LTC4251-1IS6 Negative Voltage Hot Swap Controller

The LTC4251-1IS6 from Linear Technology is a compact, feature-rich negative voltage hot swap controller designed to allow safe board insertion and removal from a live backplane. This specialized integrated circuit (IC) is housed in a space-saving 6-lead SOT-23 package, making it an ideal choice for systems where board space is at a premium.

Primarily used in negative supply environments, the LTC4251-1IS6 is engineered to control the gate voltage of an external N-channel MOSFET to gently power up capacitors, helping to avoid sparks, system glitches, and other potential issues associated with hot-swapping boards. Its robust design ensures that electronic systems such as servers, telecom, and network equipment can maintain uninterrupted operation while components are being replaced or upgraded.

Key features of the LTC4251-1IS6 include:

• Wide Operating Voltage Range: The device operates over a range of -9V to -80V, making it versatile for various applications.
• Adjustable Overcurrent Protection: Users can set the current limit threshold with a single external resistor, providing flexibility in different load conditions.
• Automatic Retry or Latch Off: The controller offers an option for automatic retry after a fault or a latch-off feature for increased safety.
• Gate Voltage Clamping: To protect the MOSFET, the IC clamps the gate voltage, preventing over-voltage stress.
• Under-Voltage Lockout: The LTC4251-1IS6 includes an under-voltage lockout feature that ensures the controller is operational only when the supply voltage is within the acceptable range.

With its integrated charge pump, the LTC4251-1IS6 can fully enhance an N-channel MOSFET without requiring any additional external components. This charge pump also works down to very low supply voltages relative to the system ground, which is critical for ensuring the MOSFET remains in the desired state throughout the operation.

The LTC4251-1IS6 is a testament to Linear Technology's commitment to providing solutions that enhance the reliability and functionality of electronic systems. Its specialized design for negative voltage environments makes it a go-to choice for engineers looking to implement hot swap capabilities with minimal impact on the overall system design.