3 System Design Considerations

Leveraging the floating ground hot-swap architecture discussed in the previous section, a complete hot-swap solution is built by using several TI components listed below.

• TPS23521: A low-side, high-performance, hot-swap controller as the core element to enable hot-plug, inrush current management, undervoltage, overvoltage, overcurrent, and short-circuit protections.
• UCC28704: Flyback controller to generate the bias power supply for all the building blocks.
• OPA210: An operational amplifier used in a differential configuration to scale down from the 800V input power supply voltage and interface with the UVEN and OV pins of the TPS23521 device.
• INA238: For precise current, voltage, and power monitoring through an I2C to enable digital telemetry over the ISO1644 (I2C isolator) device for intelligent rack management.
• ISOM8110: Opto-emulator that provides an isolation barrier between the control circuit and the output discharge circuit.

As shown in the block diagram (see Figure 3-1), the floating ground hot-swap architecture allows a truly scalable solution, whether of the power level or supply rail voltage ±400V / 800V. Thus, making the architecture compatible for installations with either two wires or three wires (including chassis ground).

Figure 3-1 Block Diagram of the Floating Ground Hot-Swap Solution on High-Side and Low-Side Power Paths