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Texas Instruments LM337LZ/LFT3
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- Part No.:
- LM337LZ/LFT3
- Manufacturer:
- Texas Instruments
- Package:
- TO-226-3, TO-92-3 (TO-226AA)
- Datasheet:
-
LM337LZ/LFT3.pdf
- Description:
- IC REG LIN NEG ADJ 100MA TO92-3
- Quantity:
- Payment:
- Shipping:
Inventory:4,602
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Product details
Overview
LM337LZ/LFT3 from Texas Instruments is a 3-terminal adjustable negative-voltage linear regulator in TO-92 package, delivering up to 100 mA output current over –1.2 V to –37 V range with 1.25 V internal reference voltage, 0.01%/V typical line regulation, and short-circuit protection. It serves as a precision negative supply for op-amp biasing, IGBT gate drive, and industrial control circuitry.
For engineers reviewing the LM337LZ/LFT3 datasheet, LM337LZ/LFT3 pinout, LM337LZ/LFT3 application, or LM337LZ/LFT3 equivalent, key selection criteria include guaranteed 100-mA output capability, thermal overload protection, adjustable output via two external resistors, and compatibility with standard TO-92 PCB footprints and hand-soldering processes.
Technical Context
The LM337LZ/LFT3 implements a floating architecture that regulates only the input-to-output differential voltage, enabling safe operation with input voltages hundreds of volts below ground when differential limits are observed. Its internal bandgap reference (1.25 V) sets the ADJ-to-VOUT potential difference, allowing precise output programming using resistor dividers.
Protection circuitry includes constant-current limiting independent of temperature, thermal shutdown, and safe-area protection-all fully functional even if the ADJ pin is disconnected. Ripple rejection reaches 80 dB with proper ADJ bypassing, exceeding fixed regulators and supporting noise-sensitive analog subsystems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 100 mA maximum-supports mid-power analog and control loads without heatsinking at moderate differentials. |
| Output Voltage Range | –1.2 V to –37 V-enables flexible negative rail generation across industrial and instrumentation systems. |
| Reference Voltage | 1.25 V ±0.05 V-defines ADJ-to-VOUT offset; enables accurate resistor-divider-based output setting. |
| Line Regulation | 0.01%/V typical-minimizes output drift under varying input conditions, critical for stable bias networks. |
| Ripple Rejection | 80 dB-suppresses AC noise on input rails, essential for low-noise op-amp and ADC reference supplies. |
| Thermal Protection | Active shutdown at 125°C junction-prevents damage during overload or poor heatsinking scenarios. |
| Adjust Pin Current | 50–100 µA-low, stable bias current simplifies divider design and minimizes load-induced error. |
Pinout & Package
LM337LZ/LFT3 is housed in a through-hole TO-92 package (4.30 mm × 4.30 mm body), compatible with legacy manual assembly and wave soldering. The device uses a standard 3-pin transistor outline with defined pin 1 (Output), pin 2 (Adjust), and pin 3 (Input) orientation per TI's LP package drawing.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 (TO-92) | Output (VOUT) | Regulated negative output terminal; connects to load return path and feedback network. |
| Pin 2 (TO-92) | Adjust (ADJ) | Reference node for output voltage setting; tied to resistor divider bottom; bypassable for enhanced PSRR. |
| Pin 3 (TO-92) | Input (VIN) | Negative input supply terminal; must maintain ≥3 V differential above VOUT for regulation. |
Key Features
| Feature | Design Value |
|---|---|
| Adjustable Output Down to –1.2 V | Enables precise negative rail generation for dual-supply op-amps and signal conditioning stages. |
| 100-mA Guaranteed Output Current | Sustains full rated load across –25°C to +125°C ambient without derating or external pass devices. |
| Short-Circuit Protected Output | Self-limiting current prevents latch-up or destruction during accidental output grounding or capacitive loading. |
| 80-dB Ripple Rejection | Reduces rectified AC noise on unregulated inputs, eliminating need for additional LC filtering in compact designs. |
| Thermal Overload Protection | Automatically disables output above 125°C junction temperature, preserving reliability in sealed enclosures. |
Applications
| Industrial Power Supplies | IGBT Gate Drive Supplies |
|---|---|
Use Scenario: Local regulation of negative bias rails in PLC backplanes and motor drive control modules. IC Role / Device Role / Timing Role: Negative voltage regulator providing stable –5 V or –12 V for logic interface and isolation circuitry. Use Value: Eliminates need for dual-output transformers or isolated DC/DC converters while maintaining tight load regulation (<0.1%) across temperature. |
Use Scenario: Generating turn-off bias for high-side IGBTs in three-phase inverters. IC Role / Device Role / Timing Role: Adjustable negative gate supply ensuring fast, reliable IGBT shut-off under varying bus voltage conditions. Use Value: Supports programmable gate voltage (e.g., –15 V) with <0.01%/V line regulation, reducing switching losses and shoot-through risk. |
| Bipolar Op-Amp Biasing | Factory Automation Sensors |
Use Scenario: Dual-rail power for precision instrumentation amplifiers in weigh scales and strain gauge interfaces. IC Role / Device Role / Timing Role: Low-noise negative rail generator complementing LM317L-based positive rail. Use Value: 80-dB ripple rejection and 1.25 V reference enable sub-10 µV output noise, preserving signal integrity in µV-level measurements. |
Use Scenario: On-board negative supply for 4–20 mA transmitter ICs and analog sensor front-ends. IC Role / Device Role / Timing Role: Compact, thermally robust regulator powering current-loop drivers and ADC references. Use Value: TO-92 footprint allows direct integration into space-constrained DIN-rail modules with no layout redesign required. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar negative adjustable regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM337LM/NOPB | SOIC-8 surface-mount package; higher thermal resistance (111.3°C/W vs. 156.9°C/W); same electrical specs. | Requires reflow assembly; better suited for automated production and higher-density layouts. | Select LM337LM/NOPB when board space is constrained and SMT manufacturing is available. |
| LM337T | TO-220 package; rated for 1.5 A output; larger footprint and mandatory heatsink for >500 mA loads. | Used where higher current or improved thermal performance is needed beyond 100 mA. | Choose LM337T only when load exceeds 100 mA or ambient temperatures exceed 85°C with sustained load. |
Compared with LM337LM/NOPB, LM337LZ/LFT3 offers lower-cost through-hole assembly and simpler thermal management; compared with LM337T, it trades current capacity for compactness and cost-making LM337LZ/LFT3 optimal for ≤100 mA, space- and cost-sensitive industrial analog rails.
