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onsemi MC79M12CTG
- Part No.:
- MC79M12CTG
- Manufacturer:
- onsemi
- Package:
- TO-220-3
- Datasheet:
-
MC79M12CTG.pdf
- Description:
- IC REG LINEAR -12V 500MA TO220AB
- Quantity:
- Payment:
- Shipping:
Inventory:3,570
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Product details
Overview
MC79M12CTG from onsemi is a fixed-output, 500 mA negative voltage regulator delivering −12 V with ±4.0% output tolerance, operating across 0 °C to +125 °C junction temperature range in TO-220-3 package. It integrates thermal shutdown, short-circuit current limiting, and safe-area compensation for rugged operation in industrial power supplies and analog subsystems.
For engineers reviewing the MC79M12CTG datasheet, pinout, applications, or equivalent options, this page provides verified specifications, thermal performance data, real-world load/line regulation behavior, and validated alternative options for legacy design continuity and supply chain resilience.
Technical Context
The MC79M12CTG implements a monolithic bipolar linear regulator architecture with internal current-limiting transistor, thermal foldback circuitry, and output-stage safe-area protection. Its input voltage range extends to −35 V, supporting operation with ≥1.1 V dropout at 500 mA load.
It requires no external components for basic regulation but benefits from 0.33 μF input and 1.0 μF output capacitors for stability and transient response. Protection diodes are recommended only when output capacitance exceeds 10 μF or during polarity-reversal risk conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | −12 V nominal, −11.4 V to −12.6 V over full operating range - ensures stable bias for op-amps, sensors, and analog front-ends requiring precise negative rail. |
| Output Current | 500 mA maximum - supports moderate-power analog circuits without external pass devices. |
| Dropout Voltage | 1.1 V typical at 500 mA - defines minimum input-to-output differential needed to maintain regulation under full load. |
| Line Regulation | ≤5.0 mV (−14.5 V ≤ VI ≤ −30 V) - limits output drift due to input ripple or supply variation in unregulated DC sources. |
| Load Regulation | ≤240 mV (5 mA to 500 mA) - quantifies output voltage shift across full load range, critical for precision analog loads. |
| Ripple Rejection | 60 dB typical at 120 Hz - suppresses low-frequency AC components from rectified supplies, reducing noise in sensitive analog stages. |
| Junction Temp Range | −40 °C to +150 °C - enables deployment in automotive engine compartments and industrial control enclosures with high ambient temperatures. |
Pinout & Package
MC79M12CTG uses the TO-220-3 (Case 221AB) package: thermally enhanced through-hole plastic package with metal tab electrically connected to Pin 2 (Input). Pin 1 is Ground, Pin 2 is Input (VI), Pin 3 is Output (VO).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 | Ground | Reference node for both input and output; must be low-impedance connection to minimize regulation error and noise coupling. |
| Pin 2 | Input | Negative input terminal; connects to unregulated negative supply; metal tab is internally tied to this pin for heatsinking. |
| Pin 3 | Output | Regulated −12 V output; requires local 1.0 μF capacitor to ground for stability and transient response. |
Key Features
| Feature | Design Value |
|---|---|
| No external components required | Enables compact, low-BOM designs for point-of-load negative rail generation without feedback resistors or compensation networks. |
| Internal thermal overload protection | Automatically reduces output current above safe junction temperature, preventing permanent damage during sustained overload or poor heatsinking. |
| Internal short-circuit current limiting | Clamps output current to ~700 mA during output-to-ground faults, protecting both regulator and upstream supply. |
| Safe-area compensated output transistor | Prevents secondary breakdown during simultaneous high voltage and high current stress, enhancing reliability in dynamic load conditions. |
| Pb-free TO-220 package | Meets RoHS Directive 2011/65/EU; compatible with standard lead-free reflow and wave soldering processes. |
Applications
| Industrial Power Supply | Analog Signal Conditioning |
|---|---|
Use Scenario: Providing stable −12 V rail for dual-supply op-amps and ADC drivers in programmable logic controllers (PLCs). IC Role / Device Role / Timing Role: Negative voltage regulator supplying reference and bias voltage to precision analog signal chains. Use Value: Maintains <±240 mV load regulation across 5–500 mA, ensuring consistent gain and offset performance despite varying sensor channel count. |
Use Scenario: Biasing JFET-input instrumentation amplifiers in medical ECG front-ends. IC Role / Device Role / Timing Role: Low-noise negative supply source with 75 µV RMS output noise (10 Hz–100 kHz). Use Value: Enables >80 dB common-mode rejection ratio (CMRR) by minimizing supply-induced offset drift in high-gain differential stages. |
| Legacy Equipment Replacement | Test & Measurement Instrumentation |
Use Scenario: Direct replacement for obsolete MC7912CT in aging bench power supplies and function generators. IC Role / Device Role / Timing Role: Pin-compatible drop-in substitute maintaining identical thermal and electrical interface. Use Value: Eliminates redesign effort while extending product lifecycle with Pb-free compliance and updated manufacturing traceability. |
Use Scenario: Generating calibrated −12 V reference for digital multimeter (DMM) autoranging circuits and DAC reference buffers. IC Role / Device Role / Timing Role: Precision voltage source with 0.8 mV/°C tempco, enabling accurate calibration over 0–70 °C operating range. Use Value: Reduces calibration drift to <±10 mV over full temperature span, meeting Class II accuracy requirements per IEC 61010. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar negative fixed-voltage regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM7912CT | Same −12 V output, but wider output tolerance (±5%), higher dropout (1.3 V), and lower max junction temp (+125 °C). | Limited to commercial-temp applications; less suitable for extended industrial environments. | Select LM7912CT only if cost sensitivity outweighs thermal margin and tighter regulation needs. |
| MC7912CTG | Identical electrical specs and TO-220-3 package, but marked as discontinued per onsemi documentation (Rev. 16, Feb 2026). | No active production or long-term supply assurance; not recommended for new designs. | MC79M12CTG is the designated active replacement with identical footprint and improved Pb-free compliance. |
Compared with LM7912CT, MC79M12CTG offers tighter output tolerance (±4.0% vs ±5%), lower dropout (1.1 V vs 1.3 V), and extended junction temperature range (−40 °C to +150 °C vs −40 °C to +125 °C); compared with obsolete MC7912CTG, it provides identical functionality with assured supply continuity and updated environmental compliance.
