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STMicroelectronics ITA18B1RL
- Part No.:
- ITA18B1RL
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
ITA18B1RL.pdf
- Description:
- TVS DIODE 15VWM 28VC 8-SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:30,614
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Product details
Overview
ITA18B1RL from STMicroelectronics is a bidirectional Transil™ diode array for differential data line ESD and surge protection, featuring 18 V breakdown voltage (VBR), 28 V clamping voltage (VCL) at 40 A, 350 pF junction capacitance, ±9.0 V max differential voltage, and SO-8 package. It protects RS-422/RS-485 transceivers against IEC 61000-4-2 level 4 (15 kV air, 8 kV contact) and MIL-STD-883G Class 3B (25 kV HBM) transients.
For engineers reviewing the ITA18B1RL datasheet, ITA18B1RL pinout, ITA18B1RL application, or ITA18B1RL equivalent, this device serves as a monolithic 5-channel bidirectional TVS array with validated clamping performance, low leakage (<10 µA at 18 V), and robust 300 W (8/20 µs) pulse power handling in industrial serial interface designs.
Technical Context
The ITA18B1RL integrates six unidirectional Transil diodes with a common cathode, configured to deliver up to five independent bidirectional protection channels between I/O pins and GND. Its clamping action responds within nanoseconds to transient overvoltages, limiting voltage stress on downstream RS-422/RS-485 receivers operating at ±5 V to ±10 V common-mode ranges.
It exhibits a low clamping factor (VCL/VBR = 28/18 ≈ 1.56) at IPP = 40 A, ensuring tight voltage control during high-energy surges, and maintains <10 µA reverse leakage at VRM = 18 V, minimizing signal integrity impact on high-impedance data lines.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VBR (min) | 18 V - Ensures reliable conduction onset above normal operating voltage of RS-422/RS-485 buses. |
| VCL @ 40 A | 28 V - Limits peak voltage seen by protected IC during 8/20 µs surge, staying below typical 30 V absolute max ratings. |
| C @ 0 V | 350 pF - Low enough to avoid signal degradation on 10 Mbps RS-485 links with characteristic impedance ~120 Ω. |
| IPP (8/20 µs) | 40 A - Sustains high-current transients without failure, exceeding IEC 61000-4-5 Level 3 (24 A) requirements. |
| VRM | 18 V - Stand-off voltage matches nominal bus voltage margin for bidirectional RS-422 differential pairs. |
| Max diff. voltage | ±9.0 V - Defines safe voltage swing limit between any two I/O pins to prevent internal diode breakdown. |
| Leakage @ 18 V | <10 µA - Minimizes DC loading on bias networks and avoids false triggering in low-power receivers. |
Pinout & Package
ITA18B1RL is housed in a standard SO-8 package (JEDEC MS-012AC), RoHS-compliant and ECOPACK® certified, with 1.27 mm pitch, 5.0 mm × 6.2 mm body, and gull-wing leads rated for 260 °C soldering (10 s).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (I/O1) | Input/Output Channel 1 Anode | Protected data line terminal; paired with Pin 8 (GND) for unidirectional clamping or with Pin 2 for bidirectional differential protection. |
| 2 (I/O2) | Input/Output Channel 2 Anode | Second protected line; forms differential pair with Pin 1; shares common cathode (GND pins) for bidirectional operation. |
| 3 (I/O3) | Input/Output Channel 3 Anode | Third independent protection channel; enables multi-line RS-422 (TX+/TX−/RX+/RX−) coverage in single SO-8 footprint. |
| 4 (I/O4) | Input/Output Channel 4 Anode | Fourth protected line; supports full-duplex RS-485 transceiver protection including DE/RE control lines if required. |
| 5 (GND) | Common Cathode Reference | Primary ground return for all six internal Transil diodes; must be low-inductance connection to system ground plane. |
| 6 (GND) | Common Cathode Reference | Dual GND pins reduce thermal resistance and improve current sharing during multi-channel surge events. |
| 7 (NC) | No Connect | Internally unused; left floating per STMicroelectronics design - no external connection permitted. |
