ADI ADM1177-2ARMZ-R7

The ADM1177 is an integrated hot swap controller that offers digital current and voltage monitoring via an on-chip, 12-bit analog-to-digital converter (ADC), communicated through an I²C interface. An internal current sense amplifier measures voltage across the sense resistor in the power path via the VCC pin and the SENSE pin. The ADM1177 limits the current through this resistor by controlling the gate voltage (via the GATE pin) of an external N-channel FET in the power path. The voltage across the sense resistor (and, therefore, the inrush current) is kept below a preset maximum. The ADM1177 protects the external FET by limiting the time that the maximum current runs through it. This current limit period is set by the value of the capacitor attached to the TIMER pin. Additionally, the device provides protection from overcurrent events that may occur once the hot swap event is complete. In the case of a short-circuit event, the current in the sense resistor exceeds an overcurrent trip threshold, and the FET is switched off immediately by pulling down the GATE pin. A soft start pin (SS) is also included. This gives the user control over the reference on the current sense amplifier. An internal current source charges a capacitor on this pin at startup, allowing the user to set the profile of the initial current ramp. A voltage can also be driven on this pin to alter the reference. A 12-bit ADC can measure the current seen in the sense resistor, as well as the supply voltage on the VCC pin. An industry-standard I²C interface allows a controller to read current and voltage data from the ADC. Measurements can be initiated by an I²C command. Alternatively, the ADC can run continuously, and the user can read the latest conversion data whenever it is required. Up to four unique I²C addresses can be created, depending on how the ADR pin is connected. The ADM1177 is packaged in a 10-lead MSOP.

• Allows safe board insertion and removal from a live backplane
• Controls supply voltages from 3.15 V to 16.5 V
• Precision current sense amplifier
• Precision voltage input
• 12-bit ADC for current and voltage readback
• Charge pumped gate drive for external N-channel FET
• Adjustable analog current limit with circuit breaker
• ±3% accurate hot swap current limit level
• Fast response limits peak fault current
• Automatic retry or latch-off on current fault
• Programmable hot swap timing via TIMER pin
• Soft start pin for reference adjustment and programming of initial current ramp rate
• Active high ON pin
• I²C fast mode-compliant interface (400 kHz maximum)
• 10-lead MSOP

• Power monitoring/power budgeting
• Central office equipment
• Telecommunications and data communications equipment
• PCs/servers