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Renesas RD18F-T8-AZ
- Part No.:
- RD18F-T8-AZ
- Manufacturer:
- Renesas
- Category:
- Single Zener Diodes
- Package:
- -
- Datasheet:
-
RD18F-T8-AZ.pdf
- Description:
- DIODE ZENER
- Quantity:
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Inventory:4,080
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Product details
Overview
RD18F-T8-AZ from Renesas Electronics is a 1 W planar-type silicon Zener diode with nominal zener voltage of 18 V (B3 grade: 17.64–18.55 V), dynamic impedance of 12 Ω at 20 mA, and temperature coefficient of +13 mV/°C. It features DO-41 glass-sealed DHD (Double Heatsink Diode) packaging and is rated for surge reverse power of 400 W (t = 10 μs), making it suitable for precision voltage reference and transient suppression in industrial power supplies.
For engineers reviewing the RD18F-T8-AZ datasheet, RD18F-T8-AZ pinout, RD18F-T8-AZ application, or RD18F-T8-AZ equivalent, this device serves as a stable 18 V shunt regulator in low-to-medium power circuits where thermal stability, tight voltage tolerance, and surge resilience are critical - especially in analog sensing front-ends and overvoltage clamp stages.
Technical Context
This Zener diode operates in reverse breakdown mode to maintain a stable reference voltage across its terminals under varying load and line conditions. Its planar junction structure ensures consistent breakdown characteristics and low noise performance, while the DO-41 glass package provides mechanical robustness and reliable thermal dissipation via axial leads.
The RD18F-T8-AZ exhibits a positive temperature coefficient (+13 mV/°C), indicating increasing zener voltage with rising junction temperature - a key consideration in thermally unregulated environments. Its 20 mA test current (IZ) and 12 Ω dynamic impedance define regulation accuracy and AC ripple rejection capability in real-world bias networks.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 17.64–18.55 V (B3 grade, tested at 20 mA); defines precise clamping threshold for 18 V rail protection |
| Power Dissipation (P) | 1.0 W at TA = 25°C; sets maximum continuous DC power handling before thermal derating |
| Dynamic Impedance (ZZ) | 12 Ω at IZ = 20 mA; determines output voltage variation under changing load current |
| Temperature Coefficient (γZ) | +13 mV/°C (typical); quantifies voltage drift per degree rise - critical for ambient-stable references |
| Surge Reverse Power (PRSM) | 400 W for t = 10 μs; enables single-pulse transient suppression without failure |
| Reverse Current (IR) | ≤10 μA at VR = 14.4 V; ensures minimal leakage in high-impedance bias networks |
| Junction Temperature (Tj) | 175°C maximum; defines upper thermal limit for safe operation and lifetime reliability |
Pinout & Package
RD18F-T8-AZ uses the JEDEC DO-41 axial-leaded glass package (3.0 mm diameter × 5.0 mm max length), with cathode indicated by a black band. The device has two terminals: anode and cathode - no internal circuitry or multi-pin functionality.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal / reference ground node | Connected to system ground or lower potential; forms return path during reverse-bias regulation |
| Cathode | Zener breakdown terminal / regulated output node | Connected to voltage rail being clamped; maintains ~18 V relative to anode when reverse-biased above VZ |
Key Features
| Feature | Design Value |
|---|---|
| 1 W Planar Zener Structure | Enables stable, low-noise voltage reference with predictable breakdown and long-term parameter stability |
| E24-Series Voltage Standardization | Supports interoperability and BOM consolidation across 18 V design variants in industrial electronics |
| DO-41 Glass Sealed DHD Package | Provides superior thermal coupling to PCB copper and resistance to moisture ingress vs. plastic packages |
| +13 mV/°C Tempco (Typ.) | Allows predictable compensation in temperature-sensitive analog circuits without external components |
| 400 W Surge Rating (10 μs) | Permits use in unprotected input stages without additional TVS devices for short-duration transients |
Applications
| Industrial Power Supply Clamp | ADC Reference Stabilizer |
|---|---|
Use Scenario: Clamping 24 V DC input rails against ESD and inductive switching spikes in PLC I/O modules. IC Role / Device Role / Timing Role: Shunt regulator providing passive overvoltage protection upstream of DC-DC converters. Use Value: Limits transient excursions to ≤18.6 V (at 25°C), preventing damage to downstream 20 V-rated regulators and logic. |
Use Scenario: Biasing precision 12-bit ADC reference inputs in sensor signal conditioning circuits. IC Role / Device Role / Timing Role: Low-drift voltage reference source for ratiometric measurement systems. Use Value: Delivers <±1.5% VZ tolerance and <12 Ω dynamic impedance, reducing reference error contribution to <0.05 LSB. |
| Motor Driver Gate Protection | Linear Regulator Feedback Divider |
Use Scenario: Protecting gate drivers from flyback voltage overshoot during MOSFET turn-off in 12 V BLDC controllers. IC Role / Device Role / Timing Role: Fast-response clamp limiting gate-source voltage to safe levels during switching transitions. Use Value: Responds within nanoseconds to 10 μs surges up to 400 W, eliminating need for slower TVS diodes in compact layouts. |
Use Scenario: Setting output voltage in adjustable LDOs (e.g., LM317-based supplies) for embedded microcontroller rails. IC Role / Device Role / Timing Role: Precision voltage node in feedback divider network to stabilize regulated 18 V output. Use Value: Maintains regulation accuracy within ±2% over −40°C to +105°C due to known +13 mV/°C tempco and low ZZ. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N4746A (ON Semiconductor) | Same 18 V nominal, but DO-41 package with ±5% tolerance (17.1–18.9 V), ZZ = 20 Ω at 19 mA, γZ = +13 mV/°C | Looser initial tolerance; higher ZZ reduces regulation fidelity in low-current bias networks | Acceptable where cost sensitivity outweighs precision requirements; verify thermal margin at full 1 W load |
| BZX85C18 (Nexperia) | 18 V, DO-41, ±5% tolerance, ZZ = 25 Ω at 5 mA, γZ = +12 mV/°C, P = 1.3 W | Higher power rating but significantly higher dynamic impedance degrades AC regulation performance | Preferred only when >1 W continuous dissipation is required; not recommended for precision reference use |
Compared with RD18F-T8-AZ, the 1N4746A offers broader availability but sacrifices voltage tightness and low-impedance regulation, while the BZX85C18 trades regulation accuracy for extra thermal headroom - making RD18F-T8-AZ optimal for designs prioritizing stability, low noise, and predictable tempco in 18 V reference or clamp roles.
