Renesas HZ9A1-90

Overview

HZ9A1-90 from Renesas is a silicon planar Zener diode engineered for low-noise voltage regulation in precision analog circuits, with a nominal zener voltage of 7.9 V (min 7.7 V, max 8.1 V), dynamic resistance of 60 Ω at 0.5 mA test current, and maximum power dissipation of 400 mW in DO-35 package. It serves as a stable reference in low-drift power supplies and sensor biasing networks.

For engineers reviewing the HZ9A1-90 datasheet, HZ9A1-90 pinout, HZ9A1-90 application, or HZ9A1-90 equivalent, key selection criteria include its low noise level (≈1/3–1/10 that of standard HZ series), tight zener voltage tolerance, temperature coefficient of ≈−0.02 %/°C near 7.9 V, and suitability for low-current (<1 mA) stabilized references requiring minimal thermal drift.

Technical Context

This device operates as a two-terminal voltage reference using avalanche breakdown in a silicon planar junction. Its low dynamic resistance (60 Ω) and low leakage current (<1 μA at VR = 2.0 V) enable high regulation accuracy under light-load conditions typical in instrumentation front-ends and ADC reference buffers.

The HZ9A1-90 exhibits a negative temperature coefficient near −0.02 %/°C, consistent with mid-voltage Zener devices (~6–8 V), and maintains stable operation up to 175°C junction temperature. Its DO-35 glass package ensures hermetic sealing and low parasitic capacitance (<2 pF), critical for noise-sensitive applications.

Key Specifications

Pinout & Package

Package: DO-35 (JEITA code GRZZ0002ZB-A), glass axial leaded, orange body with navy blue cathode band. Mass: 0.13 g. Dimensions: φD = 2.0 mm, L = 26.0 mm, E = 4.2 mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX84-C7V5 and 1N4734A, the HZ9A1-90 delivers tighter voltage tolerance, lower noise, and DO-35 compatibility for through-hole analog subsystems where long-term drift and spectral purity are prioritized over footprint size or raw power handling.

Availability

HZ9A1-90 is available at Aetrix Electronics and suitable for precision instrumentation, medical sensor interfaces, and industrial analog input modules requiring stable component supply with guaranteed long-term parametric consistency and traceable lot history.

Supply support for HZ9A1-90 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 leader specializing in microcontrollers, analog power, and mixed-signal solutions for automotive, industrial, and infrastructure markets.

The HZ-L Series was developed specifically for low-noise, high-stability voltage reference applications in measurement equipment and sensor signal conditioning, addressing limitations of earlier HZ-series diodes in spectral purity and thermal drift.

FAQ

What is the exact zener voltage range specified for HZ9A1-90?

The HZ9A1-90 has a guaranteed zener voltage range of 7.7 V to 8.1 V when tested at I_Z = 0.5 mA, per Renesas datasheet REJ03G0182-0300 Rev.3.00. This 5% tolerance band reflects manufacturing control optimized for low-noise performance rather than ultra-tight calibration. The HZ9A1-90 achieves this specification without external trimming, making it suitable for cost-sensitive yet precision-critical designs.

Is HZ9A1-90 compatible with standard DO-35 footprints on PCBs?

Yes, the HZ9A1-90 uses the JEITA-standard DO-35 package (Renesas code GRZZ0002ZB-A) with defined dimensions: body diameter 2.0 mm, length 26.0 mm, and lead spacing 4.2 mm. Its orange body with navy blue cathode band matches mechanical and soldering requirements of legacy DO-35 layouts. The HZ9A1-90 can be substituted into existing DO-35 sockets or wave-soldered assemblies without footprint modification.

How does the noise performance of HZ9A1-90 compare to generic Zener diodes?

The HZ9A1-90 exhibits approximately one-third to one-tenth the broadband voltage noise of standard HZ-series Zeners, as confirmed in Renesas' characterization data. This reduction stems from proprietary silicon processing and junction geometry optimization. In practice, the HZ9A1-90 enables >90 dB SNR in 20 kHz bandwidths where generic 8 V Zeners achieve only 80–85 dB - a measurable advantage in audio preamplifiers and high-resolution data loggers using the HZ9A1-90.

What is the maximum reverse current allowed before regulation degrades in HZ9A1-90?

The HZ9A1-90 specifies a maximum reverse leakage current of 1 μA at V_R = 2.0 V, and full regulation begins at I_Z = 0.5 mA. Operation below 0.1 mA risks unstable knee behavior and increased noise; sustained current above 50 mA exceeds the 400 mW power limit at 8 V and risks thermal runaway. For reliable regulation, maintain I_Z between 0.5 mA and 40 mA - the HZ9A1-90 performs best in this window.

Does HZ9A1-90 require derating at elevated ambient temperatures?

Yes, the HZ9A1-90 must be derated linearly above 25°C ambient: its 400 mW rating decreases by 3.2 mW/°C up to 125°C, reaching zero at 175°C. At 70°C ambient, maximum allowable power drops to ~260 mW. This derating is defined in Figure 3 of the datasheet and applies regardless of airflow or board copper area. Designers using the HZ9A1-90 in enclosed enclosures should verify junction temperature using θ_JA ≈ 312°C/W (DO-35, 10 mm lead length).