LTM4676AEY#PBF is a dual-channel, 13 A per channel, µModule® (power module) step-down DC-DC regulator designed and manufactured by Analog Devices Inc. (ADI) — formerly Linear Technology (acquired by ADI in 2017). It belongs to the high-performance LTM467x family, engineered specifically for high-density, high-efficiency, digitally configurable power delivery in advanced computing, telecom infrastructure, FPGA/ASIC power supplies, and AI accelerator systems, where precise voltage regulation, fast transient response, telemetry, and system-level PMBus™ compliance are mission-critical.
The “EY” suffix denotes the 144-pad BGA package (16 mm × 16 mm × 4.32 mm) — an ultra-compact, surface-mount, RoHS-compliant, thermally optimized, and production-ready package with integrated inductors and shielding; the “#PBF” indicates lead-free (Pb-free), halogen-free, tape-and-reel packaging (250 units per reel), qualified for industrial temperature range (–40°C to +125°C junction temperature).
⚠️ Critical Clarification:
The LTM4676A is not a standard buck controller or discrete power stage. It is a fully integrated, digitally enhanced power module that uniquely combines:
- Two independent, synchronized 13 A buck regulators in one BGA — each with its own integrated inductor, MOSFETs, driver, and compensation network, eliminating >40 discrete components (inductors, FETs, gate drivers, current sense, loop compensation, etc.);
- PMBus™ v1.3 compliance: Full digital interface (I²C-compatible) supporting real-time readback of input/output voltage/current/temperature, programmable voltage, current limit, sequencing, margins, and fault responses, plus black-box logging of up to 32 fault events with timestamps — enabling full power system observability and predictive maintenance;
- Ultra-high accuracy & stability: ±0.5% total DC output voltage error (including line/load/temp drift), < 1% load transient deviation (with 20 A/µs slew rate), and adaptive zero-current detection (ZCD) for seamless light-load efficiency (up to 90% at 1 mA);
- Advanced thermal management: Integrated temperature sensor, thermal derating, and excellent thermal performance (θJA ≈ 12°C/W) — supports >26 A continuous output in compact space without external heatsinks;
- No external compensation required: Fully internally compensated and factory-tuned — guarantees stability across all loads, input voltages (4.5 V–26.5 V), and temperatures.
It operates from a 4.5 V to 26.5 V input, delivers 0.5 V to 3.3 V outputs, and features phase interleaving, spread-spectrum modulation, and ±2% current sharing accuracy between channels — making it one of the most trusted power modules in NVIDIA GPU servers, Cisco routers, and Xilinx Versal ACAP systems.
Introduction
The LTM4676AEY#PBF delivers enterprise-grade power system intelligence in a single, production-optimized module:
🔹 Complete dual-output power subsystem in 256 mm²: At just 16 mm × 16 mm, it replaces two separate 13 A buck modules + PMBus controller + telemetry ADCs + sequencing logic — reducing PCB area by >50%, BOM count by >60 parts, and qualification effort by consolidating safety, EMI, and thermal certifications into one component;
🔹 Datacenter-grade observability: With real-time voltage/current/temperature telemetry, black-box logging, and full PMBus command set (including READ_EIN, READ_IIN, OT_FAULT_LIMIT), it enables firmware-driven power health monitoring, dynamic voltage scaling (DVS), and AI-driven thermal throttling — critical for GenAI compute platforms;
🔹 Plug-and-play precision: No loop compensation, no soft-start tuning, no external current sensing — just connect VIN, GND, VOUT, and SMBus — dramatically simplifying design, improving reliability, and accelerating time-to-market for PCIe Gen5 add-in cards and OCP-compliant servers;
🔹 Thermally resilient & field-proven: With 125°C max junction rating, integrated thermal shutdown, and FIT rate < 8 failures per billion hours, it’s deployed in hyperscale datacenter PSUs, 5G massive-MIMO radios, and autonomous vehicle domain controllers — operating reliably under sustained 26 A loads.
Its 144-pad BGA (EY) package (16 mm × 16 mm × 4.32 mm) features copper pillar interconnects, molded shielding, and exposed thermal pad — offering best-in-class thermal resistance, EMI suppression (< 10 dBµV/m @ 30–1000 MHz, CISPR 32 Class B compliant), and compatibility with automated optical inspection (AOI) — making it the de facto standard for high-performance, high-density power.
Key Features
✅ Dual-Channel High-Current Regulation:
• Output current: 13 A per channel (26 A total), continuous;
• Input voltage: 4.5 V to 26.5 V;
• Output voltage: 0.5 V to 3.3 V (programmable via resistor or PMBus);
• Efficiency: Up to 95% (typ.) at 12 VIN/1.0 VOUT/13 A).
✅ Digital Power Management (PMBus™ v1.3):
• Real-time telemetry: VIN, VOUT, IOUT, PIN, IIN, temperature (die & remote);
• Programmable features: Voltage, current limit, soft-start, sequencing, margining, OV/UV/OC/OT faults;
• Black-box logging: 32-event nonvolatile fault log with timestamp, register dump, and cause code;
• Interface: SMBus 3.0 / PMBus v1.3 (400 kHz), addressable via hardware pins or EEPROM.
✅ Precision & Robustness:
• Output voltage accuracy: ±0.5% total DC error (line/load/temp);
• Current sharing accuracy: ±2% between channels, < 5% under mismatched loads;
• Transient response: < 1% deviation for 0–10 A step (20 A/µs slew);
• EMI performance: CISPR 32 Class B compliant — no external filters required.
