Texas Instruments LM3492

Description

The LM3492 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 15W and an output voltage of up to 65V. The boost converter employs a proprietary Projected- On-Time control method to give a fast transientresponse with no compensation required, and a nearly constant switching frequency programmable from 200 kHz to 1 MHz. The application circuit isstable with ceramic capacitors and produces no audible noise on dimming. The programmable peak current limit and soft-start features reduce currentsurges at startup, and an integrated 190 m ohm, 3.9A N Channel MOSFET switch minimizes the solution size.

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 programmablefrom 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 comes with a versatile COMM pin which serves as a bi-directional I/O pin interfacing with an external MCU for the followingfunctions: power-good, over-temperature, IOUT over- and under-voltage indications, switching frequency tuning, and channel 1 disabling. Other supervisory functions of the LM3492 include precise enable, VCC under-voltage lock-out, current regulator over-power protection, and thermal shutdown protection. The LM3492 is available in the thermally enhanced 20-pin HTSSOP package.

Features

• Boost Converter:
• LM3492Q is an Automotive Grade Product that is AEC Q100 Grade 1 Qualified
• Very Wide Input Voltage Ranged from 4.5V- 65V
• 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 65V, total 15W (typically 28 LEDs at 150mA)
• 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

Typical applications

• marine GPS display
• Automotive display
• Ultra-high contrast ratio 6.5”-10” LCD display backlight up to 28 LEDs

More information

• Datasheet
• IC product information