Availability
LM337LZ/LFT3 is available at Aetrix Electronics and suitable for industrial power supplies, factory automation systems, and building automation systems requiring stable component supply, long-term obsolescence planning, and traceable sourcing.
Supply support for LM337LZ/LFT3 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
Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management technologies, with decades of expertise in precision linear regulators and industrial-grade ICs.
The LM337L series was designed specifically for rugged, cost-sensitive negative voltage regulation in industrial control, instrumentation, and factory automation-emphasizing reliability, wide temperature operation (–25°C to +125°C), and minimal external component count.
FAQ
What is the maximum input-to-output voltage differential for LM337LZ/LFT3?
The absolute maximum input-to-output voltage differential for LM337LZ/LFT3 is 40 V. Exceeding this rating risks permanent damage. For reliable operation, TI recommends maintaining |VIN – VOUT| ≤37 V under normal conditions, with sufficient headroom to ensure dropout compliance across temperature and load variations. This limit directly governs the highest negative input voltage usable with a given output setting-for example, –40 V input supports up to –3 V output.
Can LM337LZ/LFT3 be used as a precision current regulator?
Yes, LM337LZ/LFT3 can function as a precision current regulator by connecting a fixed resistor between the ADJ and VOUT pins. With its stable 1.25 V reference and low ADJ pin current (50–100 µA), the device delivers highly accurate current setpoints-for instance, a 12.5 Ω resistor yields 100 mA output. This configuration is widely used in LED biasing and sensor excitation circuits where LM337LZ/LFT3 provides inherent thermal and short-circuit protection.
Does LM337LZ/LFT3 require an input capacitor?
An input capacitor is not strictly required for stability but is strongly recommended when LM337LZ/LFT3 is placed more than 4 inches from the main filter capacitor. A 10 µF aluminum electrolytic or 1 µF solid tantalum capacitor at VIN improves transient response and prevents oscillation caused by trace inductance. TI specifies this as a layout best practice-not a datasheet requirement-but omission risks instability under dynamic load changes, especially in noisy industrial environments.
What is the minimum load current needed for regulation with LM337LZ/LFT3?
LM337LZ/LFT3 requires a minimum load current of 3.5 mA (at |VIN – VOUT| ≤40 V) to maintain regulation. Below this threshold, output voltage may rise unpredictably due to internal quiescent current paths. Applications like high-impedance op-amp biasing often add a 1–2 kΩ bleed resistor from VOUT to ground to guarantee compliance-ensuring stable –1.2 V to –37 V output across all operating conditions without relying on system load.
How does the ADJ pin bypass capacitor improve performance in LM337LZ/LFT3?
A capacitor (typically 10 µF) from the ADJ pin to ground in LM337LZ/LFT3 reduces noise coupling into the reference node, boosting ripple rejection from 65 dB to 80 dB. This bypass stabilizes the 1.25 V internal reference against high-frequency interference, making LM337LZ/LFT3 suitable for sensitive analog stages. Placement must be within 5 mm of the ADJ pin; longer traces degrade effectiveness and may introduce instability due to parasitic inductance.
LM337LZ/LFT3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- TO-226-3, TO-92-3 (TO-226AA)
- Packaging:
- Cut Tape (CT)
- Product Status:
- Obsolete
- Output Configuration:
- Negative
- Output Type:
- Adjustable
- Number of Regulators:
- 1
- Voltage - Input (Max):
- -40V
- Voltage - Output (Min/Fixed):
- -1.2V
- Voltage - Output (Max):
- -37V
- Voltage Dropout (Max):
- -
- Current - Output:
- 100mA
- Current - Quiescent (Iq):
- -
- Current - Supply (Max):
- -
- PSRR:
- 60dB (120Hz)
- Control Features:
- -
- Protection Features:
- Over Temperature, Short Circuit
- Operating Temperature:
- -25°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-92-3
LM337LZ/LFT3 FAQ
1.How can I place an order for LM337LZ/LFT3 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM337LZ/LFT3 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 LM337LZ/LFT3 reliable?
The price and inventory of LM337LZ/LFT3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM337LZ/LFT3 is usually 5 days.
3.What payment methods are accepted for LM337LZ/LFT3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM337LZ/LFT3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM337LZ/LFT3?
LM337LZ/LFT3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM337LZ/LFT3 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 LM337LZ/LFT3?
For technical support, including LM337LZ/LFT3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM337LZ/LFT3 requirements.
6.How does Aetrix verify that LM337LZ/LFT3 is sourced from the original manufacturer or authorized distributors?
All LM337LZ/LFT3 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 LM337LZ/LFT3 meets industry standards.
7.What is the process for return or replacement of LM337LZ/LFT3?
All LM337LZ/LFT3 units undergo pre-shipment inspection (PSI). If there is an issue with LM337LZ/LFT3, 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 LM337LZ/LFT3 part is unused and in its original packaging.
Return procedure for LM337LZ/LFT3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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