Monolithic Power Systems Inc. MCS1806GS-5-20-P

Overview

MCS1806GS-5-20-P from Monolithic Power Systems is a galvanically isolated, bidirectional Hall-effect current sensor with 5V supply, ±20A optimized primary current range, ±2.5% total output error over -40°C to +125°C, and 3kVRMS isolation rating. It replaces optoisolators in motor control and power supply feedback loops by sensing AC/DC current via differential Hall plates integrated with a 0.9mΩ internal conductor.

For engineers reviewing the MCS1806GS-5-20-P datasheet, MCS1806GS-5-20-P pinout, MCS1806GS-5-20-P application, or MCS1806GS-5-20-P equivalent, key selection criteria include its ratiometric 100mV/A sensitivity, adjustable bandwidth up to 100kHz via external FILT capacitor, and SOIC-8 package compatibility with space-constrained industrial PCB layouts.

Technical Context

The MCS1806GS-5-20-P implements a spinning-current Hall array with two matched transducers (PMCF1 = 0.6mT/A, PMCF2 = 0.3mT/A) to cancel stray magnetic fields and eliminate hysteresis. Its internal 1.5kΩ filter resistor and 1nF capacitor enable bandwidth tuning from DC to 100kHz using an external CF capacitor on the FILT pin.

Galvanic isolation is achieved through reinforced insulation between primary current terminals (IP+, IP−) and signal pins (VCC, VOUT, FILT, GND), meeting IEC62368-1 with 3000VRMS withstand voltage and 500VRMS working voltage. Propagation delay is 1.5µs and response time is 5µs at full scale, supporting fast overcurrent fault detection in switch-mode power supplies.

Key Specifications

Pinout & Package

Package: SOIC-8 (5mm × 4mm), surface-mount, RoHS-compliant, MSL Level 1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ACS724LLCTR-20AB-T and TMC1100A1XUMA1, the MCS1806GS-5-20-P uniquely combines 3kVRMS isolation, SOIC-8 compactness, ratiometric stability, and user-adjustable bandwidth-making it optimal for thermally demanding, space-constrained industrial inverters.

Availability

MCS1806GS-5-20-P is available at Aetrix Electronics and suitable for motor controls, switch-mode power supplies, and automotive onboard chargers requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for MCS1806GS-5-20-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 centers in the US, China, and Taiwan.

The MCS1806 product line delivers isolated current sensing for high-efficiency power conversion systems, targeting applications where accuracy, thermal robustness, and compact isolation are critical-such as EV charging, industrial automation, and renewable energy inverters.

FAQ

What is the maximum continuous primary current the MCS1806GS-5-20-P can handle without exceeding junction temperature limits?

The device supports ±20A as its optimized linear range, but continuous operation beyond this depends on PCB thermal design. With the evaluation board layout and TA = 25°C, self-heating data shows ≤25°C rise at 20A DC after 10 minutes. At 30A, junction temperature approaches 125°C-so sustained >25A requires enhanced copper pour or forced air cooling to stay below 165°C absolute maximum.

How does the FILT pin affect bandwidth, and what capacitor value achieves 50kHz cutoff?

The FILT pin sets bandwidth via RC filtering with internal RFI = 1.5kΩ and CFI = 1nF. Using fBW = 1/(2π × RFI × (CF + CFI)), a 1.1nF external capacitor yields ~50kHz. For example, CF = 1.1nF gives total capacitance ≈ 2.1nF, resulting in fBW ≈ 1/(2π × 1500 × 2.1×10⁻⁹) ≈ 50.5kHz. Larger CF values reduce bandwidth and improve noise rejection.

Is the output truly ratiometric, and how does supply variation impact accuracy?

Yes-both sensitivity (KSENS = 98–102%) and zero-current output (KVO = 99–101%) track VCC across 4.5–5.5V. At VCC = 4.5V, nominal VOUT(Q) = 2.25V ±5mV; at 5.5V, it is 2.75V ±5mV. This ensures measurement integrity even with ±10% supply ripple, eliminating need for separate voltage reference in ADC systems.

Can the MCS1806GS-5-20-P measure DC currents down to 0A with usable resolution?

Yes-the input-referred noise is 50mA(RMS) with 1nF on FILT (60kHz BW), enabling resolution of ~100mA RMS at 20A range. Offset voltage drift is ±10mV over -40°C to +125°C, translating to ±100mA error at 100mV/A sensitivity. For sub-100mA DC measurements, external amplification or digital post-processing is recommended.

Does the SOIC-8 package meet creepage and clearance requirements for 500VRMS working voltage?

Yes-the package provides 4.2mm external creepage and clearance between primary (IP+/IP−) and signal (VCC/VOUT/GND/FILT) leads, satisfying IEC62368-1 requirements for basic insulation at 500VRMS working voltage. No additional slotting or conformal coating is required for standard PCB layouts meeting IPC-2221B spacing guidelines.

What is the recommended decoupling for the VCC pin, and why is placement critical?

A 1µF low-ESR ceramic capacitor must be placed within 2mm of the VCC pin and connected directly to the GND pin (Pin 5) using a short, wide trace. This minimizes high-frequency impedance and prevents supply noise from modulating the Hall sensor's bias, which would otherwise increase offset drift and noise-especially critical at 100kHz bandwidth operation.

How does the device handle overcurrent events beyond ±20A?

Within absolute maximum ratings, the output remains proportional up to saturation: VOUT(H) = VCC − 0.5V and VOUT(L) = 0.5V at 5V supply. Nonlinearity exceeds ±2.5% beyond ±20A, but the monotonic response enables reliable overcurrent flagging. The 3000A surge rating (IEC61000-4-5) ensures survival during short-circuit transients without damage.