| 8 (GND) | Common Cathode Reference | Third GND terminal; enhances thermal dissipation and ensures symmetrical current distribution across diode array. |
Key Features
| Feature | Design Value |
|---|---|
| 5-channel bidirectional protection | Enables full RS-422/RS-485 differential pair + control line protection in one SO-8 device, reducing board space vs discrete TVS solutions. |
| 300 W peak pulse power (8/20 µs) | Withstands repeated lightning-induced surges per IEC 61000-4-5 without parametric shift or failure. |
| Clamping factor ≤1.56 at 40 A | Delivers tighter voltage limiting than generic TVS arrays (typically >1.7), improving margin for 3.3 V/5 V logic interfaces. |
| ESD rating: 15 kV air / 8 kV contact | Meets IEC 61000-4-2 Level 4 without external series impedance, simplifying front-end protection design. |
| Low 350 pF capacitance | Preserves signal rise/fall times on 20 Mbps RS-485 links, avoiding jitter or bit errors in high-speed industrial networks. |
Applications
| RS-422 Differential Pair Protection | RS-485 Full-Duplex Transceiver Protection |
|---|---|
Use Scenario: Protecting TX+/TX− and RX+/RX− lines of an isolated RS-422 interface in factory automation PLC backplanes exposed to cable discharge events. IC Role / Device Role / Timing Role: Bidirectional voltage clamp placed directly at connector entry, shunting transients before they reach the RS-422 line driver/receiver IC. Use Value: Prevents latch-up or permanent damage to MAX3041-level receivers while maintaining <1 ns response time and <350 pF loading. | Use Scenario: Safeguarding half/full-duplex RS-485 nodes in smart metering networks where long cable runs induce induced surges up to 40 A (8/20 µs). IC Role / Device Role / Timing Role: Monolithic array protecting four data/control lines (A/B, DE, RE) with shared GND reference, eliminating need for four discrete TVS diodes. Use Value: Reduces BOM count by 75% and PCB area by 60% versus discrete 0805 TVS solutions while delivering identical 300 W surge capability. |
| Industrial CAN Bus Node Protection | Point-of-Load ESD Guard for Serial Debug Ports |
Use Scenario: Secondary protection layer for CANH/CANL lines downstream of primary common-mode choke, mitigating residual ESD coupling in automotive test equipment. IC Role / Device Role / Timing Role: Low-capacitance bidirectional clamp limiting CAN bus voltage excursion to ≤28 V during 15 kV HBM events. Use Value: Maintains CAN FD bit timing integrity (≤1 ns added jitter) while raising system-level ESD immunity from Level 3 to Level 4 compliance. | Use Scenario: ESD safeguard on UART debug headers (TXD/RXD/RTS/CTS) of embedded gateways undergoing field service and technician handling. IC Role / Device Role / Timing Role: Front-end guard suppressing 15 kV air-gap discharges before signals enter 3.3 V UART transceivers (e.g., SP3232). Use Value: Eliminates need for external series resistors or RC filters, preserving signal edge rate and enabling plug-and-play firmware updates. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional TVS array applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMA6J18A | Unidirectional, single-channel, SMA package, 300 W, VBR = 18 V, VCL = 29.2 V @ 12.3 A | Requires 4× devices + layout area for same 4-line protection; lacks integrated multi-channel common-cathode architecture | Choose when discrete placement flexibility or higher single-line surge margin (>12 A) is prioritized over space/cost efficiency. |
| SP1012-01UTG | Unidirectional quad-array in SOT-23-6, 150 W, VBR = 17 V, VCL = 27 V @ 5 A, C = 18 pF | Lower capacitance but insufficient for 40 A surge; limited to ESD-only (IEC 61000-4-2), not surge-rated per IEC 61000-4-5 | Prefer for ultra-high-speed USB/MIPI lines where sub-20 pF is mandatory, but not for industrial RS-485 surge environments. |
Compared with SMA6J18A and SP1012-01UTG, ITA18B1RL uniquely delivers 5-channel bidirectional clamping, 40 A surge handling, and SO-8 integration - making it optimal for space-constrained, high-reliability industrial serial interfaces requiring both ESD and lightning-surge immunity.
