LM385Z-1.2RAG - 1.235V Micropower Shunt Voltage Reference | onsemi
부품 번호: LM385Z-1.2RAG ✓ 활성| 수량 | 단가 | 합계 |
|---|---|---|
| 1 | $0.62 | $0.62 |
| 10 | $0.54 | $5.40 |
| 100 | $0.41 | $41.00 |
| 500 | $0.33 | $165.00 |
| 1,000 | $0.27 | $270.00 |
| 2,000 | $0.22 | $440.00 |
LM385Z-1.2RAG 개요
A shunt voltage reference is a two-terminal device that maintains a constant voltage across its terminals when biased with a current above its minimum operating point. Within the broader power management hierarchy, the LM385Z-1.2RAG belongs to the family of voltage reference ICs, which sit alongside voltage regulators, supervisors, and DC-DC converters as foundational analog building blocks. Bandgap-based shunt references such as the LM385Z-1.2RAG are valued for their low noise floor, stable temperature coefficient, and ability to operate from very low cathode currents, making them ideal for battery-powered systems where quiescent draw directly impacts battery life.
Key features include a guaranteed 1% initial voltage tolerance, low dynamic impedance of 1 ohm, a temperature coefficient of 80 ppm/degree C typical, very low power consumption suitable for battery operation, and stable operation over time. The TO-92-3 through-hole package allows easy insertion into standard 0.1 inch pitch prototyping boards and is well suited to hand-soldered and wave-soldered assemblies in commercial-grade designs.
From an architectural perspective, the LM385Z-1.2RAG uses a bipolar bandgap reference cell. On-chip trimming tightens the initial voltage tolerance, while the internal design minimizes dynamic impedance so that output voltage stays flat as cathode current varies. The wide operating current range (10 uA to 20 mA) gives designers flexibility to trade off power consumption versus reference stability, and the bipolar process technology delivers predictable temperature performance across the commercial 0 to 70 C range.
Typical applications include portable meter references, portable test instruments, battery-operated systems, and current-loop instrumentation. The wide current range and low minimum operating current make it especially well suited to energy harvesting and remote sensor nodes where the reference must remain stable at microamp-level bias.
When designing with the LM385Z-1.2RAG, ensure cathode current stays above 10 uA at all times and below 20 mA to remain within the guaranteed specification window. A bias resistor selected from the upstream supply sets the operating point, and a decoupling capacitor placed close to the device helps suppress noise on the reference rail.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet, giving engineers a single-page decision view for selecting and sourcing the LM385Z-1.2RAG.
드롭인 대체품: LM385Z-1.2RAG — 동일 패키지, 핀 호환. PCB 재작업이 필요한 다른 패키지 부품은 제외됩니다.
빠른 비교 도구 — 나란히 비교할 대체 부품을 선택하십시오:
LM385BZ-1.2
✅ 드롭인📋 참조 대체품 (카탈로그에 없음)
LM285Z-1.2
✅ 드롭인📋 참조 대체품 (카탈로그에 없음)
LM385Z-1.2
✅ 드롭인📋 참조 대체품 (카탈로그에 없음)
LT1004CZ-1.2
✅ 드롭인📋 참조 대체품 (카탈로그에 없음)
LM385BLP-1-2
✅ 드롭인📋 참조 대체품 (카탈로그에 없음)
LT1004CZ-1.2#PBF
✅ 드롭인📋 참조 대체품 (카탈로그에 없음)
LM385Z-1.2RAG 최대 정격 & 전기적 특성
| Reference Type | Shunt |
| Output Voltage (Nominal) | 1.235 V |
| Output Voltage Tolerance | -2.4% to +2.01% (2% typical initial) |
| Initial Voltage Tolerance (Guaranteed) | 1% (LM385B grade) |
| Operating Current Range | 10 uA to 20 mA |
| Dynamic Impedance | 1 ohm |
| Temperature Coefficient | 80 ppm/degree C typical |
| 동작 온도 범위 | 0 C to +70 C |
| 패키지 | TO-92-3 (through-hole) |
| 핀 수 | 3 |
| 실장 유형 | Through-Hole |
| Technology | Bipolar bandgap |
| RoHS 상태 | Pb-Free (compliant per ON Semi datasheet) |
| Lead-Free | Yes |
| Tape and Reel Quantity | 2000 per reel |
LM385Z-1.2RAG 핀 구성
| 핀 1 | Anode — Anode (internally tied to pin 3) |
| 핀 2 | Cathode — Cathode / reference output |
| 핀 3 | Anode — Anode (internally tied to pin 1) |
일반적인 애플리케이션
LM385Z-1.2RAG 적합 용도: 6 애플리케이션s: Portable Digital Multimeter Reference, Battery-Operated Sensor Systems, Current Loop Instrumentation (4-20 mA), Portable Test Instruments, Threshold Detectors and Comparators, Data Acquisition Systems.
