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Analog Devices Inc. LT1431MJ8
- Part No.:
- LT1431MJ8
- Manufacturer:
- Analog Devices Inc.
- Category:
- Voltage Reference
- Package:
- 8-CDIP (0.300", 7.62mm)
- Datasheet:
-
LT1431MJ8.pdf
- Description:
- IC VREF SHUNT ADJ 0.4% 8CERDIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,860
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Product details
Overview
LT1431MJ8 from Analog Devices (formerly Linear Technology) is a precision adjustable shunt voltage regulator in hermetic 8-lead CERDIP package, rated for –55°C to 125°C operation. It delivers 100mA sink current, 0.4% initial reference voltage tolerance (2.5V nominal), 0.3% typical temperature stability, and 0.1Ω dynamic output impedance - enabling high-accuracy feedback in isolated DC/DC converters and programmable power supplies.
For engineers reviewing the LT1431MJ8 datasheet, LT1431MJ8 pinout, LT1431MJ8 application, or LT1431MJ8 equivalent, key selection criteria include its guaranteed military-grade temperature range, low-reference-pin current (0.2µA typ), fast turn-on response, compatibility with external current limiting via GND-F/GND-S separation, and use in 5V/±15V flyback regulation where stable cathode voltage control is critical.
Technical Context
The LT1431MJ8 implements a bipolar-based shunt regulator architecture with an internal 2.5V bandgap reference and transconductance amplifier (gm = 4mA/V). Its dual-ground structure (GND-F and GND-S) enables precise external current limiting by inserting a resistor between them, decoupling sense and force paths without compromising regulation accuracy.
It supports three configuration modes: self-contained 5V regulation using on-chip 5kΩ/5kΩ divider (RTOP–RMID–GND-S), adjustable 2.5V–36V output via two external resistors at REF, and programmable current limit via GND-F/GND-S resistor. COMP pin provides access to the amplifier's base for shutdown or frequency compensation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference Voltage | 2.500 V ±0.4% (2.490–2.510 V) at 25°C, enabling tight-setpoint feedback loops |
| Temperature Drift | 50 ppm/°C max over –55°C to 125°C, ensuring <±5 mV drift across full military range |
| Sink Current Range | 1 mA to 100 mA, supporting wide-load-range regulation without external pass devices |
| Dynamic Impedance | 0.2 Ω typical at 1 kHz, minimizing output voltage perturbation under transient load steps |
| Reference Pin Current | 0.2 µA typical at V+ ≥ 3V, reducing resistor-divider error and enabling high-impedance sensing |
| Min Operating Current | 0.6 mA minimum, allowing stable startup and regulation even at light loads |
| Cathode Voltage Range | 2.5 V to 36 V, compatible with wide-input isolated topologies including 12V, 24V, and 48V bus systems |
Pinout & Package
LT1431MJ8 is housed in an 8-lead hermetic CERDIP (J8) package with 0.300-inch width, rated for –55°C to 125°C ambient and 150°C junction temperature. Lead finish is lead-free (Pb-free), and thermal resistance is θJA = 100°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| COLL (Pin 1) | Open-collector output transistor drain | Sinks up to 100 mA; max 36 V cathode voltage; saturation ~1 V at 100 mA - defines regulated output node |
| COMP (Pin 2) | Base of output transistor driver | Enables external shutdown or phase compensation; must be left open if unused to avoid instability |
| V+ (Pin 3) | Bias supply input | Provides operating current (0.6 mA typ); min 2.5 V, max 36 V - powers internal reference and amplifier |
| RTOP (Pin 4) | Top of internal 5kΩ divider | Tied to COLL for 5V mode; allows external trimming or bypass; must not go below RMID voltage |
| GND-S (Pin 5) | Sense ground for internal divider | Reference point for RTOP/RMID divider; used with GND-F to set external current limit |
| GND-F (Pin 6) | Force ground / emitter of output transistor | Current return path; resistor between GND-F and GND-S sets collector current limit |
| RMID (Pin 7) | Middle of internal 5kΩ divider | Tied to REF for 5V mode; forms 2.5V tap; must not be driven below GND-F |
| REF (Pin 8) | Control input with 2.5V threshold | Regulation point: when REF ≥ 2.5V, COLL sinks current; bias current cancellation active above 3V V+ |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed 0.4% initial VREF tolerance | Eliminates need for post-manufacture trimming in precision 5V or adjustable references |
