STMicroelectronics ITA25B1

Overview

ITA25B1 from STMicroelectronics is a bidirectional Transil™ diode array for differential data line protection, featuring 25 V standoff voltage (VRM), 38 V clamping voltage at 40 A (8/20 µs), 300 W peak pulse power, ±12.5 V max differential voltage between I/O pins, and 300 pF capacitance at VRM - deployed in RS-485 transceiver interfaces to suppress ESD and surge transients.

For engineers reviewing the ITA25B1 datasheet, ITA25B1 pinout, ITA25B1 application, or ITA25B1 equivalent, key selection criteria include clamping performance under 40 A surge, low-leakage operation (<10 µA at 25 V), SO-8 package compatibility with board-level ESD layout constraints, and compliance with IEC 61000-4-2 Level 4 (15 kV air, 8 kV contact).

Technical Context

The ITA25B1 integrates six unidirectional Transil diodes with a common cathode, configured as five independent bidirectional protection channels between I/O pins and GND. It operates via avalanche clamping with fast response (<1 ns) and maintains stable VBR (24–33 V) across temperature due to low αT (12 × 10⁻⁴ /°C).

Its SO-8 package supports dual-rail protection of four differential lines (e.g., TX/RX, RTS/CTS) with shared ground return, and junction capacitance remains ≤300 pF at VRM, minimizing signal integrity impact on 10 Mbps RS-485 links.

Key Specifications

Pinout & Package

ITA25B1 is housed in a standard SO-8 package (JEDEC MS-012AC), with 1.27 mm pitch, 5.0 mm × 6.2 mm body, and RoHS-compliant lead-free terminations per ECOPACK® specification.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar bidirectional data-line protection applications.

Compared with SMA6J24A and SP1003-01WTG, ITA25B1 uniquely delivers five matched bidirectional channels in SO-8 with 40 A surge handling and 300 pF - enabling compact, high-fidelity protection of multi-signal industrial interfaces without channel-to-channel timing skew or layout imbalance.

Availability

ITA25B1 is available at Aetrix Electronics and suitable for RS-485 industrial bus nodes, RS-232 medical serial ports, and RS-422 railway signaling systems requiring stable component supply across extended product lifecycles.

Supply support for ITA25B1 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 protection devices for industrial, automotive, and consumer markets.

The ITAxxB1 series was developed specifically for robust, monolithic transient protection of multi-line differential communication interfaces - emphasizing matched clamping, low capacitance, and high surge endurance in compact surface-mount packages.

FAQ

What is the maximum differential voltage the ITA25B1 can withstand between two I/O pins?

The ITA25B1 supports a maximum differential voltage of ±12.5 V between any two I/O pins at 25 °C, as specified in Table 3 of the datasheet. This rating ensures safe operation across RS-485 common-mode ranges and prevents internal diode breakdown during asymmetric transients or bus faults.

Does the ITA25B1 require external current-limiting resistors in series with protected lines?

No - the ITA25B1 is designed for direct connection between I/O lines and ground without series impedance. Its low dynamic impedance and 38 V clamping voltage ensure protected ICs remain within safe operating area during 40 A surges, provided PCB layout maintains short, low-inductance ground paths to pins 5–8.

How does the ITA25B1's junction capacitance affect high-speed RS-485 data integrity?

At 300 pF per I/O-to-GND path and typical 120 Ω termination, the ITA25B1 adds <5% rise-time degradation at 10 Mbps, verified via SPICE simulation using its published C(VR) curve. This meets RS-485 standard timing budgets when placed adjacent to the connector, not the transceiver.

Is the ITA25B1 compliant with lead-free soldering standards?

Yes - the ITA25B1 uses an ECOPACK®-compliant SO-8 package with lead-free second-level interconnects, qualified for reflow profiles up to 260 °C for 10 seconds at 5 mm from case body. JEDEC J-STD-020 moisture sensitivity level is MSL3, requiring dry-pack handling prior to assembly.