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Texas Instruments LM237KC
.JPG)
- Part No.:
- LM237KC
- Manufacturer:
- Texas Instruments
- Package:
- TO-220-3
- Datasheet:
-
LM237KC.pdf
- Description:
- IC REG LIN NEG ADJ 1.5A TO220-3
- Quantity:
- Payment:
- Shipping:
Inventory:4,943
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Product details
Overview
LM237KC from Texas Instruments is a TO-220 packaged adjustable negative-voltage linear regulator delivering up to –1.5 A output current, with output voltage adjustable from –1.2 V to –37 V using two external resistors. It features internal current limiting, thermal shutdown, and safe-area compensation, and is used in precision negative power rails for industrial instrumentation and analog signal chains.
For engineers reviewing the LM237KC datasheet, LM237KC pinout, LM237KC application, or LM237KC equivalent, key selection criteria include its –1.25 V reference voltage (OUTPUT-to-ADJUST), 0.3% typical output regulation, 77 dB ripple rejection at 120 Hz with 10 µF ADJ capacitor, junction temperature range of –25°C to +150°C, and TO-220 (KC) package thermal resistance of 24.8°C/W.
Technical Context
The LM237KC implements a bandgap-referenced error amplifier driving a PNP pass transistor, with feedback taken from the ADJUST pin referenced to OUTPUT. Its architecture includes built-in foldback current limiting and thermal shutdown triggered at ~150°C junction temperature.
It operates only in adjustable negative-output mode: the ADJUST pin is held at a fixed –1.25 V relative to OUTPUT, enabling precise resistor-divider-based output setting. No fixed-output or positive-regulation modes are supported.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output voltage range | –1.2 V to –37 V - set by external R1/R2 divider; enables flexible negative rail generation across wide system requirements. |
| Max output current | –1.5 A - supports high-current analog circuits like op-amp supplies and DAC reference buffers without external boost. |
| Reference voltage | –1.25 V (OUTPUT-to-ADJUST) - stable, temperature-compensated bandgap reference enabling ±0.6% output-voltage drift over full temp range. |
| Ripple rejection | 77 dB at 120 Hz with 10 µF ADJ cap - suppresses AC line noise in sensitive analog front-ends and ADC reference supplies. |
| Input-to-output differential | –2.5 V to –37 V min/max - defines minimum dropout (2.5 V) and maximum safe input swing; requires ≥2.5 V headroom for regulation. |
| Junction temperature | –25°C to +150°C - rated for harsh industrial environments; thermal shutdown activates before permanent damage occurs. |
| Package thermal resistance | 24.8°C/W (RθJA, KC package) - determines heatsink sizing; 15 W max dissipation requires ≤10°C/W heatsink for 75°C ambient. |
Pinout & Package
LM237KC uses the standard TO-220 (KC) 3-pin package with metal tab electrically connected to INPUT. The case is designed for direct heatsinking with insulated mounting hardware.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| INPUT (Pin 2) | Unregulated negative input supply | Accepts –2.5 V to –40 V relative to OUTPUT; metal tab is internally tied to this pin - must be isolated if heatsink is grounded. |
| OUTPUT (Pin 3) | Regulated negative output | Delivers stable negative voltage; serves as return reference for ADJUST pin and load ground connection in negative-rail systems. |
| ADJUSTMENT (Pin 1) | Feedback reference node | Held at –1.25 V relative to OUTPUT; connects to resistor divider to set output; draws only 65–100 µA, minimizing divider power loss. |
Key Features
| Feature | Design Value |
|---|---|
| Internal current limiting | Peak output current remains constant over temperature (–25°C to +150°C), preventing thermal runaway during overload. |
| Thermal shutdown protection | Automatically disables output when junction temperature exceeds ~150°C; recovers once cooled - no latch-up or manual reset required. |
| Safe-area compensation | Prevents secondary breakdown of the internal PNP pass transistor under high VI–VO and high IO stress conditions. |
| Low output noise | 0.003% RMS noise (10 Hz–10 kHz) - critical for low-noise analog supplies feeding precision ADCs and audio amplifiers. |
| Adjustable reference accuracy | ±1.25 V reference tolerance of ±2.5% (–1.213 V to –1.287 V) ensures predictable output setting across production lots and temperatures. |
Applications
| Industrial Instrumentation | Audio Signal Processing |
|---|---|
Use Scenario: High-precision multimeters and programmable logic controller (PLC) analog I/O modules requiring stable dual-rail supplies. IC Role / Device Role / Timing Role: Negative voltage regulator providing –15 V rail for op-amps and ADC drivers. Use Value: 0.3% output regulation and 77 dB ripple rejection ensure measurement accuracy unaffected by line noise or load transients. |
Use Scenario: Professional audio mixing consoles needing ultra-low-noise bias for microphone preamplifiers and line drivers. IC Role / Device Role / Timing Role: Low-noise negative supply generator for discrete JFET and bipolar op-amp stages. Use Value: 0.003% output noise and thermal stability maintain dynamic range >110 dB without audible hum or drift. |
| Test & Measurement Equipment | Medical Imaging Front-Ends |
Use Scenario: Automated test equipment (ATE) with programmable voltage sources requiring accurate, adjustable negative outputs. IC Role / Device Role / Timing Role: Programmable negative regulator controlled via DAC-driven R2 in feedback network. Use Value: Adjustable –1.2 V to –37 V range with <2.5 mV long-term drift enables calibration-grade voltage sourcing. |
