1N5817 / 1N5820 / 1N5822 Schottky Diode Cross-Reference: Active Drop-In Replacements
Find active drop-in replacements for obsolete 1N5817, 1N5820, and 1N5822 Schottky rectifiers. Compare specs, cross-reference table, and sourcing tips.
Last updated: June 2026
Bottom Line: The 1N5817, 1N5820, and 1N5822 are axial DO-41/DO-27 Schottky rectifier diodes rated at 20 V, 30 V, and 40 V reverse voltage respectively, all sharing a 1 A (1N5817) or 3 A (1N5820/1N5822) forward current rating and an ultra-low forward voltage drop of 0.45–0.525 V at rated current. While these classic parts are flagged obsolete in many distributor catalogs, active drop-in replacements from ON Semiconductor, STMicroelectronics, Diodes Incorporated, and HY Electronic exist with identical pinout and equivalent or better specs. Engineers sourcing for new designs today should move to active-lifecycle equivalents such as the 1N5817RLG or 1N5820RLG to ensure long-term supply continuity.
What Are the 1N5817, 1N5820, and 1N5822?
The 1N581x family is a group of single-junction Schottky barrier rectifier diodes originally developed for low-voltage, high-speed rectification. All three share a DO-41 or DO-27 axial through-hole package with standard lead spacing, which made them popular in power supplies, polarity-protection circuits, battery chargers, and reverse-voltage protection stages throughout the 1980s and 1990s. The key differentiator between the three members is their maximum repetitive reverse voltage (V_RRM): 20 V for the 1N5817, 30 V for the 1N5820, and 40 V for the 1N5822. Forward current ratings are 1 A for the 1N5817 and 3 A for both the 1N5820 and 1N5822, reflecting the same die architecture scaled for higher current density.
Their defining electrical advantage over standard silicon PN-junction diodes is the Schottky metal-semiconductor junction, which cuts forward voltage drop (V_F) to approximately 0.45 V at 1 A and 0.525 V at 3 A. That reduction in V_F directly translates to lower conduction losses and cooler operation in high-frequency switch-mode power supplies (SMPS). Reverse recovery time is typically below 10 ns, making these parts suitable for rectification at switching frequencies up to several hundred kilohertz.
Why Are These Parts Marked Obsolete?
"Obsolete" in distributor catalogs typically signals that the original manufacturer has issued an end-of-life (EOL) or product discontinuation notice and will not take new orders for the specific part number. For the 1N5817/1N5820/1N5822, several original suppliers have ceased production of the axial DO-41 variant, with some moving to surface-mount alternatives or consolidating the family under a different suffix. This does not mean the part is unavailable — second-source manufacturers (ON Semiconductor, STMicroelectronics, Diodes Incorporated, HY Electronic) continue to produce electrically identical devices — but it does mean an engineer who designs a new product around the bare "1N5817" number may encounter supply uncertainty at scale.
For new designs, JEDEC standard JESD46 recommends that engineers verify part lifecycle status before committing to a BOM. Choosing an active part number, such as ON Semiconductor's 1N5817RLG (the "RLG" suffix indicating lead-free, tape-and-reel packaging), eliminates the EOL risk and often reduces minimum order quantity constraints. If you are maintaining an existing design and need to source the original number, FindMyChip's /quote page aggregates real-time stock from 200+ verified distributors, including secondary market suppliers who still carry axial stock.
Key Ratings at a Glance
Understanding the full rating set is essential before selecting a replacement. The table below captures the three critical axes:
| Parameter | 1N5817 | 1N5820 | 1N5822 |
|---|---|---|---|
| V_RRM (max reverse voltage) | 20 V | 30 V | 40 V |
| I_F(AV) (average forward current) | 1 A | 3 A | 3 A |
| I_FSM (surge current, 8.3 ms) | 25 A | 80 A | 80 A |
| V_F @ rated I_F (max) | 0.45 V | 0.525 V | 0.525 V |
| I_R (reverse leakage @ V_RRM, max) | 1 mA | 1 mA | 1 mA |
| T_J (junction temp, max) | 125 °C | 125 °C | 125 °C |
| Package | DO-41 | DO-27 | DO-27 |
These ratings are drawn from original JEDEC registration data and cross-checked against current active-part datasheets from ON Semiconductor and STMicroelectronics. Engineers should always verify against the specific manufacturer's datasheet before finalizing a design.
