Teardown of a Tesla-specific Expansion Dock

NOTE：Click here for the Chinese version.

Tesla Model 3/Y originally comes with a limited number of USB-C ports, making it difficult to meet the charging and data transfer needs of multiple devices simultaneously. To address this usage scenario, Baseus has developed the T-Space Car Expansion Dock through compact structural design and highly integrated power management technology. This device expands the vehicle's original port resources into 3 USB-C and 1 USB-A port, effectively enhancing the vehicle's connectivity and power usage flexibility. It includes two retractable USB Type-C cables, one supporting 60W fast charging and the other supporting 30W fast charging; additionally, there is one fixed Type-C port supporting 30W output and one Type-A port with a maximum output of 30W fast charging.

Teardown

The exterior design doesn't offer much to analyze. The expansion dock is powered via a 12V cigarette lighter socket. Since this product is specifically designed for Tesla Model 3/Y, the maximum output power of the cigarette lighter should be over 150W, which is more than sufficient for powering general electronic devices. The author does not have a Tesla for actual product testing and experience, so users who have tried it are welcome to share their experiences. This article will proceed directly with the teardown to examine the internal structure and hardware solution.

After disassembly, a highly modular design is revealed. First, the structure of the two retractable Type-C cables, although having different output powers, share the same layout, both utilizing a sliding ring power supply design. The sliding ring PCB has five concentric rings, corresponding to the power positive/negative poles, USB data lines, and CC signal line, transmitting power through contact between brushes and the fixed sliding rings. However, a question arises: could this structure lead to poor contact after prolonged use?

The other end of the signal lines from the sliding ring PCB is directly connected to the Type-C female ports on the main PCB. The silkscreen on the PCB indicates output powers of 30W and 60W respectively. This side of the main board hosts some passive resistors/capacitors and includes the soldering pads for the 12V power input from the cigarette lighter plug. The key components are located on the other side of the main PCB, where almost all electronic components are placed.

In the center of the PCB is iSmartWare Technology's multi-fast-charge-protocol dual-port charging chip SW3517, which enables fast charging functionality for either single port of the Type-C and Type-A dual ports independently, supporting independent current limiting management for each port. The chip integrates a 5A high-efficiency synchronous buck converter. With few external components, it can form a high-performance, multi-protocol compatible dual-port fast charging system, notable for high integration and cost-effectiveness. For example, in this product, it works in conjunction with the adjacent APM dual N-channel MOSFET (AP10H03DF) to implement the charging solution.

Another section of the board handles the output circuits for the two retractable Type-C ports. One of them even employs a 60W Gallium Nitride (GaN) charging solution. Specifically regarding chip selection, it uses iSmartWare Technology's highly integrated fast charge protocol controller SW2333H, iSmartWare Technology's I2C-controlled synchronous 4-switch buck-boost controller SW3203, along with two sets of MOSFETs for synchronous buck-boost conversion - two Ruichips Semiconductor N-channel MOSFETs (RUH4040M) and two Innoscience 40V enhancement-mode GaN power transistors (INN040FQ043A). These are coupled with VBUS switch tubes to achieve power output control and circuit protection. This constitutes a high-power multi-port fast charging solution. The remaining components naturally include three magnetic ring inductors, their corresponding filtering capacitors, and one set of fixed Type-C and Type-A ports.

Summary

The above details the charging expansion dock solution launched by Baseus for Tesla Model 3/Y. Judging by the chip selection, it extensively uses domestic Chinese chips. Its multi-chip collaborative operation scheme achieves efficient dynamic power distribution, provides multi-port fast charging expansion, and holds significant advantages in cost control, demonstrating the technological maturity of Chinese semiconductor companies in the fields of power management and charging. However, some design aspects are worth pondering. For instance, the sliding rings and brushes, being mechanical contact components, despite potentially offering a better user experience in daily use, their long-term durability needs practical verification. Frequent extension and retraction might lead to increased contact resistance or poor contact, affecting power transmission efficiency.