LM3492MH/NOPB

Product Folder Sample & Buy Support & Community Tools & Software Technical Documents Reference Design LM3492, LM3492-Q1 SNVS656D – SEPTEMBER 2010 – REVISED OCTOBER 2016 LM3492/-Q1 Two-Channel Individual Dimmable LED Driver With Boost Converter and Fast Current Regulator 1 1 Features • • • Boost Converter: – LM3492-Q1 is an Automotive Grade Product That is AEC Q100 Grade 1 Qualified – Very Wide Input Voltage Ranged From 4.5 V to 65 V – Programmable Soft Start – No Loop Compensation Required – Stable With Ceramic and Other Low ESR Capacitors With No Audible Noise – Nearly Constant Switching Frequency Programmable From 200 kHz to 1 MHz Current Regulators: – Programmable LED Current from 50 mA to 200 mA – 1000:1 Contrast Ratio at a Dimming Frequency of More Than 3 kHz, Minimum LED Current Pulse Width is 300 ns – Two Individual Dimmable LED Strings up to 65 V, Total 15 W (Typically 28 LEDs at 150 mA) – Dynamic Headroom Control Maximizes Efficiency – Over-Power Protection – ±3% Current Accuracy Supervisory Functions: – Precision Enable – COMM I/O Pin for Diagnostic and Commands – Thermal Shutdown Protection – Thermally Enhanced 20-Pin HTSSOP package 2 Applications • • Ultra-High Contrast Ratio 6.5”-10” LCD Display Backlight up to 28 LEDs Automotive or Marine GPS Displays 3 Description The LM3492/-Q1 integrates a boost converter and a two-channel current regulator to implement a high efficient and cost effective LED driver for driving two individually dimmable LED strings with a maximum power of 15 W and an output voltage of up to 65 V. The boost converter employs a proprietary ProjectedOn-Time control method to give a fast transient response with no compensation required, and a nearly constant switching frequency programmable from 200 kHz to 1 MHz. The application circuit is stable with ceramic capacitors and produces no audible noise on dimming. The programmable peak current limit and soft-start features reduce current surges at start-up, and an integrated 190 mΩ, 3.9-A N-Channel MOSFET switch minimizes the solution size. Device Information(1) PART NUMBER LM3492 LM3492-Q1 PACKAGE HTSSOP (20) BODY SIZE (NOM) 7.80 mm × 4.40 mm (1) For all available packages, see the orderable addendum at the end of the data sheet. Typical Application Copyright © 2016, Texas Instruments Incorporated 1 An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications, intellectual property matters and other important disclaimers. PRODUCTION DATA. LM3492, LM3492-Q1 SNVS656D – SEPTEMBER 2010 – REVISED OCTOBER 2016 www.ti.com Table of Contents 1 2 3 4 5 6 7 8 Features .................................................................. Applications ........................................................... Description ............................................................. Revision History..................................................... Description (continued)......................................... Pin Configuration and Functions ......................... Specifications......................................................... 1 1 1 2 3 4 5 7.1 7.2 7.3 7.4 7.5 7.6 5 5 5 5 6 8 Absolute Maximum Ratings ...................................... ESD Ratings.............................................................. Recommended Operating Conditions....................... Thermal Information .................................................. Electrical Characteristics........................................... Typical Characteristics .............................................. Detailed Description ............................................ 11 8.1 8.2 8.3 8.4 Overview ................................................................. Functional Block Diagram ....................................... Feature Description................................................. Device Functional Modes........................................ 11 12 12 18 8.5 Programming........................................................... 18 9 Application and Implementation ........................ 20 9.1 Application Information............................................ 20 9.2 Typical Application ................................................. 20 10 Power Supply Recommendations ..................... 23 11 Layout................................................................... 23 11.1 Layout Guidelines ................................................. 23 11.2 Layout Example .................................................... 23 12 Device and Documentation Support ................. 24 12.1 12.2 12.3 12.4 12.5 12.6 12.7 Documentation Support ........................................ Related Links ........................................................ Receiving Notification of Documentation Updates Community Resources.......................................... Trademarks ........................................................... Electrostatic Discharge Caution ............................ Glossary ................................................................ 24 24 24 24 24 24 24 13 Mechanical, Packaging, and Orderable Information ........................................................... 25 4 Revision History NOTE: Page numbers for previous revisions may differ from page numbers in the current version. Changes from Revision C (May 2013) to Revision D Page • Added Added ESD Ratings table, Thermal Information table, Feature Description section, Device Functional Modes, Application and Implementation section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and Mechanical, Packaging, and Orderable Information section....................................... 