Achieve Power-Dense andEfficient Digital Power Systems
by Combining TI GaN FETs andC2000™ Real-Time MCUs
Cody J. Watkins

Applications engineer, C2000 real-time MCUs
Texas Instruments

Designers in the power electronics industry
need new technologies and methods to increasesystem performance. C2000 real-time MCUs
and GaN FETs join forces to meet efficiency andpower-density challenges.
Server and telecom power supplies are examples

At a glanceof markets that can benefit from the use of GaN.
The digital communications infrastructure market

This white paper explains how the features of TI

continues to grow, with some estimates projecting

gallium nitride (GaN) field-effect transistors

the rack server market to double in the next five

(FETs) with an integrated driver and TI C2000™

years and hyperscale data centers to grow at areal-time microcontrollers (MCUs) work incompound annual growth rate of nearly 20%.

harmony to solve issues that power electronics
designers face when developing modern power-

Along with rapid growth come ever-increasing

conversion systems.

efficiency, power density and transient response1

requirements. GaN FETs drastically improve

GaN is revolutionizing the powerelectronics market

switching losses and high power density,
advantages that can help solve the technicalWhile you may consider GaN an

challenges as volumes scale up in these growing

emerging technology, TI’s GaN
technology addresses industry

markets.

challenges and is ready for wide-scaleThis white paper explores how the features of

deployment.

2

TI GaN FETs with an integrated driver and TI

Choosing the right digital
controller for GaN

C2000 real-time MCUs are uniquely positioned to

The potential benefits of GaN are massive,

face when developing modern power-conversion

but can only be fully realized whensystems.

address the issues that power electronics designers

choosing the right digital controller.

3

Reducing system costs throughhigh switching frequencies
GaN enables a reduction in power

GaN is revolutionizing the powerelectronics market

magnetics, fans and heat sinks because of

While GaN technology has shown a lot of potential

its high switching frequency, while C2000

benefits, you may have some legitimate concerns

real-time MCUs address the intrinsic control

about its practicality. Although there’s a common

challenges brought on by doing so.

4

perception that GaN FETs are a new technology,

Interfacing C2000 real-time
MCUs with GaN devices

they have actually been around for over 20 years.
Cost, protection and reliability have all been

C2000 real-time MCUs enable control

prohibiting factors for the adoption of GaN, andof and all feedback from TI GaN FETs

TI’s family of GaN devices addresses each of these

without the need of external glue logic.

concerns.
Achieve Power-Dense and Efficient Digital Power Systems by Combining TI
GaN FETs and C2000™ Real-Time MCUs

2

January 2021

Cost
TI GaN FETs use a GaN-on-silicon process that

Choosing the right digital controller
for GaNleverages existing TI process technology nodes.

The higher switching frequencies enabled by GaN

Not only can we avoid expensive substrates likeallow power supplies to be more efficient and reachsilicon carbide or sapphire, but we can also harness

higher power densities. These typically require more

our years of expertise in working with siliconcomplex power topologies and control algorithms

technologies. TI performs development, testing andlike zero voltage switching, zero current switching or

packaging completely in house making GaN cost-inductor-inductor-capacitor (LLC)-resonant DC/DC

competitive today and even cheaper tomorrow.

with hybrid hysteresis control.
The adaptability of a digital controller only benefits

Protection

these complex topologies. You need one thatis capable of processing complex time-critical

TI’s GaN technology provides rich diagnostics andcalculations, offers precise control and is scalable

self-protection features. GaN FETs automaticallythrough software and peripheral compatibility.

detect and handle overcurrent, short-circuit,

C2000 real-time MCUs directly address theseundervoltage and overtemperature conditions.

considerations. Figure 1 illustrates a C2000 real-

Simultaneous reporting of these conditions to thetime MCU and a GaN FET driver.

MCU enables modifications to the control algorithm
to prevent reoccurrence.

Reliability
TI has logged over 40 million device reliability hours
for its GaN devices and a failure-in-time rate of <1
for 10-year lifetimes. In addition to intrinsic reliability
tests, we subject our GaN devices to the harshest

Figure 1. C2000 MCUs and TI GaN devices work together toachieve the most efficient, reliable and power-dense digital powersystems.

switching environments and have converted over
5-GW hours of in-application stress testing.
TI GaN devices address cost, protection andreliability concerns by combining the FET driver andC2000 real-time MCU efficiency of
instructions

GaN FET into one package. With a fast-switching,
2.2-MHz integrated gate driver, TI GaN FETs enable

C2000 real-time MCUs have an advanced

twice the power density compared to silicon while

instruction set, which drastically reduces theachieving 99% efficiency. This technology provides

number of cycles required for complex maththe lowest losses for the highest efficiency in AC/DC

calculations. This reduction in calculation time

applications. Furthermore, integrated, high-speedmeans that it is possible to increase the control-loop

protection and digital temperature reporting enablefrequency without increasing the device’s operating

active power management and thermal monitoring

frequency. Many of these efficiency gains arefor power supply units (PSUs). With all of theseseamless to the user and occur automatically. The

unique benefits, TI technology makes the adoption

code compiler, the central processing unit (CPU)of GaN real.

