“Simple, low-cost, and versatile brushed DC motors are ideal for automotive loads that require an integrated, high-power reliable motor driver, such as window lifters, sunroof controls, door locks, latches, and engine valves.
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Simple, low-cost, and versatile brushed DC motors are ideal for automotive loads that require an integrated, high-power reliable motor driver, such as window lifters, sunroof controls, door locks, latches, and engine valves.
If you’re designing an automotive system, you may face both device-level and system-level challenges, including size constraints, failure conditions, and the need for reusability to reduce development time. Therefore, this paper will analyze these challenges in detail and provide corresponding solutions.
Reduce system size with fully integrated high power density motor driver
Reducing system size and saving board space are important considerations when designing cost-optimized automotive systems. Reducing package size and integrating functionality into brushed DC drivers reduces external component count, saving board space and reducing cost.
When designing small systems, the following improvements should be considered:
• Small package size – For high power density solutions, use a small package size with high current capability. The DRV8243-Q1 series introduces an automotive HotRod quad flat no-lead package with a minimum size of 3mm x 4.5mm, which is one of the ultra-small packages in its class for brushed DC drives.
• Integrated Current Sense – Internal current regulation and current feedback pins eliminate the need for external current sense resistors, saving board space and reducing cost.
• Integrated Field Effect Transistor (FET) solution – The DRV8243-Q1 family can drive up to 32A peak H-bridge current and 46A peak half-bridge current. Save board space and reduce cost with an integrated solution that supports medium to high currents, eliminating the need for gate drivers and external FETs. Current capability depends on printed circuit board design and ambient thermal conditions, so be sure to check out our transient thermal calculator to see how much current your system can drive.
Using a smaller package (as shown in Figure 1) and minimizing the number of external components can reduce board size and bill of materials costs.
Figure 1: DRV8245-Q1 Device Family Size Comparison
Protection and diagnostic functions for a reliable solution
Motor drives play an important role in applications ranging from electric trunk doors to gas engine valves. Therefore, it is necessary to design reliable solutions that can detect and prevent various failure conditions.
The DRV8243-Q1 device family is the first to provide open-load detection and short-circuit protection when the motor driver is both on and off. Figure 2 shows how the device offline protection feature uses a passive resistor network connected to the H-bridge to detect system problems before enabling the FET. This feature helps avoid damage or erratic behavior of the motor driver even when the H-bridge is off.
Figure 2: Off-State Diagnostics of the DRV8243-Q1
Offline diagnostics help protect motor drives from failures elsewhere in the system and avoid overall wear. For more information on how TI’s offline protection feature protects automotive systems, see the application note “Open Load Detection in Motor Drives”
The Serial Peripheral Interface option provides detailed diagnostics designed to identify the type and location of the fault, saving designers time troubleshooting by providing the root cause of motor driver faults.
Optimized design with scalable drives
Motor drivers drive various loads in the car, such as relays, solenoid valves, and motors. Sometimes these loads are all pooled in the same application, such as door modules or body control modules.
The DRV8243-Q1 family of H-bridge and half-bridge drivers enables design reuse to extend different loads in automotive systems. This family of devices has similar firmware, features and package pinouts, enabling reuse over a wide range of loads and currents, helping to reduce design time. When used in standalone mode, the H-bridge driver can drive two unidirectional brushed DC motors, solenoids, or relays without the need for two separate half-bridge drivers; as shown in Figure 3.
Figure 3: Scaling Across Multiple Loads Using DRV8243-Q1 Series Models
In addition to having similar firmware, the DRV8243-Q1 and DRV8244-Q1 leaded packages are pin-to-pin compatible, making it easier to insert and replace these devices when scaling up or down power levels.
Solution size, protection performance and design reuse are key factors to consider when designing an automotive solution. If you have any questions related to the content in this article, you are welcome to ask them in the TI E2E Motor Driver Forum.
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