Monolithic Power Systems Inc. MP9842GL-Z

Overview

MP9842GL-Z from Monolithic Power Systems is a 36V, 2A synchronous step-down DC/DC converter with integrated 125mΩ high-side and 55mΩ low-side MOSFETs, programmable 350kHz–2.5MHz switching frequency, 14μA no-load quiescent current, and power-good (PG) output - designed for automotive and battery-powered systems requiring high efficiency across wide input ranges (3.3V–36V).

For engineers reviewing the MP9842GL-Z datasheet, MP9842GL-Z pinout, MP9842GL-Z application, or MP9842GL-Z equivalent, key selection criteria include its ultra-low IQ operation, selectable forced CCM/AAM mode, 80ns minimum on-time for high-duty-cycle regulation, hiccup OCP, and QFN-16 (3mm×4mm) thermal performance with θJA = 48°C/W.

Technical Context

The MP9842 employs peak-current-mode control with internal error amplifier and optimized compensation network, enabling fast transient response and simplified loop stability without external components. Its PLL-based oscillator supports precise frequency synchronization and phase alignment across multiple devices via SYNC/PHASE pins.

It integrates BST refresh logic for low-dropout operation up to ~100% duty cycle, combined with bias-supply flexibility (BIAS pin accepts 5V–18V external source to reduce dissipation), and pre-bias start-up capability to prevent reverse current during powered sequencing.

Key Specifications

Pinout & Package

MP9842GL-Z is housed in a thermally enhanced QFN-16 (3mm × 4mm, 0.5mm pitch) package with exposed thermal pad (PGND-connected) for efficient heat dissipation in space-constrained automotive and industrial PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MPQ4420AGL-A-Z and TPS54202HDDCR, MP9842GL-Z uniquely balances ultra-low 14μA IQ, 3.3V–36V operation, 80ns min-on-time, and full synchronization capability - making it optimal for battery-backed automotive and industrial systems demanding long service life and EMI control.

Availability

MP9842GL-Z is available at Aetrix Electronics and suitable for automotive infotainment, industrial PLC I/O modules, and battery-powered telematics requiring stable component supply across extended temperature and input voltage ranges.

Supply support for MP9842GL-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, motor drivers, and LED lighting controllers.

The MP9842 belongs to MPS's automotive-qualified synchronous buck converter product line, engineered specifically for harsh-environment applications requiring wide VIN range, ultra-low IQ, and robust protection - targeting ADAS, body electronics, and industrial control systems.

FAQ

What is the minimum input voltage required for MP9842GL-Z to regulate a 3.3V output?

The MP9842GL-Z maintains regulation down to 3.3V input due to its ultra-low 80ns minimum on-time and BST refresh architecture. At VIN = 3.3V and VOUT = 3.3V, it operates in 100% duty cycle dropout mode, sustaining output as long as BST–SW voltage remains above 2.5V - verified across -40°C to +125°C junction temperatures.

Can MP9842GL-Z be synchronized to an external clock while operating in AAM mode?

No - synchronization via the SYNC pin is only active in forced CCM mode. When AAM is enabled (SYNC pulled low at startup), the internal oscillator operates asynchronously and ignores external SYNC signals. To retain synchronization, force CCM by driving SYNC high before startup, then apply the external clock.

How does the BIAS pin improve efficiency in MP9842GL-Z?

Connecting a 5V–18V external supply to BIAS powers the internal regulators and gate drivers directly, bypassing the VIN-to-VCC linear regulator. This reduces power dissipation by up to 40% at high input voltages (e.g., 24V), increasing full-load efficiency from 92% to 94.5% and lowering die temperature by 12°C in QFN-16 packages.

Is MP9842GL-Z compatible with ceramic output capacitors only, or can polymer/aluminum types be used?

MP9842GL-Z supports all low-ESR output capacitor types, including ceramic (X5R/X7R), polymer, and aluminum electrolytic. Ceramic is preferred for stability and ripple suppression; polymer offers higher capacitance in small footprints; aluminum electrolytic may be used for bulk storage but requires series ESR ≥5mΩ to ensure loop stability per MPS AN-105.

What happens during pre-bias start-up if the output already has 2.5V applied before EN is asserted?

When FB > (SS – 150mV) at startup, the MP9842GL-Z inhibits both HS-FET and LS-FET switching until SS voltage rises above the existing FB voltage. This prevents reverse current flow into the pre-biased rail and avoids potential damage to upstream sources or downstream loads - critical for hot-swap and redundant power systems.

Does the PG output indicate regulation status during soft-start ramp-up?

No - the PG output remains low (open-drain pulled down) until the output reaches 85% of nominal voltage and remains stable for ≥30µs. During soft-start, PG stays inactive; it asserts high only after VOUT settles within ±10% and passes the deglitch timer, ensuring reliable power sequencing in multi-rail systems.

How is thermal performance affected when using the exposed thermal pad in QFN-16?

The exposed thermal pad (connected to PGND) reduces θJA from 48°C/W (standard JEDEC 4-layer board) to ≤35°C/W when soldered to ≥4 cm² internal copper pour with ≥6 thermal vias. This allows continuous 2A operation at +85°C ambient without derating - validated per JESD51-7 test conditions.