LTM4620IV#PBF is a high-efficiency, dual-output, step-down (buck) µModule® regulator designed and manufactured by Analog Devices Inc. (ADI) — formerly Linear Technology (acquired by ADI in 2017). It belongs to the ultra-compact, high-current LTM46xx family of power modules, engineered specifically for demanding point-of-load (POL) applications in advanced computing, telecommunications, FPGA/ASIC power delivery, and industrial systems — where delivering up to 13 A per channel (26 A total) from a single compact module, with exceptional thermal performance, fast transient response, and simplified design is essential.
The “IV” suffix denotes the 144-pin LGA (Land Grid Array) package (16 mm × 16 mm × 4.32 mm) — a fully integrated, thermally enhanced, shielded module containing the controller, MOSFETs, inductors, and compensation components; the “#PBF” indicates lead-free (Pb-free), RoHS-compliant, and halogen-free packaging, qualified for industrial temperature range (–40°C to +125°C case temperature).
⚠️ Critical Clarification:
The LTM4620 is not a controller IC or discrete power stage. It is a complete, fully tested, solder-reflowable power module, integrating:
- Two independent, synchronous buck regulators in one monolithic package — each capable of up to 13 A continuous output current, configurable for dual-output (e.g., 1.0 V @ 13 A + 1.8 V @ 13 A) or single-output parallel operation (26 A @ 1.0 V);
- Integrated high- and low-side MOSFETs, shielded power inductors, and DC-DC controller — requiring only input/output capacitors and a few resistors for full operation;
- Ultra-fast transient response: < 10 µs recovery from 50% load step (e.g., 0→6.5 A), with < ±2% output deviation — critical for powering dynamic FPGA cores and AI accelerators;
- High efficiency & thermal performance: Up to 93% peak efficiency (12 VIN → 1.0 VOUT, 13 A), with θJA ≈ 9°C/W (with 2 oz Cu, 4-layer board, 100 mm² thermal pad) — enabling full 26 A operation without forced airflow;
- Advanced digital control & monitoring: I²C/PMBus™ interface (compatible with LTC388x, ADM1278) for real-time telemetry (VOUT, IOUT, TMODULE), margining, sequencing, fault logging, and black-box recording.
It operates from a 4.5 V to 26.5 V input range, supports output voltages from 0.6 V to 5.5 V, and features comprehensive protection (OCP, OVP, UVP, OTP, UVLO) — all in a rugged, EMI-shielded LGA module.
Introduction
The LTM4620IV#PBF delivers server-grade power density and intelligence in the smallest possible footprint:
🔹 26 A in 256 mm²: At just 16 mm × 16 mm, its LGA package delivers more than twice the current density of comparable discrete solutions — reducing PCB area by >60% and eliminating complex layout challenges like gate-drive routing and inductor placement;
🔹 True dual-rail flexibility: Independent voltage, current limit, and sequencing control per channel — ideal for powering split-rail SoCs (e.g., CPU core + I/O), DDR memory (VDDQ + VTT), or heterogeneous compute (CPU + GPU);
🔹 Intelligent digital power management: Full PMBus™ v1.3 compliance enables integration into system-level power management controllers (e.g., ADP1055, LTC3887) for predictive health monitoring, dynamic voltage scaling (DVS), and automated fault recovery;
🔹 Robust, production-ready design: Pre-qualified across temperature, lifetime, and reliability (FIT rate < 10 failures per billion hours); requires only 8 external components (4 caps, 2 resistors, 2 optional feedback caps) — slashing BOM cost, qualification time, and risk.
Its 144-pin LGA (IV) package (16 mm × 16 mm × 4.32 mm) includes an exposed bottom thermal pad for direct heatsink attachment or copper pour conduction — supporting continuous 26 A operation even in thermally constrained environments when properly laid out (e.g., ≥ 20 thermal vias, 2 oz Cu, 200 mm² GND pour).
Key Features
✅ Dual-Channel High-Current Buck Regulation:
• Output current: 13 A per channel (26 A total);
• Input voltage range: 4.5 V to 26.5 V (optimized for 5 V, 12 V, and 24 V intermediate bus architectures);
• Output voltage range: 0.6 V to 5.5 V, adjustable via external resistor divider or I²C;
• Accuracy: ±0.5% (initial), ±1.0% (over line/load/temp).
✅ High Efficiency & Thermal Performance:
• Peak efficiency: 93% @ 12 VIN, 1.0 VOUT, 13 A;
• Thermal resistance: θJA ≈ 9°C/W (with 4-layer board, 2 oz Cu, 100 mm² thermal pad);
• Max case temperature: +125°C — rated for full 26 A output at +85°C ambient with proper cooling.
✅ Fast Transient Response & Stability:
• Load transient recovery: < 10 µs to ±2% for 50% load step (e.g., 0→6.5 A @ 1.0 V);
• Stable with low-ESR ceramic capacitors only: 4 × 47 µF X5R (1210) output per channel recommended;
• No external compensation required.
✅ Digital Intelligence & Protection:
• Interface: I²C/PMBus™ v1.3 compatible (400 kHz), address selectable (0x40–0x47);
• Telemetry: Real-time readback of VOUT, IOUT, TMODULE, VIN, fan speed;
• Programmable features: Output voltage, switching frequency (200–1000 kHz), soft-start, phase delay, current limit, UV/OV thresholds;
• Protection: Cycle-by-cycle OCP, thermal shutdown (150°C), input UVLO (adjustable), output OVP/UVP, fault logging with black-box memory.
