LTC7891
Info : RECOMMENDED FOR NEW DESIGNS
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LTC7891

100 V, Low IQ, Synchronous Step-Down Controller for GaN FETs

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Info : RECOMMENDED FOR NEW DESIGNS tooltip
Info : RECOMMENDED FOR NEW DESIGNS tooltip
Part Details
Part Models 2
1ku List Price Starting From $2.09
Features
  • 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
Additional Details
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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.

APPLICATIONS

  • Industrial power systems
  • Military avionics and medical systems
  • Telecommunications power systems
Part Models 2
1ku List Price Starting From $2.09

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Documentation

Documentation

Video

Part Model Pin/Package Drawing Documentation CAD Symbols, Footprints, and 3D Models
LTC7891RUFDM#PBF
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LTC7891RUFDM#TRPBF
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Software & Part Ecosystem

Software & Part Ecosystem

Evaluation Kit

Evaluation Kits 2

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EVAL-LTC7891-AZ

High Frequency Step-Down Supply with EPC GaN FETs

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EVAL-LTC7891-AZ

High Frequency Step-Down Supply with EPC GaN FETs

High Frequency Step-Down Supply with EPC GaN FETs

Product Detail

Evaluation circuit EVAL-LTC7891-AZ features the LTC®7891: a 100V Step-Down Synchronous GaN FET controller. The LTC7891 is specifically designed to drive up to 100V GaN FETs safely and easily through internally optimized bootstrap switches and smart dead time control. Split gate drivers allow for easily adjustable turn-on and turn-off of FETs. Additionally, the IC features low IQ, up to 3MHz programmable/synchronizable switching frequency, spread spectrum, and a small 28-lead (4mm x 5mm) side wettable QFN package. These features allow for a wide variety of applications including industrial, military, medical, and telecommunications systems.

The EVAL-LTC7891-AZ operates from a 15V 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 EVAL-LTC7891-AZ is set to 500kHz switching frequency, which results in a small and efficient circuit. The converter achieves over 96% efficiency with 20A load at full operating VIN, with a peak efficiency of over 99%.

This board can be easily modified to regulate output voltages from 0.8V to 60V. The evaluation circuit has been specially designed with 100V EPC GaN FET form factor. Various FETs of similar footprint can be replaced to fit a wide array of applications.

The EVAL-LTC7891-AZ 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. The data sheet must be read in conjunction with this user guide for EVAL-LTC7891-AZ. Design files for this circuit board are available at www.analog.com.

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DC2995A

LTC7891 High Frequency Step-Down Supply with GaN FETs

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DC2995A

LTC7891 High Frequency Step-Down Supply with GaN FETs

LTC7891 High Frequency Step-Down Supply with GaN FETs

Product Detail

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.

Tools & Simulations

Tools & Simulations 1

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.

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