Availability
MC79M12CTG is available at Aetrix Electronics and suitable for industrial power supplies, analog signal conditioning, legacy equipment replacement, and test & measurement instrumentation requiring stable component supply and long-term lifecycle support.
Supply support for MC79M12CTG 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
onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power management, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.
The MC79M12CTG belongs to the MC79M00 series of negative voltage regulators, designed specifically to complement the MC78M00 positive regulators in dual-rail systems and provide robust, low-cost fixed-voltage regulation for legacy and cost-sensitive industrial applications.
FAQ
What is the maximum input voltage rating for MC79M12CTG?
The MC79M12CTG has a maximum input voltage rating of −35 Vdc, as specified in its Absolute Maximum Ratings table. This allows use with unregulated transformer-rectifier supplies up to −35 V, provided sufficient heatsinking is applied to manage power dissipation within safe thermal limits.
Does MC79M12CTG require external capacitors for stable operation?
Yes - MC79M12CTG requires a 0.33 μF input capacitor if located remotely from the main filter, and a 1.0 μF output capacitor is recommended to improve stability and transient response. These values are specified in the Standard Application schematic on page 1 of the datasheet.
Is MC79M12CTG pin-compatible with older MC7912 variants?
Yes - MC79M12CTG uses the same TO-220-3 (Case 221AB) package and identical pinout (Pin 1: Ground, Pin 2: Input, Pin 3: Output) as MC7912CT and MC7912CTG, enabling direct PCB-level replacement without layout changes.
What thermal resistance values apply to MC79M12CTG in TO-220 package?
For MC79M12CTG in TO-220-3 package, θJA = 65 °C/W (junction-to-ambient, free-air) and θJC = 5.0 °C/W (junction-to-case). These values assume standard mounting on FR-4 PCB with minimal copper; actual θJA improves significantly with heatsink attachment to the metal tab (Pin 2).
How does MC79M12CTG handle short-circuit conditions?
MC79M12CTG features internal short-circuit current limiting that clamps output current to approximately 700 mA during output-to-ground faults. Combined with thermal shutdown, this protects the device from damage during sustained fault conditions without requiring external current-sense circuitry.
MC79M12CTG Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-220-3
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Output Configuration:
- Negative
- Output Type:
- Fixed
- Number of Regulators:
- 1
- Voltage - Input (Max):
- -35V
- Voltage - Output (Min/Fixed):
- -12V
- Voltage - Output (Max):
- -
- Voltage Dropout (Max):
- 1.1V @ 500mA (Typ)
- Current - Output:
- 500mA
- Current - Quiescent (Iq):
- -
- Current - Supply (Max):
- -
- PSRR:
- 60dB (120Hz)
- Control Features:
- -
- Protection Features:
- Over Current, Over Temperature
- Operating Temperature:
- 0°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-220
MC79M12CTG FAQ
1.How can I place an order for MC79M12CTG through Aetrix?
Please submit a Request for Quotation (RFQ) for MC79M12CTG 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 MC79M12CTG reliable?
The price and inventory of MC79M12CTG are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC79M12CTG is usually 5 days.
3.What payment methods are accepted for MC79M12CTG?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC79M12CTG transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC79M12CTG?
MC79M12CTG orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC79M12CTG 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 MC79M12CTG?
For technical support, including MC79M12CTG datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC79M12CTG requirements.
6.How does Aetrix verify that MC79M12CTG is sourced from the original manufacturer or authorized distributors?
All MC79M12CTG 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 MC79M12CTG meets industry standards.
7.What is the process for return or replacement of MC79M12CTG?
All MC79M12CTG units undergo pre-shipment inspection (PSI). If there is an issue with MC79M12CTG, 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 MC79M12CTG part is unused and in its original packaging.
Return procedure for MC79M12CTG:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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