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Analog Devices Inc. LM399AH
- Part No.:
- LM399AH
- Manufacturer:
- Analog Devices Inc.
- Category:
- Voltage Reference
- Package:
- TO-46-4 Metal Can
- Datasheet:
-
LM399AH.pdf
- Description:
- IC VREF SHUNT 0.17% TO46-4
- Quantity:
- Payment:
- Shipping:
Inventory:3,018
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Product details
Overview
LM399AH from Analog Devices (formerly Linear Technology) is a precision 6.95V shunt voltage reference with integrated temperature stabilization heater, designed for metrology-grade applications requiring ultra-low drift and noise. It delivers guaranteed 0.5ppm/°C tempco, ≤1Ω dynamic impedance, ≤20µVRMS noise (10Hz–10kHz), and operates over 0.5–10mA reverse current in 4-lead TO-46 metal can packaging.
For engineers reviewing the LM399AH datasheet, LM399AH pinout, LM399AH application, or LM399AH equivalent, key selection criteria include long-term stability (8ppm/√kH), warm-up time to ±0.05% (3s), heater supply requirements (9–40V), and thermal shield integration for ambient isolation - critical for calibration standards and high-resolution ADC references.
Technical Context
The LM399AH uses a subsurface Zener diode monolithically integrated with a precision heater on a single silicon die, maintaining junction temperature near 90°C to nullify Zener voltage drift across ambient temperatures. Its thermal shield minimizes external thermal gradients, enabling stable operation without external oven control.
It functions as a two-terminal shunt reference: reverse-biased operation sets VZ = 6.95V, while the heater circuit (pins 1 and 4) draws 8.5–15mA at 30V to sustain thermal equilibrium. Dynamic impedance remains ≤1Ω up to 100Hz, supporting low-noise buffered designs.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VZ (Reverse Breakdown) | 6.95V ±0.15V @ 0.5–10mA - precise, stable reference point for 10V buffered circuits and calibration standards. |
| Tempco (0°C to 70°C) | 0.5ppm/°C max - enables sub-1ppm total drift over industrial temperature range without compensation. |
| Dynamic Impedance | ≤1Ω @ 1mA, 10Hz–100Hz - ensures minimal load regulation error in precision current-source or DAC reference designs. |
| RMS Noise (10Hz–10kHz) | ≤20µV - supports 24-bit+ data converters where noise floor directly limits effective resolution. |
| Long-Term Stability | 8ppm/√kH @ 22–28°C - guarantees predictable aging behavior for multi-year metrology instrument deployments. |
| Warm-Up Time | 3 seconds to ±0.05% of VZ - allows rapid stabilization after power-on in portable calibrators and automated test equipment. |
| Heater Supply Voltage | 9–40V - accommodates standard lab supplies and battery-backed systems while maintaining thermal setpoint. |
Pinout & Package
LM399AH is housed in a hermetically sealed 4-lead TO-46 metal can (H package) with internal thermal shield. Pin 1 is heater anode, Pin 2 is cathode (Zener output), Pin 3 is anode (Zener input), Pin 4 is heater cathode - heater and reference share no common terminal, requiring isolated heater biasing.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Heater Anode | Positive supply connection to internal heating element; requires current-limiting resistor and bypass capacitor per datasheet. |
| 2 | Zener Cathode | Reference output node - connected to load or op-amp inverting input for buffered 10V generation. |
| 3 | Zener Anode | Reference return path - tied to system ground or negative rail; substrate-connected for thermal stability. |
| 4 | Heater Cathode | Heater return; electrically isolated from Zener terminals but thermally coupled to die via shared substrate. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated Temperature Stabilizer | Monolithic heater maintains ~90°C junction temperature, eliminating need for external oven and reducing system size/cost. |
| Thermal Shield Construction | Valox-insulated metal can isolates die from ambient airflow and thermal gradients, improving short-term stability by >3× vs. unshielded variants. |
| Subsurface Zener Architecture | Reduces surface leakage and 1/f noise, enabling 7nV/√Hz low-frequency noise density critical for DC precision. |
| Guaranteed Initial Tolerance | ±2% VZ - allows direct use in production without individual trimming, reducing calibration labor in multimeter manufacturing. |
| Wide Operating Current Range | 0.5–10mA reverse bias - supports low-power handheld instruments and high-current buffered reference designs with same device. |
Applications
| Precision Digital Multimeters | Calibration Equipment Voltage Standards |
|---|---|
Use Scenario: High-accuracy handheld and benchtop DMMs requiring stable 6.95V reference for ADC scaling and auto-zero circuits. IC Role / Device Role / Timing Role: Primary shunt voltage reference establishing absolute measurement baseline; heater enables consistent performance across environmental shifts. Use Value: Enables 7½-digit resolution with <1ppm/year drift, meeting ANSI C12.20 Class 0.01 accuracy requirements. | Use Scenario: Portable and rack-mounted calibrators used in ISO/IEC 17025 labs to verify voltage sources and transducers. IC Role / Device Role / Timing Role: Traceable voltage standard referenced to national labs; used in 10V buffered configurations with LT1001 op-amps. Use Value: Provides 0.5ppm/°C tempco and 8ppm/√kH stability, satisfying ISO 17025 uncertainty budgets for 10V calibrations. |
| Laboratory Measurement Equipment | High-Accuracy Data Converters |
