Monolithic Power Systems Inc. MP18851-A4BGSE-P

Overview

MP18851-A4BGSE-P from Monolithic Power Systems is an isolated, dual-input, independent dual-channel gate driver IC with 4A peak source/sink current per channel, 50ns typical propagation delay, and >100kV/µs common-mode transient immunity (CMTI). It uses capacitive isolation to achieve 5kVRMS input-to-output withstand voltage (UL 1577) in SOIC-16 WB package and supports half-bridge or dual independent configurations for high-efficiency isolated DC/DC converters.

For engineers reviewing the MP18851-A4BGSE-P datasheet, MP18851-A4BGSE-P pinout, MP18851-A4BGSE-P application, or MP18851-A4BGSE-P equivalent, this device delivers verified functional isolation between secondary-side drivers (1500VDC), configurable UVLO thresholds (5V option), TTL/CMOS-compatible inputs, and dual independent enable/disable control - critical for robust power stage design in offline AC/DC and motor drive systems.

Technical Context

The MP18851-A4BGSE-P implements MPS's proprietary capacitive isolation barrier separating primary-side logic control (VDDI = 2.8–5.5V) from two fully independent secondary-side driver channels, each with dedicated VDDA/VSSA and VDDB/VSSB supplies up to 30V. Its dual-input architecture accepts separate INA/INB signals with internal pull-downs, while EN/DIS pins provide complementary enable logic.

Each output channel features matched propagation delay (±6ns max), <6ns pulse-width distortion, and 10–20ns rise/fall times into 1.8nF load. The A4B variant specifies 5V output-side UVLO threshold, enabling stable operation with 6.5–30V secondary supply range and integrated under-voltage lockout on all supply rails.

Key Specifications

Pinout & Package

MP18851-A4BGSE-P is supplied in SOIC-16 wide-body (WB) package, providing 5kVRMS isolation and 8mm minimum creepage/clearance. Pin functions are validated per MPS MP18851 Rev. 1.0 datasheet (pp. 6–7).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-channel isolated gate driver applications.

Compared with Si823H4BD-IS and ADUM4223BRIZ, MP18851-A4BGSE-P uniquely combines dual independent enable/disable control, selectable 5V output UVLO, and 1500VDC inter-channel isolation - enabling safer, more flexible power stage supervision in high-reliability industrial inverters and server PSUs.

Availability

MP18851-A4BGSE-P is available at Aetrix Electronics and suitable for half-bridge motor drives, isolated DC/DC converters, and offline AC/DC power supplies requiring stable component supply, long-term lifecycle support, and certified safety isolation.

Supply support for MP18851-A4BGSE-P 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 power management ICs, with over 20 years of expertise in DC/DC conversion, gate driving, and isolation technologies.

The MP18851 product line delivers isolated dual-channel gate drivers optimized for high-density, high-efficiency power conversion systems including server PSUs, EV chargers, and industrial motor drives - emphasizing robustness, timing precision, and safety compliance.

FAQ

What is the function of the EN and DIS pins on MP18851-A4BGSE-P? The EN pin is active-high with internal pull-up; asserting it enables both output channels. The DIS pin is active-high with internal pull-down; asserting it disables both outputs. They provide complementary control for system-level fault response and power sequencing without external logic.

Does MP18851-A4BGSE-P support half-bridge configuration?

Yes - the device supports half-bridge mode by connecting VSSA to the switch node and VSSB to power ground (or vice versa), while routing OUTA to high-side FET gate and OUTB to low-side FET gate. Its independent secondary grounds and matched timing ensure shoot-through prevention.

What is the significance of the "A4B" suffix in MP18851-A4BGSE-P?

The "A4B" denotes the UVLO configuration: "A" indicates dual-input logic (INA/INB), "4" specifies 4A peak current, and "B" selects the 5V output-side UVLO threshold (6.5–30V operational range), distinguishing it from A4A (3V), A4C (8V), etc.

Can MP18851-A4BGSE-P drive GaN HEMTs effectively?

Yes - its 4A peak source/sink current, 10–20ns rise/fall times into 1.8nF, and 50ns propagation delay meet the dynamic gate drive requirements of enhancement-mode GaN FETs used in high-frequency totem-pole PFC and LLC converters.

How does the capacitive isolation in MP18851-A4BGSE-P compare to transformer-based isolators?

MPS's capacitive isolation provides higher CMTI (>100kV/µs), smaller die area, and better high-frequency timing consistency than magnetic coupling. It achieves 5kVRMS withstand and 1500VDC inter-channel isolation without air gaps or windings, enabling compact SOIC-16 WB packaging.

Is thermal derating required for continuous operation at 125°C ambient?

Yes - at TA = 125°C, SOIC-16 WB safety power dissipation drops to ~1100mW per channel (per Fig. 14). Designers must limit switching frequency, load capacitance, and supply voltage to stay within derated limits and avoid thermal shutdown.