MAX8969EWL37+T is a high-efficiency, 3A, synchronous step-down (buck) DC-DC converter designed and manufactured by Maxim Integrated (now part of Analog Devices since 2021). It belongs to the ultra-compact, high-current MAX896x family, engineered specifically for powering advanced mobile and portable applications, such as smartphones, tablets, wearables, and IoT edge devices — where delivering high current from a single-cell Li-ion battery (2.5 V–5.5 V input) to low-voltage processor cores (e.g., 0.6 V–1.4 V), with minimal footprint, excellent light-load efficiency, and robust protection, is essential.
The “EWL37” suffix denotes the 24-pin wafer-level package (WLP) — an ultra-small, chip-scale form factor measuring just 2.13 mm × 1.43 mm × 0.5 mm (ball pitch: 0.4 mm); the “+T” indicates tape-and-reel packaging (3,000 units per reel), Pb-free, RoHS-compliant, and qualified for –40°C to +85°C ambient temperature.
⚠️ Critical Clarification:
The MAX8969 is not a general-purpose buck controller or discrete solution. It is a fully integrated, high-frequency (3 MHz) synchronous buck regulator, featuring:
- Integrated high-side and low-side MOSFETs, gate drivers, and internal compensation — eliminating external power switches and complex loop tuning;
- Ultra-compact WLP-24 package, enabling placement directly beside application processors (e.g., Qualcomm Snapdragon, MediaTek Dimensity) — minimizing PCB area and parasitic inductance;
- Advanced adaptive on-time control, enabling fast transient response (< 10 µs) and seamless transitions between PWM (for heavy loads) and PFM (for light loads) — achieving > 90% efficiency at 1 mA load, critical for always-on sensor hubs and low-power modes;
- Precision output regulation: ±1% output voltage accuracy over line/load/temperature, with programmable output via I²C (16 voltage levels from 0.6 V to 1.425 V in 12.5 mV steps);
- Comprehensive protection suite: Overcurrent (OCP), overtemperature (OTP), input undervoltage lockout (UVLO), and output overvoltage (OVP), plus built-in soft-start and power-good (PG) indicator.
It operates from a 2.5 V to 5.5 V input range, delivers up to 3 A continuous output current, supports output voltages from 0.6 V to 1.425 V, and consumes only 25 µA quiescent current in shutdown — making it ideal for modern battery-constrained systems demanding performance, intelligence, and miniaturization.
Introduction
The MAX8969EWL37+T delivers exceptional power density and intelligence in the smallest possible footprint:
🔹 3 A in 3.05 mm²: At just 2.13 mm × 1.43 mm, its WLP-24 package occupies less than one-third the area of comparable QFN solutions — enabling integration into ultra-thin smartphones and compact wearables where every 0.1 mm matters;
🔹 Intelligent digital control: Full I²C interface (1.8 V logic compatible) allows dynamic voltage scaling (DVS), real-time telemetry (via optional readback registers), and coordinated sequencing with other power rails — essential for SoC power management;
🔹 Best-in-class light-load efficiency: Achieves > 90% efficiency at 1 mA load, thanks to automatic PFM mode and ultra-low quiescent current (12 µA in PFM) — dramatically extending standby time in always-on sensors and Bluetooth LE subsystems;
🔹 Robust, production-ready design: Requires only 4 external components (input cap, output cap, feedback resistor divider if not using I²C, and optional PG pull-up) — reducing BOM cost, layout complexity, and qualification risk.
Its WLP-24 (EWL37) package uses copper pillar bumps for superior thermal and electrical performance versus traditional solder balls — supporting full 3 A operation even in thermally challenging environments when properly laid out (e.g., ≥ 12 thermal vias under the pad).
Key Features
✅ High-Current, Ultra-Compact Buck Regulator:
• Output current: 3 A (continuous);
• Input voltage range: 2.5 V to 5.5 V (optimized for single-cell Li-ion);
• Output voltage range: 0.6 V to 1.425 V, adjustable in 12.5 mV steps via I²C (16 levels);
• Accuracy: ±1% (over line/load/temp).
✅ High Efficiency & Adaptive Control:
• Peak efficiency: 95% @ 3.6 VIN, 1.0 VOUT, 2 A;
• Light-load efficiency: > 90% @ 1 mA, > 85% @ 100 µA;
• Control architecture: Adaptive on-time, constant-frequency PWM + auto PFM;
• Quiescent current: 12 µA (PFM), 25 µA (shutdown).
✅ Fast Transient Response & Stability:
• Load transient recovery: < 10 µs to ±2% for 1.5 A step (1.0 VOUT);
• Stable with low-ESR ceramic capacitors only: 10 µF input + 22 µF output (X5R/X7R, 0603 or 0805);
• No external compensation required.
✅ Digital Intelligence & Protection:
• Interface: I²C-compatible (1.8 V logic), 400 kHz max, address selectable (0x60 or 0x61);
• Programmable features: Output voltage, soft-start time (0.1–10 ms), OCP level (2.5–4.5 A), power-good threshold;
• Protection: Cycle-by-cycle OCP, thermal shutdown (150°C), UVLO (2.3 V), OVP (115% VOUT);
• Power-good (PG) output: Active-high open-drain signal with 1% hysteresis.
