ADM1073 Datasheet

• Precision In-Rush Linear Current Limit
• Adjustable Soft Start In-Rush Current Limit Profiling
• Max On-Time Modulated by FET Drain Voltage for Additional SOA Protection
• Adjustable PWM Retry Scheme and Multiple Device Cascading
• Precision Maximum On Time in Current Limit
• Capability for Charging Large Capacitive Loads
• Shunt Regulator Topology Allows For Very Large Transient Input Supplies
• Precision UnderVoltage and OverVoltage Monitors with Separate UV and OV Pins and Programmable UV and OV Hysteresis

• Central office switching
• Telecommunication and data communication equipment
• −48 V distributed power systems
• Negative power supply control
• High availability servers
• −48 V power supply modules
• Disk arrays

The ADM1073 is a full-feature, negative voltage, hot swap controller that allows boards to be safely inserted and removed from a live −48 V backplane. The part provides precise and robust current limiting, and protection against both transient and nontransient short circuits in overvoltage and undervoltage conditions. The ADM1073 can operate from a negative voltage of −18 V to −80 V and can tolerate transient voltages of up to −200 V.

Inrush current is limited to a programmable value by control-ling the gate drive of an external N-channel FET. The maximum current limit is set by the choice of the sense resistor, R_SENSE.

A built-in soft start function allows control of the inrush current profile by an external capacitor on the soft start (SS) pin.

An external capacitor on the TIMER pin determines the time for which the FET gate is controlled to be high when maximum inrush current flows. The ADM1073 employs a limited consecutive retry scheme, whereby, if the load capacitance is not fully charged within one attempt, the FET gate is pulled low and retries after a cooling period.