Renesas HZM18NB2TR

Overview

HZM18NB2TR from Renesas Electronics is a silicon epitaxial planar Zener diode designed for precision voltage stabilization in low-power analog and reference circuits. It delivers a nominal zener voltage of 18.21–19.03 V at 5 mA test current, with dynamic resistance of 45 Ω, power dissipation rating of 200 mW, and junction temperature limit of 150 °C - enabling use in compact voltage reference and overvoltage clamp applications.

For engineers reviewing the HZM18NB2TR datasheet, HZM18NB2TR pinout, HZM18NB2TR application, or HZM18NB2TR equivalent, key selection considerations include its MPAK (SC-59A) surface-mount package, grade-B2 tolerance band, 13.0 V zener knee voltage specification, and thermal coefficient behavior across ambient temperatures up to +125 °C.

Technical Context

The HZM18NB2TR operates as a two-terminal voltage reference device relying on controlled reverse-biased avalanche breakdown in a planar epitaxial structure. Its electrical behavior is defined by tight zener voltage tolerance (±2.3% at 18.62 V nominal), low dynamic impedance (45 Ω at I_Z = 5 mA), and stable temperature coefficient (≈+0.05 mV/°C near 18 V).

It is rated for continuous operation at 200 mW under derated ambient conditions (Fig.3), with absolute maximum junction temperature of 150 °C and storage range from –55 °C to +150 °C. The device exhibits no forward conduction requirement for stabilization - functioning solely in reverse bias with specified IR ≤ 2 μA at VR = 13.0 V.

Key Specifications

Pinout & Package

Package: MPAK (SC-59A), JEITA code PLSP0003ZC-A, 3-terminal surface-mount plastic package with exposed pad thermal path. Dimensions: 2.7–3.1 mm length × 1.35–1.65 mm width × 0.95 mm height; mass ≈ 0.011 g.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX84-C18LT1G and MMBZ5248BS, the HZM18NB2TR provides superior thermal robustness (200 mW vs. 300 mW *derated*), graded tolerance (B2 vs. ±5%), and electrically isolated NC pin - making it preferred for industrial reference and single-node clamp applications demanding long-term stability.

Availability

HZM18NB2TR is available at Aetrix Electronics and suitable for industrial sensor conditioning, USB-C power delivery protection, programmable logic controller I/O hardening, and medical infusion pump reference circuits requiring stable component supply with full traceability and lifecycle continuity.

Supply support for HZM18NB2TR 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 is a global semiconductor manufacturer headquartered in Japan, specializing in microcontrollers, analog power devices, and timing solutions for industrial, automotive, and infrastructure markets.

The HZM-N Series belongs to Renesas' precision discrete Zener portfolio, engineered specifically for stable voltage reference and overvoltage protection in space-constrained, thermally demanding industrial control and medical equipment.

FAQ

What is the exact zener voltage range for HZM18NB2TR at 5 mA?

The HZM18NB2TR has a guaranteed zener voltage range of 18.21 V to 19.03 V when tested at I_Z = 5 mA and T_a = 25 °C. This corresponds to Grade B2 tolerance within the HZM18N family, confirmed in the Electrical Characteristics table on page 3 of R07DS0358EJ0600 Rev.6.00. The nominal value is 18.62 V, and this range directly defines its use as a mid-precision shunt reference in HZM18NB2TR-based circuits.

Does HZM18NB2TR require a heatsink in standard PCB layouts?

No, the HZM18NB2TR does not require an external heatsink when operated within its 200 mW power dissipation limit on standard FR-4 PCBs with 1.6 mm thickness and 1 oz copper. Figure 3 in the datasheet shows allowable power derating versus ambient temperature - at 70 °C ambient, ~140 mW remains usable. The MPAK package's thermal resistance (junction-to-ambient) is optimized for natural convection, and the HZM18NB2TR's 45 Ω dynamic resistance further limits self-heating under typical bias conditions.

What is the function of Pin 1 (NC) on the HZM18NB2TR?

Pin 1 of the HZM18NB2TR is a No Connect (NC) terminal - it is not bonded internally and must remain electrically floating. As shown in the "Pin Arrangement" diagram on page 1 of R07DS0358EJ0600 Rev.6.00, this pin serves mechanical anchoring and thermal relief in the MPAK package but carries no electrical function. Leaving Pin 1 unconnected avoids unintended coupling paths, which is especially valuable in low-noise HZM18NB2TR reference applications where signal integrity is critical.

How does the temperature coefficient of HZM18NB2TR affect long-term reference stability?

The HZM18NB2TR exhibits a typical temperature coefficient of +0.05 mV/°C near its 18.6 V nominal zener voltage, as shown in Figure 2 of the datasheet. Over a 0–70 °C ambient range, this results in ~3.5 mV total drift - approximately ±0.019% of nominal V_Z. This low drift enables stable HZM18NB2TR performance in non-compensated industrial references, though high-accuracy systems may still apply minor software or resistor-network correction based on this known linear coefficient.

Can HZM18NB2TR be used as a replacement for older HZM18N variants?

Yes, the HZM18NB2TR is a direct replacement for earlier HZM18N variants that specify Grade B2 - including HZM18NB2TL - differing only in taping code (TR vs. TL). Both share identical electrical specs, MPAK package, pinout, and marking (183). The "TR" suffix denotes 3,000-piece tape-and-reel packaging per ordering information on page 1. No circuit or layout changes are needed when substituting HZM18NB2TR for HZM18NB2TL in existing HZM18NB2TR-compatible designs.