Linear Technology Corporation introduces the LT3754, a 16-channel LED driver that uses a step-up DC/DC controller capable of driving up to 45V of 50mA LEDs (per channel). Its internal 60V, 1MHz DC/DC boost mode controller is designed to act as a constant current LED driver for driving up to 160 white LEDs. The LT3754 can drive up to 16 channels from a 12V input, with up to 10 50mA white LEDs in series per channel, while delivering over 92% efficiency. Its multi-channel capability makes the device ideal for medium to large size TFT-LCD backlighting applications. Its 6V to 40V input voltage range makes the device ideal for automotive, avionics, high definition television (HDTV) and industrial display applications.
The LT3754 provides ±2.8% (typically ±0.7%) LED current matching to ensure consistent display brightness. Up to 3,000:1 dimming ratio can be achieved by using True Color PWM dimming. Programmable 100kHz to 1MHz fixed frequency operation and current mode architecture provides stable operation over a wide range of supply and output voltages while minimizing the size of external components. In addition, the switching frequency can be synchronized to an external clock. Its thermally enhanced 5mm x 5mm QFN-32 package provides a very compact footprint for LED backlighting applications.
The LT3754 uses an external N-channel MOSFET switch to provide a boost mode constant current source. However, even when VIN exceeds VOUT, the LT3754 will continue to accurately regulate the LED current. The internal boost controller uses an adaptive feedback loop to regulate the output voltage slightly above the required LED voltage to ensure maximum efficiency. If any of the LED strings are open, it will continue to adjust the existing LED string and signal the OPENLED alarm pin. If a larger current LED is required, multiple LED strings can be combined, allowing the LT3754 to drive up to 8 LED strings, each consisting of 10 100mA LEDs, or driving 4 channels, with 10 channels per channel. 200mA LED. Other features include programmable undervoltage protection, LED current derating based on junction temperature and/or LED temperature, and output voltage limiting when all LED strings are disconnected.
The LT3754EUH is available in a 32-lead 5mm x 5mm QFN package and is priced at $4.25 each in 1,000-piece quantities. The industrial grade version of the LT3754IUH is tested and guaranteed to operate over the -40°C to 125°C operating junction temperature range and is priced at $5.00 each in 1,000-piece quantities. All versions are available from stock.
Performance Summary: LT3754
???; 50mA LED, 16-channel LED driver up to 45V
???; Wide input range: 6V to 40V
???; with ±2.8% LED current matching at 20mA (typically ±0.7%)
???; True Color PWM dimming range up to 3,000:1
???; Single resistor sets LED current (10mA to 50mA)
???; provides LED current regulation even under PVIN VOUT conditions
???; output adapts to LED VF for optimum efficiency
???; open LED tag fault marking and protection
??? Protect LED pins from VOUT short circuit damage
???; parallel channel to achieve greater LED current
???; programmable LED current derating and temperature relationship
???; accurate undervoltage lockout threshold with programmable hysteresis
???; programmable frequency (100kHz to 1MHz)
???; can be synchronized to an external clock
???; heat-resistant enhanced 32-pin (5mm × 5mm) QFN package
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