Gate-Driver IC for Automotive Three-Phase Brushless Motor: TB9084FTG

A gate-driver IC with the minimum functions required for automotive applications, with an emphasis on versatility. For all body-related systems, pumps, and motor generators that use three-phase brushless motors.

• Contributes to system design flexibility
• Contributes to ECU^[1] size reduction by adopting a small package

The number of motors used within automotive equipment continues to increase, and the growth of three-phase brushless motors, which are relatively superior in terms of long life and quietness, is remarkable. Toshiba Electronic Devices & Storage Corporation ("Toshiba") is working to strengthen its product lineup to meet this demand, and the TB9084FTG shown here is part of that strengthening (Table 1).

Table 1. Our lineup of automotive gate-driver IC for three-phase brushless motor

The TB9084FTG drives external Nch-MOSFETs that drive a three-phase brushless motor. Since a voltage is output to this gate, it is called a gate driver IC. It also has one more output pin channel to control an external Nch-MOSFET. It can be used for protection against battery reverse connection, as well as for power shutdown relay, etc. Regarding SPI communication, in addition to the function of reading abnormality detection flags, it has functions for setting thresholds between normal and abnormal states, as well as configuring reaction operations after detecting abnormal states, allowing it to accommodate various use cases. In addition, it has one channel of operational amplifiers to monitor the current flowing in the motor. This operational amplifier is equipped with a function to calibrate the input offset voltage, which is ±1mV under standard conditions^[3] after this function is executed.

The TB9084FTG is designed to be mounted in an ECU that consists of a microcontroller, Nch-MOSFET, power supply IC, and communication PHY^[4] as individual components (right side of Figure 2). Although this configuration has disadvantages in terms of total component size and cost, it is flexible enough to accommodate changes in system requirements, since only the relevant components need to be replaced when changes occur. On the other hand, there is a configuration in which motor control is performed by hard logic (left side of Figure 2). This configuration offers advantages in terms of total size and cost, however, it is limited in its ability to respond to changes in the environment surrounding motors. Another configuration is one in which motor control is performed by a microcontroller while its peripheral components are integrated into a single product (center of Figure 2). This configuration has the best balance of advantages/disadvantages. However, the microcontroller, which is often seen as a universal component, has a finite processing capacity, and when changes in system requirements exceed that capacity, changes tend to be large because functions other than the microcontroller are also renewed.

As mentioned above, the disadvantage of ECUs composed of individual components is the total size of the components. To minimize this, we were able to select the world's smallest class package^[5] for the TB9084FTG by reducing the chip size and the number of pins. The size is 36mm² with 36 pins of QFN.

The power supply (VB, VCC) is intended for use in 12V battery systems and jump-start environments. The guaranteed chip temperature range is -40°C to 175°C, which corresponds to Grade 0 in the AEC-Q100^[6]. As for the electrical characteristics of the gate driver, its output voltage is sufficient to drive an external Nch-MOSFET even with a low VB supply. Its current capability enables PWM^[7] control at 20 kHz for a MOSFET with a gate input charge (Qg) of around 55 nC and an ID^[8] equivalent to 50 A. The main specifications are shown below.

Please refer to the following page for our MOSFET that meets these characteristics.
Recommended MOSFET (TPH1R104PB)

The gate driver for high-side MOSFETs switches the output circuit configuration according to the VB voltage status. When the VB voltage is sufficient, a clamped voltage is output because of the sufficient charge pump voltage (Spec#9.4.5). When the VB voltage is not sufficient, the charge pump voltage is also low, so the charge pump voltage is output as it is (Spec#9.4.6).

To enable customers to easily verify the characteristics of the TB9084FTG, we provide evaluation boards free of charge. Of course, engineering samples can be submitted. Please contact our sales staff or our business partners at your service.