or higher
• LED cable: 5-position ribbon cable
• PC to run GUI software
• GUI software
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2.3 Hardware Setup
Figure 2-2 shows the hardware setup of the LP8864EVM.
• Connect a 12-V external power supply between the power input terminals VBAT+ and GNDin on the
LP8864EVM
• Connect the USB2ANY module to the PC with the USB cable
• Connect the USB2ANY module to the LP8864EVM with the provided ribbon cable
• Connect the LP8864EVM to the LP886X-LEDLOAD-EVM with a 5-position ribbon cable
Figure 2-2. LP8864EVM Hardware Setup
2.4 Software Installation
Download the GUI software from the LP8864EVM tools folder. Follow the instructions to finish the GUI
installation. Once installed, a shortcut to the GUI is found on the desktop and also in the start-up menu under the
Texas Instruments folder.
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2.5 Quick Start-Up Procedure
1. After the hardware is connected successfully, run the GUI software. Turn on the 12-V external power supply.
Select the right device variant of the EVM, which is LP8864, as shown in Figure 2-3.
Figure 2-3. LP8866/4 Family GUI Landing Page
2. Check the connection status button on the bottom left corner of the GUI. The button should be like the one
shown in Figure 2-3. There should be a Hardware Connected message on the status bar next to the button. If it
shows Hardware not Connected, click the button to manually connect the hardware. This button can be used to
connect or disconnect the GUI to the hardware during the evaluation. Besides the connection status button, the
device should be enabled to be connected to the GUI. Ensure the Enable button on the LED Control Page (see
Figure 2-5) is enabled.
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3. Click the EXPLORE LP8864 button to go to the LP8864EVM GUI home page (see Figure 2-4).
Figure 2-4. LP8864EVM GUI Home Page
4. Click the START button to go to the LED Control page (see Figure 2-5). On the LED Control page, the user
can control all the register-based control functions of the device, like brightness control, current control, sloper
control, dither control, boost synchronization configuration, and spread spectrum configuration.
Figure 2-5. LP8864EVM LED Control Page
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2.6 Additional GUI Functions
In the selection tab on the left-hand side, the user can switch between LED Control, Monitor Faults, Diagnostics
and Register Map tabs. This section introduces GUI functions provided in the Monitor Faults, Diagnostics, and
Register Map tabs.
2.6.1 Monitor Faults Page
From the Monitor Faults page (see Figure 2-6), the user has access to LP8864-Q1 fault status bits. Faults can
be cleared by software by clicking the Clear All button. Fault interrupt can be enabled or disabled globally by
toggling the Interrupt All button. Besides that, each fault interrupt and each fault status can be controlled
individually.
Figure 2-6. LP8864EVM Monitor Faults Page
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2.6.2 Diagnostics Page
From the Diagnostics page (see Figure 2-7), the user can read back the following diagnostics register values
and corresponding device status.
• FSM_LIVE_STATUS: current status of the functional state machine
• PWM_INPUT_STATUS: 16-bit value for detected duty cycle of PWM input signal
• PWM_OUTPUT_STATUS: 16-bit value for configured duty cycle of PWM output signal
• LED_CURRENT_STATUS: 12-bit current DAC code that brightness path is driving to OUT1-4 output
• VBOOST_STATUS: 11-bit boost voltage code that adaptive voltage control loop sending to analog boost
block
• AUTO_PWM_FREQ_SEL: LED PWM frequency value from PWM_SEL resistor detection
• AUTO_LED_STRING_CFG: LED string configuration from LED_SET resistor detection
• AUTO_BOOST_FREQ_SEL: boost switching frequency value from PWM_FSET resistor detection
• MODE_SEL: LED dimming mode value from MODE resistor detection
Figure 2-7. LP8864VM Diagnostics Page
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2.6.3 Register Map Page
Figure 2-8 shows the registers map page. All the registers are available on this page. When Auto Read is set to
other than "Off", all the registers will be read automatically and periodically according to the interval time the user
selects. Otherwise, the user needs to click the READ REGISTER button to read the selected register or click the
READ ALL REGISTERS button to read all of the registers.
Clicking on the row of a register automatically updates the corresponding field view on the right side of the page.
The register value can be updated by modifying the hexadecimal value in the Value column or by double-clicking
the corresponding bit in the Bits column. The modified value is effective immediately if "Immediate Write" is
selected in the drop-down menu. When "Deferred Write" is selected, the modified value will not take effect until
the user clicks the WRITE REGISTER button. The value of all the registers can be updated together by clicking
the WRITE ALL REGISTERS button.
Figure 2-8. LP8864EVM Register Map Page
2.7 Instructions for Standalone Evaluation
The LP8864EVM can be used for standalone evaluation (without GUI software and PC connection). To support
standalone mode, it must be modified from its default settings as described in the following list:
1. Mount R20 to pull up EN input.
2. Change pullup and pulldown resistors to select spread spectrum enable (R18) or disable (R25) option.
3. Mount R19 to pull up PWM input for 100% brightness. If brightness needs to be changed from 100%, connect
external PWM source at PWM pin.
The minimum procedures for turning on the LEDs after the previously-listed modifications are as follows:
1. Connect a 12-V external power supply between the power input terminals VBAT+ and GNDin on the
LP8864EVM.
2. Connect the LP886X-LEDLAOD-EVM board (4 strings, 8 LEDs per string) to J10 on the LP8864EVM.
3. Turn on the external power supply.
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3 LP8864EVM Board Layout
Figure 3-1 and Figure 3-2 illustrate the EVM board layout.
Figure 3-1. LP8864EVM Layout - Top
Figure 3-2. LP8864EVM Layout - Bottom
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