Portable Digital Multimeter Reference
The LM385Z-1.2RAG is well suited to portable digital multimeter (DMM) reference circuits where its 1.235 V fixed output provides a stable bias for the ADC reference input. Its 10 uA minimum operating current enables extended battery life in handheld meters, while the 1 ohm dynamic impedance ensures the reference voltage stays flat across varying load conditions typical of autoranging DMM front ends. The TO-92-3 package simplifies hand assembly of low-volume meter designs and supports wave soldering for high-volume production. The 80 ppm/degree C temperature coefficient is adequate for the 0 C to +70 C commercial operating range of most handheld instrumentation, and the bipolar bandgap architecture provides low 1/f noise that does not degrade ADC linearity. Compared to zener-based references, the LM385Z-1.2RAG offers tighter initial tolerance and lower minimum operating current, which directly improves DMM accuracy at low voltage measurement ranges.
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Battery-Operated Sensor Systems
In battery-operated sensor systems such as remote weather stations, IoT environmental monitors, and handheld gas detectors, the LM385Z-1.2RAG provides a stable 1.235 V reference from a single lithium cell or 2x AA battery pack. Its micropower 10 uA minimum cathode current means the reference itself draws negligible current from the battery budget, while the 20 mA maximum supports direct biasing of low-power sensor front ends. The 1.235 V output is conveniently compatible with many low-voltage ADC internal reference requirements, simplifying system design. Compared to active series references, the shunt topology of the LM385Z-1.2RAG does not require a minimum load current, making it ideal for duty-cycled sensor applications where the reference may be biased only during measurement intervals. The bipolar bandgap design provides excellent long-term stability, reducing calibration frequency in field-deployed sensors.
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Current Loop Instrumentation (4-20 mA)
The LM385Z-1.2RAG is widely used in 4-20 mA current-loop transmitters as the precision reference for the loop sense resistor and V-to-I converter network. Its 1.235 V output provides a stable reference against which the sense voltage is compared, and the shunt topology allows the reference to share the same loop current that powers the transmitter, eliminating the need for a separate bias supply. The 1 ohm dynamic impedance ensures the reference voltage does not collapse under loop current variations, and the wide 10 uA to 20 mA operating range accommodates the full span of loop current from the 4 mA zero-scale to 20 mA full-scale. Industrial process control transmitters using the LM385Z-1.2RAG benefit from the 80 ppm/degree C temperature coefficient, which is adequate for the typical 0 C to +70 C commercial temperature range and meets the accuracy requirements of most process control loops.
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Portable Test Instruments
Handheld oscilloscope probes, LCR meters, and field service test instruments rely on the LM385Z-1.2RAG to provide a stable onboard reference voltage for self-calibration routines and ADC reference inputs. Its TO-92-3 through-hole package allows easy replacement in field service scenarios, and the wide operating current range means a single reference can support both low-power standby modes and full measurement active modes. The 2% initial tolerance is sufficient for most field service calibration routines, and the LM385BZ-1.2 variant offers 1% tolerance for higher-precision bench instruments. Compared to buried-zener references, the LM385Z-1.2RAG operates at much lower current, enabling smaller battery packs in portable instruments and longer operating time between charges. Its bipolar technology ensures consistent performance across the commercial temperature range encountered in field service environments.
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Threshold Detectors and Comparators
The LM385Z-1.2RAG serves as an ideal voltage reference for undervoltage and overvoltage threshold detection circuits in battery chargers, power supply monitors, and reset controllers. Its 1.235 V reference can be compared against a divided supply voltage using a low-power comparator to generate logic-level reset signals or interrupt requests. The micropower operation is critical in battery-charging applications where quiescent draw directly impacts charge time and efficiency, and the shunt topology means the reference continues to operate correctly even when the main supply is heavily loaded. The 1 ohm dynamic impedance ensures the threshold trip point does not drift with supply noise, improving detection accuracy. The TO-92-3 package supports both hand-soldered prototype designs and automated assembly in volume production, with the same footprint usable across all LM385 voltage options (1.235 V, 2.5 V) for design flexibility.