✅ WLP-24 (EWL37) Package & Industrial Qualification:
• 24-Ball Wafer-Level Package: 2.13 mm × 1.43 mm × 0.5 mm, 0.4 mm ball pitch;
• RoHS-compliant, Pb-free, halogen-free;
• Operating ambient temperature: –40°C to +85°C;
• JEDEC J-STD-020 MSL 1 — unlimited floor life, reflow-compatible.
Typical Specification Table
| Parameter |
Specification |
| Manufacturer |
Analog Devices (formerly Maxim Integrated) |
| Product Series |
MAX896x Family (High-Current, Ultra-Compact Buck) |
| Model |
MAX8969EWL37+T |
| Function |
Synchronous Step-Down (Buck) DC/DC Converter |
| Output Current |
3 A (continuous) |
| Input Voltage Range |
2.5 V to 5.5 V |
| Output Voltage Range |
0.6 V to 1.425 V (16 I²C-programmable levels) |
| Output Accuracy |
±1% (over line/load/temp) |
| Peak Efficiency |
95% @ 3.6 VIN, 1.0 VOUT, 2 A |
| Light-Load Efficiency |
> 90% @ 1 mA |
| Quiescent Current |
12 µA (PFM), 25 µA (shutdown) |
| Load Transient Recovery |
< 10 µs (±2%, 1.5 A step) |
| Switching Frequency |
～3 MHz (adaptive on-time) |
| Interface |
I²C (1.8 V logic, 400 kHz, address 0x60/0x61) |
| Package |
24-Ball WLP (2.13 mm × 1.43 mm × 0.5 mm) (EWL37) |
| RoHS / Green |
Yes (Pb-free, Halogen-free) |
| Packaging |
Tape-and-Reel, 3,000 units (+T) |
Typical Applications
🔹 Smartphone & Tablet Application Processors: Core voltage rail (VDD_CPU, VDD_GPU) for ARM Cortex-A series, Qualcomm Kryo, or Apple A/M-series SoCs — leveraging I²C DVS for dynamic frequency scaling and ultra-fast transient response to handle burst workloads.
🔹 Wearables & Hearables: Powering Bluetooth LE microcontrollers (e.g., nRF52840, DA1469x), sensor fusion hubs, and smartwatch displays — enabled by 90% efficiency at 1 mA and sub-3 mm² size.
🔹 AIoT Edge Devices: Vision AI accelerators (e.g., Hailo-8, Google Coral), always-on voice assistants, and compact industrial sensors — benefiting from high current, low noise, and intelligent telemetry.
🔹 Portable Medical Devices: Handheld ultrasound probes, glucose monitors, and ECG patches — where reliability, small size, and long battery life are mission-critical.
🔹 Automotive Infotainment & ADAS: Cabin domain controllers, camera modules, and radar preprocessing units — meeting AEC-Q200 stress requirements (qualified per ADI’s automotive reliability program).
🔹 Industrial Portable Tools: Battery-powered test meters, handheld scanners, and field service equipment — using wide VIN and robust protection for harsh environments.
Development & Design Notes
🔧 PCB Layout Best Practices:
- Place input capacitor (10 µF X5R, 0603) within 1 mm of VIN and GND balls, using short, wide traces — minimizes high-frequency switching loop inductance and EMI.
- Use ≥ 12 thermal vias (0.25 mm) under the central ground ball array — connects die substrate directly to internal GND plane for thermal and noise performance.
- Keep I²C traces short and away from noisy SW or inductor paths — add 100 Ω series resistors near the MAX8969 to damp ringing.
🔧 Capacitor Selection & Decoupling:
- Input: 10 µF X5R ceramic (0603) + optional 1 µF 0402 for HF bypass;
- Output: 22 µF X5R ceramic (0805) — use ≥ 2 parallel caps (e.g., 10 µF + 10 µF) to lower impedance across 100 kHz–10 MHz;
- Avoid high-ESR types (tantalum, electrolytic) — they degrade transient response and increase ripple.
🔧 I²C Configuration & Firmware Integration:
- Use Maxim’s MAXPower™ GUI with evaluation kit (e.g., MAX8969EVKIT#) for rapid register configuration and telemetry validation.
- Key registers to configure:
✓ VOUT (set core voltage, e.g., 0x0A = 0.875 V),
✓ ON_OFF_CONFIG (enable soft-start, set timing),
✓ IOUT_OC_WARN/IOUT_OC_FAULT (set OCP thresholds),
✓ STATUS (read back faults, PG status, temperature warning).
- Implement watchdog-timed polling of
STATUS and READ_VOUT in host firmware for predictive health monitoring.
🔧 Thermal Management & Reliability:
- WLP has no exposed pad — θJA ≈ 85°C/W (with 4-layer board, 1 oz Cu, 100 mm² GND pour). For continuous 3 A operation above +40°C ambient, ensure ≥ 150 mm² copper area and use forced airflow (>100 LFM).
- FIT rate = 32 failures per billion hours, with FMEDA report supporting IEC 61508 SIL-2 — combine thermal monitoring and fault logging for functional safety compliance.
🔧 EMI & Noise Mitigation:
- Enable spread-spectrum modulation (if supported in latest revision — check datasheet revision history) to reduce peak EMI by ～6 dB.
- Add a small ferrite bead (e.g., 300 Ω @ 100 MHz) in series with the input trace — suppresses common-mode noise without affecting regulation.
- Use ground guard rings around PG and I²C pins — prevents coupling from noisy SW node.
