ADM1278 Hot Swap Controller and Digital Power and Energy Monitor with PMBus Interface

The ADM1278 is a hot swap controller that allows a circuit board to be removed from or inserted into a live backplane. It also features current, voltage, and power readback via an integrated 12-bit analog-to-digital converter (ADC), accessed using a PMBus™ interface. The load current is measured using an internal current sense amplifier that measures the voltage across a sense resistor in the power path via the HS+ and HS− pins. A default current limit of 20 mV is set, but this limit can be adjusted, if required, using a resistor divider network from the internal reference voltage to the ISET pin.

The ADM1278 limits the current through the sense resistor by controlling the gate voltage of an external N-channel FET in the power path, via the GATE pin. The sense voltage, and therefore the load current, is maintained below the preset maximum. The ADM1278 protects the external FET by limiting the time that the FET remains on while the current is at its maximum value. This current-limit time is set by the choice of capacitor connected to the TIMER pin. In addition, a constant power foldback scheme is used to control the power dissipation in the MOSFET during power-up and fault conditions. The level of this power, along with the TIMER regulation time, can be set to ensure that the MOSFET remains within the safe operating area (SOA) limits. A programmable start-up current limit is also available for dv/dt power-up.

In case of a short-circuit event, a fast internal overcurrent detector responds within 320 ns and signals the gate to shut down. A 1500 mA pull-down device ensures a fast FET response.

The ADM1278 features overvoltage (OV) and undervoltage (UV) protection, programmed using external resistor dividers on the UV and OV pins. A PWRGD signal can be used to detect when the output supply is valid, using the PWGIN pin to accurately monitor the output.

The 12-bit ADC can measure the current in the sense resistor, the supply voltage on the HS+ pin, the output voltage, and the temperature at the external NPN device. A PMBus interface allows a controller to read data from the ADC. As many as 16 unique I2C addresses can be selected, depending on how the two ADRx pins are connected.

The ADM1278 is available in a 32-lead LFCSP with a RETRY pin that can be configured for automatic retry or latch-off when an overcurrent fault occurs.

Applications

Features and Benefits
  • ±0.3% accurate, 12-bit ADC for IOUT, VIN, VOUT, and temperature
  • 320 ns response time to short circuit
  • Shutdown on detection of FET health fault
  • Split hotswap and power monitor inputs to allow for additional external ADC filtering
  • Constant power foldback for tighter FET SOA protection
  • Remote temperature sensing with programmable warning and shutdown thresholds
  • Resistor-programmable 5 mV to 25 mV VSENSE current limit
  • Programmable start-up current limit
  • 1% accurate UV and OV thresholds
  • Reports power and energy consumption over time
  • Peak detect registers for current, voltage, and power
  • See datasheet for additional features
  • Power Management
    Data Sheets
    Documentnote
    ADM1278: Hot Swap Controller and Digital Power and Energy Monitor with PMBus Interface Data Sheet (Rev. A)PDF 980 kB
    Application Notes
    Documentnote
    AN-1338: ADM1278 Design Guide (Rev. 0)PDF 142.11 K
    AN-1343: Energy Metering on Hot Swap and Power Monitor Devices (Rev. 0)PDF 113.69 K
    User Guides
    Documentnote
    UG-601: ADM1278 Evaluation Board User GuidePDF 725 kB
    UG-353: Hot Swap and Power Monitor SoftwarePDF 478 kB
    Order Information
    Part NumberPackagePacking QtyTemp RangePrice 100-499Price 1000+RoHS
    ADM1278-1AACPZ Production32 ld LFCSP (5x5x.80mm) w/3.3exposed padOTH 490-40 to 85C5.384.89Y
    ADM1278-1AACPZ-RL Production32 ld LFCSP (5x5x.80mm) w/3.3exposed padREEL 004.89Y
    ADM1278-1ACPZ Production32 ld LFCSP (5x5x.80mm) w/3.3exposed padOTH 490-40 to 85C3.853.5Y
    ADM1278-1ACPZ-RL Production32 ld LFCSP (5x5x.80mm) w/3.3exposed padREEL 5000-40 to 85C03.5Y
    ADM1278-1BCPZ Production32 ld LFCSP (5x5x.80mm) w/3.3exposed padOTH 490-40 to 85C3.182.89Y
    ADM1278-1BCPZ-RL Production32 ld LFCSP (5x5x.80mm) w/3.3exposed padREEL 5000-40 to 85C02.89Y
    ADM1278-2ACPZ Production32 ld LFCSP (5x5x.80mm) w/3.3exposed padOTH 490-40 to 85C3.853.5Y
    ADM1278-2ACPZ-RL Production32 ld LFCSP (5x5x.80mm) w/3.3exposed padREEL 5000-40 to 85C03.5Y
    ADM1278-3ACPZ Production32 ld LFCSP (5x5x.80mm) w/3.3exposed padOTH 490-40 to 85C3.853.5Y
    ADM1278-3ACPZ-RL Production32 ld LFCSP (5x5x.80mm) w/3.3exposed padREEL 5000-40 to 85C03.5Y
    Evaluation Boards
    Part NumberDescriptionPriceRoHS
    EVAL-ADM1278EBZEvaluation Board120Y
    ADM1278: Hot Swap Controller and Digital Power and Energy Monitor with PMBus Interface Data Sheet (Rev. A) adm1278
    AN-1338:ADM1278 设计指南 (Rev. 0) adm1278
    AN-1338: ADM1278 Design Guide (Rev. 0) adm1278
    AN-1343: Energy Metering on Hot Swap and Power Monitor Devices (Rev. 0) adm1276
    UG-601: ADM1278 Evaluation Board User Guide adm1278
    UG-353: Hot Swap and Power Monitor Software adm1275