| Dual-ground architecture (GND-F/GND-S) | Enables accurate, temperature-stable current limiting without additional op-amps or sense resistors |
| On-chip 5kΩ/5kΩ divider | Permits self-contained 5V shunt regulation with only COLL and REF connected - no external components required |
| 0.1Ω typical dynamic output impedance | Ensures minimal output voltage deviation during fast load transients in switching regulator feedback paths |
| Low 0.2µA REF pin current (≥3V V+) | Reduces divider resistor thermal noise and loading error, improving long-term stability and accuracy |
Applications
| Isolated Flyback Converter | Programmable Lab Power Supply |
|---|---|
|
Use Scenario: Secondary-side voltage regulation in 5V-to-±15V isolated flyback converters with optocoupler feedback. IC Role / Device Role / Timing Role: Shunt regulator providing precise cathode voltage reference for optocoupler LED drive, enabling tight cross-regulation across multiple outputs. Use Value: 0.4% VREF tolerance and 50 ppm/°C drift ensure ±15V outputs remain within ±1.5% over –55°C to 125°C, critical for analog signal chains. |
Use Scenario: Adjustable 2.5V–36V bench power supply with digital voltage setting and current limiting. IC Role / Device Role / Timing Role: Core voltage reference and current-sink element; REF pin accepts DAC output, GND-F/GND-S resistor sets current limit. Use Value: Dual-ground current limiting enables accurate, temperature-stable foldback protection without external current-sense amplifiers. |
| High-Reliability 5V LDO Monitor | Industrial Switching Regulator Feedback |
|
Use Scenario: 5V power supply monitoring with ±500mV window and 50mV hysteresis for brown-in/out detection in avionics systems. IC Role / Device Role / Timing Role: Precision comparator with built-in reference; configured as window detector using external resistor network on REF and COLL. Use Value: Guaranteed 0.4% VREF and low drift ensure reliable trip points across extended temperature range without recalibration. |
Use Scenario: Voltage feedback element in 12V-to-5V buck converter with foldback current limiting for industrial motor drives. IC Role / Device Role / Timing Role: Shunt regulator referenced to output, driving optocoupler LED to close primary-side control loop. Use Value: 0.2Ω dynamic impedance maintains feedback stability under 10A load transients; COMP pin allows pole-zero compensation for wide bandwidth. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar shunt regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TL431ACDR | Commercial-grade (0°C to 70°C), 2% initial VREF tolerance, no GND-F/GND-S separation, SO-8 package | Lacks military temperature rating and precision current limiting; suitable only for non-critical consumer power supplies | Select TL431ACDR only for cost-sensitive, non-military applications where ±2% output tolerance is acceptable. |
| LM4040CIM3-2.5 | Fixed 2.5V shunt reference, 0.5% initial tolerance, 100µA max cathode current, SOT-23 package | No adjustable output or current limiting; limited to low-current (<100µA) reference buffering, not regulation | Choose LM4040CIM3-2.5 only for fixed-voltage reference buffering - not as a replacement for LT1431MJ8's regulation or sinking capability. |
Compared with TL431ACDR and LM4040CIM3-2.5, the LT1431MJ8 uniquely combines military-grade temperature range, 0.4% reference accuracy, 100mA sink capability, and dual-ground current limiting - making it irreplaceable in high-reliability isolated power systems requiring precision and robustness.
Availability
LT1431MJ8 is available at Aetrix Electronics and suitable for isolated flyback converters, programmable lab power supplies, avionics voltage monitors, and industrial switching regulators requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT1431MJ8 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 acquired Linear Technology in 2017 and maintains full product support, manufacturing, and documentation for legacy Linear parts including the LT1431 family.
The LT1431 product line was designed specifically for high-accuracy, high-reliability shunt regulation in isolated power supplies, telecom infrastructure, and aerospace systems - emphasizing precision, temperature stability, and configurability over cost or integration.
