Monolithic Power Systems Inc. MP18851-A4BGY-P

Overview

MP18851-A4BGY-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 drives high-side and low-side power switches in isolated half-bridge topologies using capacitive isolation, supporting up to 30V secondary-side supply and operating across –40°C to +125°C for offline AC/DC and isolated DC/DC converters.

For engineers reviewing the MP18851-A4BGY-P datasheet, MP18851-A4BGY-P pinout, MP18851-A4BGY-P application, or MP18851-A4BGY-P equivalent, key selection criteria include its SOIC-16 WB package with 5kVRMS UL 1577 isolation, 3V UVLO threshold on output supplies, dual independent input logic (INA/INB), and functional isolation between secondary-side drivers (1500VDC).

Technical Context

The MP18851-A4BGY-P implements MPS's proprietary capacitive-based isolation barrier between primary and secondary sides, enabling reinforced insulation (UL 1577, VDE 0884-17) and CMTI >100kV/µs. Its dual-channel architecture supports fully independent control of two gate drivers-each with separate VDDA/VSSA and VDDB/VSSB supplies-allowing flexible configuration as half-bridge HS/LS or dual independent drivers.

Input-side logic accepts TTL/CMOS-compatible signals (2.8V–5.5V VDDI), while secondary-side supplies tolerate 4.2V–30V with selectable UVLO thresholds (3V for -A variant). The device integrates internal pull-downs on INA/INB and pull-up on EN, with DIS pin offering complementary enable/disable logic.

Key Specifications

Pinout & Package

MP18851-A4BGY-P is supplied in a SOIC-16 wide-body (WB) package with 1.27mm pitch, 10.3mm × 7.5mm footprint, and creepage/clearance ≥8mm between primary and secondary sides per safety standards.

Key Features

Applications

Equivalent & Alternatives

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

Compared with Si823Hx and ADuM4223, MP18851-A4BGY-P uniquely combines 5kVRMS isolation, >100kV/µs CMTI, dual independent inputs, and 3V UVLO - making it optimal for high-reliability SiC/GaN converters requiring precise timing and robust noise immunity.

Availability

MP18851-A4BGY-P is available at Aetrix Electronics and suitable for offline AC/DC adapters, isolated DC/DC modules, and solar inverter gate drive stages requiring stable component supply, long-term lifecycle assurance, and certified reinforced isolation.

Supply support for MP18851-A4BGY-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 converters, gate drivers, and motor drivers.

The MP18851 product line delivers isolated dual-channel gate drivers optimized for high-efficiency, high-density power conversion systems - targeting SiC/GaN-based industrial, telecom, and renewable energy applications where timing precision and noise immunity are critical.

FAQ

What does the "-A4BGY" suffix indicate in MP18851-A4BGY-P?

The "-A" denotes 3V output UVLO threshold, "4" indicates 4A peak output current, "B" specifies the 5V input UVLO option, "GY" identifies the SOIC-16 wide-body package, and "-P" is the tape-and-reel packaging indicator. This exact variant is rated for 3V VDDA/VDDB UVLO and 5V VDDI UVLO.

Can MP18851-A4BGY-P drive both high-side and low-side switches in a half-bridge without external bootstrap components?

Yes - its fully isolated dual outputs (VSSA/OUTA/VDDA and VSSB/OUTB/VDDB) allow direct connection to high-side and low-side power devices with independent ground references. No bootstrap diodes or capacitors are needed, unlike non-isolated drivers.

How does the EN and DIS pin logic differ, and which should be used for system shutdown?

EN is active-high with internal pull-up; DIS is active-high with internal pull-down. Either can disable outputs, but DIS is preferred for fail-safe shutdown because pulling DIS high guarantees disable even if EN is floating or misconfigured - aligning with IEC 61508 functional safety principles.

What is the maximum recommended PCB trace length between VDDA and VSSA for stable gate drive?

MPS recommends placing the 0.1µF ceramic bypass capacitor within 2mm of VDDA and VSSA pins. Trace inductance must be minimized - total loop inductance should remain below 10nH to prevent ringing during 4A switching transitions, especially with GaN FETs.

Does MP18851-A4BGY-P support negative gate drive for enhanced SiC MOSFET turn-off?

No - the output stage is designed for positive-only gate drive (VSSA/VSSB as reference). It does not provide negative voltage capability; for negative turn-off, an external charge pump or split-rail supply referenced to VSSA/VSSB is required.

Is the 5kVRMS isolation rating valid for continuous operation or only for safety testing?

The 5kVRMS rating is a dielectric withstand voltage validated per UL 1577 for 60 seconds during qualification. For continuous operation, the maximum working voltage is 630VRMS (VIOWM), as certified per VDE 0884-17 - this defines the safe long-term AC stress limit.

How does thermal derating affect output current at 105°C ambient temperature?

At TA = 105°C, SOIC-16 WB package derates to ~65mA per channel safety current (VDDA/VDDB = 12V), limiting usable peak current to ~3.2A in sustained high-temp operation. Layout with 2oz copper and thermal vias is essential to maintain performance.