ADI ADM1178-1ARMZ-R7

The ADM1178 is an integrated hot swap controller and current sense amplifier 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 ADM1178 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 ADM1178 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 after the hot swap event is complete. In 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 12-bit ADC can measure the current seen in the sense resistor, as well as the supply voltage on the VCC pin. An alert output can be set to trigger when the ADC current reading exceeds a programmed overcurrent limit threshold.

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 ADM1178 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
• Active high ON pin
• ALERTB output for overcurrent interrupt
• 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