Features and Benefits
- GaN drive technology fully optimized for GaN FETs
- Wide VIN range: 4 V to 100 V
- Wide output voltage range: 0.8 V ≤ VOUT ≤ 60 V
- No catch, clamp, or bootstrap diodes needed
- Internal smart bootstrap switches prevent overcharging of high-side driver supplies
- Internally optimized, smart near zero dead times or resistor adjustable dead times
- Split output gate drivers for adjustable turn on and turn off driver strengths
- Accurate adjustable driver voltage and UVLO
- Low operating IQ: 5 μA (48 VIN to 5 VOUT)
- Programmable frequency (100 kHz to 3 MHz)
- Phase lockable frequency (100 kHz to 3 MHz)
- Spread spectrum frequency modulation
- 28-lead (4 mm × 5 mm) side wettable QFN package
The LTC7891 is a high performance, step-down, dc-to-dc switching regulator controller that drives all N-channel synchronous gallium nitride (GaN) field effect transistor (FET) power stages from input voltages up to 100 V. The LTC7891 solves many of the challenges traditionally faced when using GaN FETs. The LTC7891 simplifies the application design while requiring no protection diodes and no other additional external components compared to a silicon metal-oxide semiconductor field effect transistor (MOSFET) solution.
The internal smart bootstrap switch prevents overcharging of the BOOST pin to SW pin high-side driver supplies during dead times, protecting the gate of the top GaN FET. The LTC7891 internally optimizes the gate driver timing on both switching edges to achieve smart near zero dead times, significantly improving efficiency and allowing for high frequency operation, even at high input voltages. Alternatively, the user can adjust the dead times with external resistors for margin or to tailor the application.
The gate drive voltage of the LTC7891 can be precisely adjusted from 4 V to 5.5 V to optimize performance, and to allow the use of different GaN FETs, or even logic level MOSFETs.
Note that throughout this data sheet, multifunction pins, such as PLLIN/SPREAD, are referred to either by the entire pin name or by a single function of the pin, for example, PLLIN, when only that function is relevant.
- Industrial power systems
- Military avionics and medical systems
- Telecommunications power systems
Product Lifecycle Recommended for New Designs
This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.
Evaluation Kits (1)
Demonstration circuit 2995A is a buck regulator featuring the LTC7891. The DC2995A operates from a 36V to 72V input voltage range and generates a 12V, 20A output. The LTC7891 has a precision voltage reference which can generate an output voltage with 2% tolerance over the full operating conditions. The 500kHz switching frequency operation results in a small and efficient circuit. The converter achieves over 96% efficiency with 20A load.
The demonstration circuit can be easily modified to regulate output voltages from 0.8V to 60V.
The DC2995A provides a high performance cost-effective solution for generating a 12V output. The LTC7891 data sheet gives a complete description of this part, its operation and application information and must be read in conjunction with the demo manual.
Documentation & Resources
DC2995A - Demo Manual (Rev. A)6/9/2022767 K
Tools & Simulations
LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.
To launch ready-to-run LTspice demonstration circuits for this part:
Step 1: Download and install LTspice on your computer.
Step 2: Click on the link in the section below to download a demonstration circuit.
Step 3: If LTspice does not automatically open after clicking the link below, you can instead run the simulation by right clicking on the link and selecting “Save Target As.” After saving the file to your computer, start LTspice and open the demonstration circuit by selecting ‘Open’ from the ‘File’ menu.
Models for the following parts are available in LTspice:
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.View our quality and reliability program and certifications for more information.
|Part Number||Material Declaration||Reliability Data||Pin/Package Drawing||CAD Symbols, Footprints & 3D Models|
|LTC7891RUFDM#PBF||Material Declaration||Reliability Data||28-Lead QFN (4mm x 5mm, Plastic Side Wettable)|
|LTC7891RUFDM#TRPBF||Material Declaration||Reliability Data||28-Lead QFN (4mm x 5mm, Plastic Side Wettable)|
|Wafer Fabrication Data|
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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.