How to Deliver More Than 100A of Current to ADAS Processors

The electrification of automotive systems in advanced driver assistance systems (ADAS), including autonomous driving vision analysis, parking assistance and adaptive control functions, is becoming increasingly prevalent. Intelligent connectivity, safety-critical software applications and neural network processing all require increased real-time computing power.

Meeting these advanced requirements requires multi-core processors, such as the TDA4VH-Q1, that can support electronic control units (ECUs) exceeding 100 A. 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.

Providing ADAS processing capabilities

The TPS62876-Q1 step-down converter helps designers break through current limits of more than 30A through a new stacking feature that enables the high currents required to charge system-on-chips (SoCs) such as the TDA4VH-Q1. The devices in this family offer currents from 15A to 30A in the same package and can support load currents greater than 100A through the stacking feature.

Stacking these devices not only enables powering the next generation ADAS SoC core, but also improves thermal performance and increases efficiency by reducing thermal constraints. See Figure 1.

Figure 1: Two TPS62876-Q1 devices in a stacked configuration

The stacking function is made possible by using a daisy-chain approach. 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 can also set the output voltage and control regulation. If there is a 47-kΩ resistor between the SYNCOUT pin and ground, the device operates as a slave device. If the SYNCOUT pin is in a high-impedance state, the device operates as a master device. Figure 2 shows the stack configuration deployed on a printed circuit board.

Figure 2: Evaluation module example of three TPS62876-Q1 buck converters stacked

Additional features of this family of step-down converters include:

• Drop compensation, also known as 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, resulting in a cost-optimized, high power density solution. The REGISTER pin enables or disables the drop compensation and is disabled by default.

• Remote sense capability supports a wide range of SoC processors with tighter output voltage requirements that require more margin during load transients. The device's remote sense lines connect directly to the point of load, allowing the voltage to be set with 0.8% accuracy.

• The I2C interface monitors system performance and issues warnings when temperature and output current exceed specified limits. Dynamic voltage scaling can also be used to adjust the output voltage between 0.4V and 1.675V. If the I2C functionality is not required, the same device can still be used by grounding the SCL and SDA pins.

Functional Safety

Functional safety is very important in ADAS, especially for autonomous driving. The TPS62876-Q1 step-down converter provides multiple TI functional safety grade documents, including:

• Functional safety time-based failure rates of semiconductor components estimated according to industry reliability standards.

• Component failure modes and their distribution based on the device's primary functions.

• Pin failure mode analysis.

Meet Automotive Safety Integrity Level standards by adding an external monitor to your design.

Conclusion

To achieve higher levels of autonomous driving, such as SAE Level 2, higher computing power is required to provide higher resolution and fast response in a very short time. Embedded features such as artificial intelligence technology are also driving the demand for higher power ADAS SoC processors. The stackable function of the TPS62876-Q1 series can help achieve a core power supply greater than 100A, thereby achieving higher levels of autonomous driving.