ADM1278-1ACPZ-RL - Hot Swap Controller + PMBus Monitor | ADI
MPN: ADM1278-1ACPZ-RL ⚠ Last Time Buy| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $14.5 | $14.50 |
| 10 | $12.95 | $129.50 |
| 100 | $11.4 | $1,140.00 |
| 500 | $9.85 | $4,925.00 |
| 1,000 | $8.62 | $8,620.00 |
ADM1278-1ACPZ-RL Overview
A hot-swap controller is a specialized power-management IC that sits between a live backplane and a removable circuit card, controlling the inrush current that flows when bulk load capacitance charges up. Without it, the charged capacitor looks like a momentary short, which can trip upstream supplies, cause connector arcing, or damage FETs. The ADM1278 combines that inrush-control role with on-board telemetry: a PMBus interface reports voltage, current, power and energy in real time so the system host can implement digital energy budgets, logging, and predictive analytics. Within the broader taxonomy, hot-swap controllers sit under hot-swap and ORing controllers -> power management ICs -> power management.
Key features include constant-power folded-back current limiting for tighter FET SOA protection, programmable linear inrush current profile on power-up, FET-health monitoring with auto-shutdown on fault, and remote temperature sensing with programmable warning and shutdown thresholds. The integrated PMBus block supports readback of voltage, current, power and energy in a standard format readable by any supervisory MCU or BMC. The -1 suffix in the part number denotes the LFCSP package variant with specific pin assignments as described in the datasheet.
Architecturally, the chip uses an external N-channel MOSFET as the high-side pass element, a high-side current-sense amplifier, a precision bandgap-referenced 12-bit ADC, and an I2C/SMBus-compatible PMBus interface block. The ADI datasheet (Rev. C) describes a constant-power foldback mode that derates the gate drive as VDS across the FET rises, holding the FET inside its thermal envelope during sustained fault events.
Typical applications include server and datacenter hot-swap boards, network switches and routers with removable line cards, RAID/HBA cards, blade-server mezzanine cards, PCI Express add-in cards, and -48 V distribution systems with intermediate bus converters. Industrial applications requiring PMBus telemetry such as programmable DC supplies and remote radio units (RRUs) also benefit from the integrated monitoring.
When designing with the ADM1278, choose the external MOSFET first - its SOA and RDSon drive efficiency, fault tolerance and thermal performance. The sense resistor value (RSENSE) directly sets the current-limit threshold, and a 1% tolerance part is strongly recommended for accurate telemetry. The PMBus address is resistor-programmable, allowing multiple hot-swap ICs to coexist on a single bus.
Drop-in alternatives for ADM1278-1ACPZ-RL — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ADM1281ACPZ
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ADM1278-2ACPZ
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ADM1278-1ACPZ
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ADM1272-1ACPZ
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ADM1260ACPZ
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LTC4282IUHF
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ADM1278-1ACPZ-RL Specifications
| Function | Hot Swap Controller with Digital Power Monitor |
| Number of Channels | 1 |
| Operating Voltage Range | 1.4 V to 20 V |
| Current Limit Sense Threshold | 5 mV to 25 mV (programmable) |
| Short-Circuit Response Time | 290 ns |
| ADC Resolution | 12 bit |
| Telemetry Channels | VIN, VOUT, IOUT, Temperature |
| Digital Interface | PMBus (SMBus/ I2C compatible) |
| External Pass Element | N-Channel MOSFET (high-side) |
| Current-Limit Topology | Constant-power foldback with linear inrush ramp |
| FET-Health Monitoring | Yes (auto-shutdown on fault) |
| Temperature Sensing | On-die and remote diode (programmable thresholds) |
| Package | 32-LFCSP (5 mm x 5 mm) with exposed pad |
| Pin Count | 32 |
| Operating Temperature Range | -40 C to +85 C (industrial) |
| Mounting Type | Surface Mount |
| Lead-Free / RoHS | Yes (RoHS compliant) |
| Recommended Replacement | ADM1281 (pin-to-pin, recommended by ADI) |
ADM1278-1ACPZ-RL Pin Configuration
| Pin 1 | SENSE+ — Positive current-sense input (Kelvin to RSENSE hot side) |
| Pin 2 | SENSE- — Negative current-sense input (Kelvin to RSENSE load side) |
| Pin 3 | GATE — External N-FET gate drive output |