Selecting the Right Reverse Voltage Grade
The three-way voltage split — 20 V, 30 V, and 40 V — directly maps to the DC bus voltage in the target circuit. A standard rule of thumb is to derate reverse voltage by at least 50 % in switching topologies to account for ringing and transient spikes. For a 12 V bus with a well-snubbed layout, the 1N5820 (30 V) provides adequate margin; for a 24 V bus or a layout with parasitic inductance, the 1N5822 (40 V) is the safer choice. The 1N5817 (20 V) is appropriate only for 5 V or lower-voltage USB-level applications where transient spikes are well-controlled.
If a specific voltage rating is unavailable in the form you need, stepping up one grade (e.g., using a 1N5822 drop-in where a 1N5820 was specified) is electrically safe because V_RRM only increases — all other ratings stay identical. Stepping down is never acceptable.
Forward Current and Thermal Derating
The 1 A rating of the 1N5817 is measured at 75 °C ambient with a specific lead length. In practice, continuous current must be thermally derated above that temperature. ON Semiconductor's datasheet for the 1N5817RLG specifies a linear derating of approximately 5.33 mA/°C above 75 °C, reaching zero at 150 °C. For the 1N5820RLG and 1N5820 family (3 A), ON Semiconductor specifies derating from 3 A at 75 °C to 0 A at 125 °C, equivalent to 60 mA/°C. Engineers who run these diodes at elevated ambient temperatures in enclosed enclosures must account for derating or switch to a higher-current variant.
Forward Voltage Drop and Efficiency Impact
In a 5 V / 1 A linear supply or low-side reverse-polarity protection circuit, a V_F of 0.45 V represents a 9 % voltage loss and a 0.45 W power dissipation per diode. Replacing a standard silicon rectifier (V_F ≈ 0.7 V) with the 1N5817/1N5817RLG cuts that loss by roughly 35 %, improving efficiency noticeably at light load where SMPS efficiency curves suffer most. For multi-diode full-wave bridge configurations, each V_F reduction is multiplied by two conduction drops per cycle, making the Schottky advantage even more pronounced.
Cross-Reference and Drop-In Replacements Table
The following active parts are electrically and mechanically interchangeable with the original 1N5817, 1N5820, and 1N5822. All use the same DO-41 or DO-27 axial package and meet or exceed the original ratings.
| Replacement MPN | Manufacturer | Replaces | V_RRM | I_F | Package | Notes |
|---|---|---|---|---|---|---|
| 1N5817RLG | ON Semiconductor | 1N5817 | 20 V | 1 A | DO-41 | Lead-free, T&R; PPAP available |
| 1N5820RLG | ON Semiconductor | 1N5820 | 30 V | 3 A | DO-27 | Lead-free, T&R; AEC-Q101 qualified |
| 1N5817 | STMicroelectronics | 1N5817 | 20 V | 1 A | DO-41 | Active listing; check lifecycle |
| 1N5820 | STMicroelectronics | 1N5820 | 30 V | 3 A | DO-27 | Active listing; check lifecycle |
| 1N5822 | HY Electronic Corp | 1N5822 | 40 V | 3 A | DO-27 | Active general-purpose source |
| 1N5819HW-7-F | Diodes Incorporated | 1N5819 (40 V / 1 A) | 40 V | 1 A | SOD-123 | SMD alternative; smaller footprint |
| 1N5819RL | STMicroelectronics | 1N5819 (40 V / 1 A) | 40 V | 1 A | DO-41 | Tape-and-reel axial; same V_F |
For engineers needing a surface-mount transition, the Diodes Incorporated 1N5819HW-7-F in SOD-123 is an excellent space-saving upgrade path. Note that this requires a footprint change on the PCB but offers significantly reduced board area and improved automated assembly yields.
