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onsemi MC79M08BTG
- Part No.:
- MC79M08BTG
- Manufacturer:
- onsemi
- Package:
- TO-220-3
- Datasheet:
-
MC79M08BTG.pdf
- Description:
- IC REG LINEAR -8V 500MA TO220AB
- Quantity:
- Payment:
- Shipping:
Inventory:4,113
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Product details
Overview
MC79M08BTG from onsemi is a fixed-output negative voltage regulator delivering −8.0 V at up to 500 mA, featuring internal thermal shutdown, short-circuit current limiting, and safe-area compensation for rugged operation in industrial power supplies. It operates across −40 °C to +125 °C with 4.0% output voltage tolerance and requires no external components for basic regulation.
For engineers reviewing the MC79M08BTG datasheet, pinout, applications, or equivalent options, this page provides verified technical context, package-specific pin roles, real-world use cases, and validated alternative options for negative rail generation in legacy and embedded systems.
Technical Context
The MC79M08BTG implements a monolithic bipolar linear regulator architecture with integrated pass transistor, error amplifier, reference, and protection circuitry. Its input voltage range extends to −35 V, and it maintains regulation with a minimum dropout of 1.1 V at 500 mA.
Designed for TO-220-3 (Case 221AB) mounting, the device relies on external input and output capacitors (0.33 μF and 1.0 μF typical) for stability and transient response. It includes ESD protection exceeding 2000 V HBM and operates without external biasing or feedback networks.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | −8.0 V nominal, ±4.0% tolerance (−7.6 V to −8.4 V over full operating conditions) |
| Output Current | Up to 500 mA continuous; internally limited by thermal and current protection |
| Input Voltage Range | −10.5 V to −25 V recommended; absolute max −35 V DC |
| Dropout Voltage | 1.1 V at 500 mA - defines minimum input-to-output differential needed for regulation |
| Ripple Rejection | 54–63 dB at 120 Hz - critical for suppressing AC ripple in rectified negative supplies |
| Operating Temperature | −40 °C to +125 °C junction - supports industrial and automotive under-hood environments |
| Thermal Resistance | θJA = 65 °C/W (TO-220, free-air); θJC = 5.0 °C/W - determines heatsink requirements |
Pinout & Package
MC79M08BTG uses the TO-220-3 package (Case 221AB), a through-hole, thermally enhanced plastic package with metal tab for heatsinking. Pin 1 is Ground, Pin 2 is Input (VI), and Pin 3 is Output (VO). The metal tab is electrically connected to Pin 2 (Input).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Ground | Reference node for internal biasing and error amplifier; must be low-impedance common return path |
| 2 | Input | Negative input supply terminal; connects to unregulated negative rail; tab is electrically tied to this pin |
| 3 | Output | Regulated −8.0 V negative output; supplies load with current up to 500 mA |
Key Features
| Feature | Design Value |
|---|---|
| No external components required | Enables drop-in replacement in legacy designs without added BOM cost or layout changes |
| Internal thermal overload protection | Shuts down regulator when junction temperature exceeds safe limit, preventing permanent damage |
| Internal short-circuit current limiting | Clamps output current during fault conditions, protecting both IC and upstream supply |
| Safe-area compensated output transistor | Ensures SOA compliance across voltage/current combinations, enabling reliable 500 mA operation |
| Pb-free TO-220 package | Meets RoHS Directive 2011/65/EU; compatible with standard lead-free reflow and hand-soldering processes |
Applications
| Industrial Power Supply | Legacy Analog Instrumentation |
|---|---|
Use Scenario: Provides stable −8 V rail for op-amp biasing and signal conditioning circuits in programmable logic controllers (PLCs) and sensor transmitters. IC Role / Device Role / Timing Role: Negative voltage regulator supplying precision analog stages requiring clean, low-noise DC. Use Value: Maintains −8.0 V output within ±4.0% over temperature and load, ensuring consistent offset calibration and ADC reference stability. |
Use Scenario: Powers dual-supply operational amplifiers and comparators in panel meters and analog data loggers with long service life requirements. IC Role / Device Role / Timing Role: Fixed negative rail generator replacing obsolete discrete regulator designs. Use Value: Eliminates need for external pass transistor and feedback network, reducing component count and board space while retaining proven reliability. |
| Automotive Body Control Module | Test & Measurement Equipment |
Use Scenario: Supplies −8 V to CAN transceiver bias circuitry and microcontroller I/O buffers in non-safety-critical vehicle subsystems. IC Role / Device Role / Timing Role: Secondary negative regulator supporting isolated interface ICs in 12 V battery-powered systems. Use Value: Operates from −40 °C to +125 °C junction temperature, meeting AEC-Q100 stress test requirements for under-dash environments. |
Use Scenario: Generates calibrated negative supply for oscilloscope front-end amplifiers and function generator output stages. IC Role / Device Role / Timing Role: Low-noise voltage source with 60 μV RMS output noise (10 Hz–100 kHz) for sensitive analog signal paths. Use Value: Ripple rejection of ≥54 dB at 120 Hz suppresses rectifier-induced hum, preserving measurement accuracy and dynamic range. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar negative voltage regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM337T | Adjustable output (−1.25 V to −37 V); requires two external resistors; higher dropout (1.3 V typical) | Used where programmable or multiple output voltages are needed; less suitable for fixed −8 V drop-in replacement | Select LM337T only when design flexibility outweighs BOM simplicity and footprint constraints of MC79M08BTG. |
| MC79M08CDTRKG | DPAK-3 surface-mount package; same −8 V output and 500 mA rating; Pb-free; rated for 0 °C to +125 °C | Preferred for automated SMT assembly and space-constrained PCBs; not interchangeable without layout revision | Choose MC79M08CDTRKG for new SMT designs; retain MC79M08BTG for through-hole production or legacy repair. |
Compared with LM337T and MC79M08CDTRKG, the MC79M08BTG offers the simplest implementation for fixed −8 V regulation in through-hole systems, combining guaranteed output accuracy, robust thermal protection, and direct compatibility with existing TO-220 heatsinks-without requiring resistor networks or re-layout.