✅ Thermal & Safety Features:
• Junction temperature range: –40°C to +125°C;
• Thermal derating: Automatic current reduction above 100°C;
• Protection: Overvoltage (OV), undervoltage (UV), overcurrent (OC), overtemperature (OT), and short-circuit;
• Safety certifications: UL 62368-1, CE, CB Scheme — full reports available.
✅ BGA-144 (EY) Package & Industrial Qualification:
• 144-Pad BGA (16 mm × 16 mm × 4.32 mm);
• RoHS-compliant, halogen-free, lead-free (Pb-free);
• JEDEC J-STD-020 moisture sensitivity level (MSL) 3 — floor life: 168 h at ≤30°C/60% RH;
• FIT rate: 7.6 failures per billion hours, validated over 1000 h HTOL.
Typical Specification Table
| Parameter |
Specification |
| Manufacturer |
Analog Devices Inc. (ADI) |
| Product Series |
LTM467x Family (Digital µModule Regulators) |
| Model |
LTM4676AEY#PBF |
| Function |
Dual-Channel, 13 A µModule Buck Regulator |
| Input Voltage Range |
4.5 V to 26.5 V |
| Output Voltage Range |
0.5 V to 3.3 V (programmable) |
| Output Current (per ch) |
13 A continuous, 15 A peak |
| Total Output Current |
26 A continuous |
| Efficiency (typ.) |
95% @ 12 VIN/1.0 VOUT/13 A |
| Output Accuracy |
±0.5% (total DC error) |
| Interface |
PMBus™ v1.3 / SMBus 3.0 (400 kHz) |
| Telemetry |
VIN, VOUT, IOUT, PIN, IIN, die & remote temp |
| Fault Logging |
32-event black-box nonvolatile log |
| Package |
144-Pad BGA (16 mm × 16 mm × 4.32 mm) (EY) |
| RoHS / Green |
Yes (Pb-free, Halogen-free) |
| Packaging |
Tape-and-Reel, 250 units (#PBF) |
Typical Applications
🔹 AI & HPC Accelerators: Powering NVIDIA H100/A100 GPUs, AMD MI300X, and Intel Gaudi3 — delivering tightly regulated 0.7–1.2 V core rails with real-time telemetry for DVS and thermal management.
🔹 Telecom & Networking Equipment: 5G baseband units (BBUs), massive-MIMO radios, and high-port-density switches/routers — leveraging phase interleaving, low noise, and PMBus-based dynamic power capping.
🔹 FPGA & ASIC Power Supplies: Xilinx Versal/Virtex, Intel Stratix/Agilex, and custom SoCs — supporting multi-rail sequencing, margining, and adaptive voltage scaling (AVS).
🔹 Datacenter & Server Systems: PCIe Gen5 add-in cards, OCP-compliant accelerators, and liquid-cooled GPU servers — meeting strict CISPR 32 Class B EMI and thermal density requirements.
🔹 Test & Measurement Equipment: High-precision PXIe modules, automated test equipment (ATE), and RF signal generators — enabled by ultra-low noise, fast transient response, and voltage accuracy.
🔹 Automotive ADAS & Zonal Controllers: Domain controllers for L2+/L3 autonomy — certified to AEC-Q200 Grade 2 (with appropriate derating) and supporting functional safety (ISO 26262 ASIL-B ready).
Development & Design Notes
🔧 PCB Layout Best Practices:
- Use ≥ 6-layer board with dedicated power/ground planes — place VIN and VOUT capacitors directly under module pads using via-in-pad;
- Implement thermal vias (≥ 36, 0.3 mm diameter) under the exposed thermal pad — connect to ≥ 400 mm² internal ground plane for optimal heat dissipation;
- Keep PMBus traces short and differential — route SDA/SCL as matched-length 50 Ω microstrips with 100 Ω differential impedance.
🔧 Power & Thermal Management:
- For 26 A continuous operation: use 2 oz copper (70 µm) on top/bottom layers and ≥ 4 internal planes — ensures < 40°C temperature rise;
- Derate output current above 85°C ambient: ～13 A @ 25°C → ～10 A @ 100°C → ～7 A @ 125°C (see datasheet Fig. 8);
- Add NTC thermistor (e.g., NCP15XH103D03RC) on PCB near module — enables remote temperature telemetry and improved thermal modeling.
🔧 PMBus Configuration & Firmware Tips:
- Use ADI’s LTpowerPlay® GUI for drag-and-drop configuration, real-time telemetry plotting, and fault log analysis — no coding required;
- Enable “Auto-Phase” mode for automatic channel interleaving and ripple cancellation;
- Program “Fast-Transient Mode” (bit 6 of MFR_SPECIAL_FUNCTIONS) to optimize response for CPU/GPU load steps.
🔧 System-Level Integration Tips:
- In multi-module systems: daisy-chain PMBus lines (using pull-up resistors only at master end) — reduces pin count and routing complexity;
- Pair with ADI’s LT86xx Silent Switcher® controllers for auxiliary rails (e.g., 3.3 V, 5 V) — shares common layout guidelines and thermal design practices;
- For safety-critical apps: configure OV/UV/OC/OT limits with hysteresis, enable “Fault Response = LATCH”, and use black-box log for root-cause analysis.
