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onsemi MC79M08CTG
- Part No.:
- MC79M08CTG
- Manufacturer:
- onsemi
- Package:
- TO-220-3
- Datasheet:
-
MC79M08CTG.pdf
- Description:
- IC REG LINEAR -8V 500MA TO220AB
- Quantity:
- Payment:
- Shipping:
Inventory:826
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Product details
Overview
MC79M08CTG from onsemi is a fixed-output, 500 mA negative voltage linear regulator delivering −8.0 V with ±4.0% tolerance over 0 °C to +125 °C, featuring internal thermal shutdown, short-circuit current limiting, and safe-area compensation for rugged operation in industrial power rails and analog subsystems.
For engineers reviewing the MC79M08CTG datasheet, pinout, applications, or equivalent options, this page provides verified electrical specs, TO-220-3 package details, thermal performance data, protection diode guidance, and validated alternative parts for legacy design continuity and supply chain resilience.
Technical Context
The MC79M08CTG implements a monolithic PNP pass transistor architecture with integrated bandgap reference, error amplifier, and protection circuitry. It requires no external components for basic regulation but benefits from input (0.33 µF) and output (1.0 µF) capacitors for stability and transient response.
Its dropout voltage is 1.1 V at 500 mA, enabling operation with input as low as −9.1 V while maintaining −8.0 V output. Ripple rejection is 54–63 dB at 120 Hz, and output noise is 60 µVRMS (10 Hz–100 kHz), supporting noise-sensitive analog circuits.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | −8.0 V ±4.0% at TJ = 25 °C; ensures stable biasing for op-amps, sensors, and dual-supply analog stages |
| Output Current | 500 mA max; supports moderate-power analog loads without external boost transistors |
| Dropout Voltage | 1.1 V at 500 mA; enables use with minimal input-to-output differential, reducing power loss and heat |
| Ripple Rejection | 54 dB min at 120 Hz; suppresses AC line ripple in unregulated DC supplies feeding sensitive circuitry |
| Thermal Resistance θJA | 65 °C/W (TO-220-3, free air); defines heatsink requirement for continuous 500 mA operation at TA = 50 °C |
| Operating Temperature | 0 °C to +125 °C junction; qualified for industrial-grade embedded systems and motor control interfaces |
| Protection Features | Internal thermal shutdown, short-circuit current limiting, and safe-area compensation; eliminates need for discrete protection circuitry |
Pinout & Package
MC79M08CTG uses the TO-220-3 (Case 221AB) package - a through-hole, single-gauge thermally enhanced plastic package with metal tab for heatsinking. Pin 1 is Ground, Pin 2 is Input (VI), Pin 3 is Output (VO).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Ground | Common reference node; must be connected to system ground plane with low-inductance path for stability |
| 2 | Input | Negative input terminal; accepts −9.1 V min to −35 V max; requires 0.33 µF ceramic capacitor if >10 cm from filter cap |
| 3 | Output | Negative regulated output; delivers −8.0 V to load; 1.0 µF output capacitor improves transient response and PSRR |
Key Features
| Feature | Design Value |
|---|---|
| No external components required | Self-contained regulation with built-in reference, error amp, and pass element - reduces BOM count and layout area |
| Internal thermal overload protection | Shuts down automatically above TJ ≈ 150 °C; prevents catastrophic failure during sustained overload or poor heatsinking |
| Safe-area compensated output transistor | Prevents second breakdown under high-voltage/low-current stress, enabling reliable operation across line and load transients |
| Pb-free TO-220-3 package | RoHS-compliant lead finish (G suffix); compatible with standard wave-solder and reflow profiles per J-STD-020 |
| Reverse-polarity and overvoltage protection ready | Supports external MBRS140 diodes for reverse-input and output-capacitor discharge protection in fault-prone environments |
Applications
| Industrial Power Supply | Analog Sensor Interface |
|---|---|
Use Scenario: Providing clean −8 V rail for op-amp biasing and signal conditioning in PLC I/O modules. IC Role / Device Role / Timing Role: Negative voltage regulator supplying stable reference for dual-supply instrumentation amplifiers. Use Value: 60 µV RMS output noise and 63 dB ripple rejection preserve SNR in 16-bit ADC front-ends. |
Use Scenario: Biasing precision temperature sensors and bridge-based pressure transducers requiring symmetric supplies. IC Role / Device Role / Timing Role: Fixed negative rail generator ensuring matched positive/negative headroom for ratiometric sensor excitation. Use Value: ±4.0% output tolerance and 0.4 mV/°C tempco maintain calibration accuracy across 0–125 °C industrial range. |
| Motor Control Feedback | Legacy Communication Interface |
Use Scenario: Powering isolated gate drivers and current-sense amplifiers in H-bridge motor controllers. IC Role / Device Role / Timing Role: Local negative supply for level-shifting and biasing of isolated analog feedback paths. Use Value: 500 mA output current supports multiple downstream LDOs or op-amps without derating at 70 °C ambient. |
Use Scenario: Generating −8 V for RS-232 transceivers and legacy serial interface ICs in industrial gateways. IC Role / Device Role / Timing Role: Dedicated negative rail source replacing obsolete charge-pump solutions in space-constrained designs. Use Value: TO-220-3 mechanical compatibility allows drop-in replacement of MC79M08CT in existing PCB footprints. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar negative voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM7908CT | Same −8 V output, but wider output tolerance (±5%), higher dropout (2.0 V), and lower ripple rejection (45 dB) | Suitable for cost-sensitive, non-critical analog rails where tighter regulation and noise performance are not required | Select LM7908CT only when thermal margin exceeds 15 °C and ripple below 100 mV is acceptable |
| MC79M08CDTRKG | DPAK-3 surface-mount variant; identical electrical specs but different thermal resistance (θJA = 92 °C/W vs. 65 °C/W) | Used in automated SMT production; requires PCB copper area optimization for equivalent thermal performance | Choose MC79M08CDTRKG for new SMT designs; avoid direct substitution in TO-220 layouts without thermal redesign |
Compared with LM7908CT, MC79M08CTG offers tighter output tolerance, lower dropout, and superior ripple rejection-critical for precision analog systems. Versus MC79M08CDTRKG, it delivers better thermal performance in free-air conditions but requires through-hole assembly and heatsinking hardware.
