Hardware Design
This page keeps carrier-board design rules only and avoids repeating connector descriptions and pin tables.
Power Design
The X3399 core board uses 3.3V power. Pins 51 and 52 require 3.3V/4.3A, and pin 42 requires 3.3V/300mA. The main 3.3V rail on pins 51/52 must not be merged with the secondary 3.3V rail on pin 42, otherwise the power-off state may become undefined.
- Pin 42: 3.3V/300mA always-on input for the PMU.
- Pins 51 and 52: 3.3V/4.3A main input, enabled only when the board is powered on.
- Pins 53, 84, and 182: common ground.
- Pin 120: 1.8V/1.5A output for carrier-board peripherals. It becomes 0V after suspend or power-off.
USB Design
RK3399 provides USB HOST and Type-C interfaces. USB2.0 supports up to 480Mbps, while USB3.0 supports up to 5Gbps, so routing quality is critical. Differential pairs must be length-matched, routed with a complete reference plane, and designed for approximately 90Ω differential impedance.
USB Differential Pairs
| Differential Pin No. | Differential Signal |
|---|---|
| 114、115 | USB3_DM、USB3_DP |
| 116、117 | HOST0_DM、HOST0_DP |
| 118、119 | HOST1_DM、HOST1_DP |
| 109、110 | USB3_SSRXP、USB3_SSRXN |
| 107、108 | USB3_SSTXP、USB3_SSTXN |
| 105、106 | TYPEC0_DM、TYPEC0_DP |
| 103、104 | TYPEC0_TX2P、TYPEC0_TX2N |
| 101、102 | TYPEC0_RX2N、TYPEC0_RX2P |
| 99、100 | TYPEC0_TX1P、TYPEC0_TX1N |
| 97、98 | TYPEC0_RX1N、TYPEC0_RX1P |
HDMI Design
RK3399 includes an HDMI controller and supports HDMI2.0. Pins 85 to 92 carry four HDMI differential pairs. They must be length-matched and designed for approximately 100Ω differential impedance to avoid color errors, flickering, or intermittent link loss.
EDP Design
The EDP interface includes five differential pairs corresponding to pins 135 to 144. It can drive high-resolution displays such as 2K and 4K panels. Route the pairs with length matching and approximately 100Ω differential impedance.
MIPI Design
RK3399 supports DSI for display and CSI for camera. MIPI lanes have much higher data rates than LVDS, so differential length matching, impedance control, fewer vias, and a continuous reference plane are required.