1SMB5931BT3G - 18V 3W Zener Diode ±5% | onsemi | SMB
料号： 1SMB5931BT3G ✓ 量产中| 数量 | 单价 | 小计 |
|---|---|---|
| 1 | $0.55 | $0.55 |
| 10 | $0.42 | $4.20 |
| 100 | $0.27 | $27.00 |
| 500 | $0.21 | $105.00 |
| 1,000 | $0.17 | $170.00 |
| 2,500 | $0.14 | $350.00 |
1SMB5931BT3G 概述
A Zener diode is a specialized pn-junction diode engineered to operate reliably in the reverse-breakdown region, where it maintains a nearly constant voltage across its terminals despite large variations in reverse current. Zeners belong to the broader diode family -> discrete semiconductor -> voltage-reference device hierarchy, and are used as low-cost shunt voltage regulators, voltage clamps, and reference elements. The 1SMB5931BT3G's 18 V nominal makes it a mid-range member of the 1SMB59xxB family suitable for typical industrial and consumer rails.
Key features include a wide Zener breakdown voltage range across the family (3.3 V to 200 V), an ESD rating of Class 3 (>16 kV HBM), a flat handling surface that improves pick-and-place yield, and a lead-free, halogen-free, RoHS-compliant matte-tin finish that supports lead-free reflow profiles. The SMB (DO-214AA) body is a JEDEC-standard outline, with a cathode-marked polarity band for unambiguous placement.
In typical operation the 1SMB5931BT3G is reverse-biased at or near its 18 V knee and biased with a current-limiting resistor from a higher-voltage rail. The Zener's dynamic impedance Zz (at the test current Izt) defines how tightly the voltage is held under current variation; thermal resistance from junction to ambient and to mounting tab govern the achievable power dissipation on a given PCB footprint.
Typical applications include 18 V shunt regulation in industrial control boards, voltage clamping on telecom line interfaces, reference voltage generation in white-goods and appliance power supplies, over-voltage protection of 12 V-15 V analog signal lines, and crowbar/auxiliary regulation in switched-mode power supply secondary stages. The 18 V nominal also pairs naturally with 15 V operational amplifier supplies and 12 V battery-backed rails.
When designing with the 1SMB5931BT3G, derate power dissipation for ambient temperatures above 50 °C using the datasheet derating curve and keep the land pattern large enough to keep the junction-to-ambient thermal resistance near the JEDEC reference value. Series resistance must limit worst-case Zener current to within Pmax at minimum supply voltage.
This page synthesizes distributor pricing, drop-in same-package alternatives, and practical shunt-regulator design guidance not consolidated on a single distributor product page.
直接替换替代料： 1SMB5931BT3G ——相同封装，引脚兼容。需要 PCB 改动的不同封装料号已排除。
快速对比工具——选择替代料号进行并排对比：
1SMB5931BT3G-Q
✅ 直接替换 ⚠️ 规格未核验📋 参考替代料（不在目录中）
SZ1SMB5931BT3G
✅ 直接替换📋 参考替代料（不在目录中）
1SMB5932BT3G
✅ 直接替换 ⚠️ 规格未核验📋 参考替代料（不在目录中）
1SMB5930BT3G
✅ 直接替换 ⚠️ 规格未核验📋 参考替代料（不在目录中）
SMBJ5931B-TP
✅ 直接替换📋 参考替代料（不在目录中）
BZT52C18S-7-F
✅ 直接替换📋 参考替代料（不在目录中）
1SMB5931BT3G 最大额定值与电气特性
| Diode Type | Zener (Voltage Regulator Diode) |
| Nominal Zener Voltage (Vz) | 18 V |
| Vz Tolerance | ±5% |
| Power Dissipation (Pd) | 3.0 W (on JEDEC reference PCB) |
| ESD Rating | Class 3 (>16 kV) per Human Body Model |
| 封装 | SMB (DO-214AA) |
| 安装类型 | Surface Mount |
| 工作温度范围 | -55 °C to +150 °C (junction) |
| Polarity Marking | Cathode band |
| Lead Finish | Matte tin, lead-free |
| RoHS Compliance | Yes (per onsemi datasheet Notes) |
| 无卤 | Yes (per onsemi datasheet Notes) |
| Series | 1SMB59xxB |
| Packaging | Tape and Reel (T3 suffix) |
1SMB5931BT3G 引脚配置
| 引脚 1 | Cathode — Marked by polarity band on package body; reverse-biased terminal for Zener operation |
| 引脚 2 | Anode — Forward-biased terminal for Zener operation; opposite end from cathode band |
典型应用
1SMB5931BT3G 适用于 6 应用s: 18V Shunt Voltage Regulator, Over-Voltage Protection Clamp, Reference Voltage for ADCs and Op-Amps, White Goods and Appliance Power Supplies, Telecom Line Interface Protection, Automotive 12V/24V Subsystem Clamping.
