STMicroelectronics LNBTVS4-304S

Overview

LNBTVS4-304S from STMicroelectronics is a unidirectional transient voltage suppressor (TVS) diode designed for lightning and ESD protection of LNB voltage regulators in satellite set-top box front-ends. It features a 31.5 V minimum breakdown voltage, 45 V clamping voltage at 334 A (8/20 µs), 0.2 µA leakage at 25 °C, 150 °C max junction temperature, and SMC (DO-214AB) package.

For engineers reviewing the LNBTVS4-304S datasheet, LNBTVS4-304S pinout, LNBTVS4-304S application, or LNBTVS4-304S equivalent, key selection criteria include clamping performance under IEC 61000-4-5 surges, low forward voltage (1.2 V @ 3 A), compatibility with LNBH-series supply ICs, and thermal robustness up to 150 °C junction temperature.

Technical Context

The LNBTVS4-304S employs planar junction technology to achieve stable clamping behavior across the consumer temperature range (–55 °C to +85 °C ambient) while maintaining IEC 61000-4-5 compliance at T_j = 85 °C. Its unidirectional configuration enables integration on DC bias lines without reverse conduction path concerns.

Designed specifically for LNBH23/LNBH24/LNBH25/LNBH26-based satellite receiver power paths, it operates between the 12 V input and IF signal chain, requiring series inductance (>13 nH) to isolate RF attenuation caused by its intrinsic capacitance (~4 pF). The device's 9.8 × 10^–4/°C voltage temperature coefficient allows precise V_BR prediction across operating junction temperatures.

Key Specifications

Pinout & Package

Package: SMC (JEDEC DO-214AB), molded plastic case with solderable leads compliant to MIL-STD-750 Method 2026; cathode indicated by band marking.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar transient voltage suppression applications.

Compared with SMBJ33A and SMCJ33A, LNBTVS4-304S delivers 8.6× higher peak pulse current capability (334 A), 15% lower clamping ratio (1.43 vs. ~1.62), and documented thermal stability up to 85 °C ambient-making it uniquely suited for satellite receiver LNB power path protection where reliability under sustained thermal stress is critical.

Availability

LNBTVS4-304S is available at Aetrix Electronics and suitable for satellite set-top box manufacturing, LNBH-series IC reference designs, and multi-switch distribution system development requiring stable component supply and full IEC 61000-4-5 compliance.

Supply support for LNBTVS4-304S 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 LNBTVS series belongs to ST's dedicated protection portfolio, engineered specifically for low-noise block downconverter (LNB) power regulation in satellite reception systems-prioritizing low clamping, thermal resilience, and seamless integration with LNBH-family supply ICs.

FAQ

What is the recommended PCB layout for LNBTVS4-304S to ensure optimal surge performance?

Place the device within 5 mm of the LNBH VIN pin with direct, low-inductance traces to both anode and cathode. Use ≥2 cm² of internal ground plane beneath the SMC footprint and connect cathode to ground via ≥2 thermal vias (0.3 mm diameter, spaced ≤1 mm apart). Avoid routing high-speed IF signals near the device body to minimize capacitive coupling.

Can LNBTVS4-304S be used without a series inductor in the LNB power path?

No. Due to its ~4 pF junction capacitance, direct connection to the IF connector would attenuate satellite RF signals above 900 MHz. The datasheet mandates a series inductance >13 nH between the TVS cathode and ground to form a high-pass filter that blocks surge energy while passing 22 kHz DiSEqC and RF signals. Omitting this inductor degrades signal integrity and violates design intent.

How does LNBTVS4-304S maintain IEC 61000-4-5 compliance at 85 °C ambient?

It achieves this through planar junction construction and thermal design enabling 1250 W surge dissipation (10/1000 µs) at T_j = 150 °C. With R_th(j-l) = 15 °C/W and typical PCB thermal resistance of ~35 °C/W, junction temperature rise during a 334 A surge remains within safe limits even when ambient reaches 85 °C-verified per Figure 3 in the datasheet.

Is LNBTVS4-304S compatible with LNBH23L and LNBH24L variants?

Yes. The device is explicitly validated for use with LNBH23L, LNBH24L, LNBH25, and LNBH26 in Figures 6–8 of the datasheet. Its 1.2 V forward voltage ensures DiSEqC 22 kHz envelope detection remains functional, and its 31.5–33 V V_BR range aligns with the overvoltage protection thresholds of all listed LNBH ICs.