Ways to deliver more than 100A to ADAS processors

The electrification of automotive systems in advanced driver assistance systems (ADAS), including visual analytics for autonomous driving, parking assistance and adaptive control functions, is becoming increasingly popular. Intelligent connectivity, safety-critical software applications, and neural network processing all require enhanced real-time computing capabilities.

Meeting these advanced requirements requires multi-core processors such as the TDA4VH-Q1 that can support electronic control units (ECUs) exceeding 100A. However, high power also brings design challenges, including achieving high efficiency at higher current rails, controlling thermal performance and load transients under full load conditions, and meeting functional safety requirements.

Provide ADAS processing capabilities

The TPS62876-Q1 buck converter helps designers exceed current limits exceeding 30A with a new stacking feature that enables the high currents required to charge system-on-chip (SoC) such as the TDA4VH-Q1. The devices are available in the same package, delivering currents from 15A to 30A, and can support load currents greater than 100A through stacking capabilities.

Stacking these devices will not only power next-generation ADAS SoC cores, but also improve thermal performance and increase efficiency by reducing thermal constraints. See Figure 1.

Figure 1: Two TPS62876-Q1 devices in stacked configuration

Using the daisy chain method allows stacking functionality to work properly. The master device controls a compensation network, a POWERGOOD pin, an ENABLE pin, and an I2C interface. For optimal current sharing, all devices in the stack must be programmed to use the same current rating, switching frequency, and current level.

The master device in the stack also sets the output voltage and controls voltage regulation. If there is a 47-kΩ resistor between the SYNCOUT pin and ground, the device will operate as an auxiliary device. If the SYNCOUT pin is in a high-impedance state, the device operates as a master. Figure 2 shows the stacked configuration deployed on the printed circuit board.

Additional features of this family of buck converters include:

Voltage drop compensation, also called load line (automatic voltage positioning). Adjusting the nominal output voltage provides better load transient tolerance based on output current (15A to 30A) and reduces output capacitance, enabling a cost-optimized, high power density solution. The REGISTER pin enables or disables voltage drop compensation, which is disabled by default.

The remote detection feature supports a variety of SoC processors with stricter output voltage requirements that require more headroom during load transients. The device's remote sense line connects directly to the point of load, allowing voltage to be set with 8% accuracy.

The I2C interface monitors system performance and issues warnings when temperature and output current exceed specified limits. Alternatively, dynamic voltage scaling can be used to adjust the output voltage between 4V and 1.675V. If I2C functionality is not required, the same device can still be used by connecting the SCL and SDA pins to ground.

Functional safety

Functional safety is very important in ADAS, especially for autonomous driving. The TPS62876-Q1 buck converter is available with multiple TI functional safety level documents, including:

Estimated functional safety time-based failure rates for semiconductor components based on industry reliability standards.

Component failure modes and their distribution based on the primary function of the device.

Pin failure mode analysis.

Meet automotive safety integrity level standards by adding external monitors to your design.

Conclusion

To achieve higher autonomous driving levels such as Society of Automotive Engineers Level 2, higher computing power is required to provide higher resolution and rapid response in a very short time. Embedded features such as artificial intelligence technology are also driving increased demand for higher-power ADAS SoC processors. The stackable features of the TPS62876-Q1 family enable core power supplies greater than 100A, enabling higher levels of autonomous driving.