Strategies to reduce a
3-Phase BLDC motor control
and drive system
12/2013 • www.ECNmag.com
By Brian Chu, Product Line Marketing Manager
Analog and Interface Products Division
Microchip Technology Inc.
Highly integrated semiconductor products are not only a trend in consumer products, but also in motor-control applications. Concurrently, the
share of Brushless DC (BLDC) motors is gradually
increasing over other motor types in a number of
markets, such as automotive and medical applications. With the demand growth and mature technology of BLDC motors, the strategies to develop
BLDC motor-control systems have evolved from
discrete circuits into three distinct categories. These
primary approaches can be classified as systems on
chip (SoCs), application-specific standard products
(ASSPs), and two-chip Solutions.
These three main categories are steadily increasing in popularity with motor-system design engineers because they reduce the number of required
components and the design complexity. However,
each strategy has its strengths and weaknesses.
This article will examine each approach and how it
balances the design tradeoffs between integration
A basic motor system contains three major blocks:
power supply, motor driver, and control unit.
Figure 1 depicts a traditional discrete motor-system
design. A motor system typically includes a simple
RISC processor with integrated Flash memory that
controls gate drivers, which then drive external
MOSFETs. Alternatively, the processor can drive
the motor directly via integrated MOSFETs and a
voltage regulator, which powers the processor and
The SoC motor driver integrates all of the blocks
that are listed above. Its programmability enables its
use in a variety of applications. Additionally, it is an
ideal candidate for space-constrained applications
where optimization is required. However, its lower
The evolution of BLDC motor-control
Figure 1. Typical discrete BLDC motor system block diagram.
Figure 2. Standalone fan motor driver block diagram.