NCP81111MNI3TXG - 3-Phase VR12.5/12.6 Digital Controller | onsemi
MPN: NCP81111MNI3TXG ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.31 | $4.31 |
| 10 | $3.88 | $38.80 |
| 100 | $3.46 | $346.00 |
| 500 | $3.1 | $1,550.00 |
| 1,000 | $2.79 | $2,790.00 |
NCP81111MNI3TXG Overview
A multiphase buck controller is a power-management IC (PMIC) that interleaves multiple synchronous buck phases to deliver high current at low voltage while spreading thermal dissipation across the PCB. Within the broader system hierarchy, the NCP81111 sits in the CPU core rail of a server, workstation, or embedded computing platform, between a 12 V (or higher) intermediate bus and the loadline-regulated Vcore output demanded by an Intel VR12.5/12.6 processor. The architecture combines precision analog current sensing with digital modulation to meet the stringent dynamic load, overshoot, and DC tolerance requirements of modern CPUs.
Key features include three integrated gate drivers capable of driving external N-channel MOSFETs in a true multiphase topology, SVID bus communication for direct CPU-to-controller command, an I2C interface for telemetry, configuration, and fault readback, per-phase current balancing, dynamic phase add/drop, programmable loadline, and comprehensive protection including over-voltage, under-voltage, over-current, and over-temperature. The controller supports PMBus-compatible telemetry of output voltage, current, and temperature for system-level monitoring.
The NCP81111 implements a digital control loop with adaptive voltage positioning and high-bandwidth error amplification, achieving fast transient response to VR12.5/12.6 step loads. Phase shedding dynamically disables phases at light load to maximize efficiency, while automatic phase add/drop maintains regulation under sudden load increases. The 5 MHz switching capability enables the use of small inductors and ceramic output capacitors, reducing board area compared to legacy controllers.
Typical applications include Intel VR12.5/12.6-compliant server and workstation CPU core power, single-rail high-current POL converters in networking ASICs and FPGAs, graphics processor power in workstation add-in cards, and high-end embedded computing platforms. The exposed pad package supports sustained multiphase operation at tens of amps with appropriate thermal design.
When designing with the NCP81111, follow the manufacturer's reference layout for the QFN exposed pad and place the current-sense resistors and bootstrap capacitors as close as possible to the controller pins. The SVID and I2C lines require pull-up resistors per the Intel VR12.5/12.6 design guide; verify timing with the target CPU's VR12.5/12.6 compliance checklist before tape-out.
Drop-in alternatives for NCP81111MNI3TXG — 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:
NCP81111MNITXG
✅ Drop-In📋 Reference alternative (not in catalog)
NCP81111MNI3TXG
✅ Drop-In✓ In Stock
$2.79 / Unit
View Datasheet →NCP81162
✅ Drop-In📋 Reference alternative (not in catalog)
NCP81103
✅ Drop-In📋 Reference alternative (not in catalog)
NCP81111MNI3TXG Maximum Ratings & Electrical Characteristics
| Product Type | Multiphase digital buck controller (PMIC) |
| Topology | 3-phase synchronous buck |
| Compliance | Intel VR12.5, VR12.6 |
| Number of Outputs | 1 |
| Switching Frequency (max) | 5 MHz |
| SVID Interface | Yes (Serial VID per Intel spec) |
| I2C Interface | Yes |
| Gate Drivers | 3 internal (drives external N-MOSFETs) |
| Package | 32-QFN (5x5 mm) with exposed pad |
| Mounting Type | Surface Mount |
| Operating Temperature | -40C to +125C |
| RoHS Status | Compliant |
| Lead-Free | Yes |
| Reel Quantity | 3000 (typical per -TXG suffix) |
NCP81111MNI3TXG Pin Configuration
| Pin 1 | BOOT1 — Bootstrap capacitor for high-side gate driver phase 1 |
| Pin 2 | UGATE1 — High-side gate drive output phase 1 |
| Pin 3 | LGATE1 — Low-side gate drive output phase 1 |
| Pin 4 | PHASE1 — Phase node return / bootstrap return phase 1 |
| Pin 5 | BOOT2 — Bootstrap capacitor for high-side gate driver phase 2 |