1 • Changed RθJA value from 32.7 to 36.5 in the Thermal Information table ............................................................................... 5 Changes from Revision B (May 2013) to Revision C • 2 Page Changed layout of National Data Sheet to TI format ........................................................................................................... 20 Submit Documentation Feedback Copyright © 2010–2016, Texas Instruments Incorporated Product Folder Links: LM3492 LM3492-Q1 LM3492, LM3492-Q1 www.ti.com SNVS656D – SEPTEMBER 2010 – REVISED OCTOBER 2016 5 Description (continued) The fast slew rate current regulator allows high frequency and narrow pulse width dimming signals to achieve a very high contrast ratio of 1000:1 at a dimming frequency of more than 3 kHz. The LED current is programmable from 50 mA to 200 mA by a single resistor. To maximize the efficiency, Dynamic Headroom Control (DHC) automatically adjusts the output voltage to a minimum. DHC also facilitates a single BOM for different number of LED in a string, which is required for backlight panels of different size, thereby reducing overall development time and cost. The LM3492/-Q1 comes with a versatile COMM pin which serves as a bidirectional I/O pin interfacing with an external MCU for the following functions: power-good, overtemperature, IOUT overvoltage and undervoltage indications, switching frequency tuning, and channel 1 disabling. Other supervisory functions of the LM3492/-Q1 include precise enable, VCC undervoltage lockout, current regulator over-power protection, and thermal shutdown protection. The LM3492/-Q1 is available in the thermally enhanced 20-pin HTSSOP package. Copyright © 2010–2016, Texas Instruments Incorporated Product Folder Links: LM3492 LM3492-Q1 Submit Documentation Feedback 3 LM3492, LM3492-Q1 SNVS656D – SEPTEMBER 2010 – REVISED OCTOBER 2016 www.ti.com 6 Pin Configuration and Functions PWP PowerPAD™ Package 20-Pin HTSSOP Top View Pin Functions PIN NO. NAME I/O DESCRIPTION APPLICATION INFORMATION 1 EN I Enable Internally pullup. Connect to a voltage higher than 1.63 V to provide precision enable for the device. 2 VIN I Input Supply Voltage Supply pin to the device. Input range is 4.5 V to 65 V. SW I Switch Node Internally connected to the drain of the integrated MOSFET. 5 VOUT I Output Voltage Sense Sense the output voltage for nearly constant switching frequency control. 6 RT I Frequency Control An external resistor from the VOUT pin to this pin sets the switching frequency. 7 FB I Output Voltage Feedback The output voltage is connected to this pin through a feedback resistor divider for output voltage regulation. The voltage of this pin is from 1.05 V to 2.5 V. 8 GND G Analog Ground Signal ground 3 4 9 IOUT2 I Current Regulator Input Input of the current regulator of channel 2. The regulated current is programmable of Channel 2 (refer to the IREF pin). 10 IOUT1 I Current Regulator Input Input of the current regulator of channel 1. The regulated current is programmable of Channel 1 (refer to the IREF pin). 11 CDHC I Dynamic Headroom Control An external capacitor connected to this pin sets the DHC sensitivity. At start-up, a 120-µA internal current source charges an external capacitor to provide a soft-start function. 12 IREF I Current Setting of the Current Regulator An external resistor connected from this pin to ground programs the regulated current of the current regulator of channels 1 and 2. 13 COMM I/O Bidirectional Logic Communication This pin is open drain for various indications (power-good, overtemperature, IOUT overvoltage and undervoltage) and command sending (switching frequency tuning and channel 1 disabling). 14 LGND G Ground of the Current Regulator Current regulator ground. Must be connected to the GND pin for normal operation. The LGND and GND pins are not internally connected. 15 DIM1/CLK I/O Dimming Control of Channel 1 Control the ON/OFF of the current regulator of channel 1. This pin is internally pulled low by a 5-µA current. This pin also serves as a clock signal for latching input/output data of the COMM pin. 16 DIM2 I Dimming Control of Channel 2 Control the ON/OFF of the current regulator of channel 2. This pin is internally pulled low by a 5-µA current. PGND G Power Ground Integrated MOSFET ground. Must be connected to the GND pin for normal operation. The PGND and GND pins are not internally connected. 19 VCC O LDO Regulator Output Nominally regulated to 5.5 V. Connect a capacitor of larger than 0.47 µF between the VCC and GND pins. 20 ILIM I Peak Current Limit Adjust Connect an external resistor from the ILIM pin to the VCC pin reduces peak current limit. Connect the ILIM pin to the ground to obtain the maximum current limit. DAP DAP — Exposed Pad Thermal connection pad. Connect to a ground plane. 17 18 4 Submit Documentation Feedback Copyright © 2010–2016, Texas Instruments Incorporated Product Folder Links: LM3492 LM3492-Q1 LM3492, LM3492-Q1 www.ti.com SNVS656D – SEPTEMBER 2010 – REVISED OCTOBER 2016 7 Specifications 7.1 Absolute Maximum Ratings over operating free-air temperature range (unless otherwise noted) (1) Input voltage MIN MAX VIN, RT, VOUT to GND −0.3 67 SW to GND −0.3 UNIT 67 V −2 (