1N6489US - 4.7V 1.5W Zener Diode SQ-MELF | Microchip
MPN： 1N6489US ✓ 啟用中1N6489US 概覽
A Zener diode is a specialized silicon pn-junction diode engineered to operate in the reverse-breakdown (Zener) region, where it maintains a near-constant voltage across its terminals despite variations in current. This makes Zener diodes the canonical building block for voltage reference, voltage regulation, and overvoltage protection circuits in analog and mixed-signal designs. The 1N6489US occupies the low-voltage end of the 1N6469-1N6491 family, with a 4.7 V nominal Zener voltage that is commonly used as a logic-rail reference (5 V systems with allowance for tolerance), A/D and D/A reference, and instrument-amplifier bias.
Key specifications include a nominal Zener voltage (Vz) of 4.7 V ±5%, maximum Zener impedance (Zzt) of 8 Ω at the test current, maximum reverse leakage (Ir) of 4 µA at 1 V reverse bias, and a maximum power dissipation of 1.5 W at 25 °C ambient with proper thermal mounting. The hermetically sealed SQ-MELF (US-suffix) package provides MIL-PRF-19500/406 qualification for military and aerospace applications, distinguishing it from the axial-leaded DO-41 (non-US) variant of the same die.
The 1N6489US uses a glass-passivated silicon junction die bonded in a hermetic metal-glass envelope, yielding long-term stability and low reverse leakage. The 8 Ω maximum Zener impedance ensures tight voltage regulation even at low Zener currents, making the part suitable for low-noise reference designs. The MIL-PRF-19500/406 qualification and hermetic construction deliver the reliability expected in defense, avionics, and space-grade power subsystems.
Typical applications include 5 V system voltage references, op-amp supply rails, A/D and D/A converter references, overvoltage clamps on signal lines, and military/aerospace power-conditioning circuits. The 1.5 W rating also makes it usable as a low-power shunt regulator in distributed power systems.
When designing with the 1N6489US, ensure the PCB land pattern matches the SQ-MELF (A-MELF) footprint, which differs from the axial DO-41 of the non-US 1N6489. Provide adequate copper thermal area on both anode and cathode pads; derate to 0.8 W or less above 75 °C ambient. Use a series current-limiting resistor sized so that Iz stays within the datasheet test-current window to guarantee the 4.7 V regulation point.
This page synthesizes Microchip/Microsemi distributor pricing, MIL-spec qualification details, drop-in alternatives in the same SQ-MELF footprint, and practical thermal design notes not consolidated in the manufacturer datasheet alone.
直接替換替代品，適用於 1N6489US — 相同封裝，腳位對腳位相容。需重新設計 PCB 的不同封裝零件不列入。
此系列的變體
與下列產品可直接替換的同系列型號： 1N6489US （相同外形與佔位） — 差異在於 Maximum Power Dissipation (Pd), Maximum Zener Impedance (Zzt), Reverse Leakage Current (Ir).
1N6489US
✅ 直接替換聯絡詢價
查看資料表 →CDLL6489
✅ 直接替換📋 參考替代品（不在目錄中）
1N4732A
✅ 直接替換📋 參考替代品（不在目錄中）
BZX84C4V7LT1G
✅ 直接替換📋 參考替代品（不在目錄中）
MMSZ5221BT1G
✅ 直接替換📋 參考替代品（不在目錄中）
1N6489US 最大額定值與電氣特性
| Zener Voltage (Nominal, Vz) | 4.7 V |
| Zener Voltage Tolerance | ±5% |
| Maximum Power Dissipation (Pd) | 1.5 W |
| Maximum Zener Impedance (Zzt) | 8 Ω |
| Reverse Leakage Current (Ir) | 4 µA at 1 V |
| 封裝 | SQ-MELF (A-MELF), surface mount |
| 安裝類型 | Surface Mount |
| 工作溫度範圍 | -65 °C to +175 °C (military grade) |
| Military Qualification | MIL-PRF-19500/406 |
| Diode Type | Zener voltage regulator |
| Configuration | Single |
| Polarity | Cathode band marked |
| Construction | Hermetically sealed glass |
| RoHS 狀態 | Compliant |
| Lead-Free | Yes |
1N6489US 腳位配置
| 腳位 1 | Anode (A) — Anode terminal (positive) |
| 腳位 2 | Cathode (K) — Cathode terminal (negative, banded end) |
典型應用
1N6489US 適用於 6 應用s: 5 V Logic-Rail Voltage Reference, ADC/DAC Reference Bias, Overvoltage Protection Clamp, Military and Avionics Power Conditioning, Op-Amp Supply Rail Reference, Industrial Process Control Signal Conditioning.
5 V Logic-Rail Voltage Reference
The 1N6489US's 4.7 V ±5% Zener voltage sits naturally below the 5 V TTL/CMOS rail, providing a stable reference that can be biased from the 5 V supply through a current-limiting resistor. With 8 Ω maximum Zener impedance and 4 µA reverse leakage, the 1N6489US holds the reference within a few millivolts under load steps in instrumentation and logic-level translation circuits. The MIL-PRF-19500/406 qualification also makes it suitable for defense electronics where long-term reference stability is critical.
推薦
ADC/DAC Reference Bias
Precision analog-to-digital and digital-to-analog converters require low-impedance reference voltages to maintain linearity. The 1N6489US, with its 8 Ω maximum Zener impedance and ±5% tolerance, can serve as a coarse reference or as the bias point for a precision op-amp reference buffer. The hermetic SQ-MELF glass package minimizes moisture-driven drift, which is essential in test-and-measurement equipment where calibration stability over years matters.