Availability
MC79M08CTG is available at Aetrix Electronics and suitable for industrial power supplies, analog sensor interfaces, motor control feedback circuits, and legacy communication interfaces requiring stable component supply and long-term manufacturability.
Supply support for MC79M08CTG 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 technologies for automotive, industrial, and cloud infrastructure markets.
The MC79M00 series was designed specifically as robust, drop-in complementary regulators to the MC78M00 positive series-targeting industrial control, instrumentation, and legacy system upgrades where reliability and long-lifecycle support are essential.
FAQ
What is the maximum input voltage rating for MC79M08CTG?
The MC79M08CTG has a maximum input voltage rating of −35 Vdc, as specified in the Absolute Maximum Ratings table. Exceeding this voltage risks permanent damage. For reliable operation, the input should remain ≥1.1 V more negative than the output (i.e., ≤ −9.1 V) under all load and ripple conditions, per the standard application guidelines.
Does MC79M08CTG require external capacitors for stable operation?
Yes, MC79M08CTG requires an input capacitor (0.33 µF ceramic) if located more than a few centimeters from the main power supply filter, and an output capacitor (1.0 µF) to ensure stability and improve transient response. These values are explicitly recommended in the datasheet's Standard Application section and are critical for achieving specified ripple rejection and load regulation.
Is MC79M08CTG pin-compatible with older non-Pb-free versions like MC79M08CT?
Yes, MC79M08CTG is mechanically and electrically pin-compatible with MC79M08CT. Both use the TO-220-3 (Case 221AB) package with identical pinout (Pin 1: Ground, Pin 2: Input, Pin 3: Output) and share identical electrical specifications. The "G" suffix denotes Pb-free finish only-no functional or footprint changes.
What thermal considerations apply when using MC79M08CTG at full 500 mA load?
At 500 mA and TA = 50 °C, MC79M08CTG dissipates up to 5.5 W (VI = −13.5 V → VO = −8.0 V). With θJA = 65 °C/W, junction temperature rises ~360 °C above ambient-exceeding its 150 °C limit. A heatsink reducing θJA to ≤20 °C/W is mandatory; refer to Figure 1 in the datasheet for copper pad length guidance.
Can MC79M08CTG be used in reverse-polarity protection configurations?
MC79M08CTG itself does not provide reverse-polarity protection, but the datasheet recommends adding an external MBRS140 Schottky diode (D1) between input and ground to protect against output polarity reversal during startup or fault conditions. This configuration is shown in Figure 2 and is required for robust deployment in field-replaceable or battery-backed systems.
MC79M08CTG 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:
- 0°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-220
MC79M08CTG FAQ
1.How can I place an order for MC79M08CTG through Aetrix?
Please submit a Request for Quotation (RFQ) for MC79M08CTG 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 MC79M08CTG reliable?
The price and inventory of MC79M08CTG are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC79M08CTG is usually 5 days.
3.What payment methods are accepted for MC79M08CTG?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC79M08CTG transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC79M08CTG?
MC79M08CTG orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC79M08CTG 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 MC79M08CTG?
For technical support, including MC79M08CTG datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC79M08CTG requirements.
6.How does Aetrix verify that MC79M08CTG is sourced from the original manufacturer or authorized distributors?
All MC79M08CTG 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 MC79M08CTG meets industry standards.
7.What is the process for return or replacement of MC79M08CTG?
All MC79M08CTG units undergo pre-shipment inspection (PSI). If there is an issue with MC79M08CTG, 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 MC79M08CTG part is unused and in its original packaging.
Return procedure for MC79M08CTG:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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