Achieve Power-Dense and Efficient Digital Power Systems by Combining TI
GaN FETs and C2000™ Real-Time MCUs

pipeline and the instruction set are all designed in
3

January 2021

a way to get the maximum amount of computing

today’s standards require 2.5 A/µs or higher.

power per instruction cycle.

Increasing the frequency of your control loop directly

More visible to users are the floating-point unit (FPU)

helps by changing how fast you can sense andreact to varying conditions. The unique processing

and trigonometric math unit (TMU). Integrating theseabilities of C2000 real-time MCUs can help addressenhanced instructions closely into the C28x coreallows the instructions to be pipelined and executed

these transient response requirements.

in parallel like normal CPU instructions, further

To meet the most extreme transient response

increasing the efficiency of every clock cycle.

requirements of 5 A/µs or higher, C2000 real-time

For example, the FPU yields a >2.5 times

MCUs leverage their integrated analog, which PWM
signals entirely through hardware, without the use

improvement in speed over standard fixed-pointof external components. This control is achieved by

calculations. At the same time, the FPU alsousing the integrated analog comparator to compare

enables the C28x core to leverage model-based

the feedback signals with a fixed setpoint or ramp

simulation and code-generation tools, which use

generator, implemented through the internal 12-bit

floating-point math. This means that you will spend

digital-to-analog converter (DAC). This techniqueless time developing code and validating youradds the unique speed benefits of an entirely

system, and get your product to market faster.

hardware-based control loop while maintaining the

The TMU complements the FPU and yields a

flexibility of a digital controller. During execution,

similarly impressive 20 times improvement overthe PWM trip points are continually monitored andthe FPU alone. In the Bidirectional High-Density

adjusted by tweaking the DAC’s output inside of

GaN CCM Totem Pole PFC Using C2000 real-

the software control loop entirely independently

time MCU reference design, the benefits become

from the tripping of the PWM. Ultimately, thisclear when trying to calculate control of pulse-widthmeans that C2000 real-time MCUs can offer themodulators (PWM) on time and the dead time,

fastest response time to varying load conditions

reducing these calculations from ~10 µs to lesswhile maintaining the flexibility to meet efficiency

than 0.5 µs. This makes it possible to perform an

standards.

adaptive dead-band calculation on a cycle-by-cycle
basis, allowing for the most precise and efficient

Enable precise and safe system control

control of the GaN FET.

Shoot-through and the potential of third-quadrant
conduction in GaN FETs require high-precision

Meeting transient response
requirements

control. The high-resolution PWM in a C2000 realtime MCU enables 150-ps resolution for the PWM’s

Why are small cycle-by-cycle efficiencies important?

period, duty cycle, phase and dead band. While theWell, one reason is that these efficiencies enable

trip-zone submodule — along with built-in analog

you to meet faster transient response requirements.

comparators — safely handles error conditions,

Transient response requirements describe howthese operate entirely asynchronously and provide

quickly a power supply can react to changing loads.

the ability to shut down the PWM’s output in just 25

For example, due to the higher power requirements

ns without CPU intervention.

of modern processors used in servers, meetingtransient response requirements has become moredifficult. Historically, 1 A/µs was common; however,Achieve Power-Dense and Efficient Digital Power Systems by Combining TI
GaN FETs and C2000™ Real-Time MCUs

4

January 2021

Multiphase systems done the easy way

F280025C extends the C2000 portfolio of realtime MCUs, shown in Figure 2 on the following

Expanding the scope beyond single-phase designs,

page, to a cost point that fits in small server power

C2000 real-time MCUs also address issues withdesigns, while still offering unique processing andmultiphase designs, where all phases must remain

control features. As system requirements change,

in sync in order to prevent system failure. You must

the C2000 platform enables the scaling of real-consider modifying the frequency, duty cycle ortime MCU features (analog-to-digital converter

dead band of the PWM. Sequential updates to(ADC) inputs, computation power, PWM channels,

these values are common today, but sequential

packages) up or down while maintaining software

updates require intricate knowledge of the hardware

investments to achieve a faster time to market.

