Features and Benefits
- Control Pin Provides Accurate Control of Regulated Output Current
- ±1.5% Voltage Regulation Accuracy
- ±6% Current Regulation Accuracy
- 6V to 36V Input Voltage Range
- Wide Output Voltage Range Up to (VIN – 2V)
- Average Current Mode Control
- <1μA Shutdown Current
- Up to 94% Efficiency
- Additional Pin for Thermal Control of Load Current
- Thermally Enhanced 4mm × 4mm QFN and 20-Pin FE Package
The LT3741 and LT3741-1 are fixed frequency synchronous step-down DC/DC controllers designed to accurately regulate the output current at up to 20A. The average current-mode controller will maintain inductor current regulation over a wide output voltage range of 0V to (VIN – 2V). The regulated current is set by an analog voltage on the CTRL pins and an external sense resistor. Due to its unique topology, the LT3741 is capable of sourcing and sinking current. If sinking current is not required, or for parallel applications, use the LT3741-1. The regulated voltage and overvoltage protection are set with a voltage divider from the output to the FB pin. Soft-Start is provided to allow a gradual increase in the regulated current during startup. The switching frequency is programmable from 200kHz to 1MHz through an external resistor on the RT pin or through the use of the SYNC pin and an external clock signal.
Additional Features include an accurate external reference voltage for use with the CTRL pins, an accurate UVLO/EN pin that allows for programmable UVLO hysteresis, and thermal shutdown.
- General Purpose Industrial
- Super-Cap Charging
- Applications Needing Extreme Short-Circuit Protection and/or Accurate Output Current Limit
- Constant Current or Constant Voltage Source
Product Lifecycle Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Evaluation Kits (1)
Demonstration circuit 1602 is a High Power Constant Current, Constant Voltage Synchronous Buck Controller featuring the LT3741. The demo board is optimized for 20A output from a 12V input. Being an LED driver, the output current is being regulated until the output voltage reaches a programmed voltage limit. The voltage limit on this demo board is set to around 6V by R11 and R14. The 6V is chosen because of the 10V voltage rating of the output capacitors. Higher output voltage can be easily achieved with higher voltage rated output capacitors.
The ideal load to be used with this demo board is a single LED, such as PT120 from Luminus Devices. Smaller LEDs may not be able to handle the high current, even for a short period of time. At 20A, the demo circuit can operate continuously. However, it is necessary to mount the LED load on a proper heat sink and possibly with a fan to avoid exceed its maximum temperate rating.
Documentation & Resources
R548 Reliability Data3/26/201828 K
DC1602A - Demo Board4/8/2016254K
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Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.