STMicroelectronics ISOSD61

Overview

ISOSD61 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 delivers high-accuracy current/voltage sensing in high-voltage industrial power stages including solar inverters and EV chargers using embedded transformer isolation.

For engineers reviewing the ISOSD61 datasheet, ISOSD61 pinout, ISOSD61 application, or ISOSD61 equivalent, key selection criteria include its 5000 V_PEAK isolation voltage, 30 kV/µs CMTI, SO-16 wide package, LVDS/TTL output options, and support for SINC3 digital filtering at up to 25 MHz clock input.

Technical Context

The ISOSD61 implements a second-order sigma-delta modulator core on the high-voltage side, converting differential analog inputs into a 1-bit serial bitstream synchronized to an external MCLKIN (5–25 MHz). Its galvanic isolation barrier uses proprietary transformer coupling-not optocouplers-enabling 5000 V_PEAK VIOTM and 30 kV/µs CMTI.

Digital output is delivered via LVDS (ISOSD61L) or single-ended TTL/CMOS (ISOSD61) signaling, with data latency fixed at 2 clock cycles. The modulator requires external digital decimation (e.g., SINC3 filter) to reconstruct 16-bit samples; no internal ADC or digital interface logic is integrated.

Key Specifications

Pinout & Package

ISOSD61 is housed in a SO-16 wide (SO16W) package with 8 mm minimum creepage/clearance, rated per IEC 60747-17 and UL 1577. High- and low-voltage sides are physically segregated across the package body.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AMC1305M05 and AD7403, ISOSD61 uniquely combines 25 Msps speed, 30 kV/µs CMTI, LVDS/TTL flexibility, and 86 dB SNR-making it optimal for high-bandwidth, high-noise applications like EV traction inverters and servo drives.

Availability

ISOSD61 is available at Aetrix Electronics and suitable for industrial motor control, solar inverter design, and electric vehicle charger development requiring stable component supply across extended temperature and high-isolation reliability.

Supply support for ISOSD61 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, Switzerland, designing and manufacturing microcontrollers, power ICs, sensors, and analog/mixed-signal devices for industrial, automotive, and consumer markets.

The ISOSD61 belongs to ST's high-precision isolated sensing portfolio, engineered specifically for real-time current monitoring in high-voltage power conversion systems demanding reinforced insulation and extreme noise immunity.

FAQ

What digital filtering is required to recover 16-bit samples from the ISOSD61 bitstream?

The ISOSD61 outputs a 1-bit sigma-delta bitstream that must be decimated using a digital filter-ST recommends a third-order sinc (SINC3) filter. This filter is commonly implemented in FPGAs or STM32 MCUs with hardware accelerators; it achieves 16-bit resolution at OSR=256 with 25 MHz input clock yielding ~98 kSPS effective rate.

Can ISOSD61 operate with a 3.3 V low-side supply while maintaining full 25 Msps performance?

Yes-ISOSD61 supports VDD = 3.3 V with guaranteed 25 Msps operation. At 3.3 V and 25 MHz, IDD is 12.5 mA (typical), and LVDS output compliance remains valid per Table 10. However, TTL/CMOS output VOH drops to VDD – 0.05 V, requiring compatible receiver thresholds.

How does the ISOSD61 handle common-mode voltage transients exceeding 1000 V?

With 30 kV/µs typical CMTI and 5000 V_PEAK VIOTM, ISOSD61 maintains data integrity during fast-rising transients up to 1000 V common-mode step. Its transformer-coupled isolation barrier suppresses capacitive coupling far more effectively than optocouplers or capacitive isolators, preventing metastability in motor drive gate drivers.

Is there a difference in isolation rating between ISOSD61 and ISOSD61L variants?

No-the isolation specifications (VIOTM = 5000 V_PEAK, VIORM = 1700 V_PEAK, CMTI = 30 kV/µs) are identical for both ISOSD61 (TTL/CMOS output) and ISOSD61L (LVDS output). The only differences are pin assignments (MDAT+/MDAT− vs. MDAT), output driver type, and minor timing parameters-not isolation robustness.