Texas Instruments LP8861-Q1 User Manual Download Page 9 | Manualshive

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Texas Instruments LP8861-Q1 User Manual Download Page 9

Start-Up of the EVM and Power Sequences

Figure 5. Typical Start-up Sequence

6.2

Shutdown Sequence

The backlight is shut down (LEDs turned off) by setting PWM input low or when VDDIO/EN = 0. If
VDDIO/EN is set low, the LP8861-Q1 will enter low power mode with internal LDO disabled.

9

SNVU456 – July 2015

LP8861-Q1EVM Evaluation Module

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Copyright © 2015, Texas Instruments Incorporated

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Summary of Contents for LP8861-Q1

Page 1: ...Using the LP8861 Q1EVM Evaluation Module User s Guide Literature Number SNVU456 July 2015 ...

Page 2: ... Shutdown Sequence 9 7 Boost Converter 10 7 1 Switching Frequency 10 7 2 Spread Spectrum and Synchronization 10 7 3 Voltage Control 11 8 LED Current Sinks 12 8 1 Output Configuration 12 8 2 Current Setting 12 8 3 Brightness Control 12 9 External Temperature Sensor Functionality 13 9 1 Overview 13 9 2 Calculator 13 10 Fault Detection 13 10 1 Fault Indicator 13 11 Evaluation Board Schematic 14 12 Bi...

Page 3: ...ISET 12 9 Temperature Compensation Calculator 13 10 Evaluation Board Schematic 14 11 LED Load Board Top Side 17 12 LED Load Board Bottom View 17 13 LED Load Board Schematic Diagram 18 14 Forward Voltage for Cree Xlamp ML B LEDs 19 Excel is a registered trademark of Microsoft Corporation All other trademarks are the property of their respective owners 3 SNVU456 July 2015 List of Figures Submit Docu...

Page 4: ... to correct this interference 1 4 If You Need Assistance Contact your local TI sales representative 2 Introduction The Texas Instruments LP8861 Q1EVM evaluation module EVM helps designers to evaluate the operation and performance of the LP8861 Q1 device The LP8861 Q1EVM uses the LP8861 Q1 to drive up to 4 LED strings for LCD backlighting with high efficiency Information about output voltage and cu...

Page 5: ...ng and extend LED life time The input voltage range for LP8861 Q1 is from 4 5 V to 40 V to support car stop start and load dump condition The LP8861 Q1 device supports PWM brightness dimming ratio up to 10 000 1 for input PWM frequency of 200 Hz The device integrates extensive safety and protection features 3 1 Features Four High Precision Current Sinks Current Matching 1 typ Output Current up to ...

Page 6: ...OINTS CONTROL POINTS Hardware Setup www ti com 4 Hardware Setup Figure 1 shows connectors and main components on the LP8861 Q1 board Figure 1 Evaluation Board Connectors and Setup 6 LP8861 Q1EVM Evaluation Module SNVU456 July 2015 Submit Documentation Feedback Copyright 2015 Texas Instruments Incorporated ...

Page 7: ...out Figure 2 Top Layer Figure 3 Bottom Layer GND See the LP8861 Q1 datasheet SNVSA50 for PCB layout guidelines 7 SNVU456 July 2015 LP8861 Q1EVM Evaluation Module Submit Documentation Feedback Copyright 2015 Texas Instruments Incorporated ...

Page 8: ...O logic Device starts when VIN voltage is present and above the VIN UVLO voltage level 4 V and the VDDIO EN voltage is set above threshold voltage 1 2 V By default boost switching frequency is 400 kHz jumper J4 connecting R3 160 kΩ to FSET and boost maximum voltage is 37 V R12 750 kΩ and R13 130 kΩ See Section 7 1 and Section 7 3 for description on how to change boost settings By default LED curre...

Page 9: ...ce The backlight is shut down LEDs turned off by setting PWM input low or when VDDIO EN 0 If VDDIO EN is set low the LP8861 Q1 will enter low power mode with internal LDO disabled 9 SNVU456 July 2015 LP8861 Q1EVM Evaluation Module Submit Documentation Feedback Copyright 2015 Texas Instruments Incorporated ...

Page 10: ... frequency remove jumper J4 short pins 7 and 8 on jumper J17 and connect the external resistor to connector J18 Boost internal parameters will be adjusted automatically according to chosen frequency during start up 7 2 Spread Spectrum and Synchronization The SYNC pin is used to enable boost spread spectrum or alternatively to synchronize boost switching with an external frequency To disable spread...

Page 11: ... 2 V R12 R13 values are in kΩ 2 Figure 7 Converter Maximum Output Voltage vs R12 Maximum voltage should be chosen based on the maximum voltage required for LED strings Recommended maximum voltage is about 30 higher than maximum LED string voltage Initial boost voltage is about 88 of maximum voltage Boost output voltage is adjusted automatically based on LED current sink headroom voltage Default se...

Page 12: ...o the ISET pin Maximum current can be calculated as follows where VBG 1 2 V RISET current setting resistor R4 kΩ ILED output current per output mA 3 Figure 8 Output Current vs RISET 8 3 Brightness Control The LP8861 Q1 controls the brightness of the display with conventional PWM Output PWM will directly follow the input PWM Input PWM frequency can be in the range of 100 Hz to 20 kHz An external di...

Page 13: ... to choose components for the temperature compensation with an external NTC Contact your local TI sales representative Figure 9 Temperature Compensation Calculator 10 Fault Detection 10 1 Fault Indicator The LP8861 Q1 has fault detection for LED open and short VIN input overvoltage VIN undervoltage lockout power line overcurrent boost overcurrent and thermal shutdown Open drain FAULT pin indicates...

