First 5A eFuse for server designs

Technology News |
By Nick Flaherty

Alpha and Omega Semiconductor has launched its first eFuse product for sub-power rails in server applications.

The AOZ18101DI is a 5A eFuse in a compact 3mm x 3mm DFN package, combining a protection IC with a trench MOSFET with a high safe operating area (SOA). The device consists of two low RDS(ON) (20mohm) back-to-back MOSFETs to isolate the load from the input bus when the eFuse is off and operates from 3.5 to 14V.

Due to high-reliability requirements for server products, all critical power rails are monitored and protected by an eFuse device to protect the main power bus from interruption due to abnormal load under fault conditions. The eFuse continuously monitors the current flowing through the power switch. If the current is higher than the set limit, the switch will limit the current to the maximum allowed. If the high current load persists, the switch will eventually turn off, protecting downstream loads from damage, thus acting as a fuse.

The AOZ18101DI-01 and AOZ18101DI-02 integrated True Reverse Current Blocking (TRCB) for the fault conditions that the power rail at VOUT is higher than the main bus at VIN, allowing no reverse current. Control for external blocking FET is also available for designs already in production by offering a drop-in replacement to existing eFuse products requiring external FETs to implement the TRCB feature. For loads with high inductive kickback such as hard disc drive, and server fans, the AOZ18101DI-03 and AOZ18101DI-04 has this TRCB feature disabled to avoid shut down of the input power bus due to a reverse current. All devices feature startup SOA management and other protections allowing for glitch-free power-up of the system or hot plug into the 12V backplane.

“High-reliability systems such as servers and storage require input bus protection. Traditional designs use a hot-swap controller and an external discrete FET. Still, this solution is increasingly dropped in favor of a more compact solution offered by an eFuse. AOS’s ability to combine TrenchFET technology with leading IC design enables compact, robust eFuse products,” said Peter Cheng, Power IC Senior Marketing Director at AOS.

Protection features in the eFuse include Programmable Over-Current Protection, True Reverse Current Blocking (AOZ18101DI-01 and AOZ18101DI-02), Under-Voltage Lock-Out, Over-Voltage Clamp, Thermal Shutdown Protection, Programmable Soft-Start and Startup SOA Management.

Part Number Reverse Current Blocking Fault Recovery
AOZ18101DI-01 Built-In Auto-Restart
AOZ18101DI-02 Built-In Latch-Off
AOZ18101DI-03* Inactive Auto-Restart
AOZ18101DI-04 Inactive Latch-Off

*Available Q1’22

efuse pricing and availability

The AOZ18101DI series are immediately available in production quantities with a lead-time of 14 weeks. The unit price for AOZ18101DI-01, AOZ18101DI-02, AOZ18101DI-03, and AOZ18101DI-04 starts at $0.72 in 1,000-unit quantities.

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