FAQ
What is the maximum cathode voltage rating for the LT1431MJ8?
The LT1431MJ8 has an absolute maximum cathode voltage (VKA, equivalent to V+ and COLL pins) of 36V. Operation beyond this voltage risks permanent damage. The device is commonly used in 12V, 24V, and 48V input isolated converters where the cathode is clamped to regulated output rails well within this limit. Always observe derating guidelines per MIL-STD-883 for high-reliability applications.
Does the LT1431MJ8 require external compensation for stability?
The LT1431MJ8 is inherently stable with capacitive loads up to 18µF on the COLL pin, but excessive capacitance (>0.01µF) on the REF pin can cause oscillation when configured for >2.5V outputs. For such cases, phase-lead compensation (capacitor from COLL to REF) or dominant-pole compensation (resistor + capacitor from COLL to COMP) is recommended. The COMP pin provides direct access to the amplifier base for precise loop shaping.
How does the dual-ground (GND-F/GND-S) feature enable current limiting in the LT1431MJ8?
In the LT1431MJ8, GND-F is the emitter of the output transistor and current return path, while GND-S is the reference ground for the internal resistor divider. Inserting a resistor RLIM between them creates a voltage drop proportional to collector current (ICOLL ≈ 0.7V / RLIM). This effectively lowers the effective reference threshold seen by the internal amplifier, reducing sink current - enabling accurate, externally programmable current limiting without additional components.
Can the LT1431MJ8 be used as a simple 5V shunt regulator without external resistors?
Yes - the LT1431MJ8 includes an internal 5kΩ/5kΩ resistor divider. To configure it as a self-contained 5V regulator, connect RTOP (Pin 4) and RMID (Pin 7) directly to COLL (Pin 1), and tie REF (Pin 8) to RMID. This uses the internal divider to set VOUT = 2 × VREF = 5.000V ±1%, requiring no external components. Full details are shown in Figure TA04 of the datasheet.
What is the significance of the J8 package designation for the LT1431MJ8?
The J8 package denotes an 8-lead hermetic CERDIP (Ceramic Dual In-line Package) with 0.300-inch width, qualified for military temperature range (–55°C to 125°C) and high-reliability applications. Unlike plastic DIP (N8) or SO (S8) variants, J8 offers superior moisture resistance, hermetic sealing, and long-term parameter stability - essential for aerospace, defense, and downhole industrial systems where field failure is unacceptable.
LT1431MJ8 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Package/Case:
- 8-CDIP (0.300", 7.62mm)
- Series:
- -
- Packaging:
- Tube
- Product Status:
- Obsolete
- Reference Type:
- Shunt
- Output Type:
- Adjustable
- Voltage - Output (Min/Fixed):
- 2.5V
- Voltage - Output (Max):
- 36 V
- Current - Output:
- 100 mA
- Tolerance:
- ±0.4%
- Temperature Coefficient:
- 50ppm/°C Typical
- Noise - 0.1Hz to 10Hz:
- -
- Noise - 10Hz to 10kHz:
- -
- Voltage - Input:
- -
- Current - Supply:
- -
- Current - Cathode:
- 1 mA
- Operating Temperature:
- -55°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-CERDIP
LT1431MJ8 FAQ
1.How can I place an order for LT1431MJ8 through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1431MJ8 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 LT1431MJ8 reliable?
The price and inventory of LT1431MJ8 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1431MJ8 is usually 5 days.
3.What payment methods are accepted for LT1431MJ8?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1431MJ8 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1431MJ8?
LT1431MJ8 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1431MJ8 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 LT1431MJ8?
For technical support, including LT1431MJ8 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1431MJ8 requirements.
6.How does Aetrix verify that LT1431MJ8 is sourced from the original manufacturer or authorized distributors?
All LT1431MJ8 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 LT1431MJ8 meets industry standards.
7.What is the process for return or replacement of LT1431MJ8?
All LT1431MJ8 units undergo pre-shipment inspection (PSI). If there is an issue with LT1431MJ8, 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 LT1431MJ8 part is unused and in its original packaging.
Return procedure for LT1431MJ8:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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