as well as all possible permutations of the code
– something that’s especially difficult in interruptbased embedded systems.
The C2000 real-time MCU’s global-load mechanism

Reducing system costs through highswitching frequencies

addresses PWM updates by allowing the updating

Now that the individual benefits of TI GaN andof all required PWM registers in one instruction

C2000 have been discussed, let’s address thecycle, entirely without CPU intervention. Thissystem-level benefits. FET switching losses haveinnovation enables control of high-frequency

traditionally limited the maximum speed at whichinterleaved LLC topologies while simultaneously

you can efficiently switch a converter to a few

eliminating bugs, which commonly appear as

hundreds of kilohertz. The switching frequency thenintermittent nonrepeatable errors introduced

places minimum size requirements on magnetics,

by sequential updates. Use of the global-load

which negatively impact power density and systemmechanism not only results in a more robust andcost requirements.

safer system, but also reduces system validation

As mentioned, the integrated driver in TI GaNefforts.

devices enables switching frequencies of up to 2.2
MHz, with switching speeds greater than

Scalability of the C2000 real-time MCU
portfolio

150 V/ns, resulting in twice the speed and half
the losses compared to discrete GaN FETs.

A low-cost C2000 real-time MCU such as theThis integration, combined with low-inductance

Figure 2. The C2000 real-time MCU portfolio that supports TI GaN devices.
Achieve Power-Dense and Efficient Digital Power Systems by Combining TI
GaN FETs and C2000™ Real-Time MCUs

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January 2021

packaging, delivers clean switching and minimal

Reducing the input inductor in a totem-pole PFC

ringing. These efficiencies enable a reduction in thecan cause an increased current spike at the zero-

size of the magnetics used in power systems andcrossing point, negatively impacting total harmonic

ultimately reduce system costs by eliminating thedistortion. The increased current spike occurs

need for fans or heat sinks while increasing power

when the input waveform switches between its

density.

positive and negative half, causing inrush current
as the synchronous and active FETs are reversed.
The inrush current is largely due to a buildup of

Overcoming the challenges inherent tohigher switching frequencies

voltage across the inductor as well as any output
capacitance of the FETs and diodes. C2000

TI GaN devices can drive system switchingreal-time MCUs address these issues through afrequencies higher, enabling the magnetics tosophisticated shadow loading scheme that enables

be reduce to one-fifth their previous size overall

the MCU to implement a soft-starting algorithm withenabling a three times higher power density

minimal CPU overhead.

over similar silicon power-factor correction (PFC)

Finally, the speed and parallelism of integrated

application. The benefits are not just realized in PFC

analog is fundamental to increasing the control-

stages, but in all power electronic systems.

loop frequency in a digital microcontroller. Without

So what’s the catch? Well, as with all good things,

this, it is not possible to realize the full benefits of TI

increasing switching frequencies adds drawbacks

GaN devices with integrated driver. The F28002x

and design challenges. For example, in a totem-poleseries has up to 16 individual analog channels

PFC, reducing the size of the inductor can cause

which connect to 2 independent Analog to Digital

additional control challenges, such as increasing

Converters, each offering great performance withdead-band-induced third-quadrant losses.The

an integral nonliearity (INL) of 2 Least Significant

unique feature set in C2000 real-time MCUs

Bits (LSB), Differential non linearity (DNL) of 1 LSB,

addresses this with the following features:

and an Effective Number of Bits (ENOB) of 11 bits

• C2000 real-time MCUs offer a 150-ps high-at a rate of up to 3.45 Mega Samples Per Second

resolution dead band, enabling finer edge

(MSPS). The implementation of multiple ADCs

placement and reducing unnecessary third-

specifications enable the sampling of multiple

quadrant losses. Learn more about third-

sources of feedback simultaneously because of thequadrant operation of TI GaN in the application

flexible start of conversion triggers, which are closelyreport, “Does GaN Have a Body Diode? –coupled with the PWM unit and allow adjustments

Understanding the Third Quadrant Operation

for the best real-time control strategy. For example,of GaN.”

you could measure the AC grid’s line and neutral
voltages simultaneously to enable the control loop

• The TMU enables adaptive dead-band control

to run faster and provide more system accuracy.

schemes, as discussed previously, further

As GaN drives the ability to reach higher efficiency

reducing losses by enabling faster calculations.

standards and power density requirements new

See these features in action in a 3.3kW

challenges have been presented. C2000 real-time

Bidirectional interleaved CCM Totem Pole PFC

microcontrollers are uniquely designed to address

reference design with 98.75% peak efficiency andthe intrinsic control problems introduced whenless than 2% THD.

reducing magnetics and increasing your systemfrequency.