Availability
RD18F-T8-AZ is available at Aetrix Electronics and suitable for industrial power supply clamp, ADC reference stabilizer, motor driver gate protection, and linear regulator feedback divider applications requiring stable component supply, long-lifecycle support, and traceable sourcing.
Supply support for RD18F-T8-AZ 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 infrastructure markets.
RD18F-T8-AZ belongs to Renesas' legacy planar Zener diode family designed for high-reliability voltage regulation and transient suppression in standard-grade industrial equipment - emphasizing thermal stability, tight parametric control, and DO-41 mechanical ruggedness.
FAQ
What is the exact zener voltage range for RD18F-T8-AZ?
The RD18F-T8-AZ is specified as a B3-grade device with a zener voltage range of 17.64 V to 18.55 V at 20 mA test current (IZ), per Renesas Data Sheet D13936EJ5V0DS. This tight ±2.5% tolerance supports precision regulation tasks where voltage repeatability is essential, and the value is measured after 40 ms stabilization post-power-on.
Does RD18F-T8-AZ have a positive or negative temperature coefficient?
RD18F-T8-AZ has a positive temperature coefficient of +13 mV/°C (typical), meaning its zener voltage increases linearly with junction temperature. This behavior is confirmed in Figure 4 of the official datasheet and must be accounted for in thermally variable environments - for example, adding series NTC compensation in high-accuracy reference designs.
What is the maximum surge reverse power rating for RD18F-T8-AZ?
RD18F-T8-AZ is rated for 400 W of surge reverse power at a pulse width of 10 μs (non-repetitive), as defined in the Absolute Maximum Ratings table. This rating enables effective single-event transient suppression without device failure, provided the pulse repetition rate remains low and average power stays within the 1 W DC limit.
Is RD18F-T8-AZ RoHS compliant?
Yes, RD18F-T8-AZ complies with the EU RoHS Directive, as confirmed by Renesas' environmental compliance documentation. The device contains no lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls (PBB), or polybrominated diphenyl ethers (PBDE), and meets all substance restrictions applicable to standard-grade industrial components.
What package type does RD18F-T8-AZ use, and how is polarity marked?
RD18F-T8-AZ uses the JEDEC-standard DO-41 axial glass package (3.0 mm Ø × 5.0 mm max length), with cathode identified by a black band on the body. The marking "RD18F" is laser-etched or printed adjacent to the band, and the device is mechanically and thermally optimized for through-hole mounting with direct PCB copper contact for heatsinking.
RD18F-T8-AZ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Renesas
- Series:
- *
- Package/Case:
- -
- Packaging:
- Bulk
- Product Status:
- Active
- Voltage - Zener (Nom) (Vz):
- -
- Tolerance:
- -
- Power - Max:
- -
- Impedance (Max) (Zzt):
- -
- Current - Reverse Leakage @ Vr:
- -
- Voltage - Forward (Vf) (Max) @ If:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- -
- Supplier Device Package:
- -
RD18F-T8-AZ FAQ
1.How can I place an order for RD18F-T8-AZ through Aetrix?
Please submit a Request for Quotation (RFQ) for RD18F-T8-AZ on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for RD18F-T8-AZ reliable?
The price and inventory of RD18F-T8-AZ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for RD18F-T8-AZ is usually 5 days.
3.What payment methods are accepted for RD18F-T8-AZ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for RD18F-T8-AZ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for RD18F-T8-AZ?
RD18F-T8-AZ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your RD18F-T8-AZ order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for RD18F-T8-AZ?
For technical support, including RD18F-T8-AZ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your RD18F-T8-AZ requirements.
6.How does Aetrix verify that RD18F-T8-AZ is sourced from the original manufacturer or authorized distributors?
All RD18F-T8-AZ products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that RD18F-T8-AZ meets industry standards.
7.What is the process for return or replacement of RD18F-T8-AZ?
All RD18F-T8-AZ units undergo pre-shipment inspection (PSI). If there is an issue with RD18F-T8-AZ, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The RD18F-T8-AZ part is unused and in its original packaging.
Return procedure for RD18F-T8-AZ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
RD18F-T8-AZ Tags
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MM5Z5V1ST1G
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