18V Shunt Voltage Regulator
The 1SMB5931BT3G's 18 V nominal Vz and 3 W dissipation make it ideal as a shunt regulator on rails above 18 V, where a series resistor drops the excess voltage and the Zener holds the load within tolerance. In a typical 24 V industrial rail the diode clamps the load at 18 V ±5% while the series resistor limits current to roughly (24-18)/R. Use a 1% resistor to minimize reference drift and verify worst-case power dissipation stays within the 3 W rating.
推荐
Over-Voltage Protection Clamp
Placed across a sensitive input or interface line, the 1SMB5931BT3G clamps transients above 18 V, protecting downstream op-amps, ADC inputs or MCU pins from ESD and inductive spikes. Its 16 kV HBM ESD rating exceeds typical IEC 61000-4-2 air-discharge requirements, and the SMB package handles the inrush energy of typical industrial transient events. Combine with a TVS for higher-energy surges and a fuse for sustained over-voltage events.
推荐
Reference Voltage for ADCs and Op-Amps
The 1SMB5931BT3G can serve as a low-cost reference element for 15 V op-amp rails or ADC reference inputs that tolerate ±5% initial accuracy. Driven by a current source or large series resistor, the 18 V Zener provides a stable point that can be divided down to lower reference voltages. For applications requiring tighter tolerance than ±5%, choose a 1% or 2% tolerance Zener from the 1SMB59xxB family or upgrade to a dedicated voltage-reference IC.
推荐
White Goods and Appliance Power Supplies
In white-goods SMPS secondary stages, the 1SMB5931BT3G provides a low-cost auxiliary 18 V rail for gate drivers, fans or small relays. Its 3 W dissipation handles the modest current draw of these loads, while the SMB footprint is compatible with high-volume automated assembly. The lead-free matte-tin finish and 260 °C reflow compatibility meet modern RoHS manufacturing requirements for consumer appliances worldwide.
推荐
Telecom Line Interface Protection
The 1SMB5931BT3G clamps tip-and-ring telecom line interfaces at 18 V, protecting SLICs and codecs from induced transients on long cable runs. Its 16 kV HBM ESD rating provides a robust secondary protection layer behind primary PTC fuses or gas discharge tubes. The SMB package's low parasitic inductance preserves signal integrity on the protected line, while the ±5% Vz tolerance is acceptable for protection (non-precision) applications.
推荐
Automotive 12V/24V Subsystem Clamping
In 12 V automotive subsystems the 1SMB5931BT3G clamps inductive loads (relays, solenoids, motors) above 18 V, while in 24 V truck systems it serves as a mid-rail reference or auxiliary regulator. The onsemi 1SMB5931BT3G-Q and SZ1SMB5931BT3G variants provide AEC-Q101 qualification for under-hood applications. Always check load-dump and jump-start transients against the maximum ratings in the family datasheet.
