Monolithic Power Systems Inc. MP38900DL-B-Z

Overview

MP38900DL-B-Z from Monolithic Power Systems is a high-efficiency, fast-transient, 10A synchronous step-down converter in a QFN20 (3×4mm) package. It integrates 27mΩ high-side and 10mΩ low-side MOSFETs, operates from 4.5V–16V input, delivers adjustable 0.8V–13V output, and uses Constant-On-Time (COT) control for rapid load-step response in notebook I/O and POL systems.

For engineers reviewing the MP38900DL-B-Z datasheet, MP38900DL-B-Z pinout, MP38900DL-B-Z application, or MP38900DL-B-Z equivalent, key selection criteria include its built-in 5V VCC regulator, hiccup-mode over-current protection, Hi-Z shutdown behavior, 1% reference voltage accuracy, and thermal shutdown with 25°C hysteresis - all critical for reliable point-of-load power delivery in space-constrained designs.

Technical Context

The MP38900DL-B-Z employs proprietary Constant-On-Time (COT) control with line feed-forward via the FREQ pin, enabling stable regulation and sub-100ns minimum off-time across wide VIN and load ranges. Its internal 5V VCC regulator eliminates external biasing, while integrated power MOSFETs support continuous 10A output with minimal external components.

Protection architecture includes cycle-by-cycle current limiting (16.5A threshold), hiccup-mode OCP/SCP recovery, 0.7×VFB undervoltage detection, 1.25×VFB overvoltage lockout, and thermal shutdown at 150°C with 25°C hysteresis - ensuring robust operation under fault conditions without latch-off.

Key Specifications

Pinout & Package

MP38900DL-B-Z is housed in a thermally enhanced QFN20 (3×4mm, 0.5mm pitch) package with exposed thermal pad (Pin 11–16 PGND). The layout prioritizes low-inductance power paths: IN (Pins 8,19), SW (Pins 9,10,17,18), and PGND (Pins 11–16) are grouped for optimal current return and thermal dissipation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous step-down converter applications.

Compared with MP38900DL-B-Z, MPQ38900-AF-P adds automotive qualification and thermal margin at identical performance, while MP2315GJ-Z trades current capability, protection depth, and integration for smaller size and lower IQ - making them non-interchangeable outside their specific design envelopes.

Availability

MP38900DL-B-Z is available at Aetrix Electronics and suitable for notebook I/O power, networking POL rails, optical module biasing, and distributed industrial power systems requiring stable component supply throughout product lifecycles.

Supply support for MP38900DL-B-Z includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Monolithic Power Systems (MPS) is a fabless semiconductor company specializing in high-performance analog and power ICs, with over two decades of leadership in DC/DC conversion technology.

The MP38900 series belongs to MPS's high-current synchronous buck converter product line, engineered specifically for compact, high-efficiency point-of-load regulation in computing, communications, and optical infrastructure where fast transient response and thermal resilience are critical.

FAQ

What is the function of the FREQ pin on MP38900DL-B-Z?

The FREQ pin sets the switching frequency via an external resistor to IN, enabling line feed-forward for stable COT operation. Its value determines ON-time per cycle: t_ON ≈ 0.45 × (V_IN − V_OUT) × R7 + 12ns. This allows designers to optimize between efficiency, EMI, and inductor size without changing control loop compensation.

How does MP38900DL-B-Z handle pre-biased outputs during startup?

MP38900DL-B-Z supports pre-biased outputs because its MP38900-B variant disables soft-stop: when EN goes low, the SS pin is actively pulled low instead of discharging slowly. This prevents reverse current flow into the output capacitor, avoiding potential damage or system instability during hot-swap or multi-rail sequencing.

What is the difference between OCP latch-off and hiccup mode in MP38900DL-B-Z?

MP38900DL-B-Z uses hiccup-mode OCP: upon current limit violation, it shuts down, waits ~10ms, then attempts restart. If fault persists, it repeats. This contrasts with latch-off (used in MP38900), which requires full power cycle. Hiccup mode enables autonomous recovery in intermittent overload scenarios common in networking and optical systems.

Why does MP38900DL-B-Z specify both VCC and VIN UVLO thresholds?

MP38900DL-B-Z has separate UVLO circuits: VIN UVLO (3.8–4.2V rising) ensures input rail stability before enabling switching, while VCC UVLO (not applicable here, since VCC is internally generated) is omitted - the device relies solely on VIN monitoring. The datasheet notes VIN UVLO applies to MP38900-B variants, confirming this behavior is intentional for self-biased operation.

Can MP38900DL-B-Z operate with ceramic output capacitors without external ramp compensation?

No - with low-ESR ceramic capacitors, the MP38900DL-B-Z requires external ramp compensation (R4/C4 network) on the FB pin to ensure PWM-mode stability. Without it, insufficient VFB ripple slope causes jitter and potential subharmonic oscillation. The ramp must satisfy equation-based criteria (e.g., R4 × C4 < 1/(2π × f_SW × 5 × R1//R2)) to maintain noise immunity and loop stability.

What thermal resistance values apply to MP38900DL-B-Z in its QFN20 package?

MP38900DL-B-Z exhibits θ_JA = 48°C/W and θ_JC = 10°C/W when mounted on a JEDEC-standard 4-layer PCB per JESD51-7. These values assume proper thermal pad soldering to a solid copper pour with ≥6 thermal vias - achieving ≤125°C junction temperature at 10A/12V→1.2V requires ≥2.5cm² of 2oz copper on the bottom layer.