| Pin 4 | TIMER — Fault timing capacitor pin |
| Pin 5 | UVLO — Undervoltage lockout threshold setting |
| Pin 6 | OVLO — Overvoltage lockout threshold setting |
| Pin 7 | ENABLE — Active-high enable input |
| Pin 8 | PWRGD — Power-good open-drain output |
| Pin 9 | FAULT — Active-low latched fault output |
| Pin 10 | SDA — PMBus serial data (I2C/SMBus SDA) |
| Pin 11 | SCL — PMBus serial clock (I2C/SMBus SCL) |
| Pin 12 | ADDR — PMBus address setting resistor pin |
| Pin 13 | ALERT — SMBus alert output (active low) |
| Pin 14 | CTRL — PMBus control input |
| Pin 15 | DGND — Digital ground |
| Pin 16 | GND — Analog ground |
| Pin 17 | VIN — Supply input voltage sense |
| Pin 18 | VOUT — Output voltage sense (after MOSFET) |
| Pin 19 | VCC — Supply voltage to IC (decoupled) |
| Pin 20 | VDD — Internal regulator output (bypass pin) |
| Pin 21 | REGOUT — Regulator output voltage (internal LDO bypass) |
| Pin 22 | DVC — Decoupling capacitor for internal regulator |
| Pin 23 | TSET — Temperature threshold setting |
| Pin 24 | D1P — Diode temperature sense anode (remote) |
| Pin 25 | D1N — Diode temperature sense cathode (remote) |
| Pin 26 | TEMP — On-die temperature sense output |
| Pin 27 | SS — Soft-start capacitor pin (ramp setting) |
| Pin 28 | FOLDBACK — Constant-power foldback threshold setting |
| Pin 29 | ISET — Current-limit threshold setting |
| Pin 30 | INTR — Interrupt / event signal output |
| Pin 31 | A0 — PMBus address bit 0 strap |
| Pin 32 | EP — Exposed thermal pad (connect to GND plane) |
Typical Applications
ADM1278-1ACPZ-RL is suitable for 6 applications: Server and Datacenter Hot-Swap Boards, Network Switch and Router Line Cards, RAID / HBA Storage Controllers, PCIe Add-In Cards and Mezzanine Boards, Industrial 24 V Power Distribution, Telecom 48 V Intermediate Bus Distribution.
Server and Datacenter Hot-Swap Boards
In server and datacenter power distribution, the ADM1278-1ACPZ-RL controls 12 V hot-plug events into the backplane, limiting the inrush current that flows as bulk capacitors on the inserted card charge up. The device's 290 ns short-circuit response and constant-power foldback keep the high-side N-FET inside its SOA during sustained faults, while the integrated 12-bit ADC and PMBus interface report VIN, VOUT, IOUT, and on-die temperature in real time. This telemetry feeds the BMC and OS-level PMBus stacks for digital-energy dashboards and predictive-failure analytics. The LFCSP-32 footprint and exposed pad make it compatible with high-density server PCB layouts and 1 oz copper inner-layer thermal designs.
Recommended
Network Switch and Router Line Cards
Network switches and routers with removable line cards require live-insertion hot-swap control on each port slot to prevent connector arcing and upstream supply drop. The ADM1278-1ACPZ-RL drives an external high-side N-FET with a programmed linear inrush ramp, while PMBus reports line-card power consumption for the switch chassis controller. The wide 1.4 V to 20 V operating range covers intermediate bus voltages and 5 V/12 V standard rails used in enterprise switching products. Real-time fault telemetry from the integrated ADC allows the supervisor to power-cycle a stuck line card without affecting neighboring slots.
Recommended
RAID / HBA Storage Controllers
RAID controllers and HBA cards plug into PCIe hot-plug slots where bus-resident load capacitance can exceed 1000 uF. The ADM1278-1ACPZ-RL holds the inrush ramp within the connector-contact rating, while its constant-power foldback prevents the high-side FET from entering thermal runaway during a sustained overcurrent. PMBus telemetry reports 12 V AUX current to the storage controller firmware for power-budgeting multiple SSDs or HDDs. The exposed-pad LFCSP-32 keeps junction temperature rise modest even when dissipating fault energy in a stalled 3.5-inch HDD backplane event.
Recommended
PCIe Add-In Cards and Mezzanine Boards
PCIe add-in cards and mezzanine modules must tolerate 12 V hot-insertion events where the upstream connector pins make uneven contact during insertion. The ADM1278-1ACPZ-RL monitors VIN before energizing the load, ramps the gate of the external pass FET smoothly, and disables the output if any voltage, current, or temperature fault window is exceeded. The 5 mV to 25 mV programmable current-limit range supports RSENSE values from 1 to 5 milliohm, accommodating a wide range of load classes. Placed adjacent to the PCIe power pin cluster, it maintains ATX-defined slot power-up sequencing.
