Renesas RKZ5.1B2KJ#R1

Overview

RKZ5.1B2KJ from Renesas Electronics is a silicon planar Zener diode designed for precision voltage stabilization and transient surge absorption in low-power signal paths. It delivers a nominal Zener voltage of 5.1 V (4.98–5.20 V), maximum dynamic resistance of 130 Ω at 5 mA, reverse current ≤5 μA at 1.5 V, and 150 mW power dissipation on PCB - deployed in ESD-protected I/O interfaces of industrial sensors and microcontroller reset circuits.

For engineers reviewing the RKZ5.1B2KJ datasheet, RKZ5.1B2KJ pinout, RKZ5.1B2KJ application, or RKZ5.1B2KJ equivalent, key selection criteria include its UFP (SC-79) surface-mount package, ±2% Zener tolerance at 5 mA, 30 kV ESD capability (IEC 61000-4-2), and thermal derating behavior above 25°C ambient.

Technical Context

This device operates as a two-terminal voltage reference and clamping element in reverse-biased mode, with junction temperature limited to 150°C and storage range from −55°C to +150°C. Its ultra-small flat lead (UFP) package enables high-density PCB layout while maintaining reliable solder joint integrity on polyimide boards.

Zener voltage exhibits a positive temperature coefficient near 5.1 V (≈+0.02 %/°C per Fig.2), enabling stable regulation across industrial temperature ranges. Surge reverse power handling follows non-repetitive pulse profiles up to 1 W for sub-millisecond transients, validated per reference data in Fig.4.

Key Specifications

Pinout & Package

RKZ5.1B2KJ uses the Ultra Small Flat Lead (UFP) package per JEITA code PWSF0002ZA-A, also known as SC-79. The package has two terminals: Pin 1 is cathode (marked), Pin 2 is anode. Dimensions are 1.7 mm (L) × 1.2 mm (W) × 0.6 mm (H), with 0.7 mm terminal pitch and exposed lead tips for verified solderability.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX584-C5V1 and MMSZ5231B, RKZ5.1B2KJ uniquely balances compact UFP packaging, 150 mW power capability, tight ±2% Zener tolerance, and certified 30 kV ESD robustness - making it optimal for space-constrained, safety-critical I/O protection where both regulation accuracy and transient immunity are required.

Availability

RKZ5.1B2KJ is available at Aetrix Electronics and suitable for industrial sensor interfaces, microcontroller reset circuits, and USB port ESD protection requiring stable component supply, full traceability, and long-term lifecycle support.

Supply support for RKZ5.1B2KJ 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 specializing in microcontrollers, analog, power, and timing solutions for industrial, automotive, and enterprise systems.

RKZ5.1B2KJ belongs to the RKZ-KJ Series of silicon planar Zener diodes engineered specifically for dual-role operation: precision voltage stabilization in low-current bias networks and robust surge absorption in I/O protection circuits.

FAQ

What is the Zener voltage tolerance of RKZ5.1B2KJ at 5 mA test current?

The RKZ5.1B2KJ exhibits a Zener voltage range of 4.98 V to 5.20 V when tested at I_Z = 5 mA, corresponding to a ±2.1% tolerance about the nominal 5.1 V value. This tight tolerance is confirmed in the Electrical Characteristics table on page 2 of the REJ03G1588-0100 datasheet and supports accurate voltage monitoring in 5 V system rails without trimming components. RKZ5.1B2KJ maintains this specification across its rated junction temperature range.

Does RKZ5.1B2KJ meet industry-standard ESD requirements for I/O protection?

Yes, RKZ5.1B2KJ is rated for 30 kV human-body-model (HBM) ESD per C = 150 pF / R = 330 Ω, tested in both forward and reverse directions with 10 pulses. This exceeds IEC 61000-4-2 Level 4 (8 kV contact / 15 kV air) requirements and qualifies RKZ5.1B2KJ for direct placement on exposed I/O lines in industrial and medical-grade equipment. The RKZ5.1B2KJ datasheet explicitly lists this value in the Electrical Characteristics table.

What is the thermal derating behavior of RKZ5.1B2KJ above 25°C ambient?

RKZ5.1B2KJ's power dissipation derates linearly above 25°C ambient temperature, as shown in Fig.3 of the datasheet. At 50°C ambient, its usable power drops to approximately 115 mW; at 75°C, it falls to ~85 mW. This behavior stems from its 150°C maximum junction temperature and thermal resistance characteristics inherent to the UFP package. Designers must apply this curve when sizing bias resistors for RKZ5.1B2KJ in thermally constrained enclosures.

Can RKZ5.1B2KJ be used as a replacement for standard 5.1 V Zener diodes like 1N4733A?

No - RKZ5.1B2KJ is not a drop-in replacement for through-hole Zeners such as 1N4733A. It uses the UFP (SC-79) surface-mount package (1.7 × 1.2 × 0.6 mm), differs in thermal performance (150 mW vs. 1 W), and features optimized ESD robustness (30 kV) absent in legacy parts. While both regulate near 5.1 V, RKZ5.1B2KJ targets modern SMT designs requiring miniaturization and integrated ESD protection, not general-purpose through-hole voltage references.

What does the "B2KJ" suffix indicate in RKZ5.1B2KJ?

The "B2KJ" suffix in RKZ5.1B2KJ denotes the specific variant within the RKZ-KJ Series: "B" indicates ±2% Zener voltage tolerance, "2" identifies the second revision of the electrical specification, and "KJ" designates the UFP package with embossed taping. This coding aligns with Renesas' ordering nomenclature in the datasheet's Ordering Information section and distinguishes RKZ5.1B2KJ from variants like RKZ5.1BKJ (±5% tolerance) or RKZ5.1B2SJ (different package).