Use Scenario: CT/MRI detector bias supplies where EMI immunity and reliability under continuous operation are critical. IC Role / Device Role / Timing Role: Fault-tolerant negative rail generator with thermal shutdown and current limiting. Use Value: Built-in protections prevent field failures during extended scans; 150°C junction rating supports sealed enclosure operation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar adjustable negative-voltage regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM337KCSE3 | Same TO-220 (KCS) package, but rated for 0°C to +125°C junction range (vs. LM237KC's –25°C to +150°C); identical electrical specs. | Optimized for commercial/industrial ambient environments; not rated for extended cold-start or high-temp industrial use. | Select LM337KCSE3 only if operating ambient stays above 0°C and thermal margin is sufficient without extended low-temp qualification. |
| LM337KTTR | TO-263 (KTT) surface-mount package; same –1.25 V reference and –1.5 A rating; RθJA = 25.3°C/W (vs. 24.8°C/W for KC). | Enables automated PCB assembly and compact layouts; requires reflow-compatible layout and thermal pad soldering. | Choose LM337KTTR for space-constrained, SMT-based designs where board area and assembly automation outweigh through-hole serviceability needs. |
Compared with LM237KC, LM337KCSE3 trades extended low-temperature capability for broader commercial availability, while LM337KTTR replaces through-hole mounting with SMT compatibility - neither is pin-compatible due to differing package footprints and thermal tab connections.
Availability
LM237KC is available at Aetrix Electronics and suitable for industrial instrumentation, medical imaging front-ends, and test & measurement equipment requiring stable component supply with guaranteed long-term continuity.
Supply support for LM237KC 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 company headquartered in Dallas, Texas, specializing in analog, embedded processing, and digital signal technologies since 1930.
The LM237KC belongs to TI's legacy LMx37 family of adjustable negative linear regulators, engineered for rugged industrial power management where reliability, thermal resilience, and precision regulation are mandatory.
FAQ
What is the absolute maximum input-to-output differential voltage for LM237KC?
The absolute maximum input-to-output differential voltage for LM237KC is –40 V, meaning the input can be up to 40 V more negative than the output. Exceeding this rating risks permanent device damage. For reliable operation, TI specifies a recommended range of –2.5 V to –37 V, with |VI – VO| ≤ 40 V and power dissipation limited to 15 W.
Does LM237KC require an output capacitor for stability, and what value is recommended?
Yes, LM237KC requires an output capacitor for stability. TI specifies a minimum of 1 µF solid tantalum or 10 µF aluminum electrolytic capacitor on the OUTPUT pin. This capacitor compensates the internal control loop and prevents oscillation, especially under varying load conditions. Omitting it may cause instability or excessive output ripple.
Can LM237KC be used in parallel for higher current output?
No, LM237KC is not designed for direct parallel operation. Its output voltage tolerance (±2.5% on reference) and lack of current-sharing circuitry mean mismatched units will result in unequal current distribution and possible thermal imbalance. For higher current, use a single higher-rated regulator or a discrete current-sharing design with external ballast resistors.
What is the purpose of the ADJUSTMENT pin on LM237KC, and how is it connected?
The ADJUSTMENT pin on LM237KC serves as the feedback reference node, held at a precise –1.25 V relative to OUTPUT. It connects to the junction of two external resistors (R1 from OUTPUT to ADJUST, R2 from ADJUST to ground) to set the output voltage via VO = –1.25 V × (1 + R2/R1). This pin draws only 65–100 µA, minimizing power loss in the divider network.
Is LM237KC RoHS compliant, and what is its lead finish?
LM237KC is obsolete per TI's packaging addendum and was not released with Pb-Free (RoHS) compliance. Its lead finish is not specified in available documentation, and TI lists its eco-plan as "TBD". For RoHS-compliant alternatives, consider LM237KCSE3 (Pb-Free CU SN) or LM337KTTR (Green RoHS with no Sb/Br).
LM237KC Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- TO-220-3
- Packaging:
- Tube
- 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:
- 1.5A
- Current - Quiescent (Iq):
- -
- Current - Supply (Max):
- -
- PSRR:
- 77dB (120Hz)
- Control Features:
- -
- Protection Features:
- Over Current, Over Temperature
- Operating Temperature:
- -25°C ~ 150°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-220-3
LM237KC FAQ
1.How can I place an order for LM237KC through Aetrix?
Please submit a Request for Quotation (RFQ) for LM237KC 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 LM237KC reliable?
The price and inventory of LM237KC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM237KC is usually 5 days.
3.What payment methods are accepted for LM237KC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM237KC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM237KC?
LM237KC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM237KC 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 LM237KC?
For technical support, including LM237KC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM237KC requirements.
6.How does Aetrix verify that LM237KC is sourced from the original manufacturer or authorized distributors?
All LM237KC 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 LM237KC meets industry standards.
7.What is the process for return or replacement of LM237KC?
All LM237KC units undergo pre-shipment inspection (PSI). If there is an issue with LM237KC, 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 LM237KC part is unused and in its original packaging.
Return procedure for LM237KC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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