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onsemi MC79M08BDT
- Part No.:
- MC79M08BDT
- Manufacturer:
- onsemi
- Package:
- TO-252-3, DPAK (2 Leads + Tab), SC-63
- Datasheet:
-
MC79M08BDT.pdf
- Description:
- IC REG LINEAR -8V 500MA DPAK
- Quantity:
- Payment:
- Shipping:
Inventory:4,510
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Product details
Overview
MC79M08BDT from onsemi is a fixed-output, 500 mA negative voltage linear regulator delivering −8.0 V with ±4.0% tolerance over −40 °C to +125 °C junction temperature. It features internal thermal shutdown, short-circuit current limiting, and safe-area compensation for rugged operation in industrial power rails and legacy analog subsystems.
For engineers reviewing the MC79M08BDT datasheet, pinout, applications, or equivalent options, this page provides verified specifications, DPAK-3 package details, thermal performance data, protection diode guidance, and validated alternative options for negative rail regulation in embedded control, instrumentation, and telecom infrastructure.
Technical Context
The MC79M08BDT implements a monolithic bipolar transistor-based series pass architecture with integrated error amplifier, reference, and protection circuitry. Its −8.0 V output is stabilized using internal feedback resistors and trimmed during production to meet ±4.0% tolerance at TJ = 25 °C.
It operates with a minimum input-to-output differential of 1.1 V (dropout) at 500 mA and achieves 54–63 dB ripple rejection at 120 Hz. Thermal protection activates at TJ ≥ 150 °C, and safe-area compensation prevents secondary breakdown under overload conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | −8.0 V nominal, −7.7 V to −8.3 V at TJ = 25 °C - ensures stable biasing for op-amps and analog ICs requiring precise negative supply. |
| Output Current | 500 mA maximum - supports moderate-power analog stages, sensor signal conditioning, and legacy logic families. |
| Input Voltage Range | −35 V maximum - accommodates unregulated −12 V or −24 V supplies with ripple margin. |
| Dropout Voltage | 1.1 V typical at 500 mA - enables operation with minimal headroom, reducing power dissipation in low-differential designs. |
| Ripple Rejection | 54 dB min / 63 dB typ at 120 Hz - suppresses line-frequency noise in AC/DC-derived negative rails. |
| Thermal Resistance (Junction-to-Ambient) | 92 °C/W (DPAK-3, free air) - requires PCB copper area or heatsinking for >250 mA continuous operation at TA = 50 °C. |
| Operating Junction Temperature | −40 °C to +150 °C - qualified for extended industrial environments including motor drives and outdoor equipment. |
Pinout & Package
DPAK-3 (Case 369C) surface-mount package with exposed drain pad for thermal conduction; dimensions 6.10 × 6.54 × 2.28 mm, pitch 2.29 mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Ground | Reference node for internal feedback and protection circuits; must be low-impedance connection to system ground plane. |
| 2 | Input | Negative input terminal; accepts unregulated −9.1 V to −35 V (min −10.5 V for full load regulation). |
| 3 | Output | Regulated −8.0 V output; requires 1.0 µF ceramic or tantalum capacitor for stability and transient response. |
Key Features
| Feature | Design Value |
|---|---|
| No external components required | Internal feedback network and compensation eliminate need for external resistors or capacitors beyond input/output bypassing. |
| Internal thermal overload protection | Automatic shutdown at TJ ≥ 150 °C prevents permanent damage during sustained overload or poor heatsinking. |
| Internal short-circuit current limiting | Clamps output current to ~500 mA during output-to-ground fault, enabling safe recovery without external fusing. |
| Safe-area compensated output transistor | Prevents secondary breakdown during simultaneous high voltage and high current stress (e.g., startup into capacitive load). |
| Pb-free DPAK-3 packaging | RoHS-compliant lead-free finish (marked with "G") suitable for modern reflow assembly and environmental compliance. |
Applications
| Industrial Sensor Signal Conditioning | Legacy Analog Instrumentation |
|---|---|
|
Use Scenario: Powering dual-supply op-amps and precision ADC drivers in 4–20 mA loop-powered transmitters. IC Role / Device Role / Timing Role: Provides stable −8.0 V rail for analog front-end biasing and reference generation. Use Value: Maintains ±4.0% output accuracy across −40 °C to +125 °C, ensuring consistent gain and offset calibration over temperature. |
Use Scenario: Supplying negative rails in benchtop multimeters, oscilloscope vertical amplifiers, and function generators. IC Role / Device Role / Timing Role: Delivers low-noise (60 µV RMS), regulated −8.0 V for high-impedance analog stages. Use Value: 63 dB ripple rejection eliminates 120 Hz hum from transformer-based power supplies, preserving measurement fidelity. |
| Telecom Line Card Biasing | Motor Control Feedback Circuitry |
|
Use Scenario: Generating isolated negative bias for RS-232 transceivers and line driver ICs in access equipment. IC Role / Device Role / Timing Role: Supplies −8.0 V to interface ICs requiring symmetric dual supplies. Use Value: Internal short-circuit limiting protects against cable faults and ESD-induced latch-up during field deployment. |
Use Scenario: Powering current-sense amplifiers and gate driver bias in three-phase inverter control boards. IC Role / Device Role / Timing Role: Provides robust −8.0 V rail tolerant of high dv/dt noise from IGBT switching. Use Value: Safe-area compensation prevents failure during rapid bus voltage transients and inductive kickback events. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar negative voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM337MDTX/NOPB | −1.25 V to −37 V adjustable output; 1.5 A max; higher dropout (1.7 V); no safe-area compensation. | Requires two external resistors for −8 V setting; better for variable-rail systems but less accurate at fixed −8 V. | Select when design flexibility or higher current is needed; verify thermal design due to higher dropout and no safe-area protection. |
| MC79M08CDTRKG | Same −8.0 V output, DPAK-3 package, Pb-free, but rated for 0 °C to +125 °C (vs. −40 °C to +125 °C for MC79M08BDT). | Not suitable for cold-start industrial environments below 0 °C; identical electrical specs otherwise. | Use only in commercial-temperature applications; MC79M08BDT remains preferred for extended temperature range compliance. |
Compared with LM337MDTX/NOPB, MC79M08BDT offers tighter fixed-voltage accuracy and built-in safe-area protection at lower cost and simpler layout; compared with MC79M08CDTRKG, it delivers guaranteed operation down to −40 °C without derating, making it essential for outdoor or automotive-adjacent industrial use cases.
