Monolithic Power Systems Inc. MCS1805GS-340-B-P

Overview

MCS1805GS-340-B-P from Monolithic Power Systems is a bidirectional linear Hall-effect current sensor IC with galvanic isolation, ±40A sensing range, 33 mV/A sensitivity, 3kVRMS isolation voltage, and integrated over-current detection (OCD) with 1µs response time. It replaces optoisolators in motor control and power supply current monitoring where high accuracy, noise immunity, and compact SOIC-8 footprint are required.

For engineers reviewing the MCS1805GS-340-B-P datasheet, MCS1805GS-340-B-P pinout, MCS1805GS-340-B-P application, or MCS1805GS-340-B-P equivalent, this page delivers verified specifications including ±2.5% total output error, 120kHz bandwidth, differential magnetic field rejection, ratiometric VOUT, and OCD threshold set to 100% of IPMAX (±40A) - critical for safety-critical current sensing in industrial and automotive systems.

Technical Context

The MCS1805GS-340-B-P employs a differential Hall array to cancel stray magnetic fields and uses spinning current technique for ultra-low offset drift. Its primary conductor (1.2 mΩ) carries up to ±40A while maintaining 3kVRMS isolation between power and signal domains per IEC 62368-1.

It integrates fast open-drain /OCD output with 1µs response and supports 3.3V single supply (3.0–3.6V), delivering ratiometric analog output (VOUT = VCC/2 ±13.2V at ±40A) with 100 µA/√Hz input-referred noise density and 0.5% nonlinearity across full scale.

Key Specifications

Pinout & Package

Package: SOIC-8 (5mm × 4mm), surface-mount, RoHS-compliant, MSL Level 1. Galvanically isolated construction separates primary current path (pins 1–4) from signal domain (pins 5–8).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar isolated current sensing applications.

Compared with ACS724LLCTR-40AB-T and TMCS1108A4U, the MCS1805GS-340-B-P uniquely combines 3kVRMS isolation, 1µs OCD, ±2.5% error, and SOIC-8 packaging - making it optimal for space-constrained, safety-critical 40A current sensing where integrated fault signaling is mandatory.

Availability

MCS1805GS-340-B-P is available at Aetrix Electronics and suitable for motor control, switch-mode power supplies, automotive traction inverters, and over-current fault protection requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for MCS1805GS-340-B-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 design focus on efficiency, integration, and reliability for industrial, automotive, and computing applications.

The MCS1805 product line delivers isolated Hall-effect current sensors optimized for real-time, high-accuracy current measurement in next-generation power electronics - emphasizing low noise, fast fault response, and seamless optocoupler replacement.

FAQ

What is the default OCD threshold for MCS1805GS-340-B-P?

The default OCD threshold is set to 100% of IPMAX (±40A), meaning /OCD asserts when instantaneous current exceeds ±40A. This is factory-configured and does not require external programming or resistor networks. Threshold hysteresis is 3–12% of the OCD level to prevent chatter during transient overloads.

Can MCS1805GS-340-B-P measure unidirectional current?

No - the "B" suffix denotes bidirectional operation (±40A range). For unidirectional sensing (0–40A), the correct part is MCS1805GS-340-U-P, which has different zero-current output (0.1×VCC) and sensitivity (66 mV/A). Using the -B variant for unidirectional applications results in reduced dynamic range and potential saturation near 0A.

What is the maximum continuous primary current the device can handle?

The MCS1805GS-340-B-P supports continuous ±40A primary current with a 1.2 mΩ internal conductor resistance, resulting in ≤2W power dissipation at full scale. Thermal derating is required above +105°C ambient; maximum junction temperature is 165°C, and surge current rating is 3000A (8/20µs pulse).

Does the device require external calibration for accuracy?

No - the MCS1805GS-340-B-P is factory-trimmed for sensitivity, offset, and linearity. Total output error remains within ±2.5% over -40°C to +125°C without user calibration. Ratiometric output (VOUT proportional to VCC) further eliminates supply voltage drift effects in precision systems.

How is galvanic isolation achieved in this package?

Isolation is achieved through internal mold compound and physical separation of primary (pins 1–4) and secondary (pins 5–8) leads, with 4.2mm creepage and clearance. It is type-tested to 3000 VRMS per IEC 62368-1 and 100% production-tested - no internal transformers or capacitors are used; magnetic coupling occurs solely through the Hall effect across the isolation barrier.

What bypass capacitor value is recommended on VCC?

A ceramic capacitor of 0.1 µF to 1 µF must be placed between VCC (pin 8) and GND (pin 5), located as close as possible to the device. This suppresses high-frequency noise and stabilizes the internal regulator during fast OCD transitions and load transients.

Is the /OCD pin compatible with 5V logic systems?

No - /OCD is an open-drain output referenced to the device's VCC (3.3V). To interface with 5V logic, an external level-shifting circuit (e.g., transistor or dedicated level shifter) is required. Direct connection to 5V may damage the output stage due to exceeding absolute maximum ratings.