STMicroelectronics ISOSD61TR

Overview

ISOSD61TR from STMicroelectronics is a galvanically isolated second-order sigma-delta modulator with ±320 mV full-scale analog input range, 16-bit resolution (no missing codes), 86 dB typical SNR, and 25 Msps data rate. It uses embedded transformer coupling for high-voltage isolation and delivers LVDS or single-ended digital output for precision current/voltage sensing in high-noise industrial power systems.

For engineers reviewing the ISOSD61TR datasheet, ISOSD61TR pinout, ISOSD61TR application, or ISOSD61TR equivalent, this page provides verified technical context, real-world design meaning of key specs, validated pin functions, application-specific implementation guidance, and confirmed alternative parts with documented functional trade-offs.

Technical Context

The ISOSD61TR implements a second-order sigma-delta modulator core on the high-voltage side, sampling differential analog inputs at up to 25 MHz and converting them into a 1-bit bitstream. Its galvanic isolation barrier uses high-speed transformer coupling-not optocouplers-enabling 30 kV/µs CMTI and 5000 V_PEAK isolation voltage.

Digital output supports dual interface modes: LVDS (ISOSD61L variant) with differential MDAT±/MCLKIN± pins, or single-ended TTL/CMOS (ISOSD61 variant) with MDAT/MCLKIN pins. Both operate across –40°C to +125°C and require external SINC3 decimation filtering to reconstruct 16-bit data.

Key Specifications

Pinout & Package

ISOSD61TR is housed in a SO-16 wide (SO16W) package with 8.0 mm creepage/clearance and reinforced insulation. Pin functions differ between ISOSD61 (single-ended) and ISOSD61L (LVDS) variants; ISOSD61TR corresponds to the single-ended version per ordering table.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar isolated sigma-delta modulator applications.

Compared with AMC1305L25 and AD7403, ISOSD61TR delivers superior CMTI (30 kV/µs), wider input range (±320 mV), and tighter SNR (86 dB), making it optimal for next-generation SiC/GaN systems requiring both high accuracy and reinforced insulation integrity.

Availability

ISOSD61TR is available at Aetrix Electronics and suitable for industrial motor control, solar inverter, and EV onboard charger designs requiring stable component supply, long-lifecycle assurance, and certified reinforced isolation.

Supply support for ISOSD61TR 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, designing and manufacturing microcontrollers, power ICs, sensors, and analog/mixed-signal devices for industrial, automotive, and consumer markets.

The ISOSD61TR belongs to ST's high-accuracy isolated sensing portfolio, engineered specifically for real-time current/voltage digitization in high-voltage, high-CMTI power conversion systems where reliability and safety certification are non-negotiable.

FAQ

What digital filtering is required to recover 16-bit data from the ISOSD61TR bitstream?

The ISOSD61TR outputs a 1-bit sigma-delta bitstream that must be processed by a third-order sinc (SINC3) digital filter. ST recommends OSR=256 for 16-bit output at 97.7 kSPS. This filter can be implemented in FPGA logic or STM32 MCUs using hardware accelerators like DFSDM; no external DSP is needed. Filter coefficients and Verilog/VHDL examples are provided in AN5073 and DS13605 Annex B.

Can ISOSD61TR replace optocoupler-based isolation in existing designs without layout changes?

No - ISOSD61TR requires strict PCB separation between high-side (VIN+, VIN−, VDDISO, GNDISO) and low-side (MDAT, MCLKIN, VDD, GND) domains, with ≥8 mm creepage/clearance and split ground planes. Optocoupler footprints lack this spacing and cannot accommodate the SO16W package's 10.5 mm × 7.6 mm body. Redesign of isolation barriers and decoupling networks is mandatory.

Does ISOSD61TR support both unidirectional and bidirectional current sensing?

Yes - its ±320 mV differential input range enables true bipolar measurement. When paired with a center-tapped shunt or dual-shunt configuration, it captures forward and reverse current flow in EV bidirectional OBCs and regenerative braking circuits. The 13-bit ENOB ensures sub-0.1% error across the full range, even at –40°C.

How does ISOSD61TR handle common-mode transients during fast-switching events?

ISOSD61TR achieves 30 kV/µs typical common-mode transient immunity (CMTI) via optimized transformer coupling and internal shielding - exceeding IEC 61800-3 requirements for drives. During 5-kV/µs SiC gate driver edges, it maintains data integrity without bit errors or metastability, unlike optocouplers (<15 kV/µs) or capacitive isolators (<25 kV/µs).