推荐
推荐产品汇总
工程参考数据： 1SMB5931BT3G ——对比、设计指导和合规信息。
选型指南
与替代料对比
| 参数 | 本产品 | 1SMB5931BT3G-Q | SZ1SMB5931BT3G | 1SMB5932BT3G | 1SMB5930BT3G | SMBJ5931B-TP |
|---|---|---|---|---|---|---|
| Brand | onsemi | onsemi | onsemi | onsemi | onsemi | Micro Commercial Components |
| Package | SMB (DO-214AA) | SMB (DO-214AA) - same | SMB (DO-214AA) - same | SMB (DO-214AA) - same | SMB (DO-214AA) - same | SMB (DO-214AA) - same |
| Nominal Zener Voltage (Vz) | 18 V | 18 V | 18 V | 20 V | 16 V | 18 V |
| Vz Tolerance | ±5% | ±5% | ±5% | ±5% | ±5% | ±5% |
| Power Dissipation | 3.0 W | 3.0 W | 3.0 W | 3.0 W | 3.0 W | 3.0 W |
| ESD Rating (HBM) | Class 3 (>16 kV) | Class 3 (>16 kV) | Class 3 (>16 kV) | Class 3 (>16 kV) | Class 3 (>16 kV) | Class 3 (>16 kV) |
| Automotive Grade (AEC-Q101) | No (standard grade) | Yes (automotive grade) | Yes (AEC-Q101 qualified) | No | No | No |
| RoHS / Lead-Free | Yes / Yes | Yes / Yes | Yes / Yes | Yes / Yes | Yes / Yes | Yes / Yes |
关键差异点
- 3 W dissipation in standard SMB footprint （对比 1SMA5931BT3G)
- Automotive grade option within same family （对比 SZ1SMB5931BT3G (AEC-Q101))
- Higher Vz precision available within same series （对比 Generic 18 V Zener (untoleranced))
设计说明
On the JEDEC reference PCB (FR-4, 1 oz copper, recommended land pattern) the 1SMB5931BT3G dissipates 3 W with the junction held within rated limits. Above 50 °C ambient, derate linearly toward zero at the maximum junction temperature (typically 150 °C); for example, with a 100 °C linear derating window the usable dissipation drops to roughly 1.5 W at 100 °C ambient. Estimated: based on a linear derating from 3 W at 50 °C to 0 W at 150 °C; verify against the family datasheet's actual derating curve.
Always size the series resistor so worst-case Zener current stays within Pmax at minimum supply voltage AND below the absolute maximum Zener current at maximum supply voltage. For a 24 V rail with 18 V Zener: I_zener = (V_supply - Vz) / R_series. At minimum V_supply (e.g. 20 V) the current must still bias the Zener into regulation (above Izt); at maximum V_supply (e.g. 30 V) the current must keep Pz = Vz * I below 3 W. Failing this check produces either weak regulation or thermal failure.
Use the JEDEC-recommended SMB land pattern (per the onsemi datasheet) to achieve the rated 3 W dissipation. Smaller land patterns increase thermal resistance and reduce usable power. Place the Zener close to the load it is regulating or clamping, and keep the cathode band oriented per the schematic's reverse-bias convention. For high-current pulsed clamping, add a small series resistor or ferrite bead to limit peak current and reduce EMI.
Do not confuse the 1SMB5931BT3G (SMB / DO-214AA, 3 W) with the 1SMA5931BT3G (SMA / DO-214AC, lower power) - they share the 18 V nominal but use different packages and footprints. Substituting one for the other requires a PCB land-pattern change. Also note that the ±5% Vz tolerance makes the 1SMB5931BT3G unsuitable for precision reference applications; use a TL431 or dedicated reference IC when tighter tolerance is required.
合规信息
RoHS compliant per onsemi datasheet Notes 2; lead-free matte-tin finish; halogen-free per onsemi datasheet Notes. Standard grade is NOT AEC-Q100/Q101 qualified - choose SZ1SMB5931BT3G or 1SMB5931BT3G-Q for AEC-Q101 automotive applications.