To choose an appropriate gate driver, it is important to consider the balance of robustness, size versus cost, and compatibility with other system components (for example, the microcontroller and power switches). This application note focuses on gate driver ICs for DC motor drives like brushless DC, stepper, or linear motors. Table 6-1 and Table 6-2 summarize common design considerations and compare relevant half-bridge and low-side gate drivers.
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Where there is a motor, there is a need for a driver component. Given the amount of driver options available, even from a single manufacturer, choosing the correct driver can be overwhelming. And for each one, there is a long list of parameters. Which specifications or features do you focus on to make your decision?
Driver components can come in the form of gate driver ICs (standalone gate drivers) or motor driver ICs (power switches and drivers integrated into one package). Additionally, both categories can integrate motor control. This application note focuses on design considerations for choosing half-bridge and low-side gate driver ICs to use in DC motor drive applications such as:
For more information on motor driver ICs or integrated control gate driver ICs, see Selecting the right level of integration to meet motor design requirements.
Bridge topologies for motor drive typically consist of one or more half-bridge stages: single half-bridge, two half-bridges (H-bridge), three half-bridges (BLDC), or four half-bridges (stepper). From TI’s portfolio of gate driver ICs, you can choose a single driver that integrates multiple phases or opt for standalone half-bridges. This choice often comes down to the preference of the designer, considering points like:
For driving power switches referenced to ground, low-side drivers can also be considered for motor drive applications. One of the most common motor applications for low-side drivers is a brushed DC motor. These often use a single-switch chopper topology, which only requires a single-channel low-side driver. If the system has multiple low-side switches to drive, designers can also consider dual-channel low-side drivers.
While many topics covered in this document can be applicable to multiple device categories, this application note focuses primarily on standalone half-bridge and low-side gate drivers ICs (without integrated control or power switches). To browse all of TI’s drivers for motor drives, visit the Motor Drivers overview page.
The primary specifications to consider when choosing a gate driver are:
The supply voltage (VDD) is important to consider for both half-bridge and low-side drivers. This specification is primarily tied to the power switch. In addition to general flexibility, a wide VDD range (for example, UCC27531: 10 V to 32 V) is an appropriate choice for SiC MOSFETs or IGBTs as the range provides greater margin on the gate driver output for the high gate-source voltage (VGS) of these switches. Some systems require a lower VDD operation so that the gate driver output is compatible with power switches like Si MOSFETs or GaN (for example, UCC27517: 4.5 V to 18 V).
In half-bridge driver circuits, it’s also important to consider the VDD to avoid violating key voltage specifications like VHB–VHS. So, before finalizing driver selection, check the recommended operating conditions table in the device’s data sheet to verify the selected VDD does not yield a violation in specifications.
In addition to the half-bridge driver’s specifications, the other key voltage to consider is the system’s bus voltage. This voltage, along with how much headroom makes sense for the system, informs the required VHS and VHB.
Common bus voltages for DC motor drive systems range from 12 V to 110 V (DC). Typically, systems use components rated 50–100% higher than the bus voltage. For example, for a 48-V system, a driver with 100-V or 120-V VHS voltage typically provides adequate margin against transients. Systems with well-controlled noise often do not need as much headroom. In other cases, designers prefer to utilize drivers with increased margin rather than minimizing layout noise.