SLYT863 April   2025 LM5066I

 

  1.   1
  2. 1 Introduction
  3. 2 3
  4. 3 Challenges in designing a hot-swap circuit for a 48V AI server
  5. 4 Challenge No. 1: Turnoff delay during an output short-circuit
  6. 5 Challenge No. 2: False gate turn-off during a load transient
  7. 6 Challenge No. 3: Parallel resonance during controlled (slow) turn-on
  8. 7 Proposed circuit enhancements
  9. 8 Improving the turn-off response
  10. 9 Overcoming false turn-off for dynamic loads
  11. 10Damping parasitic oscillations
  12. 11Design guidelines and component selection
  13. 12Cdv/dt discharge circuit
  14. 13Conclusion
  15. 14References
  16. 15Related Websites

1 Introduction

With advancements in artificial intelligence (AI) and machine learning, enterprise servers have become extremely power-hungry as they simultaneously process a large amount of data and storage. The steady-state power rating of each server motherboard has gone up to 5kW or 6kW, in contrast to 1kW or 2 kW for general servers. The form factor remains the same, however, which imposes system design challenges given the increased power density. The load amplitude, slew rate and frequency of transient loads on AI servers have increased three to four times compared to general servers.

Figure 1 shows a typical power distribution in a 48V rack server where the input is protected by the hot-swap circuit - and then distributed to all downstream system loads.

Typical block diagram of a 48V rack server power distribution. Figure 1 Typical block diagram of a 48V rack server power distribution.