Microchip Technology 1N5235B

Overview

1N5235B from Microsemi is a 6.8 V, ±5% tolerance, 500 mW glass axial-lead Zener diode in DO-35 (DO-204AH) package, rated for 20 mA test current and 5.0 Ω dynamic impedance at IZT, used for precision voltage regulation in low-power analog reference and overvoltage protection circuits.

For engineers reviewing the 1N5235B datasheet, 1N5235B pinout, 1N5235B application, or 1N5235B equivalent, this page delivers verified electrical parameters, thermal derating behavior, Zener temperature coefficient (+0.050 %/°C), cathode-band polarity marking, and RoHS-compliant e3 variant availability - all critical for stable biasing, feedback sensing, and clamp design in industrial control and instrumentation.

Technical Context

The 1N5235B operates as a two-terminal voltage reference with sharp reverse-breakdown knee, specified at 20 mA test current (IZT) and characterized for stable regulation across –65°C to +175°C ambient range. Its 5.0 Ω Zener impedance (ZZT) at IZT ensures minimal output voltage variation under load transients.

Thermal resistance is 250 °C/W junction-to-lead (3/8″ lead length) and 310 °C/W junction-to-ambient on FR4 board; forward voltage is ≤1.5 V at 200 mA. Cathode polarity is marked by a band; operation requires cathode positive relative to anode.

Key Specifications

Pinout & Package

DO-35 (DO-204AH) hermetically sealed glass axial-leaded package with tin-lead or RoHS-compliant matte-tin plating; cathode identified by single black band; weight 0.2 g; lead length ≥10 mm for thermal rating compliance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N5235B, the 1N4734A offers double power headroom in a larger package, while BZX55C6V8 matches form factor but trades 2× higher impedance for broader vendor availability - making 1N5235B optimal for space-constrained, low-drift analog references.

Availability

1N5235B is available at Aetrix Electronics and suitable for industrial sensor biasing, microcontroller reset clamping, and linear regulator feedback divider applications requiring stable component supply, long-term obsolescence management, and traceable sourcing.

Supply support for 1N5235B 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

Microsemi (now part of Microchip Technology) is a U.S.-based semiconductor company specializing in high-reliability analog, RF, and radiation-hardened components for aerospace, defense, and industrial markets.

The 1N52xxB series was designed for precision voltage reference and overvoltage protection in harsh-environment systems where stability, wide temperature range, and JEDEC-standard interoperability are mandatory.

FAQ

What is the Zener voltage tolerance of the 1N5235B?

The 1N5235B has a nominal Zener voltage of 6.8 V with a guaranteed tolerance of ±5%, meaning its actual breakdown voltage falls between 6.46 V and 7.14 V when measured at 20 mA and 25°C. This tolerance is defined by the "B" suffix per JEDEC standard and applies across the full operating temperature range, though voltage drift due to temperature coefficient must be accounted for in precision designs.

How does the 1N5235B behave thermally on a PCB?

The 1N5235B exhibits a thermal resistance of 310 °C/W junction-to-ambient when mounted on FR4 with 4 mm² copper pads and 1 mm track width. At 25°C ambient, it delivers full 500 mW; above 50°C lead temperature, power must be linearly derated. Engineers must maintain ≥10 mm lead length from the glass body to meet the 250 °C/W junction-to-lead spec and avoid localized overheating.

Is the 1N5235B RoHS compliant?

Yes - the RoHS-compliant version of the 1N5235B is designated with the "e3" suffix (e.g., 1N5235Be3) and features annealed matte-tin plating per MIL-STD-750 Method 2026. It retains identical electrical specifications and thermal performance as the standard tin-lead variant, with no compromise in reliability or solderability at 260°C for 10 seconds.

What is the significance of the +0.050 %/°C temperature coefficient for the 1N5235B?

The +0.050 %/°C temperature coefficient means the 1N5235B's Zener voltage increases by approximately 3.4 mV per °C rise above 25°C (0.050% × 6.8 V). This positive drift is typical for Zeners above 5.6 V and must be factored into reference stability budgets - for example, a 50°C rise causes ~170 mV total shift, requiring compensation in high-accuracy applications.

Can the 1N5235B replace the 1N4734A in existing designs?

No - although both regulate at 6.8 V, the 1N5235B (DO-35, 500 mW, 5.0 Ω ZZT) and 1N4734A (DO-41, 1 W, 7 Ω ZZT) differ in package size, power rating, and thermal profile. Substitution requires verifying PCB pad layout, thermal relief, and current requirements; the 1N5235B cannot handle sustained 1 W loads and may overheat if used without derating analysis.