Microchip Technology MCP3551T-E/SN

Overview

MCP3551T-E/SN from Microchip Technology is a single-channel, 22-bit delta-sigma analog-to-digital converter (ADC) in an 8-pin MSOP package, featuring automatic internal offset and gain calibration, 2.5 µV_RMS output noise, 21.9-bit effective resolution, and 6 ppm maximum INL error. It operates from 2.7V to 5.5V with differential inputs spanning –V_REF to +V_REF, and delivers 13.75 Hz output data rate optimized for precision industrial sensor measurement.

For engineers reviewing the MCP3551T-E/SN datasheet, MCP3551T-E/SN pinout, MCP3551T-E/SN application, or MCP3551T-E/SN equivalent, this device is selected for high-accuracy, low-noise DC and low-frequency signal acquisition where line-frequency rejection, thermal stability, and minimal external components are critical - especially in weigh scales, strain gauge interfaces, and 6-digit DVMs.

Technical Context

The MCP3551T-E/SN implements a third-order delta-sigma modulator with real-time internal offset and gain calibration on every conversion, eliminating need for user-initiated calibration cycles. Its fourth-order modified SINC4 decimation filter provides simultaneous 50 Hz and 60 Hz line-frequency rejection via staggered zeros centered at 55 Hz, achieving ≥82 dB rejection across 48–63 Hz.

It uses a highly stable internal oscillator (112.64 kHz ±1%) independent of SPI timing, enabling precise conversion time control (73.1 ms typical) and robust noise performance without external clocking. The fully differential analog input supports V_SS to V_DD common-mode range and accepts reference voltages from 0.1 V to V_DD, with INL scaling quadratically with V_REF.

Key Specifications

Pinout & Package

Package: 8-pin MSOP (3.0 mm × 3.0 mm, 0.65 mm pitch), RoHS-compliant, rated for –40°C to +125°C operation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-resolution delta-sigma ADC applications.

Compared with ADS124S08IPW and MCP3425A0T-E/MS, the MCP3551T-E/SN uniquely balances 22-bit integrity, built-in 55 Hz notch filtering, zero external timing components, and sub-120 µA operation-making it optimal for standalone, calibration-free precision sensor nodes.

Availability

MCP3551T-E/SN is available at Aetrix Electronics and suitable for weigh scales, direct temperature measurement, and 6-digit DVMs requiring stable component supply, long-term lifecycle assurance, and guaranteed traceable sourcing.

Supply support for MCP3551T-E/SN 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

Microchip Technology Inc. is a leading provider of microcontrollers, analog devices, and Flash-IP solutions, serving industrial, automotive, and consumer markets with high-reliability silicon and development tools.

The MCP355x family was designed specifically for high-accuracy, low-power, single-chip sensor digitization in harsh environments-emphasizing internal calibration, line-frequency immunity, and extended temperature operation (–40°C to +125°C).

FAQ

What is the conversion time of the MCP3551T-E/SN, and is it fixed or variable?

The MCP3551T-E/SN has a fixed conversion time of 73.1 ms ±2.0%, determined by its internal 112.64 kHz oscillator and fourth-order SINC4 filter architecture. This deterministic latency enables precise timing in closed-loop systems and eliminates variability caused by external clock jitter or software delays. Each conversion completes reliably within this window, and the RDY flag on the SDO/RDY pin asserts exactly once per cycle. The MCP3551T-E/SN does not support variable-speed conversion modes.

Does the MCP3551T-E/SN require an external crystal or clock source?

No, the MCP3551T-E/SN integrates a highly stable internal oscillator (112.64 kHz ±1%) that drives both the delta-sigma modulator and digital filter-eliminating need for external crystals, resonators, or clock generators. This reduces BOM count, PCB area, and susceptibility to board-level EMI. The oscillator remains active only during conversion, contributing to the device's ultra-low 120 µA typical supply current at 5 V. External clocks are neither supported nor required for MCP3551T-E/SN operation.

How does the MCP3551T-E/SN achieve simultaneous 50 Hz and 60 Hz line-frequency rejection?

The MCP3551T-E/SN achieves simultaneous 50 Hz and 60 Hz rejection through a modified fourth-order SINC4 digital filter with deliberately staggered zeros in its transfer function. Unlike standard SINC filters with a single deep notch, this design widens and flattens the rejection band to cover 48–63 Hz continuously-delivering ≥82 dB attenuation at both frequencies. This is enabled by the device's precise internal oscillator (±1%) and tailored oversampling ratio (OSR = 256), making external notch filters unnecessary in globally deployed equipment.

What is the meaning of the two overflow bits in the MCP3551T-E/SN's 24-bit output word?

The MCP3551T-E/SN outputs a 24-bit word comprising 22 data bits (two's complement) plus 2 dedicated overflow bits (OV1, OV0). These bits indicate analog input overrange conditions: OV1=1 signals VIN+–VIN− exceeded +V_REF by >12%, while OV0=1 signals violation below –V_REF. Both bits allow firmware to detect saturation without losing resolution on in-range measurements. The overflow bits are latched with each conversion and appear in the most significant positions of the SPI-read word-enabling real-time diagnostic monitoring alongside primary data in the MCP3551T-E/SN.

Can the MCP3551T-E/SN operate with a 2.5 V reference voltage, and how does VREF affect accuracy?

Yes, the MCP3551T-E/SN supports V_REF from 0.1 V to V_DD, including 2.5 V. However, INL error scales approximately with V_REF²-so using 2.5 V instead of 5 V reduces maximum INL from 6 ppm to ~1.5 ppm, directly improving absolute linearity. Output noise (2.5 µV_RMS) remains constant regardless of V_REF, meaning SNR degrades at lower references. For highest accuracy in ratiometric sensor applications, pairing MCP3551T-E/SN with a stable 2.5 V reference is recommended, as confirmed in Microchip's Figure 2-4 and Section 3.1.