ISL61851ACBZ

ISL61851ACBZ Application Field and Working Principle

The ISL61851ACBZ is a hot swap controller from Intersil’s ISL61851 family of devices. These devices are designed to allow PCB boards such as FPGAs, ASICs, Graphic Cards, etc. to be inserted into a live system (hot swapped) with no adverse effects. This device family is designed to protect user systems against both overvoltage and inrush current conditions.

Application Field

The ISL61851ACBZ hot swap controller is useful in applications such as:

• High performance Computing (HPC) systems
• Networking and Telecommunication Equipment
• Servers, Desktops and Laptops
• ‘Plug-and-Play’ computer hardware applications

Features

The ISL61851ACBZ hot swap controller has many features which make it an attractive choice for hot swap applications. These include:

• Current Limit Protection – This provides protection against inrush current conditions. It features a programmable trip point of up to 9A.
• Overvoltage Protection – This feature prevents users systems from being damaged by excessive voltages on the supply rails.
• Reverse Current Protection – This feature prevents energy from flowing back into an unused circuit board.
• Integrated Soft Start – This feature helps reduce the inrush current experienced during a power on situation and produces an effect known as output ‘inrush current ramping’.

Working Principle

The ISL61851ACBZ hot swap controller works by monitoring the input voltage and current on the board it is attached to. If either the voltage or current exceeds a pre-determined limit (programmable via internal registers), the device will initiate ‘current foldback’, reducing the effective current and therefore preventing damage to the user system being applied from the board.

The device also has an integrated soft start circuit which helps reduce the inrush current experienced during power up. This process is initiated when the power is first connected, and works by gradually increasing the current on both the input and output rails, until the nominal operating current is reached. This means that the initial current surge is significantly reduced, mitigating any power supply load imbalance or ‘inrush current’ issues.

Finally, the device is able to protect the user system from reverse current conditions, by shutting off the MOSFET switch on the device in the event that an excessive current flow is detected from the user system. This prevents any possible damage to the user system by diverting the current away from the board.

Conclusion

The Intersil ISL61851ACBZ hot swap controller provides a reliable and effective solution for protecting user systems against both overvoltage and inrush current conditions. Its ability to monitor the input voltage and current and control the output current makes it an attractive option for hot swap applications.