LM385M3X-1.2/NOPB - 1.235V Micropower Shunt Voltage Reference | Texas Instruments
料号： LM385M3X-1.2/NOPB ✓ 量产中| 数量 | 单价 | 小计 |
|---|---|---|
| 1 | $0.84 | $0.84 |
| 10 | $0.72 | $7.20 |
| 100 | $0.55 | $55.00 |
| 500 | $0.43 | $215.00 |
| 1,000 | $0.36 | $360.00 |
LM385M3X-1.2/NOPB 概述
A shunt voltage reference is a two-terminal (cathode + anode) device that maintains a fixed reverse voltage across its terminals once biased above its minimum operating current, much like a temperature-compensated Zener diode. Shunt references sit within the broader hierarchy of voltage reference ICs, which in turn belong to power management and precision analog product families. They are commonly used as low-cost substitutes for buried-Zener or series-mode references in cost-sensitive, low-power applications.
Key features include a 150 ppm/°C (max) low temperature coefficient, 1.235 V nominal output, an exceptionally low operating current floor of 10 µA that enables battery-life designs, and on-chip trimming for production-time accuracy. The DBZ SOT-23-3 footprint occupies roughly 7 mm² of PCB area and is compatible with TI's broader LMx85-1.2 reference family.
The LM385-1.2-N series uses a band-gap architecture with on-chip trim, producing a stable 1.235 V reference across temperature. The 1 Ω dynamic impedance translates to less than 1 mV of additional error when cathode current varies by 1 mA, which is sufficient for ADC references, threshold detectors, and comparator-set switching thresholds.
Typical applications include portable battery-powered meters, threshold detectors in comparator circuits, ADC reference rails in low-cost microcontrollers, and micropower regulators where the 1.235 V reference is amplified to higher rails.
When designing with this part, pair it with a bias resistor sized to deliver 10 µA to 20 mA across the supply range. A 0.1 µF bypass capacitor across the reference often improves transient noise immunity.
This page synthesizes distributor pricing, parametric comparison tables, drop-in alternatives and practical design notes not found in a single manufacturer datasheet, giving the engineer a one-stop reference for sourcing and qualifying the LM385M3X-1.2/NOPB.
直接替换替代料： LM385M3X-1.2/NOPB ——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：
LM385M3-1.2
✅ 直接替换📋 参考替代料（不在目录中）
LM385M3-1.2/NOPB
✅ 直接替换 ⚠️ 规格未核验📋 参考替代料（不在目录中）
LM385M3X-2.5/NOPB
✅ 直接替换📋 参考替代料（不在目录中）
LM385M3X-1.2
✅ 直接替换📋 参考替代料（不在目录中）
LM4040EIM3-1.2/NOPB
✅ 直接替换📋 参考替代料（不在目录中）
LM4040CIM3-1.2/NOPB
✅ 直接替换 ⚠️ 规格未核验📋 参考替代料（不在目录中）
XB385M3-1.2
✅ 直接替换📋 参考替代料（不在目录中）
LM385M3X-1.2/NOPB 最大额定值与电气特性
| Reference Type | Shunt Voltage Reference |
| Nominal Output Voltage | 1.235 V |
| Initial Tolerance | ±1 % to ±2 % (depending on grade) |
| Operating Current Range | 10 µA to 20 mA |
| Dynamic Impedance | 1 Ω (max, at 1 mA) |
| Temperature Coefficient | 150 ppm/°C (max) |
| 工作温度范围 | 0 °C to +70 °C |
| 封装 | SOT-23-3 (DBZ) |
| 引脚数量 | 3 |
| 安装类型 | Surface Mount |
| 拓扑 | Band-gap, two-terminal shunt |
| Cathode-Anode Terminals | 2 (Pin 1 = cathode, Pin 2 = anode, Pin 3 = cathode/anode) |
| MSL 等级 | 1 (unlimited floor life) |
| RoHS 状态 | Compliant (NOPB indicates lead-free) |
LM385M3X-1.2/NOPB 引脚配置
| 引脚 1 | CATHODE — Cathode terminal (positive side of reference) |
| 引脚 2 | ANODE — Anode terminal (ground/return) |
| 引脚 3 | CATHODE — Cathode terminal (internally connected to pin 1) |
典型应用
LM385M3X-1.2/NOPB 适用于 6 应用s: Battery-Powered Portable Meter Reference, Comparator Threshold Detector, ADC Reference Voltage Rail, Micropower Linear Regulator Reference, Threshold Sensor Bias Supply, Industrial Process Control Bias Rail.
Battery-Powered Portable Meter Reference
The LM385M3X-1.2/NOPB's 10 µA minimum operating current and 1.235 V band-gap output make it ideal as a stable rail for handheld digital multimeters and portable instrumentation. The part maintains regulation from 10 µA to 20 mA, which means a single AAA cell can bias it across its full discharge curve. Its 1 Ω dynamic impedance keeps reference error below 1 mV even when the ADC draws mA-level load transients, while the SOT-23-3 footprint occupies less than 7 mm² of PCB area. Compared to a buried-Zener reference, the LM385 trades absolute accuracy for sub-microamp quiescent drain and low cost, enabling battery-life designs approaching the shelf life of the cell.
推荐
Comparator Threshold Detector
In window detectors and overcurrent comparators, the LM385M3X-1.2/NOPB provides a precise 1.235 V threshold to a comparator's reference pin, eliminating drift from supply variation. The part's low 10 µA operating floor means it adds negligible load to battery-powered rails, while its 1 Ω dynamic impedance holds the threshold stable against comparator supply-noise coupling. The SOT-23-3 package routes the anode to ground and the cathode to the bias resistor, leaving pin 3 as an unused cathode tie for layout convenience. Designers frequently pair the LM385 with a TLV3201 or LMV331 comparator to build precision undervoltage lockouts for single-cell Li-ion systems with minimal quiescent drain.
