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onsemi MC7912BT
- Part No.:
- MC7912BT
- Manufacturer:
- onsemi
- Package:
- TO-220-3
- Datasheet:
-
MC7912BT.pdf
- Description:
- IC REG LINEAR -12V 1A TO220AB
- Quantity:
- Payment:
- Shipping:
Inventory:1,417
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Product details
Overview
MC7912BT from onsemi is a fixed-output negative voltage regulator delivering −12 V at up to 1.0 A, featuring internal thermal shutdown, short-circuit current limiting, and safe-area compensation for rugged operation in industrial power supplies. It requires no external components for basic regulation and maintains stable output across input voltages from −14.5 V to −27 V with ≤120 mV load regulation (5–1.5 A) and 61 dB ripple rejection at 120 Hz.
For engineers reviewing the MC7912BT datasheet, pinout, applications, or equivalent options, key selection criteria include its TO−220 package with heatsink-connected Pin 2, −40°C to +125°C operating range, 1.3 V dropout at 1.0 A, and compatibility with dual-rail op-amp supplies, current-boost configurations, and MECL system biasing.
Technical Context
The MC7912BT implements a monolithic PNP pass transistor architecture with integrated bandgap reference, error amplifier, and protection circuitry. Its safe-area compensation dynamically reduces short-circuit current as VCE increases, preventing second breakdown during fault conditions.
Thermal overload protection activates at +150°C junction temperature, and internal current limiting holds peak output current below 1.8 A under sustained short-circuit conditions. The device operates without external capacitors in low-noise, low-current applications but recommends ≥0.33 µF input and ≥1.0 µF output capacitance for stability with long trace lengths or high transient loads.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | −12 V nominal, −11.5 V to −12.5 V over temperature (TJ = +25°C), ensuring precision bias for analog circuits |
| Output Current | 1.0 A continuous, internally limited to prevent damage during overload or short-circuit events |
| Dropout Voltage | 1.3 V at 1.0 A, requiring minimum −13.3 V input for regulated −12 V output under full load |
| Ripple Rejection | 61 dB at 120 Hz, suppressing AC line noise in linear power supply outputs |
| Line Regulation | ≤120 mV over −14.5 V to −30 V input range, maintaining output stability despite input ripple |
| Load Regulation | ≤240 mV from 5 mA to 1.5 A, critical for consistent performance across varying load conditions |
| Thermal Resistance | Junction-to-case 5.0 °C/W, enabling >15 W dissipation with adequate heatsinking |
Pinout & Package
MC7912BT uses the TO−220 (Case 221AB) package with heatsink surface electrically connected to Pin 2. Mounting the tab to chassis ground provides both thermal conduction and EMI shielding.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 | Ground | Reference node for output voltage; must be low-impedance connection to minimize regulation error |
| Pin 2 | Input | Negative input terminal; connects to unregulated negative rail; heatsink surface tied here |
| Pin 3 | Output | Regulated −12 V source; requires local bypass capacitor for transient response and stability |
Key Features
| Feature | Design Value |
|---|---|
| No external components required | Enables compact, low-BOM-cost designs for standard −12 V rails without feedback resistors or compensation networks |
| Internal thermal overload protection | Automatically shuts down at +150°C junction temperature, preventing permanent damage during overheating |
| Internal short-circuit current limiting | Clamps output current to safe levels during faults, eliminating need for external fuses or current-sense circuitry |
| Output transistor safe-area compensation | Prevents secondary breakdown by reducing short-circuit current as VCE rises, enhancing reliability under stress |
| Pb-free lead finish (G-suffix) | Complies with RoHS Directive 2011/65/EU and JEDEC J-STD-609A Class 3 moisture sensitivity |
Applications
| Operational Amplifier Dual Supply | Industrial Control Logic Power |
|---|---|
Use Scenario: Providing symmetrical ±15 V or ±12 V rails for precision op-amps in data acquisition systems. IC Role / Device Role / Timing Role: Negative voltage regulator supplying stable −12 V bias to op-amp negative supply pin. Use Value: Enables rail-to-rail input/output swing and low offset drift by maintaining tight regulation (<±120 mV) across load transients. |
Use Scenario: Powering discrete logic families (e.g., MECL, ECL) requiring precise negative bias in factory automation controllers. IC Role / Device Role / Timing Role: Fixed −12 V source for gate bias and level-shifting in high-speed digital interface circuits. Use Value: Delivers 1.0 A with 61 dB ripple rejection, minimizing timing jitter induced by power supply noise in clock distribution paths. |
| Current-Boosted Power Rail | Protection-Critical Industrial PSU |
Use Scenario: Extending output current beyond 1.0 A using an external pass transistor in programmable lab power supplies. IC Role / Device Role / Timing Role: Master regulator controlling base drive of series NPN transistor to augment current capability. Use Value: Maintains inherent thermal and short-circuit protection while enabling 4 A+ output via external boost stage (Fig. 9). |
Use Scenario: Regulating negative supply in PLC I/O modules exposed to voltage reversals and fast power cycling. IC Role / Device Role / Timing Role: Primary −12 V regulator with optional external diodes (D1/D2 per Fig. 11) for polarity and reverse-bias protection. Use Value: Survives output capacitor discharge events and input shorts due to built-in safe-area compensation and thermal shutdown. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar negative voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MC7912CTG | Same TO−220 package, but rated for 0°C to +125°C (vs. −40°C to +125°C for MC7912BT) | Suitable for commercial-grade equipment without extended cold-start requirements | Select MC7912CTG when ambient operating temperature stays above 0°C and cost optimization is prioritized |
| LM337T | Adjustable negative regulator (−1.25 V to −37 V); requires two external resistors for −12 V setting; higher quiescent current (5 mA vs. 4.4 mA typical) | Offers design flexibility for non-standard voltages but adds BOM and layout complexity | Choose LM337T only if future voltage reconfiguration or tighter tolerance (±1%) is needed beyond MC7912BT's ±4% spec |
Compared with MC7912CTG, the MC7912BT supports wider industrial temperature range and matches identical electrical specs except for TJ min; versus LM337T, it eliminates resistor network errors and improves long-term stability by removing external component drift dependencies.
