Electronics Industry Welcomes the Era of New Semiconductors for Powering World

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Prominence and need of Power segment is unquestionable. Power is needed for all applications, and without channeling electricity into circuits and maintaining the supply, no digital or analog application would function.  Power electronics applications are proliferate everywhere. This is because the cost of power electronics is decreasing along with the reduction of size and improvement of performance, and energy cost is increasing almost every day. Power segment plays a very important role in solving or mitigating our global warming problem, which is a very serious concern in our society. Let us see the powerful power products showcased by Texas instruments.

Latest Power products Introduced

TI has introduced the latest GaN( Gallium Nitride)  power FETs. These GaN FETs come with the driving circuitry included in them, hence are also quite often referred as modules. There are basically 2 products, the high voltage 600V LMG3410 and the medium voltage 80V LMG5200.

 LMG3410LMG3410

  • 600V GaN Power stage
  • Single Channel
  • 12A/70mOhm
  • 8 X 8mm QFN PKG

 

 LMG5200                                     

  • 80V GaN Power stage
  • Half Bridge
  • 10A/ 18mohm
  • 6 X 8mm QFN PKG

Technology Behind

  • Gallium Nitride (GaN) is one of the best silicon alternatives in today’s world.
  • GaN transistors have switching performance advantages than Silicon Fets due to lower terminal capacitances for the same Ron and lack of body diode reverse recovery loss. Because of these features they can switch at high switching frequencies (high slew rates) improving power density, transient performance and system running cooler.
  • At higher slew rates certain packages of GaN fets can limit the switching performance. Though GaN have been in production from a number of years, TI has gone one step ahead in integrating the GaN FET and driver in the same package reducing the parasitic inductance and improving switching performance. This integration also enabled to implement protection features thus helping in the reliability of the system.

Striking Specifications

LMG5200

  • Integrated 15-mΩ GaN FETs and Driver with 80 V Continuous, 100 V pulsed, Voltage Rating.
  • Package optimized for easy PCB layout, eliminating need for under fill, creepage, and clearance requirements.
  • Very low common source inductance to ensure high slew rate switching without causing excessive ringing in hard-switched topologies
  • Ideal for isolated and non-isolated applications up to 10MHz
  • Excellent Propagation Delay (29.5 ns Typical) and Matching (2 ns Typical)

LMG3410

  • Integrated 70-mΩ, 600-V GaN and Driver
  • Single Package for Ease of Design and Layout
  • Up to 1 MHz Steady-State Operation
  • 20-ns Typical Propagation Delay
  • Operates From a Single Unregulated 12-V Supply
  • Externally-Adjustable Drive Strength for Switching Performance and EMI Control :supports 25 to 100V/ns
  • Fault Output Ensures Safety: UVLO Protection, Over-current Protection, Over-temperature Protection
  • Integrated DC-DC Converter for Negative Drive
  • Only single +12V supply needed. No need of external negative supply

Applications

LMG3410 applications

  • Server/Telecom AC-DC Supplies
    • They are well-suited for hard-switched half-bridge applications, such as the totem-pole bridgeless PFC circuit which is the front end in the Server/Telecom AC-DC supplies. It is also well-suited for second stage isolated resonant DC-DC converters in the same application, such as the LLC and phase-shifted full-bridge.
  • Rack-Mount Server DC Power Distribution
    • GaN devices are used to convert high voltage (400V) to lower voltage (48-12V) for distribution around the server. It enables higher efficiency LLC (resonant) stages and phase-shifted full bridge running at higher frequency to increase power density.
  • Solar Inverters
    • Used to boost the output voltage from the panels, and generate the AC output sine wave. The use of GaN enables higher modulation frequencies which reduces output filtering requirements, allowing greater power density.

LMG5200 applications

  • Server/telecom 48V – POL : A great application example of LMG5200 is in telecom/server POL. It can be used in a single conversion design from high input 48V  down to lower point of load voltages  such as 1V. This topology not only cuts the number of components in half but also increase power density by a factor of 4X. With GaN we no longer need to trade off efficiency for size. We can achieve both.
  • 48V motor drives : LMG5200 is also finding its application in high speed motors which require high precision and lower mechanical Vibration. Due to the lower switching losses, one can operate the GaN base motor driving stage at frequency upto 100KHz , thus reducing current and torque ripple.
  • High Density DCDC Converters : GaN enables efficient hard-switched converters at higher voltages. The single conversion reduces component count in half, and enables 4x power density.

Product status wrt Indian market

Currently the main traction we have seen is in the Telecom/Server power supply application. Due to the space constraint and high operating cost of the Server plants, GaN devices find a perfect home due to their high energy density and high-efficiency characteristics. Due to the device cost being compared to that of the MOSFETs , the GaN devices are still looked upon as expensive alien devices by the mass market thus making their use currently restricted only to advanced power supply manufacturers.

  Future Trends

 With the increased switching frequency of a GaN FET, one needs to reconsider the total system bandwidth.

  • A simple analogy to give is of a motorcycle. Even though the engine is capable of taking the motor cycle upto 300 km/hr, one needs to evaluate if the suspension, brakes, steering, infact, the rider himself !!is capable of sustaining such high speeds. Thus it’s the entire ecosystem that one needs to consider.
  • Higher-performance controllers with enough feedback bandwidth to reap the benefits from higher-frequency operation, drivers with finer resolution for dead time, duty cycle and frequency are also required to upgrade the system on the whole.
  • TI is thus also investing heavily in digital controller ( UCDxx based Digital PWM Controller) , near zero propagation drivers ,highly match half bridge drivers , Advanced Power Peripherals operating autonomous from the processor solely to drive the power FET with inbuilt feedback loops.

Contributors:

Mr. Harmeet Singh, MGTS-Analog Lead, Texas Instruments.
Mr. Shreenidhi Patil, Analog Applications Engineer, Texas Instruments

 

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