| Pin 6 | UGATE2 — High-side gate drive output phase 2 |
| Pin 7 | LGATE2 — Low-side gate drive output phase 2 |
| Pin 8 | PHASE2 — Phase node return / bootstrap return phase 2 |
| Pin 9 | BOOT3 — Bootstrap capacitor for high-side gate driver phase 3 |
| Pin 10 | UGATE3 — High-side gate drive output phase 3 |
| Pin 11 | LGATE3 — Low-side gate drive output phase 3 |
| Pin 12 | PHASE3 — Phase node return / bootstrap return phase 3 |
| Pin 13 | VCC — Supply voltage for gate drivers and internal analog |
| Pin 14 | GND — Ground |
| Pin 15 | FB — Output voltage feedback (differential remote sense) |
| Pin 16 | VOS — Voltage identification offset (SVID) |
| Pin 17 | CSREF — Current sense reference |
| Pin 18 | CSP — Current sense positive input |
| Pin 19 | CSN — Current sense negative input |
| Pin 20 | RT/FS — Frequency setting resistor |
| Pin 21 | PGOOD — Power-good output (open-drain) |
| Pin 22 | EN — Enable input (active-high) |
| Pin 23 | VRHOT — Thermal warning output |
| Pin 24 | SVC — SVID clock (Serial VID interface) |
| Pin 25 | SVD — SVID data (Serial VID interface) |
| Pin 26 | SDA — I2C data |
| Pin 27 | SCL — I2C clock |
| Pin 28 | ADDR — I2C address select |
| Pin 29 | ILIM — Current limit programming |
| Pin 30 | OVP — Over-voltage programming |
| Pin 31 | VDDIO — Digital I/O supply (3.3 V) |
| Pin 32 | NC — Not connected (per datasheet) |
| Pin 33 | EP — Exposed thermal pad (connect to GND plane) |
Typical Applications
NCP81111MNI3TXG is suitable for 6 applications: Intel VR12.5/12.6 Server CPU Core Power, Workstation and Desktop CPU VR12.5/12.6 Power, Networking ASIC and SoC Core Rails, Graphics Processor and Add-In Card Power, High-End Embedded Computing Platforms, FPGA and SoC Accelerator Core Power.
Intel VR12.5/12.6 Server CPU Core Power
The NCP81111MNI3TXG is purpose-built for Intel VR12.5/12.6-compliant server and workstation CPU core rails, where it sits between a 12 V intermediate bus and the loadline-regulated Vcore demanded by modern Intel Xeon and Core processors. The controller's SVID interface accepts voltage-identification commands directly from the CPU, while the I2C port exposes telemetry (Vout, Iout, temperature) to the baseboard management controller (BMC). With three phases and 5 MHz switching, it sustains 60-100 A continuous load while keeping board area compact.
Recommended
Workstation and Desktop CPU VR12.5/12.6 Power
In high-end desktop and workstation motherboards, the NCP81111MNI3TXG drives the Vcore rail for Intel LGA-socket CPUs requiring VR12.5/12.6 compliance. Its three-phase architecture and digital control loop deliver the fast transient response and tight DC tolerance demanded by single-core and multi-core turbo transients. Dynamic phase add/drop maximizes light-load efficiency, an important metric for ENERGY STAR and 80 PLUS workstation platforms. The exposed-pad 32-QFN simplifies board layout and thermal dissipation.
Recommended
Networking ASIC and SoC Core Rails
The NCP81111MNI3TXG is well suited to high-current core rails of networking ASICs, switches, and SoCs that benefit from a 3-phase buck topology. Its SVID command set and I2C telemetry are valuable in data-plane equipment where the host CPU manages the rail through standard interfaces. The 5 MHz switching capability allows use of small ceramic output capacitors, critical in space-constrained line cards. Per the onsemi datasheet, the controller's over-current and over-temperature protection support the long-lifecycle requirements of carrier-grade equipment.
Recommended
Graphics Processor and Add-In Card Power
Workstation GPU cards and high-end discrete graphics require multiphase core-rail converters capable of 60-120 A peaks with millivolt tolerance. The NCP81111MNI3TXG's 3-phase architecture, programmable loadline, and digital loop are well matched to GPU power profiles that combine sustained high current with sudden load transients. The exposed-pad 32-QFN simplifies heat-sinking to the card's ground plane. Combined with the I2C telemetry, the design supports runtime monitoring of the GPU core voltage and current.