Availability
MC7912BT is available at Aetrix Electronics and suitable for industrial control systems, test and measurement instrumentation, and dual-rail analog signal conditioning requiring stable component supply with full traceability and lifecycle management.
Supply support for MC7912BT 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 manufacturer specializing in energy-efficient power management, analog, sensor, and connectivity solutions for automotive, industrial, and cloud infrastructure markets.
The MC7900 Series-including MC7912BT-is designed specifically for robust, drop-in replacement of legacy negative linear regulators in industrial power supplies, offering enhanced thermal protection and safe-area compensation over earlier generations.
FAQ
What is the maximum input voltage rating for MC7912BT?
The MC7912BT supports a maximum input voltage of −35 V DC for output voltages between −5.0 V and −18 V, and −40 V DC for −24 V output variants. For the MC7912BT specifically, the absolute maximum input is −35 V, verified in the "Maximum Ratings" table on page 2 of the official datasheet (Rev. 21, October 2021). Exceeding this risks permanent damage.
Does MC7912BT require input and output capacitors for stable operation?
While the MC7912BT can operate without external capacitors in low-current, low-noise applications, the datasheet recommends a minimum 0.33 µF input capacitor (tantalum or low-ESR film) and 1.0 µF output capacitor for reliable stability-especially when traces exceed 2 inches or load transients exceed 100 mA/µs. These values prevent oscillation and improve ripple rejection.
What is the thermal resistance and heatsinking requirement for MC7912BT at 1.0 A load?
The MC7912BT has θJC = 5.0 °C/W and θJA = 65 °C/W (TO−220, no heatsink). At 1.0 A with 1.3 V dropout, power dissipation is 1.3 W. With no heatsink, junction temperature rise is 84.5 °C-exceeding safe limits. A heatsink with θSA ≤ 15 °C/W is required to maintain TJ < +125°C at full load and +50°C ambient.
Can MC7912BT be used in parallel for higher current output?
No-MC7912BT is not designed for parallel operation. Its output voltage tolerance (±4%) and lack of current-sharing features cause unequal load division, risking thermal runaway in one unit. For >1.0 A, use the current-boost configuration shown in Figure 9 of the datasheet with an external pass transistor and base-drive resistor.
What protection features are integrated into MC7912BT?
The MC7912BT integrates three core protections: (1) thermal shutdown at +150°C junction temperature, (2) internal short-circuit current limiting (typically 1.8 A), and (3) output transistor safe-area compensation that reduces fault current as VCE increases. These functions operate autonomously without external components, ensuring robustness in industrial environments.
MC7912BT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-220-3
- Packaging:
- Tube
- 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):
- 1.3V @ 1A (Typ)
- Current - Output:
- 1A
- Current - Quiescent (Iq):
- -
- Current - Supply (Max):
- -
- PSRR:
- 61dB (120Hz)
- Control Features:
- -
- Protection Features:
- Over Current, Over Temperature
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-220
MC7912BT FAQ
1.How can I place an order for MC7912BT through Aetrix?
Please submit a Request for Quotation (RFQ) for MC7912BT 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 MC7912BT reliable?
The price and inventory of MC7912BT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC7912BT is usually 5 days.
3.What payment methods are accepted for MC7912BT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC7912BT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC7912BT?
MC7912BT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC7912BT 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 MC7912BT?
For technical support, including MC7912BT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC7912BT requirements.
6.How does Aetrix verify that MC7912BT is sourced from the original manufacturer or authorized distributors?
All MC7912BT 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 MC7912BT meets industry standards.
7.What is the process for return or replacement of MC7912BT?
All MC7912BT units undergo pre-shipment inspection (PSI). If there is an issue with MC7912BT, 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 MC7912BT part is unused and in its original packaging.
Return procedure for MC7912BT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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