Page 14: ...d Schematic www ti com 11 Evaluation Board Schematic Figure 10 Evaluation Board Schematic 14 LP8861 Q1EVM Evaluation Module SNVU456 July 2015 Submit Documentation Feedback Copyright 2015 Texas Instruments Incorporated ...

Page 15: ...mil above insulator J29 J2 J3 J6 J10 Header TH 100mil 3x1 Gold plated 230 Samtec TSW 103 07 G S 4 mil above insulator J9 J19 J20 J21 J22 CONN HEADER 1POS 100 SNGL TIN Samtec TSW 101 17 T S 9 J23 J24 J27 J30 TH J15 J17 Header TH 100mil 8x2 Gold plated 230 Samtec TSW 108 07 G D 2 mil above insulator J16 Header TH 100mil 10x2 Gold plated Samtec TSW 110 07 G D 1 230 mil above insulator J18 Header TH 1...

Page 16: ... Dale CRCW060310K0FKEA 1 R20 RES 100k ohm 1 0 1W 0603 Vishay Dale CRCW0603100KFKEA 1 R19 RES 165 k 1 0 1 W 0603 Yageo America RC0603FR 07165KL 1 R21 RES 10 0k ohm 1 0 1W 0603 Yageo America RC0603FR 0710KL 1 R22 RES 0 ohm 5 0 125W 0805 Vishay Dale CRCW08050000Z0EA 1 RT1 Thermistor NTC 10 0k ohm 1 0603 MuRata NCP18XH103F03RB 1 U1 Low EMI High Performance 4 Channel Texas Instruments LP8861PWPQ1 1 1 L...

Page 17: ... LEDs with maximum current 175 mA and maximum forward voltage 3 5 mA at 80 mA 3 3 V typical are used on the board For theLP8861 Q1 4 strings are assembled NOTE The LED board is not included with the EVM contact your local TI sales representative if board is needed Figure 11 LED Load Board Top Side Figure 12 LED Load Board Bottom View 17 SNVU456 July 2015 LP8861 Q1EVM Evaluation Module Submit Docum...

Page 18: ... J58 1 2 3 J59 1 2 3 J60 1 2 3 J61 1 2 3 J62 1 2 3 J63 GND 1 2 3 4 J64 D80 D79 D78 D77 D76 D75 D74 D73 1 2 3 J77 1 2 3 J78 1 2 3 J79 1 2 3 J80 1 2 3 J81 1 2 3 J82 1 2 3 J83 1 2 3 J84 GND 1 2 3 4 J85 D100 D99 D98 D97 D96 D95 D94 D93 1 2 3 J98 1 2 3 J99 1 2 3 J100 1 2 3 J101 1 2 3 J102 1 2 3 J103 1 2 3 J104 1 2 3 J105 GND 1 2 3 4 J106 D120 D119 D118 D117 D116 D115 D114 D113 1 2 3 J119 1 2 3 J120 1 2...

Page 19: ...eader 100mi 2x2 Samtec TSW 102 07 G D 7 J85 J106 J127 J2 J21 J23 J42 J44 J63 Header 100mi 3x1 Samtec TSW 103 07 G S 121 J65 J84 J86 J105 J107 J126 J129 J130 Header 100mi 7x1 Samtec TSW 107 07 G S 1 D1 D120 Cool White SMD LED XLamp mL B Cree MLBAWT A1 0000 000W51 120 Figure 14 Forward Voltage for Cree Xlamp ML B LEDs 19 SNVU456 July 2015 LP8861 Q1EVM Evaluation Module Submit Documentation Feedback ...

Page 20: ...ring the warranty period to the address designated by TI and that are determined by TI not to conform to such warranty If TI elects to repair or replace such EVM TI shall have a reasonable time to repair such EVM or provide replacements Repaired EVMs shall be warranted for the remainder of the original warranty period Replaced EVMs shall be warranted for a new full ninety 90 day warranty period 3 ...

Page 21: ... by Industry Canada to operate with the antenna types listed in the user guide with the maximum permissible gain and required antenna impedance for each antenna type indicated Antenna types not included in this list having a gain greater than the maximum gain indicated for that type are strictly prohibited for use with this device Concernant les EVMs avec antennes détachables Conformément à la rég...

Page 22: ... connecting any load to the EVM output If there is uncertainty as to the load specification please contact a TI field representative During normal operation even with the inputs and outputs kept within the specified allowable ranges some circuit components may have elevated case temperatures These components include but are not limited to linear regulators switching transistors pass transistors cu...

Page 23: ...F REMOVAL OR REINSTALLATION ANCILLARY COSTS TO THE PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES RETESTING OUTSIDE COMPUTER TIME LABOR COSTS LOSS OF GOODWILL LOSS OF PROFITS LOSS OF SAVINGS LOSS OF USE LOSS OF DATA OR BUSINESS INTERRUPTION NO CLAIM SUIT OR ACTION SHALL BE BROUGHT AGAINST TI MORE THAN ONE YEAR AFTER THE RELATED CAUSE OF ACTION HAS OCCURRED 8 2 Specific Limitations IN NO EVENT SHALL T...

Page 24: ...esponsible for compliance with all legal regulatory and safety related requirements concerning its products and any use of TI components in its applications notwithstanding any applications related information or support that may be provided by TI Buyer represents and agrees that it has all the necessary expertise to create and implement safeguards which anticipate dangerous consequences of failur...

Page 25: ...Mouser Electronics Authorized Distributor Click to View Pricing Inventory Delivery Lifecycle Information Texas Instruments LP8861Q1EVM ...

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