Texas Instruments ISO1541QDRQ1

Overview

ISO1541QDRQ1 from Texas Instruments is an automotive-grade, low-power, bidirectional I²C isolator with unidirectional clock (SCL1→SCL2) and bidirectional data (SDA1↔SDA2) channels, 2500 VRMS isolation rating, ±50 kV/µs CMTI, and 3–5.5 V dual-supply operation. It enables isolated I²C communication in battery management systems where side-1 hosts the controller and side-2 connects to isolated slave devices.

For engineers reviewing the ISO1541QDRQ1 datasheet, ISO1541QDRQ1 pinout, ISO1541QDRQ1 application, or ISO1541QDRQ1 equivalent, key selection criteria include its AEC-Q100 Grade 1 qualification (–40°C to +125°C), 1-MHz max I²C speed, open-drain output capability (3.5 mA sink on side-1, 35 mA on side-2), and functional safety documentation support for ISO 26262 ASIL-B system integration.

Technical Context

The ISO1541QDRQ1 implements capacitive isolation using a silicon dioxide (SiO₂) barrier, enabling galvanic separation between side-1 (controller domain) and side-2 (target/sensor domain). Its asymmetric channel architecture-unidirectional SCL and bidirectional SDA-eliminates clock-stretching conflicts in single-controller topologies while maintaining full I²C protocol compatibility.

It features offset low-level output voltage on side-1 (> high-level input threshold on side-1) to prevent internal logic latching during bidirectional data transfer. Safety-limiting current (198–303 mA) and thermal shutdown (139–197°C) are integrated to protect the isolation barrier under fault conditions.

Key Specifications

Pinout & Package

ISO1541QDRQ1 uses an 8-pin SOIC (D package) with 4.90 mm × 3.91 mm body size and reinforced insulation barrier separating side-1 (pins 1–4) and side-2 (pins 5–8).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar I²C isolator applications.

Compared with ISO1540QDRQ1, ISO1541QDRQ1 trades bidirectional clock flexibility for enhanced noise immunity and simpler timing in single-controller systems; versus ADUM1250ARZ-RL7, it eliminates external component dependencies and guarantees I²C electrical compliance without firmware or layout adaptation.

Availability

ISO1541QDRQ1 is available at Aetrix Electronics and suitable for battery management, motor control, and automotive body electronics requiring stable component supply, AEC-Q100-compliant sourcing, and long-term industrial lifecycle support.

Supply support for ISO1541QDRQ1 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

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and automotive electronics, with decades of expertise in isolation technology and functional safety.

The ISO154x-Q1 product line delivers automotive-qualified, capacitive-isolation I²C interfaces designed specifically for high-reliability, safety-critical subsystems including battery monitoring, motor drives, and domain controllers.

FAQ

What is the maximum I²C bus speed supported by ISO1541QDRQ1?

The ISO1541QDRQ1 supports up to 1 MHz I²C operation under recommended conditions (≤40 pF load on side-1, ≤400 pF on side-2, 3–5.5 V supplies). At lower bus capacitance, speeds may exceed 1 MHz, but timing margins must be verified per Figure 6-10 and 6-11 in the datasheet. The ISO1541QDRQ1 achieves this with propagation delays as low as 31 ns (tpLH1-2) and pulse distortion under 123 ns.

Does ISO1541QDRQ1 support clock stretching by target devices?

No - ISO1541QDRQ1 has a unidirectional SCL channel (SCL1→SCL2 only), so clock stretching initiated by side-2 targets cannot propagate back to the side-1 controller. For applications requiring target-initiated clock stretching (e.g., slow EEPROMs or ADCs), TI recommends ISO1540QDRQ1 instead. The ISO1541QDRQ1 is optimized for single-controller systems where the controller fully manages clock timing.

What safety certifications does ISO1541QDRQ1 hold?

ISO1541QDRQ1 is certified to UL 1577 (2500 VRMS), DIN EN IEC 60747-17 (VDE 0884-17, 4242 VPK), CSA/IEC 62368-1, and GB4943.1-2011. It carries AEC-Q100 Grade 1 qualification (–40°C to +125°C), HBM ±4 kV (±8 kV on bus pins), and CDM ±1.5 kV. Functional safety documentation is provided to support ISO 26262 ASIL-B system integration.

Can ISO1541QDRQ1 operate with different supply voltages on side-1 and side-2?

Yes - ISO1541QDRQ1 supports independent 3–5.5 V supplies on VCC1 and VCC2, enabling true I²C level shifting (e.g., 3.3 V MCU ↔ 5 V sensor). Input thresholds scale with respective VCC (VIH1 = 0.7×VCC1; VIH2 = 0.7×VCC2), and output low voltages remain compatible (VOL1 ≤ 800 mV, VOL2 ≤ 400 mV). This eliminates external level translators in mixed-voltage systems using ISO1541QDRQ1.

How does ISO1541QDRQ1 prevent internal logic latching during bidirectional data transfer?

ISO1541QDRQ1 offsets the side-1 low-level output voltage (VOL1) to exceed the side-1 high-level input threshold (VIHT1) - a ΔVOIT1 ≥ 50 mV ensures the local side-1 receiver never misreads its own output as a high signal. This patented offset technique avoids the latch condition inherent in standard digital isolators, enabling reliable SDA1↔SDA2 bidirectional operation without external control logic or timing constraints in the ISO1541QDRQ1.