RK3568 Entry-Level Edge AI Computing Board

Project Overview

NimblePCB developed the PCB for an entry-level edge AI computing evaluation kit targeting cost-sensitive AIoT deployments. Based on the Rockchip RK3568 SoC, the board provides a capable AI inference platform for smart retail analytics, industrial vision inspection, and intelligent gateway applications at a fraction of the cost of high-end edge AI platforms.

Challenge

• Cost-optimized HDI: The RK3568 BGA package required high-density fanout, but the target price point demanded conventional PCB construction rather than expensive HDI buildup processes.
• Multiple high-speed interfaces: LPDDR4X at 4266 Mbps, PCIe 3.0, USB 3.0, and dual MIPI CSI-2 camera lanes all required impedance-controlled routing on a cost-effective stackup.
• NPU power delivery: The RK3568’s neural processing unit (NPU) creates dynamic high-current transients during AI inference operations, stressing the power delivery network.
• Versatile I/O: The evaluation board needed to expose all RK3568 interfaces for customer evaluation, maximizing I/O connector count while maintaining signal integrity.

Solution

• 8-layer conventional construction: Achieved full BGA fanout using through-hole vias with optimized dog-bone escape pattern. No HDI or blind/buried vias needed, reducing cost by 40% vs HDI approach.
• LPDDR4X routing: Memory traces routed with 50-ohm single-ended and 100-ohm differential impedance on dedicated signal layers adjacent to unbroken ground planes. Length matching within 3 mil across all byte lanes.
• PDN optimization: Two dedicated power plane pairs with low-ESR decoupling strategy. NPU power rail designed with 10mV max droop under 2A transient load steps.
• Connector placement: Systematic I/O grouping by interface type with short, direct routes from SoC to connector. All high-speed connectors placed for straight-through routing without layer transitions.

PCB Specifications

Results

• LPDDR4X memory passed all compliance tests at full 4266 Mbps speed
• AI inference benchmark achieved 1.0 TOPS using on-chip NPU, matching reference design
• Board cost reduced 40% vs HDI alternative while maintaining identical functionality
• Over 500 evaluation kits shipped to customer development teams in first quarter