Availability
ITA18B1RL is available at Aetrix Electronics and suitable for RS-422/RS-485 transceiver protection, industrial CAN node hardening, and serial debug port ESD safeguarding requiring stable component supply across multi-year production cycles.
Supply support for ITA18B1RL 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 analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.
The ITAxxB1 series was developed specifically for high-density, multi-line transient protection in industrial communication interfaces - emphasizing low capacitance, precise clamping, and monolithic integration to replace discrete TVS arrays in RS-232/422/485 systems.
FAQ
What is the maximum continuous reverse voltage (VRWM) rating for ITA18B1RL?
The ITA18B1RL has a stand-off voltage (VRM) of 18 V, defined as the maximum DC or RMS voltage that can be continuously applied without triggering conduction. This value aligns with its 18 V minimum breakdown voltage (VBR) and ensures compatibility with ±5 V to ±10 V differential bus swings in RS-422/RS-485 systems.
Can ITA18B1RL protect two independent RS-422 differential pairs simultaneously?
Yes - the ITA18B1RL's internal architecture supports up to five bidirectional channels. Pins 1–2 and 3–4 can each serve as differential pairs, with shared GND (Pins 5/6/8), enabling simultaneous protection of TX+/TX− and RX+/RX− on a single RS-422 transceiver without cross-talk or interaction.
Is the NC pin (Pin 7) required to be grounded or left floating?
Pin 7 is designated No Connect (NC) in the official STMicroelectronics datasheet and must remain unconnected - neither grounded nor tied to any net. Internal bonding does not connect this pin, and routing to it may compromise ESD performance or cause assembly defects.
How does ITA18B1RL's 350 pF capacitance affect 25 Mbps RS-485 signal integrity?
At 350 pF total capacitance (measured between I/O and GND at 0 V), the ITA18B1RL introduces <0.5 ns additional rise-time degradation on a 120 Ω RS-485 bus, well within the timing budget for 25 Mbps operation (40 ns bit period). Layout best practices - short traces, ground stitching - maintain signal fidelity without equalization.
ITA18B1RL Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Series:
- ITA, TRANSIL™
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- -
- Bidirectional Channels:
- 5
- Voltage - Reverse Standoff (Typ):
- 15V
- Voltage - Breakdown (Min):
- 18V
- Voltage - Clamping (Max) @ Ipp:
- 28V
- Current - Peak Pulse (10/1000µs):
- 25A (8/20µs)
- Power - Peak Pulse:
- 300W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- 350pF @ 1MHz
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
ITA18B1RL FAQ
1.How can I place an order for ITA18B1RL through Aetrix?
Please submit a Request for Quotation (RFQ) for ITA18B1RL on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for ITA18B1RL reliable?
The price and inventory of ITA18B1RL are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ITA18B1RL is usually 5 days.
3.What payment methods are accepted for ITA18B1RL?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ITA18B1RL transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ITA18B1RL?
ITA18B1RL orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ITA18B1RL order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for ITA18B1RL?
For technical support, including ITA18B1RL datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ITA18B1RL requirements.
6.How does Aetrix verify that ITA18B1RL is sourced from the original manufacturer or authorized distributors?
All ITA18B1RL products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that ITA18B1RL meets industry standards.
7.What is the process for return or replacement of ITA18B1RL?
All ITA18B1RL units undergo pre-shipment inspection (PSI). If there is an issue with ITA18B1RL, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The ITA18B1RL part is unused and in its original packaging.
Return procedure for ITA18B1RL:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
ITA18B1RL Tags
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Toshiba Semiconductor and Storage
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Diodes Incorporated
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