Recommended
Industrial 24 V Power Distribution
Industrial 24 V backplane distribution needs hot-swap controllers with overvoltage headroom and PMBus telemetry for SCADA dashboards. The ADM1278-1ACPZ-RL operates up to 20 V with derating, making it ideal for industrial 19 V to 24 V rail systems where direct insertion is required on field-replaceable I/O modules. Its constant-power foldback mode protects the MOSFET when downstream DC motors or relay coils generate switching transients. The integrated ADC reports supply voltage drift, letting a programmable-logic-controller (PLC) adjust analog-loop setpoints in real time.
Recommended
Telecom 48 V Intermediate Bus Distribution
Telecom rectifier shelves and power distribution units stage down -48 V inputs to 12 V intermediate buses; downstream bricks need hot-swap isolation. The ADM1278-1ACPZ-RL sits on the 12 V distribution side, controlling brick insertion and reporting per-slot power to the shelf supervisor. The combination of fast 290 ns short-circuit response and PMBus telemetry supports parallel N+1 redundant supplies with deterministic fault propagation. Designers typically pair it with a holdup capacitor to ride through upstream bulk-supply brownouts.
Recommended
Recommended Products Summary
Engineering reference data for ADM1278-1ACPZ-RL — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ADM1281ACPZ | ADM1278-2ACPZ | ADM1278-1ACPZ | ADM1272-1ACPZ | ADM1260ACPZ |
|---|---|---|---|---|---|---|
| Package | LFCSP-32 (5x5 mm) | LFCSP-32 (5x5 mm) - same | LFCSP-32 (5x5 mm) - same | LFCSP-32 (5x5 mm) - same | LFCSP-32 (5x5 mm) - same | LFCSP-32 (5x5 mm) - same |
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Function | Hot Swap + PMBus monitor | Hot Swap + PMBus monitor | Hot Swap + PMBus monitor | Hot Swap + PMBus monitor | Hot Swap only (no PMBus) | Supervisory/sequencer (no inrush FET driver) |
| PMBus Telemetry | Yes (VIN/VOUT/IOUT/Temp) | Yes | Yes | Yes | No | N/A |
| Recommended Use | 12 V server hot-swap, last time buy | New designs, pin-to-pin replace | Legacy field replacement | Tray-pack alternative on same die | No telemetry requirement | Supervisory-only role |
Key Differentiators
- Pin-to-pin recommended replacement available (vs ADM1281ACPZ)
- Integrated 12-bit ADC for voltage/current/power/temperature readback (vs ADM1272-1ACPZ)
- True hot-swap controller with inrush FET driver (vs ADM1260ACPZ)
- 290 ns short-circuit response keeps external FET inside SOA (vs LM25066 (TI))
Design Notes
Estimated: the LFCSP-32 package dissipates heat primarily through the exposed pad; solder it to a 1 oz copper thermal plane covering at least 1 square inch of PCB area for typical server applications. At full-load sustained fault foldback, the FET is the major heat source; the ADM1278 itself may stay below 60 C junction. Place thermal vias on a 1.0 mm pitch array under the exposed pad for 4-layer PCBs, per the ADI datasheet land-pattern recommendation.
Place the current-sense resistor RSENSE in the Kelvin path between SENSE+ and SENSE- with traces routed as a 4-wire connection to avoid IR-drop error; lay the SENSE traces directly above or below their corresponding source/return paths. Keep the high di/dt gate-drive loop compact: GATE, the external FET gate, and the local gate-return bypass capacitor should form a loop less than 25 mm in perimeter to limit ringing. Decouple VCC with a 1 uF X7R ceramic immediately adjacent to pin 19.
Do not omit the TIMER capacitor or set it below 1 nF; the resulting timing may latch a fault during normal inrush and prevent turn-on at large load-capacitance values. Verify the RSENSE resistance and tolerance - 1% tolerance parts give telemetry accuracy in the single-digit percent range; 5% parts will not meet PMBus precision requirements. Finally, the PMBus address is strap-programmed, so multiple ADM1278s on a single bus need unique resistor settings to avoid bus collision.
Estimate: at 12 V and 5 A the external N-FET dissipates VIN minus VOUT times current; with a 5 milliohm RDSon, loss is approximately 0.125 W at full load. Sustained inrush or fault events drive constant-power foldback, where the chip actively regulates VDS across the FET to keep PD below the programmed foldback threshold; verify the chosen FET's SOA curve covers the worst-case 7 V * 5 A = 35 W region for the desired fault-timer duration.
Compliance Information
RoHS compliance and lead-free status confirmed from ADI product page and DigiKey listing. Halogen-free status not explicitly stated in verified data; AEC-Q100 qualification not applicable (server/industrial part). Last Time Buy status per ADI recommends the ADM1281 for new designs.