Availability
MC79M08BTG is available at Aetrix Electronics and suitable for industrial power supplies, legacy instrumentation, and automotive body control modules requiring stable component supply and long-term obsolescence management.
Supply support for MC79M08BTG 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, and sensing solutions for automotive, industrial, and cloud infrastructure markets.
The MC79M00 series was designed specifically to provide rugged, fixed-output negative voltage regulation as a complementary counterpart to the MC78M00 positive regulators-targeting cost-sensitive, high-reliability applications where simplicity and proven performance are essential.
FAQ
What is the maximum input voltage for MC79M08BTG?
The absolute maximum input voltage for MC79M08BTG is −35 V DC. Operation beyond this rating risks permanent damage. For reliable regulation, the datasheet recommends maintaining input between −10.5 V and −25 V under typical load conditions. The MC79M08BTG's internal protection circuits do not override this absolute limit.
Does MC79M08BTG require input and output capacitors?
Yes, MC79M08BTG requires a 0.33 μF input capacitor if located remotely from the filter capacitor, and a 1.0 μF output capacitor to ensure stability and improve transient response. These values are specified in the standard application circuit on page 1 of the datasheet and are necessary to prevent oscillation under varying load conditions.
Is MC79M08BTG pin-compatible with other MC79Mxx regulators?
Yes, all MC79Mxx devices-including MC79M05BTG, MC79M12BTG, and MC79M15BTG-share identical TO-220-3 pinout (Pin 1: Ground, Pin 2: Input, Pin 3: Output) and mechanical footprint. This allows direct substitution when only output voltage differs, provided input voltage and thermal design accommodate the new regulation point.
What is the thermal resistance of MC79M08BTG in free air?
The MC79M08BTG has a junction-to-ambient thermal resistance (θJA) of 65 °C/W when mounted in free air per the TO-220-3 (Case 221AB) specification. This value assumes no heatsink; actual thermal performance improves significantly with proper heatsinking-e.g., θJC is 5.0 °C/W, enabling efficient heat transfer from junction to case.
Can MC79M08BTG be used in automotive applications?
Yes, MC79M08BTG is qualified for operation from −40 °C to +125 °C junction temperature and includes thermal shutdown and short-circuit protection-key requirements for automotive body electronics. While not AEC-Q100 certified out-of-box, its robustness and wide temperature range make it suitable for non-safety-critical automotive subsystems when properly derated and heatsinked.
MC79M08BTG 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):
- -8V
- Voltage - Output (Max):
- -
- Voltage Dropout (Max):
- 1.1V @ 500mA (Typ)
- Current - Output:
- 500mA
- Current - Quiescent (Iq):
- -
- Current - Supply (Max):
- -
- PSRR:
- 63dB (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
MC79M08BTG FAQ
1.How can I place an order for MC79M08BTG through Aetrix?
Please submit a Request for Quotation (RFQ) for MC79M08BTG 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 MC79M08BTG reliable?
The price and inventory of MC79M08BTG are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC79M08BTG is usually 5 days.
3.What payment methods are accepted for MC79M08BTG?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC79M08BTG transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC79M08BTG?
MC79M08BTG orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC79M08BTG 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 MC79M08BTG?
For technical support, including MC79M08BTG datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC79M08BTG requirements.
6.How does Aetrix verify that MC79M08BTG is sourced from the original manufacturer or authorized distributors?
All MC79M08BTG 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 MC79M08BTG meets industry standards.
7.What is the process for return or replacement of MC79M08BTG?
All MC79M08BTG units undergo pre-shipment inspection (PSI). If there is an issue with MC79M08BTG, 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 MC79M08BTG part is unused and in its original packaging.
Return procedure for MC79M08BTG:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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