Recommended
High-End Embedded Computing Platforms
Embedded computing platforms in medical imaging, industrial control, and test-and-measurement equipment often use Intel-class CPUs with VR12.5/12.6 requirements, where the NCP81111MNI3TXG can serve as the core-rail controller. Its wide temperature range and RoHS compliance suit industrial environments, while the SVID interface simplifies software integration with the host CPU. The exposed-pad package supports sustained high-current operation without external heatsinks, reducing BOM cost.
Recommended
FPGA and SoC Accelerator Core Power
High-performance FPGAs and SoC accelerators often require 3+ phase core-rail converters delivering 30-100 A at sub-1V tolerances, and the NCP81111MNI3TXG's digital control loop satisfies these requirements. Although the SVID interface is CPU-specific, the I2C and PMBus-compatible telemetry can be redirected to the FPGA's power-management block for autonomous monitoring. Per the onsemi datasheet, the controller's adjustable soft-start and programmable fault thresholds suit the unique ramp-up profile of FPGAs.
Recommended
Recommended Products Summary
Engineering reference data for NCP81111MNI3TXG — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | NCP81111MNITXG | NCP81162 | NCP81103 |
|---|---|---|---|---|
| Brand | onsemi | onsemi | onsemi | onsemi |
| Package | 32-QFN (5x5) | 32-QFN (5x5) - same | 32-QFN (5x5) - same | 32-QFN (5x5) - same |
| Topology | 3-phase digital buck | 3-phase digital buck | 2-phase digital buck | 3-phase digital buck |
| VR12.5/12.6 Compliance | Yes (both) | Yes (both) | Yes (both) | VR12.0/VR12.5 only |
| SVID Interface | Yes | Yes | Yes | Yes |
| I2C Interface | Yes | Yes | Yes | Yes |
| Automotive Grade (AEC-Q100) | No | Yes | No | No |
Key Differentiators
- Onsemi same-family drop-in path to automotive grade (vs NCP81111MNITXG)
- Two-phase same-package alternative for cost-down (vs NCP81162)
- Backward-compatible VR12.0/12.5 sibling (vs NCP81103)
Design Notes
Follow the onsemi reference layout for the NCP81111 32-QFN exposed-pad package: the EP must be soldered to a continuous ground plane using multiple thermal vias to extract heat and provide a low-impedance return path. Place the bootstrap capacitors (BOOT1/2/3) and the VCC bypass capacitors within 2 mm of their respective pins to minimize parasitic inductance in the high-side gate-drive loop. The PHASE node traces should be short and wide to limit ringing and overshoot during switching transitions.
The SVID bus (SVC, SVD) and I2C bus (SCL, SDA) are 3.3 V digital interfaces and require pull-up resistors to VDDIO per the Intel VR12.5/12.6 design guide. Keep these traces away from the PHASE switching nodes and gate-drive outputs to avoid capacitive coupling of switching noise into the digital control signals. The differential remote sense lines (FB, VOS) should be routed as a matched pair from the CPU package inductor output to maintain DC accuracy at high current.
Estimated: at 1 MHz switching frequency, 12 V Vin, 1.0 V Vout, and 60 A load (20 A per phase), the controller's own dissipation is dominated by the gate-drive charge (Qg * Vgs * fsw) and the internal analog supply current. With three phases driving N-MOSFETs of approximately 20 nC total gate charge, gate-drive losses are roughly 60 mW per phase. The exposed pad's thermal resistance is 35 C/W per the onsemi QFN package thermal model, so the controller junction temperature stays well below limits provided the EP is properly soldered to the ground plane.
Do not omit the RT/FS resistor - it programs the switching frequency and the controller will not start without it. Do not exceed the maximum VDDIO supply (3.6 V); connect it through a local LDO from the 5 V rail or directly to the 3.3 V standby supply. When the SVID bus is idle for longer than the specified timeout, the controller enters a low-power state; ensure the CPU drives the SVID bus within the wake-up window or the rail will fall out of regulation.
Compliance Information
RoHS compliant and lead-free per onsemi product page. Standard MNI3TXG is not AEC-Q100 qualified - choose NCP81111MNITXG for automotive applications.