Achieve Power-Dense and Efficient Digital Power Systems by Combining TI
GaN FETs and C2000™ Real-Time MCUs

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January 2021

Interfacing C2000 real-time MCUs
with TI GaN devices

peripheral set to sample the feedback signals fromTI GaN devices, including the recently launched
LMG3425R030, without the need of additional

The interface between C2000 real-time MCUs anddiscrete components. Feedback comes in from two

the GaN device includes a digital isolator, such as

major sources:

the ISO7741-Q1 shown in Figure 3 below. This
isolation device helps suppress transient noise• Fault reporting. The LMG3425R030 encodesand protects the C2000 real-time MCU. The

its fault information. Decoding this information

microcontroller, isolation and GaN devices are allin software can be hazardous given the delays

that are necessary for the interface.

associated with processing the faults in software.
For a quicker response, you can combine the

TI digital isolators featuring high isolation ratings

fault signals externally to the device, but this

up to 5.7 kVrms and supporting speeds up to 150

requires the use of discrete components. The

Mbps are a good fit as an isolation barrier between

C2000 real-time MCU uses its configurable

the C2000 real-time MCU and the GaN FET.

logic block (CLB) to read, process and respond

They provide the speed and low latency required

to the fault conditions generated by the GaN

to establish precise control and feedback paths

device without the use of software and with nobetween the devices

external components, optimizing performance andreducing system costs.

Control• Temperature monitoring. The temperature

Control of the GaN FET is achieved by using themonitoring output from the LMG3425R030

high-resolution PWM module, which provides 150-

device comes out as a fixed-frequency variable

ps resolution control on the PWM’s period, duty

duty-cycle signal. Common implementations

cycle, phase and dead band. The PWM output has

require the use of an external filter to implement

an integrated trip-zone submodule that can responda PWM-based DAC that would need to be

to feedback, without CPU intervention, in 25 ns.

sampled by an ADC. The C2000 real-time MCU’senhanced capture module completely eliminates
these external components while capturing the

Feedback

temperature information with no CPU overhead,

C2000 real-time microcontrollers integrate a uniqueFigure 3. The only components needed to interface a C2000 MCU with a TI GaN device.
Achieve Power-Dense and Efficient Digital Power Systems by Combining TI
GaN FETs and C2000™ Real-Time MCUs

7

January 2021

thus further optimizing costs and saving board
space.

– High Efficiency GaN CCM Totem Pole
Bridgeless PFC Reference Design– Vienna Rectifier-Based Three Phase Power

Conclusion
In modern digital power systems, efficiency andpower-density standards present a big set ofchallenges. TI GaN devices deliver reliable andFactor Correction Reference Design Using
C2000 real-time MCU• Papers– A New Approach to Validate GaN FETaffordable technology while enabling increased

Reliability to Power-line Surges Under Use-power density and higher efficiency. The

conditions

ISO7741-Q1 provides a cost-effective interface
while C2000 real-time MCUs address difficulties
associated with today’s complex control schemes.
These devices work in harmony to provide a– How to reduce current spikes at AC zerocrossing for totem-pole PFC• Training

flexible yet simple solution for modern digital power– C2000 Digital Power Training Seriessystems, while still providing cutting-edge features– CLB Training Series

that enable the safest, most power-dense andefficient digital power systems.
Developers can now jump into a new era of power
efficiency and power density. To make this journeyeasier, TI combines 25 years of experience inreal-time digital power control, power electronics,
hardware and software in fully tested anddocumented reference designs.

• Evaluation kits
– TMS320F28002x controlCARD evaluation
module: https://www.ti.com/tool/
TMDSCNCD280025C– LMG3422R030 600-V 30-mΩ half-bridge
daughter card: https://www.ti.com/tool/
LMG3422EVM-043– ISO7741-Q1 evaluation module: https://www.

Additional resources• Reference designs– Bidirectional High-Density GaN CCM Totem
Pole PFC Using C2000 real-time MCU

ti.com/tool/ISO7741EVM• Software tools– C2000Ware MATLAB® VisSim Embedded
Coderreference design– Highly Efficient, 1.6-kW High-Density
GaN-Based 1-MHz CrM Totem-Pole PFC
Converter Reference Design

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