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Data Acquisition Systems
The LM385Z-1.2RAG provides a compact and stable reference for low-cost data acquisition systems used in industrial monitoring, building automation, and environmental data logging. Its 1.235 V output is well matched to the input range of many low-voltage ADCs, and the micropower operation makes it suitable for solar or battery-powered remote data loggers. The shunt topology allows the reference to be powered from the same supply rail as the ADC and signal conditioning circuitry, simplifying power tree design. The 2% initial tolerance is adequate for 8-bit and 10-bit ADC applications, while the LM385BZ-1.2 1% variant supports 12-bit systems. The bipolar bandgap design provides predictable temperature behavior across the commercial 0 C to +70 C range typical of indoor and outdoor enclosure-mounted data acquisition systems, and the TO-92-3 package supports both through-hole PCB designs and breadboard prototyping for development work.
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추천 제품 요약
엔지니어링 참조 데이터: LM385Z-1.2RAG — 비교, 설계 지침 및 규정 준수 정보.
선택 가이드
대체품과의 비교
| 파라미터 | 이 제품 | LM385BZ-1.2 | LM285Z-1.2 | LM385Z-1.2 | LT1004CZ-1.2 | LM385BLP-1-2 |
|---|---|---|---|---|---|---|
| Brand | onsemi | onsemi | onsemi | Texas Instruments | Analog Devices | Texas Instruments |
| Package | TO-92-3 | TO-92-3 - same | TO-92-3 - same | TO-92-3 - same | TO-92-3 - same | TO-92-3 - same |
| Output Voltage (Nominal) | 1.235 V | 1.235 V | 1.235 V | 1.235 V | 1.235 V | 1.235 V |
| Initial Voltage Tolerance | 2% (-2.4% to +2.01%) | 1% (B-grade) | 2% | 2% | 1% | 1% |
| Operating Current Range | 10 uA to 20 mA | 10 uA to 20 mA | 10 uA to 20 mA | 10 uA to 20 mA | 10 uA to 20 mA | 10 uA to 20 mA |
| Dynamic Impedance | 1 ohm | 1 ohm | 1 ohm | 1 ohm | 1 ohm | 1 ohm |
| Operating Temperature | 0 C to +70 C (commercial) | 0 C to +70 C | -40 C to +85 C (industrial) | 0 C to +70 C | 0 C to +70 C | 0 C to +70 C |
주요 차별점
- Widest operating current range in TO-92-3 class (vs LM385BZ-1.2)
- Industrial temperature grade option available (vs LM285Z-1.2)
- Pin-compatible with legacy National Semiconductor LM385 (vs LM385Z-1.2 (TI/National))
- Lower-cost alternative to Analog Devices LT1004 (vs LT1004CZ-1.2)
설계 노트
Select the bias resistor to keep cathode current between 10 uA and 20 mA under all operating conditions. Choose R_bias = (V_supply - V_ref) / I_katode, where I_katode should be set around 100 uA to 1 mA for optimal noise-versus-power trade-off. At minimum supply, verify I_katode >= 10 uA; at maximum supply plus load transients, verify I_katode <= 20 mA. Adding a series resistor of at least 1 kohm between the supply and the reference improves noise immunity and protects the device from inrush currents.
The LM385Z-1.2RAG operates across 0 C to +70 C with a typical temperature coefficient of 80 ppm/degree C. At a 50 C temperature swing, this translates to approximately 0.4% reference voltage variation, which is acceptable for most portable meter and battery-powered applications. For higher-precision designs requiring better than 0.1% temperature stability, consider the LM285 grade (-40 C to +85 C industrial) or upgrade to the LM385BZ-1.2 (1% initial tolerance). PCB layout should keep the reference away from heat-generating components such as power resistors and linear regulators.
Place a 0.1 uF ceramic decoupling capacitor as close as possible to the cathode pin (pin 2) of the LM385Z-1.2RAG to suppress high-frequency noise. For sensitive ADC reference applications, add a 10 uF tantalum or ceramic capacitor in parallel to provide low-impedance across a wider frequency range. Keep the bias resistor and reference leads short to minimize parasitic inductance, and route sensitive analog signals away from the reference trace to avoid coupling. The TO-92-3 package should be oriented with leads pointing down and the flat side facing the operator for easy identification during hand soldering and rework.
Do not operate the LM385Z-1.2RAG below 10 uA cathode current - the device is only guaranteed to maintain its specified voltage tolerance above this minimum. Reverse polarity on the anode/cathode pins can permanently damage the device. Avoid using the reference in circuits where the cathode current can exceed 20 mA during load transients, as this may degrade long-term reliability. Do not assume the 1.235 V output is exact - the device carries a -2.4% to +2.01% initial tolerance, so critical designs should include calibration or use the LM385BZ-1.2 1% grade instead.
규정 준수 정보
Pb-Free and RoHS compliant per onsemi LM285/LM385 datasheet. Not AEC-Q100 qualified - this is a commercial-grade part for non-automotive applications. Not suitable for automotive safety-critical designs.