推荐
ADC Reference Voltage Rail
Low-cost SAR ADCs in microcontroller systems often need a quiet sub-3 V rail that is stable across supply variation, and the LM385M3X-1.2/NOPB fills that niche. The 1.235 V reference is below common supply rails, allowing direct ADC reference without resistor-divider scaling, and the 1 Ω dynamic impedance minimizes voltage shift during ADC sampling transients. With 10 µA to 20 mA operating current and 150 ppm/°C temperature coefficient, the part provides adequate accuracy for 10-12 bit ADCs across commercial temperature. For higher-resolution ADCs the LM4040 series is recommended, but for cost-sensitive 8-10 bit applications the LM385 delivers excellent value.
推荐
Micropower Linear Regulator Reference
The LM385M3X-1.2/NOPB serves as a low-power reference element in micropower linear designs, where 1.235 V is amplified by an op-amp stage to higher regulated rails such as 3.3 V or 5 V. The 10 µA minimum operating current allows the reference to remain alive while drawing essentially no overhead from the cell, dramatically extending battery life in IoT edge devices. Combined with a TLV9032 or LPV801 op-amp, designers can build a complete linear regulator consuming less than 15 µA total quiescent current, suitable for energy-harvesting applications where every microamp counts. The SOT-23-3 footprint keeps the reference compact adjacent to the op-amp.
推荐
Threshold Sensor Bias Supply
For temperature sensors and other analog sensors operating from battery-powered rails, the LM385M3X-1.2/NOPB provides a stable 1.235 V excitation voltage that is immune to battery discharge drift. Its 1 Ω dynamic impedance and 150 ppm/°C temperature coefficient ensure sensor calibration remains accurate across the commercial 0 °C to +70 °C range. The part handles bias currents from 10 µA to 20 mA, accommodating both low-power thermistor bridges and higher-current bridge sensors. Combined with op-amp signal conditioning, the LM385 is a common building block for low-power sensor interface designs.
推荐
Industrial Process Control Bias Rail
In 4-20 mA current-loop transmitters and process-control loops, the LM385M3X-1.2/NOPB generates a precision 1.235 V rail for the loop's ADC reference, ensuring accurate conversion of loop current to digital codes. The part's 0 °C to +70 °C commercial temperature range suits indoor control panels, while its 1 Ω dynamic impedance rejects switching noise from nearby digital isolators. When paired with an XTR16B or RCV420 current-loop IC, the LM385 anchors the loop's ADC reference for high-accuracy industrial measurement. The SOT-23-3 package fits compactly inside crowded 4-20 mA loop transmitter housings.
推荐
推荐产品汇总
工程参考数据： LM385M3X-1.2/NOPB ——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 | LM385M3-1.2 | LM385M3X-2.5/NOPB | LM4040EIM3-1.2/NOPB | XB385M3-1.2 |
|---|---|---|---|---|---|
| Package | SOT-23-3 (DBZ) | SOT-23-3 (DBZ) - same | SOT-23-3 (DBZ) - same | SOT-23-3 (DBZ) - same | SOT-23-3 - same |
| Brand | Texas Instruments | Texas Instruments - same | Texas Instruments - same | Texas Instruments - same | XBLW - cross-brand |
| Reference Type | Shunt Voltage Reference | Shunt - same | Shunt - same | Shunt - same | Shunt - same |
| Output Voltage | 1.235 V | 1.235 V | 2.500 V | 1.225 V | 1.235 V |
关键差异点
- Sub-microamp minimum operating current （对比 LM4040EIM3-1.2/NOPB)
- Lowest-cost 1.235 V reference in TI portfolio （对比 LM4040EIM3-1.2/NOPB)
- True dual-cathode pinout （对比 LM385M3-1.2)
设计说明
Size the bias resistor between the supply and the LM385 cathode to provide 10 µA to 20 mA cathode current under all supply and load conditions. For a 5 V supply and 1.235 V reference, a 4.7 kΩ bias resistor delivers 800 µA minimum and up to 20 mA under short-circuit conditions; for a 3.3 V supply, use 2.2 kΩ. The 10 µA minimum floor ensures regulation only above this current, so verify that the chosen resistor still delivers 10 µA at the minimum supply voltage (e.g., Vmsv = 3.0 V for a 3.3 V rail with 5 % tolerance).
Do not reverse-bias the reference beyond its maximum cathode current of 20 mA — internal power dissipation can damage the SOT-23-3 die. Add a series resistor of at least 1 kΩ between any voltage source and the cathode to limit fault current. Note that Pins 1 and 3 are internally tied cathodes, so either can be used as the reference output; however, leave Pin 3 unconnected if not used to avoid accidental ground loops. The part is rated only for the commercial 0 °C to +70 °C range; use the LM285 series for industrial applications.
Place the LM385M3X-1.2/NOPB close to the comparator or ADC reference pin it serves, with the bias resistor within 5 mm of the cathode pin. Route the anode pin directly to the analog ground plane with a wide trace to minimize ground bounce noise coupling into the reference. A 0.1 µF ceramic bypass capacitor from cathode to anode, placed within 3 mm of the package, filters high-frequency noise without affecting DC regulation. The exposed copper pour beneath the SOT-23-3 helps dissipate any fault current during transient shorts.
合规信息
NOPB suffix indicates lead-free (Pb-free) finish per TI nomenclature. RoHS and REACH compliant per current distributor product pages. Not AEC-Q100 qualified - commercial 0-70C grade only.
