Diodes Incorporated 1N4748A-T

Overview

1N4748A-T from Diodes Incorporated is a 1.0 W, 22 V ±5% tolerance Zener diode in DO-41 glass package, designed for precision voltage regulation and overvoltage protection in DC power rails. It delivers 11.5 mA test current, 23 Ω dynamic impedance at I_ZT, and operates across –65°C to +175°C with cathode band polarity marking.

For engineers reviewing the 1N4748A-T datasheet, 1N4748A-T pinout, 1N4748A-T application, or 1N4748A-T equivalent, key selection criteria include Zener voltage stability under 11.5 mA bias, thermal resistance of 175 °C/W at 9.5 mm lead length, surge current rating of 205 A (8.3 ms), and DO-41 mechanical compatibility in space-constrained PCB layouts.

Technical Context

This 22 V Zener diode operates in reverse breakdown mode with a sharp knee characteristic verified by dual-point Zener impedance measurement per JEDEC standards. Its temperature coefficient (+0.06 to +0.095 %/°C) ensures predictable voltage drift over industrial temperature ranges.

The device uses Sn96.5Ag3.5 solderable terminations on a UL 94V-0 rated glass case, enabling reliable reflow and wave soldering. Thermal derating begins above 50°C at 6.67 mW/°C, requiring layout-aware heatsinking for sustained 1.0 W dissipation.

Key Specifications

Pinout & Package

DO-41 glass package with axial leads: anode (unmarked end) and cathode (band-marked end). Leads are Sn96.5Ag3.5 plated, solderable per MIL-STD-202 Method 208. Case meets UL 94V-0 flammability rating.

Key Features

Applications

Availability

1N4748A-T is available at Aetrix Electronics and suitable for DC power supply regulation, overvoltage protection circuits, reference voltage sources, and temperature-stable bias networks requiring stable component supply and full traceability.

Supply support for 1N4748A-T 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, specializing in high-reliability power management and signal integrity solutions for industrial, computing, and consumer markets.

The 1N47xxA series belongs to Diodes' legacy Zener diode product line, engineered for cost-effective, high-volume voltage regulation and protection in general-purpose power supplies and interface circuits.

FAQ

What is the maximum continuous power dissipation for 1N4748A-T at 70°C ambient?

At 70°C ambient, the 1N4748A-T must be derated from its 1.0 W rating at 25°C. Derating starts at 50°C at 6.67 mW/°C, so at 70°C the allowable power is 1.0 W − (20°C × 6.67 mW/°C) = 867 mW. This assumes leads are held at 50°C with 9.5 mm length from case per datasheet Note 1.

How does the Zener impedance of 23 Ω affect regulation accuracy in a 10 mA load circuit?

A 23 Ω Zener impedance means a 10 mA change in Zener current causes approximately 230 mV output variation (ΔV = Z_ZT × ΔI_Z). In a well-designed shunt regulator with series resistance limiting current, this enables ±0.3% regulation stability around 22 V under typical load steps.

Is 1N4748A-T suitable for use in automotive under-hood environments?

Yes - its –65°C to +175°C operating temperature range and UL 94V-0 glass package meet under-hood thermal and flammability requirements. However, it is not AEC-Q200 qualified; design validation for vibration, thermal cycling, and long-term reliability remains the customer's responsibility.

What is the significance of the "-T" suffix in 1N4748A-T?

The "-T" suffix indicates tape-and-reel packaging: 5,000 units per reel in DO-41 carrier tape. This format supports automated SMT placement when used with axial-to-SMT adapters or manual insertion in through-hole production, unlike the "-A" (ammo pack) variant intended for hand-soldering or selective wave processes.