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Renesas RD18F
- Part No.:
- RD18F
- Manufacturer:
- Renesas
- Category:
- Single Zener Diodes
- Package:
- -
- Datasheet:
-
RD18F.pdf
- Description:
- DIODE ZENER
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Inventory:445,940
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Product details
Overview
RD18F from Renesas Electronics is a 1 W planar-type silicon Zener diode with a nominal zener voltage of 18 V (B grade: 16.37–18.55 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 up to 400 W (t = 10 μs). It is used in precision voltage regulation and overvoltage protection circuits in industrial power supplies.
For engineers reviewing the RD18F datasheet, RD18F pinout, RD18F application, or RD18F equivalent, this page delivers verified electrical specs, thermal behavior, JEDEC DO-41 terminal mapping, real-world use cases in clamping and reference circuits, and two validated alternative Zener diodes with documented parameter differences.
Technical Context
The RD18F operates as a two-terminal voltage-reference device relying on controlled reverse-breakdown conduction. Its zener voltage is specified at IZ = 20 mA with ±5.5% tolerance (B grade), and its positive temperature coefficient (+13 mV/°C) indicates increasing VZ with junction temperature - a key factor in thermal stability design.
It exhibits low dynamic impedance (12 Ω max at 20 mA), enabling stable regulation under varying load conditions, and supports transient surge absorption per Figure 7 (PRSM = 400 W, t = 10 μs). Its maximum junction temperature is 175°C, and it complies with JEDEC DO-41 mechanical standards.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 16.37–18.55 V at IZ = 20 mA - defines stable regulation range for mid-voltage rail referencing. |
| Dynamic Impedance (ZZ) | ≤12 Ω at IZ = 20 mA - ensures minimal output voltage variation under load current shifts. |
| Power Dissipation (P) | 1.0 W at TA = 25°C - sets continuous DC power limit; derates linearly above 25°C per Figure 1. |
| Temperature Coefficient (γZ) | +13 mV/°C - quantifies VZ drift with temperature; critical for high-accuracy reference designs. |
| Surge Reverse Power (PRSM) | 400 W (t = 10 μs) - enables short-duration transient suppression without failure. |
| Junction Temperature (Tj) | −65 to +175°C - defines operational thermal envelope; impacts long-term reliability and derating. |
| Reverse Current (IR) | ≤10 μA at VR = 15 V - confirms low leakage below breakdown, essential for standby power integrity. |
Pinout & Package
RD18F uses a standard JEDEC DO-41 axial-leaded glass package with cathode indicated by a black band. The device has two terminals: anode and cathode - no internal circuitry or polarity-sensitive control logic.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal / low-side connection | Connected to ground or lower-potential node in reverse-biased Zener configuration. |
| Cathode | Reverse breakdown terminal / high-side connection | Marked with black band; connected to input rail or voltage source to enable regulation/clamping. |
Key Features
| Feature | Design Value |
|---|---|
| Wide zener voltage range (2–82 V) | Enables single-family standardization across diverse supply rails - RD18F covers 18 V systems. |
| E24 series nominal values | Ensures compatibility with standard resistor ladder networks and common reference design practices. |
| Planar-type glass-sealed DHD structure | Provides robust thermal dissipation via double heatsink geometry and hermetic reliability in humid environments. |
| B-grade voltage classification | Offers three subgrades (B1/B2/B3) for tighter binning - RD18F B3 is 17.64–18.55 V for improved tolerance control. |
Applications
| Voltage Reference Circuit | Overvoltage Protection Circuit |
|---|---|
|
Use Scenario: Providing stable 18 V reference for ADC biasing or op-amp feedback in industrial sensor signal conditioning. IC Role / Device Role / Timing Role: Two-terminal passive voltage reference establishing precise DC operating point. Use Value: Low 12 Ω dynamic impedance minimizes reference error under varying load, supporting <±0.5% accuracy in 12-bit measurement systems. |
Use Scenario: Clamping 24 V supply rail against ESD or inductive spikes in PLC I/O modules. IC Role / Device Role / Timing Role: Passive shunt protector diverting transient energy to ground when voltage exceeds 18.55 V. Use Value: 400 W surge rating (10 μs) absorbs typical IEC 61000-4-5 surges without degradation, extending system MTBF. |
| Waveform Clipping Circuit | Constant-Current Bias Circuit |
|
Use Scenario: Limiting audio amplifier input swing to prevent distortion in analog front-end stages. IC Role / Device Role / Timing Role: Bidirectional clipping element (with series diode) constraining peak AC amplitude. Use Value: Sharp knee at 18 V enables clean hard-clipping at defined threshold, preserving signal fidelity below clipping level. |
Use Scenario: Setting fixed bias current for LED drivers or phototransistor amplifiers in optical encoders. IC Role / Device Role / Timing Role: Current-regulating element using VZ and series resistor to define ILED. Use Value: +13 mV/°C tempco allows predictable current drift compensation in ambient-temperature-varying environments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N4746A | Zener voltage 18 V ±5%, ZZ ≤20 Ω at 19 mA, DO-41, P = 1 W - higher dynamic impedance than RD18F's 12 Ω max. | Same 18 V regulation role but less stable under fast load transients due to higher ZZ. | Acceptable where cost or legacy sourcing dominates; verify transient response in high-dV/dt circuits. |
| BZX85C18 | Zener voltage 18 V ±5%, ZZ ≤25 Ω at 5 mA, DO-41, P = 1.3 W - lower test current and higher ZZ, different thermal profile. | Higher power rating but poorer low-current regulation; unsuitable for precision 20 mA reference designs. | Prefer only if >1.3 W continuous dissipation is required; avoid where 20 mA IZ stability is critical. |
Compared with 1N4746A and BZX85C18, RD18F offers superior dynamic impedance (12 Ω vs. ≥20 Ω) and tighter thermal coefficient control (+13 mV/°C vs. +10 to +15 mV/°C typical), making it preferred for high-stability 18 V references in temperature-variable industrial environments.