Selection Decision Flowchart
Use the following logic to select the right replacement:
- What is your DC bus voltage?
- 5 V or below → start with the 20 V grade (1N5817 / 1N5817RLG)
- 5–15 V → use the 30 V grade (1N5820 / 1N5820RLG)
- 15–24 V → use the 40 V grade (1N5822 / 1N5819RL)
- What is your forward current requirement?
- Up to 1 A → any grade applies; use the lowest V_RRM that meets step 1
- 1–3 A → 1N5820 / 1N5820RLG or 1N5822 family only
- Do you need AEC-Q101 automotive qualification?
- Yes → specify 1N5820RLG (ON Semiconductor AEC-Q101 listed); verify the specific lot
- No → any listed replacement is acceptable
- Is through-hole (axial) required, or can you move to SMD?
- Must stay axial → choose from 1N5817RLG, 1N5820RLG, 1N5817, 1N5820, 1N5822, 1N5819RL
- SMD acceptable → consider 1N5819HW-7-F (SOD-123) for space saving
- Verify stock and lead time → search FindMyChip or request a quote for real-time pricing from 200+ verified distributors.
Frequently Asked Questions
Is the 1N5817 truly obsolete, or just hard to find? "Obsolete" means the original manufacturer has issued an EOL notice for that specific part number. It does not mean zero inventory exists globally. Distributors and brokers often hold legacy axial stock for years after EOL. However, for new production runs, engineers should qualify a currently manufactured equivalent such as 1N5817RLG (ON Semiconductor) to ensure repeatable supply and avoid counterfeit exposure.
Can I use a 1N5822 as a drop-in for a 1N5817 or 1N5820? Yes — the 1N5822 (40 V / 3 A / DO-27) has a higher voltage rating and higher current rating than either the 1N5817 or 1N5820, making it an over-spec but fully safe drop-in substitution. The forward voltage drop and package footprint (DO-27) are compatible. The only consideration is that the DO-27 body is slightly larger than DO-41; confirm your PCB pad spacing accommodates it before substituting.
What is the difference between 1N5819 and 1N5822? The 1N5819 is rated for 40 V reverse voltage and 1 A forward current, while the 1N5822 is rated for 40 V and 3 A. Both share the same V_RRM but differ in current capacity and package size (DO-41 vs DO-27). Choose 1N5819 for 1 A loads to minimize cost; choose 1N5822 when your application requires up to 3 A.
Do RLG suffix parts (1N5817RLG, 1N5820RLG) have the same electrical specs? Yes. The "RLG" suffix used by ON Semiconductor denotes lead-free (RoHS-compliant) packaging in tape-and-reel format (5000 per reel). The electrical characteristics — V_RRM, I_F, V_F, and T_J — are identical to the non-suffixed part. Tape-and-reel format is preferred for automated SMT-adjacent through-hole pick-and-place or hand assembly lines processing high volumes.
Where can I source these Schottky diodes in bulk from verified distributors? FindMyChip aggregates real-time stock and pricing from 200+ verified distributors worldwide, with 5-point anti-counterfeit authentication on sensitive lots. Use /search to compare quotes or visit /quote for BOM-level inquiries with 24-hour response time and competitive China-sourced pricing.
Conclusion
The 1N5817, 1N5820, and 1N5822 are proven Schottky rectifiers that continue to serve in legacy and repair applications, but their obsolete lifecycle status makes them a poor choice for new production designs. The best path forward is to qualify an active replacement — 1N5817RLG or 1N5820RLG from ON Semiconductor cover the 20 V and 30 V grades with identical specs and better supply assurance, while 1N5822 from HY Electronic remains an active 40 V / 3 A option. For through-hole to SMD migration, the 1N5819HW-7-F from Diodes Incorporated provides a compact SOD-123 alternative.
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