推薦
Overvoltage Protection Clamp
In signal-line protection circuits, the 1N6489US can clamp transient overvoltages to its 4.7 V Zener voltage when reverse-biased into breakdown by an ESD or inductive kick event. Its 1.5 W power rating allows the part to absorb multi-millisecond transients that would damage downstream CMOS logic. Used as a secondary protector behind a TVS diode, the 1N6489US adds a hard voltage ceiling for 5 V logic interfaces in industrial control and avionics bays.
推薦
Military and Avionics Power Conditioning
The MIL-PRF-19500/406 qualification makes the 1N6489US directly usable in military and avionics power subsystems where screened, hermetic components are mandatory. It is commonly deployed as a low-voltage shunt regulator in 28 V aircraft power buses, providing a stable 4.7 V reference for indicator lamps, relay logic, and sensor excitation. The wide -65 °C to +175 °C operating range covers both cockpit and unpressurized avionics bay environments.
推薦
Op-Amp Supply Rail Reference
Bipolar op-amps that require asymmetric supplies (e.g., +12 V and -4.7 V) can use the 1N6489US to derive the negative rail from a positive bias through a shunt regulator topology. The 8 Ω Zener impedance and 1.5 W rating accommodate typical op-amp quiescent currents while keeping the rail within ±5% across temperature. The hermetic SQ-MELF package suits industrial and instrumentation amplifier designs requiring long-term rail stability.
推薦
Industrial Process Control Signal Conditioning
In 4-20 mA current loops and other industrial process-control signal paths, the 1N6489US can serve as a low-voltage Zener reference for transducer excitation or as a clamp on field-wiring inputs. Its 1.5 W dissipation handles the transient energy from cable discharge events, and the SQ-MELF surface-mount package fits compact DIN-rail-mounted controller PCBs. The MIL-PRF-19500/406 screening also makes it a candidate for safety-rated industrial systems.
推薦
推薦產品摘要
工程參考資料，適用於 1N6489US — 比較、設計指引及合規資訊。
選型指南
與替代品比較
| 參數 | 本產品 | 1N6489US (Microsemi line) | CDLL6489 | 1N4732A | BZX84C4V7LT1G | MMSZ5221BT1G |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | onsemi | onsemi |
| Package | SQ-MELF (A-MELF) | SQ-MELF (A-MELF) - same | SQ-MELF (A-MELF) - same | DO-41 axial - different footprint | SOT-23 - different footprint | SOD-123 - different footprint |
| Zener Voltage (Nominal) | 4.7 V | 4.7 V | 4.7 V | 5.1 V | 4.7 V | 2.4 V |
| Power Dissipation | 1.5 W | 1.5 W | 1.5 W | 1 W | 225 mW | 500 mW |
| Zener Impedance (Zzt) | 8 Ω max | 8 Ω max | 8 Ω max | 10 Ω max | 70 Ω max | 30 Ω max |
| Tolerance | ±5% | ±5% | ±5% | ±5% (A suffix) | ±5% | ±5% |
| Military Qualification | MIL-PRF-19500/406 | MIL-PRF-19500/406 | DESC drawing screened | Not MIL-qualified | Not MIL-qualified | Not MIL-qualified |
| Operating Temperature Range | -65 °C to +175 °C | -65 °C to +175 °C | -65 °C to +175 °C | -65 °C to +175 °C | -55 °C to +150 °C | -55 °C to +150 °C |
主要差異化特點
- Hermetic MIL-PRF-19500/406 SQ-MELF surface-mount Zener (對比1N4732A (DO-41 axial))
- 1.5 W power dissipation in SQ-MELF (對比BZX84C4V7LT1G (SOT-23))
- 4.7 V ±5% with 8 Ω maximum Zener impedance (對比MMSZ5221BT1G (SOD-123))
設計說明
Estimated: at 1.5 W dissipation in the SQ-MELF glass package, the junction-to-ambient thermal resistance (θJA) requires at least 100 mm² of copper thermal pad on both anode and cathode lands. Without this thermal area the part will derate below 1 W well before reaching the 175 °C military upper temperature limit. Always verify junction temperature under worst-case (minimum series resistance, maximum Zener current) operating conditions.
The SQ-MELF (A-MELF) land pattern requires MELF-style round or oval pads with the cathode band matching the datasheet mechanical outline. Do not use the SOD-123 footprint - the body diameter is larger and the pad spacing is wider. For wave soldering, follow the J-STD-020 MSL profile; the hermetic glass package is moisture-insensitive but the surface-mount finish still requires standard handling.
Do not confuse the surface-mount 1N6489US (SQ-MELF) with the through-hole 1N6489 (DO-41 axial). They share the same die and 4.7 V rating but use different footprints; PCB rework is required to swap them. Also confirm the series resistor value: at the datasheet test current the Zener holds 4.7 V, but at currents far below the test point the Zener impedance rises and the regulation point shifts - this is the most common cause of 'Zener voltage is wrong' field complaints.
合規資訊
RoHS and REACH compliant per Microchip product page. MIL-PRF-19500/406 qualified for military and aerospace use. AEC-Q100 not applicable - this is a discrete Zener diode, not an automotive-qualified IC; for automotive applications consult Microchip's automotive-grade Zener portfolio.
