ON Semiconductor has more than 25 years of proven leadership in the field of motor drives, and has sold more than 2 billion motor drives since 2010. It is the global leader in BLDC cooling fans and global white goods motor drive solutions. The broadest product lineup of DC and brushless DC (BLDC) motor drivers, with more than 400 products on sale, and continuous improvements to achieve zero defects and meet evolving ISO standards.

ON Semiconductor utilizes technical expertise and is committed to making motor drive solutions provide smaller size, higher energy efficiency and higher system reliability, such as smaller footprints through integrated solutions, single power supply operation, built-in system protection, and small packages. , Achieve higher energy efficiency through low on-resistance / saturation voltage, synchronous rectification, soft pulse width modulation (PWM) switching, low power consumption, etc., and built-in system protection such as over temperature, under voltage, over voltage, over current, breakdown, etc. And wide operating voltage range for higher system reliability.

Basics of motors and their drives

Motors are divided into two categories: AC motors and DC motors. Among them, the DC motor market has huge potential and the global target market capacity (SAM) is more than 1 billion US dollars. There are mainly stepper, brushed and brushless categories. A stepper motor is easy to control the position without feedback. The control signal can be a simple PWM pulse train and easy to interface to the MCU, but has low energy efficiency and relatively high noise, vibration, and electromagnetic interference (EMI) problems. Digital communication overcomes these shortcomings; brushed DC motors are easy to drive, drive speed can be controlled by PWM, low cost, high energy efficiency, but easy to wear and short life, will cause problems such as brush sparks and serious EMI, difficult to drive at high speed BLDC has more advantages. Because it has no brushes, the rotor structure is very simple and strong, so it has low noise, no wear, long service life, high reliability, and can run at high speed. However, it requires complicated driving circuits, and the cost is relatively high. Higher.

According to the degree of integration, there are three types of motor driver solutions: system-on-chip (SoC) solutions, integrated control solutions (ICS), and gate driver solutions. The SoC solution integrates DC-DC, gate drivers, controllers, inverters, and feedback / protection on a single chip. It has a high degree of integration and is suitable for space-constrained applications. It is simple and easy to use. The ICS solution is relative to the SoC solution. There is no integrated inverter, so it can support a wide range of power through external MOSFETs, suitable for higher power applications, and more flexible; the gate driver solution only integrates DC-DC, gate driver and feedback / protection, because The controller and power devices are external, so they have the highest flexibility.

Standard BLDC scheme

ON Semiconductor's BLDC motor driver solutions have been widely used in computers, servers, power tools, printers, refrigerators, microwave ovens, and automobiles. As shown in Figure 1, according to the different output current and voltage ranges, we have labeled different BLDC motor driver solutions for more suitable applications.

Figure 1: Broadcom's BLDC Motor Driver Solution Lineup
Higher energy efficiency and lower noise: single-hall 180-degree series BLDC motor driver

Energy efficiency standards are constantly improving, and consumers also expect products to work more smoothly and with lower noise. To help designers solve these challenges, ON Semiconductor has introduced three 180 ° sine wave-driven 3-phase BLDC motors: LV8811, LV8813, and LV8814 (shown in Figure 2), which are suitable for cooling fans of home appliances such as refrigerators and game consoles And computing devices, these three devices can be controlled by a single Hall sensor, reducing system cost, low on-resistance as low as 0.5 Ω, easy to adjust the lead angle, providing PWM soft switching and synchronous rectification, so that higher energy efficiency can be achieved. In terms of system reliability, these three devices combine protection functions such as overcurrent, overvoltage, undervoltage, and overtemperature. They also include locked rotor protection and automatic recovery mechanisms. They are highly integrated, simplify the design of motor control circuits, and reduce noise and vibration. The soft-start and shutdown functions ensure continuous operating stability. In addition, the three devices are highly flexible, allowing speed control via a DC voltage or PWM input, and a minimum PWM duty cycle can be set, eliminating the need for software and thus eliminating software development time.