Availability
RD18F is available at Aetrix Electronics and suitable for industrial power supplies, sensor interface modules, and programmable logic controller (PLC) I/O protection requiring stable component supply, consistent parametric performance, and long-lifecycle availability.
Supply support for RD18F 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 formed in 2010 through the merger of NEC Electronics and Renesas Technology, specializing in microcontrollers, analog, and power devices.
RD18F belongs to the RD2.0F–RD82F planar Zener diode family designed for standardized, high-reliability voltage regulation and transient suppression in industrial and commercial equipment.
FAQ
What is the exact zener voltage range for RD18F at 20 mA test current?
The RD18F has a guaranteed zener voltage range of 16.37 V to 18.55 V when tested at IZ = 20 mA and TA = 25°C (B grade). This range reflects the full manufacturing tolerance; the B3 subgrade narrows it to 17.64–18.55 V. RD18F's specification is explicitly defined in Renesas' D13936EJ5V0DS datasheet, Table on page 3.
Does RD18F have a positive or negative temperature coefficient, and what is its value?
RD18F has a positive temperature coefficient of +13 mV/°C, meaning its zener voltage increases by approximately 13 millivolts per degree Celsius rise in junction temperature. This value is specified in the "Zener Voltage Temperature Coefficient γZ" column of the RD18F row in the Electrical Characteristics table (page 3, D13936EJ5V0DS).
What is the maximum surge reverse power rating for RD18F, and under what conditions?
RD18F is rated for a surge reverse power of 400 W with a pulse width of 10 μs at TA = 25°C, as shown in Figure 7 of the datasheet. This rating applies to non-repetitive transient events and must be applied with appropriate series limiting resistance to avoid exceeding the 1 W steady-state power limit.
Is RD18F compatible with automated PCB assembly processes?
Yes, RD18F uses the JEDEC-standard DO-41 axial package with 0.8 mm lead diameter and 25 mm minimum lead length, fully compatible with wave soldering, selective soldering, and hand-soldering. Its glass body and black cathode marking meet IPC-A-610 Class 2/3 visual inspection requirements.
What quality grade does RD18F carry, and which applications is it qualified for?
RD18F carries the "Standard" quality grade per Renesas' classification (page 7, D13936EJ5V0DS), making it suitable for computers, office equipment, communications gear, test instruments, audio/video systems, home appliances, machine tools, personal electronics, and industrial robots - but not for automotive safety, medical life-support, or aerospace applications without explicit Renesas approval.
RD18F 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 FAQ
1.How can I place an order for RD18F through Aetrix?
Please submit a Request for Quotation (RFQ) for RD18F 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 reliable?
The price and inventory of RD18F are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for RD18F is usually 5 days.
3.What payment methods are accepted for RD18F?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for RD18F transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for RD18F?
RD18F orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your RD18F 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?
For technical support, including RD18F datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your RD18F requirements.
6.How does Aetrix verify that RD18F is sourced from the original manufacturer or authorized distributors?
All RD18F 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 meets industry standards.
7.What is the process for return or replacement of RD18F?
All RD18F units undergo pre-shipment inspection (PSI). If there is an issue with RD18F, 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 part is unused and in its original packaging.
Return procedure for RD18F:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
RD18F Tags
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MMBZ5240B-7-F
Diodes Incorporated
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BZT52C5V6T-7
Diodes Incorporated
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MMSZ5231B-7-F
Diodes Incorporated
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BZT52C15-7-F
Diodes Incorporated
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BZX84C3V3LT1G
onsemi
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MMSZ5245BS-7-F
Diodes Incorporated
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MMSZ4682T1G
onsemi
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BZT52C15S-7-F
Diodes Incorporated
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MM5Z5V1ST1G
onsemi
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SMAJ4744A-TP
Micro Commercial Co
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BZT52C3V6LP-7
Diodes Incorporated
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SMAZ12-13-F
Diodes Incorporated
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