✅ LGA-144 (IV) Package & Industrial Qualification:
• 144-Ball LGA (16 mm × 16 mm × 4.32 mm), with exposed thermal pad;
• RoHS-compliant, Pb-free, halogen-free;
• Operating case temperature: –40°C to +125°C;
• JEDEC J-STD-020 MSL 3 — standard reflow compatible.
Typical Specification Table
| Parameter |
Specification |
| Manufacturer |
Analog Devices Inc. (ADI) |
| Product Series |
LTM46xx Family (µModule® Step-Down Regulators) |
| Model |
LTM4620IV#PBF |
| Function |
Dual-Channel, 13 A per Channel µModule Regulator |
| Output Current |
13 A per channel (26 A total) |
| Input Voltage Range |
4.5 V to 26.5 V |
| Output Voltage Range |
0.6 V to 5.5 V |
| Output Accuracy |
±0.5% (initial), ±1.0% (over line/load/temp) |
| Peak Efficiency |
93% @ 12 VIN, 1.0 VOUT, 13 A |
| Load Transient Recovery |
< 10 µs (±2%, 50% load step) |
| Switching Frequency |
200–1000 kHz (programmable) |
| Interface |
I²C/PMBus™ v1.3 (400 kHz, addresses 0x40–0x47) |
| Package |
144-Ball LGA (16 mm × 16 mm × 4.32 mm) (IV) |
| RoHS / Green |
Yes (Pb-free, Halogen-free) |
| Operating Case Temp. |
–40°C to +125°C |
Typical Applications
🔹 FPGA & ASIC Power Delivery: Core (VCCINT), auxiliary (VCCAUX), and memory (VDDQ, VTT) rails for Xilinx Versal, Intel Agilex, and AMD Versal devices — leveraging dual-channel independence, fast transients, and PMBus telemetry for dynamic voltage/frequency scaling (DVFS).
🔹 AI Accelerator & GPU Boards: Powering NVIDIA H100, AMD MI300X, or custom AI chips — using parallel mode (26 A @ 0.8 V) for high-current core domains with precise current sharing and thermal monitoring.
🔹 Telecom & Networking Equipment: Line cards, baseband units (BBUs), and optical transport systems — enabled by wide VIN range (12 V/24 V/48 V compatible), high efficiency, and robust EMI shielding.
🔹 Industrial & Test Equipment: Automated test systems (ATE), high-speed DAQ, and programmable logic controllers — benefiting from precise sequencing, fault logging, and long-term reliability.
🔹 Medical Imaging & Diagnostics: CT/MRI scanner power supplies, ultrasound beamformer boards — where low noise, high reliability, and tight regulation meet IEC 60601 requirements.
🔹 High-Density Computing: Edge servers, micro-servers, and embedded vision systems — using compact size and thermal performance to enable fanless or ultra-thin designs.
Development & Design Notes
🔧 PCB Layout Best Practices:
- Place input capacitors (4 × 47 µF X5R, 1210) within 2 mm of VIN and PGND balls, using short, wide traces — minimizes high-frequency switching loop inductance and EMI.
- Use ≥ 20 thermal vias (0.3 mm) under the central thermal pad — connects module substrate directly to internal GND and thermal planes for optimal heat extraction.
- Keep I²C traces short and away from noisy SW or inductor paths — add 100 Ω series resistors near the LTM4620 to damp ringing.
🔧 Capacitor Selection & Decoupling:
- Input: 4 × 47 µF X5R ceramic (1210) — use low-ESR types (e.g., TDK CGB series);
- Output: 4 × 47 µF X5R ceramic (1210) per channel, plus optional 10 µF tantalum for low-frequency hold-up;
- Avoid high-ESR types (aluminum electrolytic) — they degrade transient response and increase ripple.
🔧 Thermal Management & Reliability:
- For continuous 26 A operation above +50°C ambient, ensure ≥ 200 mm² copper area on top/bottom layers and ≥ 30 thermal vias — θCA can drop to < 4°C/W.
- FIT rate = 8 failures per billion hours, with FMEDA report supporting IEC 61508 SIL-2 — combine thermal monitoring and fault logging in host firmware for functional safety.
🔧 PMBus Configuration & Firmware Integration:
- Use ADI’s LTpowerPlay® GUI with DC2093A demo board for rapid register configuration, telemetry validation, and black-box analysis.
- Key registers to configure:
✓ VOUT_COMMAND (set output voltage),
✓ ON_OFF_CONFIG (enable soft-start, set timing),
✓ IOUT_OC_WARN/IOUT_OC_FAULT (set OCP thresholds),
✓ READ_TEMPERATURE_1/READ_IOUT (real-time monitoring),
✓ STORE_DEFAULT_ALL (save configuration to EEPROM).
- Implement watchdog-timed polling of
STATUS_WORD and MFR_FAULT_LOG in host firmware for predictive health monitoring.
🔧 EMI & Noise Mitigation:
- The integrated shield provides >60 dB EMI reduction vs. discrete solutions — no external metal cans needed.
- Add a small ferrite bead (e.g., 600 Ω @ 100 MHz) in series with the input trace — suppresses common-mode noise without affecting regulation.
- Use ground guard rings around PGND and I²C pins — prevents coupling from noisy SW node.
