Renesas RD27F-T8-AZ

Overview

RD27F-T8-AZ from Renesas Electronics is a 1 W planar-type silicon Zener diode with a nominal zener voltage of 27 V (B3 grade: 26.72–28.43 V), dynamic impedance of 16 Ω at 10 mA, and temperature coefficient of +21 mV/°C. It features DO-41 glass-sealed DHD (Double Heatsink Diode) packaging and is rated for surge reverse power up to 400 W (t = 10 μs). It is used in precision voltage reference and transient suppression circuits in industrial power supplies.

For engineers reviewing the RD27F-T8-AZ datasheet, RD27F-T8-AZ pinout, RD27F-T8-AZ application, or RD27F-T8-AZ equivalent, this page delivers verified electrical specs, thermal behavior, JEDEC DO-41 terminal mapping, real-world clipping/limiting use cases, and two validated alternative Zeners with voltage and impedance trade-offs.

Technical Context

This device operates as a two-terminal voltage-regulating element relying on controlled reverse-biased avalanche breakdown. Its planar junction structure ensures stable zener voltage tolerance and low dynamic impedance across its 10 mA test current. The DO-41 package provides defined thermal resistance (R_th ≈ 200 °C/W at 5 mm PCB copper area) and supports pulsed surge handling up to 400 W for 10 μs.

The RD27F-T8-AZ belongs to the RD2.0F–RD82F family with E24-standardized nominal voltages and B/B1–B3 grading. Its +21 mV/°C temperature coefficient indicates positive drift above 20 V, enabling predictable thermal compensation in bias networks. It is not intended for high-frequency regulation or low-noise references due to inherent noise and impedance limitations.

Key Specifications

Pinout & Package

RD27F-T8-AZ uses the JEDEC DO-41 axial-leaded glass package (3.0 mm Ø × 5.0 mm max length), with cathode identified by a black band. Thermal performance depends on PCB copper area (e.g., R_th ≈ 200 °C/W at 5 mm²).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar Zener diode applications.

Compared with RD27F-T8-AZ, the 1N4750A offers near-identical voltage and thermal behavior but looser initial tolerance, while the BZX85C27 trades lower dynamic impedance stability for greater thermal headroom-making each suitable for distinct thermal or precision requirements in 27 V clamp designs.

Availability

RD27F-T8-AZ is available at Aetrix Electronics and suitable for industrial power supplies, PLC I/O protection, analog signal conditioning, and embedded voltage reference circuits requiring stable component supply and long-term obsolescence management.

Supply support for RD27F-T8-AZ 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

Renesas Electronics Corporation is a global semiconductor leader delivering microcontrollers, analog, power, and timing solutions for industrial, automotive, and infrastructure markets.

RD27F-T8-AZ belongs to Renesas' legacy planar Zener diode product line, designed specifically for cost-sensitive, high-reliability voltage regulation and transient suppression in industrial control and power conversion systems.

FAQ

What is the exact zener voltage range for RD27F-T8-AZ?

The RD27F-T8-AZ is specified as a B3-grade device with a zener voltage range of 26.72 V to 28.43 V at 10 mA test current (TA = 25°C), per Renesas datasheet D13936EJ5V0DS. This tighter tolerance than standard B grade makes RD27F-T8-AZ suitable for applications demanding higher initial accuracy without post-calibration.

Does RD27F-T8-AZ have a specified junction-to-case thermal resistance?

No, the RD27F-T8-AZ datasheet does not list junction-to-case (R_θJC) thermal resistance. Instead, it provides ambient-based derating curves (Figure 1) and transient thermal impedance data (Figure 8), with effective thermal resistance dependent on PCB copper area-e.g., ~200 °C/W at 5 mm². Designers must use these empirical curves rather than fixed R_θJC values.

Can RD27F-T8-AZ be used in place of RD27F without the "-T8-AZ" suffix?

Yes-RD27F-T8-AZ is a Renesas-marked variant of the base RD27F Zener diode, with identical electrical specifications, DO-41 package, and B3 voltage grade. The "-T8-AZ" suffix denotes tape-and-reel packaging (T8) and RoHS-compliant finish (AZ); the core device remains functionally and electrically equivalent to RD27F in all operating conditions.

What is the maximum allowable reverse voltage before breakdown for RD27F-T8-AZ?

The RD27F-T8-AZ exhibits less than 10 μA reverse leakage current at V_R = 20 V (TA = 25°C), per its Electrical Characteristics table. Breakdown begins gradually above this point, with full zener regulation established at the specified V_Z (26.72–28.43 V) at 10 mA. Operating continuously below 20 V ensures negligible power dissipation and no avalanche activity.

Is RD27F-T8-AZ qualified for automotive applications?

No-RD27F-T8-AZ is classified as a "Standard" quality grade device per Renesas documentation, intended for computers, office equipment, industrial robots, and communications gear. It is not qualified to AEC-Q101 or rated for automotive under-hood temperatures; use only in non-safety-critical industrial or commercial systems unless explicitly requalified by the customer.