Features

• Allows Safe Board Insertion and Removal from a Live Backplane
• Configurable Power Supply Sequencing
• Soft-Start with Current Foldback Limits Inrush Current
• No External Gate Capacitor Required
• Adjustable Dual Level Circuit Breaker Protection
• Controls Supply Voltages from 1V to 13.5V
• Independent N-Channel MOSFET High Side Drivers
• FB Pin Monitors V_OUT for Overvoltage Protection
• Latch Off or Automatic Retry on Current Fault
• FAULT and PWRGD Outputs
• Narrow 16-Pin SSOP Package

Typical Application

Description

The LTC4221 is a 2-channel Hot Swap controller that allows a board to be safely inserted and removed from a live backplane. Using two independent high side gate drivers to control two external N-channel pass transistors, the output voltages can be ramped up with current foldback to limit the inrush current during the start-up period. No external compensation capacitors are required at the GATE pins. The two channels can be configured to ramp up and down separately or simultaneously for supply voltages ranging from 2.7V to 13.5V and 1V to 13.5V for channels 1 and 2 respectively.

Each channel has two current limit comparators that provide dual level and dual speed overcurrent circuit breaker protection after the start-up period. If any current sense voltage exceeds 100mV for 1µs or 25mV for the timeout delay (set by the C_FILTER at the FILTER pin), then the FAULT latch is set and both GATE pins are pulled low.

The FB pins monitor the respective channel output voltages and provide the inputs for the PWRGD comparators as well as overvoltage protection.