Availability
MC79M08BDT is available at Aetrix Electronics and suitable for industrial sensor signal conditioning, legacy analog instrumentation, telecom line card biasing, and motor control feedback circuitry requiring stable component supply and long-term lifecycle support.
Supply support for MC79M08BDT 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 complementary counterparts to the MC78M00 positive regulators, targeting reliability-critical analog subsystems in harsh environments.
FAQ
What is the maximum input voltage rating for the MC79M08BDT?
The MC79M08BDT has an absolute maximum input voltage rating of −35 Vdc. Exceeding this value may cause permanent damage. For reliable operation, the input should remain at least 1.1 V more negative than the output (i.e., ≤ −9.1 V) under full load to maintain regulation, with recommended operating range between −10.5 V and −25 V for optimal line regulation performance per datasheet testing conditions.
Does the MC79M08BDT require external capacitors, and if so, what values are recommended?
Yes, the MC79M08BDT requires an input capacitor (Cin) if located appreciably far from the main power supply filter, and an output capacitor (CO) to ensure stability and improve transient response. The datasheet recommends 0.33 µF for Cin and 1.0 µF for CO. Ceramic or tantalum types are acceptable; CO must be placed close to pins 2 (Input) and 3 (Output) with low-inductance routing to prevent oscillation.
Is the MC79M08BDT still in active production, or is it discontinued?
The MC79M08BDT is marked as discontinued in the official onsemi datasheet (Rev. 16, Feb. 2026), with no new shipments planned. However, Aetrix Electronics maintains legacy inventory and offers traceable, tested units for ongoing production and repair programs. Customers are advised to consult Aetrix for remaining stock levels and last-time-buy planning support.
How does thermal performance differ between the DPAK-3 and TO-220 packages for the MC79M08BDT?
The MC79M08BDT in DPAK-3 (Case 369C) has θJA = 92 °C/W in free air, while the TO-220 version (MC79M08BT) has θJA = 65 °C/W. This means the DPAK-3 requires more PCB copper area or heatsinking to achieve equivalent power dissipation. At 500 mA and 1.1 V dropout (0.55 W), DPAK-3 junction temperature rise is ~51 °C above ambient - necessitating thermal relief pads and ≥25 mm² 2-oz copper for reliable operation at TA = 50 °C.
Can the MC79M08BDT be used without protection diodes in standard applications?
Protection diodes are not required for output capacitance <10 µF, per the datasheet. However, they are recommended when using ≥10 µF output capacitance or when the input may experience fast transients (e.g., hot-plug, power-off sequencing). Diode D1 prevents reverse polarity damage; D2 prevents output capacitor discharge through the regulator during input short-circuit - both critical for system-level reliability in industrial deployments of MC79M08BDT.
MC79M08BDT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-252-3, DPAK (2 Leads + Tab), SC-63
- 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:
- Surface Mount
- Supplier Device Package:
- DPAK
MC79M08BDT FAQ
1.How can I place an order for MC79M08BDT through Aetrix?
Please submit a Request for Quotation (RFQ) for MC79M08BDT 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 MC79M08BDT reliable?
The price and inventory of MC79M08BDT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC79M08BDT is usually 5 days.
3.What payment methods are accepted for MC79M08BDT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC79M08BDT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC79M08BDT?
MC79M08BDT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC79M08BDT 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 MC79M08BDT?
For technical support, including MC79M08BDT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC79M08BDT requirements.
6.How does Aetrix verify that MC79M08BDT is sourced from the original manufacturer or authorized distributors?
All MC79M08BDT 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 MC79M08BDT meets industry standards.
7.What is the process for return or replacement of MC79M08BDT?
All MC79M08BDT units undergo pre-shipment inspection (PSI). If there is an issue with MC79M08BDT, 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 MC79M08BDT part is unused and in its original packaging.
Return procedure for MC79M08BDT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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