Use Scenario: Precision source-measure units (SMUs), programmable power supplies, and nanovoltmeters demanding ultra-low noise references. IC Role / Device Role / Timing Role: Low-noise shunt reference feeding instrumentation-grade op-amps; thermal shield suppresses air-current-induced drift. Use Value: Delivers ≤20µVRMS broadband noise and <1µV peak-to-peak low-frequency noise, enabling sub-nanovolt measurements. | Use Scenario: Reference for 24-bit sigma-delta ADCs in seismic monitoring, medical imaging, and weigh-scale systems. IC Role / Device Role / Timing Role: Stable excitation source for ratiometric sensor interfaces and high-resolution analog front-ends. Use Value: Guarantees <0.001% gain error drift over temperature, preserving ENOB across full operating range. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar precision shunt reference applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTZ1000CH | 7V output, 0.05ppm/°C tempco, higher heater current (≈12mA), requires external transistor for heater control. | Better stability for primary standards; not drop-in due to different pinout, heater interface, and voltage. | Select when ultimate long-term stability (<0.2ppm/√kH) and lower tempco outweigh complexity and cost. |
| LT1021ACN8-10 | 10V series reference, ±0.01% initial tolerance, –40°C to 125°C range, no heater required. | Simpler layout and power design; lacks active thermal stabilization, limiting tempco to 10ppm/°C. | Select for wide-temperature industrial systems where 10ppm/°C is acceptable and heater-free operation is preferred. |
Compared with LTZ1000CH and LT1021ACN8-10, the LM399AH offers best-in-class balance of metrology-grade stability (0.5ppm/°C), low noise (20µVRMS), and plug-and-play heater integration - making it ideal for mid-tier calibration tools and portable instruments where LTZ1000's complexity is unnecessary and LT1021's drift is excessive.
Availability
LM399AH is available at Aetrix Electronics and suitable for precision digital multimeters, calibration equipment voltage standards, and laboratory measurement equipment requiring stable component supply and traceable metrological performance.
Supply support for LM399AH includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Analog Devices, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing technologies, serving precision instrumentation, industrial automation, and aerospace markets.
The LM399AH belongs to ADI's legacy Linear Technology precision reference family, engineered specifically for metrology-grade voltage standards where thermal drift, noise, and long-term stability dominate system accuracy.
FAQ
What is the nominal output voltage of the LM399AH?
The LM399AH provides a nominal reverse breakdown voltage of 6.95V, guaranteed between 6.75V and 7.3V at 0.5–10mA operating current. This value serves as the core reference point for buffered 10V designs and direct-use applications in high-accuracy measurement systems.
Does the LM399AH require external heating circuitry?
Yes, the LM399AH integrates a heater but requires external biasing: pins 1 and 4 must be supplied with 9–40V through a current-limiting resistor and bypassed with ≥2µF tantalum capacitor. The heater draws 8.5–15mA at 30V to maintain ~90°C junction temperature - no external oven is needed.
What is the maximum dynamic impedance specification for LM399AH?
The LM399AH guarantees a maximum dynamic impedance of 1Ω at 1mA test current and frequencies from 10Hz to 100Hz. This low impedance ensures minimal voltage shift under varying load conditions, critical for driving op-amp inputs in precision 10V buffer circuits.
Can LM399AH operate outside its specified 0°C to 70°C ambient temperature range?
No - the LM399AH is characterized and rated only for 0°C to 70°C ambient operation. While the internal heater stabilizes the die at ~90°C, exceeding ambient limits risks violating absolute maximum ratings and invalidates the guaranteed 0.5ppm/°C tempco and long-term stability specs.
How does the thermal shield in the LM399AH TO-46 package improve performance?
The Valox-based thermal shield inside the LM399AH's TO-46 metal can reduces sensitivity to ambient airflow and thermal gradients by >3× versus unshielded packages. This directly improves short-term stability (e.g., during door-opening in lab environments) and supports repeatable metrology-grade measurements without enclosure redesign.
LM399AH Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Package/Case:
- TO-46-4 Metal Can
- Series:
- -
- Packaging:
- Bulk
- Product Status:
- Active
- Reference Type:
- Shunt
- Output Type:
- Fixed
- Voltage - Output (Min/Fixed):
- 6.95V
- Voltage - Output (Max):
- -
- Current - Output:
- 10 mA
- Tolerance:
- ±0.17%
- Temperature Coefficient:
- 1ppm/°C
- Noise - 0.1Hz to 10Hz:
- -
- Noise - 10Hz to 10kHz:
- 7µVrms
- Voltage - Input:
- -
- Current - Supply:
- -
- Current - Cathode:
- 500 µA
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-46-4
LM399AH FAQ
1.How can I place an order for LM399AH through Aetrix?
Please submit a Request for Quotation (RFQ) for LM399AH on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LM399AH reliable?
The price and inventory of LM399AH are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM399AH is usually 5 days.
3.What payment methods are accepted for LM399AH?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM399AH transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM399AH?
LM399AH orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM399AH order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LM399AH?
For technical support, including LM399AH datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM399AH requirements.
6.How does Aetrix verify that LM399AH is sourced from the original manufacturer or authorized distributors?
All LM399AH products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LM399AH meets industry standards.
7.What is the process for return or replacement of LM399AH?
All LM399AH units undergo pre-shipment inspection (PSI). If there is an issue with LM399AH, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LM399AH part is unused and in its original packaging.
Return procedure for LM399AH:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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