 

1. LV8811, LV8813 and LV8814 can meet different needs of design applications

The LV8811, LV8813, and LV8814 have the same maximum supply voltage, maximum output current, and maximum output current at the REG and HB pins. The VCC operating voltage ranges are 3.6 V to 16 V, 6 V to 16 V, and 3.6 V to 16 V, with low-voltage shutdown thresholds of 2.5 V, 3.8 V, and 2.5 V, respectively. Designers can choose the right model according to different application needs. The biggest difference between these three devices is the duty cycle: the startup of the LV8811 is relatively complicated, and its pulse width changes relatively smoothly. The duty cycle ranges from 6% to 5%, to 20%, and finally to 15%, which can reduce the startup time. LV8813 and LV8814 start-up PWM duty cycle is set from 50% to 25%, which helps provide greater torque at start-up. LV8811 and LV8813 are packaged in TSSOP20 with integrated heat sink, and LV8814 is packaged in SSOP20 without integrated heat sink.
2. Single-Hall Solution Startup Process

First, the motor finds a fixed position by adjusting the operating mode to reduce start-up failures due to dependence on the starting position. If the Hall IC detects a change in the adjustment process, it will extend the adjustment operation, and then execute a 180-degree drive immediately after the adjustment process is completed. As shown in Figure 3, the polarity (N or S) of the rotor is first detected by the Hall IC, and then the target position is entered according to the detection result. Then the torque is raised, and the rotation is started. The sine wave drive is finally started by detecting the switching time.

 

Figure 3: Generating a set of A to C and D to F positions from information in a single Hall IC
3. Advantages of single Hall compared to other driving methods

Compared with 3-Hall 3-Phase Driver, Single-Hall 3-Phase Driver, and Sensorless 3-Phase Driver, the 3-Hall driver has the highest reliability and fast speed, but it needs to use 3 Halls, occupying a large area of the board and bias current Higher cost; sensorless driver does not require Hall element, small board area, compact structure, no bias current, but driven by non-sinusoidal drive, reliability and speed are lower than Hall driver; single Hall driver It is a compromise between 3 Hall and sensorless solutions.

Table 1 compares the operating voltage range, maximum output current Io, drive method, sensor, speed control signal, external components, and adjustment components of ON Semiconductor's single-hall drive solution LV8813 and sensorless BLDC drive solution LV8804. It can be seen that the LV8813 is more flexible in speed control and requires fewer and simpler adjustment element pins.

LV8813 uses a soft-start startup method. After the start-up adjustment time is 1 s, it starts to run at a duty cycle of 25%, and then shifts to the working mode of the target duty cycle. The rate of change of this process is 26% / s. Because the LV8813 uses 180 ° drive mode, the sinusoidal waveform is smoother and more complete while the LV8804FV uses 150 ° drive mode, the waveform will have some glitches and irregularities.

In addition, we performed energy efficiency tests on the LV8813 and LV8804. As shown in Figure 4, when the speed is lower than 1,100 rpm, the LV8804 and LV8813 show similar energy efficiency (motor A), but when the speed is increased above 1,100 rpm, the LV8813 is more energy efficient than the LV8804 (motor B).

Figure 4: LV8804 vs. LV8813 energy efficiency test
Stepping scheme

ON Semiconductor also provides stepper motor driver solutions. The series below 15 V are widely used in toys, surveillance cameras, refrigerators, microwave ovens, gas stoves, washing machines, stage lights, etc. The 24 V series are mainly concentrated in industrial applications such as printer , Vending machines, radios, sewing machines, industrial robots, etc. Figure 5 shows the lineup of ON Semiconductor's 12 V and 3-15 V H-bridge / stepper motor drivers.

Figure 5: ON Semiconductor's H-Bridge / Stepper Motor Driver Lineup
Automotive BLDC Solution

In addition to traditional BLDC and stepping applications, ON Semiconductor also focuses on automotive BLDC applications, such as various pumps, automatic air conditioning (HVAC) fans, seat fans, radiator fans, LED headlight fans, etc., which can be targeted at different The power level provides the corresponding BLDC scheme. Such as sensorless 150-degree 3-phase BLDC pre-driver LV8907 suitable for oil pump, water pump, radiator fan, HVAC and other applications, with built-in gate driver, LIN transceiver and low-dropout regulator (LDO), reducing the board area to Minimal, with external power MOSFET can achieve different power level output. The device has passed AEC-Q100 certification, with a junction temperature of up to 175 ⁰C, without software. It integrates cycle-by-cycle current limit, over-current protection, over-voltage / under-voltage protection, over-temperature protection, stall protection and other rich protection features. Very sexual. In addition, the LV8907 can flexibly implement individual working modes via OTP settings and real-time control via SPI.

Figure 6: LV8907 block diagram
to sum up

ON Semiconductor has strong motor drive technology and mature motor drive market experience. Its broad product line covers application areas such as BLDC, stepper motors and automobiles, and it continues to innovate to meet the needs of the market and designers. Its latest single Hall 180 degree BLDC drive series LV881X, through 180 ° sinusoidal drive to improve the energy efficiency of the motor system and reduce noise, and save software development, saving development time and workload, ideal for drive applications such as refrigerator cooling fans and game consoles and computing equipment Program.