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onsemi MC7908ACT
- Part No.:
- MC7908ACT
- Manufacturer:
- onsemi
- Package:
- TO-220-3
- Datasheet:
-
MC7908ACT.pdf
- Description:
- IC REG LINEAR -8V 1A TO220AB
- Quantity:
- Payment:
- Shipping:
Inventory:4,259
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Product details
Overview
MC7908ACT from onsemi is a fixed-output negative voltage regulator delivering −8.0 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 −10.5 V to −23 V with ≤80 mV load regulation (5–1000 mA) and ≥62 dB ripple rejection at 120 Hz.
For engineers reviewing the MC7908ACT datasheet, pinout, applications, or equivalent options, this device is selected for dual-rail op-amp supplies, MECL logic biasing, and legacy analog systems requiring robust −8 V regulation with minimal BOM count and proven thermal resilience under sustained load.
Technical Context
The MC7908ACT employs a monolithic bipolar pass transistor with integrated safe-area compensation, enabling reliable operation without external foldback circuitry. Its internal current-limit threshold and thermal shutdown activate at junction temperatures exceeding +150°C, while dropout voltage remains fixed at 1.3 V (IO = 1.0 A, TJ = +25°C).
Line regulation is specified across two input ranges (−10.5 to −25 Vdc and −11 to −17 Vdc), with worst-case variation ≤160 mV; load regulation holds ≤80 mV over 5 mA to 1.0 A at constant junction temperature, confirming stability in dynamic load environments.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | −8.0 V nominal, −7.6 V to −8.4 V over full operating range (VI = −10.5 V to −23 V, IO = 5–1000 mA, TJ = 0°C to +125°C) |
| Output Current | 1.0 A maximum continuous, internally limited; derates with ambient temperature and heatsinking per θJA = 65°C/W (TO-220) |
| Dropout Voltage | 1.3 V typical at 1.0 A - defines minimum input-to-output differential required for regulation |
| Ripple Rejection | 62 dB at 120 Hz - suppresses AC line noise on negative rail in linear power supplies |
| Thermal Shutdown | Activates at TJ = +150°C - protects against sustained overload or inadequate heatsinking |
| Package | TO-220 (Case 221AB), Pin 2 = Input, Pin 3 = Output, Pin 1 = Ground; heatsink surface electrically connected to Pin 2 |
Pinout & Package
MC7908ACT uses the standard TO-220 package (Case 221AB) with heatsink surface electrically tied to Pin 2 (Input). Mounting requires isolation if heatsink is grounded.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 | Ground | Reference node for both input and output; must be low-impedance common return path |
| Pin 2 | Input | Negative input supply connection; also serves as mechanical and thermal interface to heatsink |
| Pin 3 | Output | Regulated −8.0 V output; bypass capacitor (≥1.0 µF) recommended for transient stability |
Key Features
| Feature | Design Value |
|---|---|
| No external components required | Enables single-device −8 V supply implementation - reduces PCB area, BOM cost, and qualification effort |
| Internal thermal overload protection | Auto-shutdown at +150°C junction temperature - eliminates need for discrete thermal sensors or control logic |
| Safe-area compensated output transistor | Prevents second breakdown during output short-circuit or high VI–VO differential - enables reliable fault recovery |
| 2% output voltage tolerance (A-grade) | Guarantees −7.84 V to −8.16 V at +25°C - meets precision analog supply requirements without trimming |
Applications
| Operational Amplifier Dual Supply | MECL Logic Biasing |
|---|---|
Use Scenario: Powering ±15 V or ±12 V op-amp stages in test equipment and signal conditioning circuits. IC Role / Device Role / Timing Role: Provides stable, low-noise −8 V rail paired with MC7808 or similar positive regulator. Use Value: Eliminates need for external feedback or compensation; ripple rejection >62 dB ensures clean analog performance. | Use Scenario: Generating negative bias for ECL/MECL gate arrays and high-speed comparators. IC Role / Device Role / Timing Role: Supplies precise −8.0 V reference to emitter followers and differential pairs. Use Value: Tight 2% tolerance and low tempco (−1.0 mV/°C) maintain logic threshold stability across temperature. |
| Industrial Sensor Signal Conditioning | Legacy Analog Instrumentation |
Use Scenario: Powering isolated transducer interfaces and 4–20 mA loop receivers with negative supply rails. IC Role / Device Role / Timing Role: Delivers regulated −8 V to op-amps and ADC drivers in harsh industrial environments. Use Value: Internal short-circuit limiting and thermal shutdown ensure survivability during field wiring faults. | Use Scenario: Retrofitting aging benchtop instruments (e.g., oscilloscopes, spectrum analyzers) requiring −8 V rails. IC Role / Device Role / Timing Role: Direct replacement for obsolete discrete or hybrid −8 V regulators. Use Value: Pin-compatible drop-in upgrade with identical footprint and electrical behavior to legacy MC7908 variants. |
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 (±2% vs. ±2% for MC7908ACT); higher quiescent current (6.5 mA vs. 4.3 mA typical) | Suitable for general-purpose use where tighter initial accuracy is not critical | Select LM7908CT only if sourcing constraints require TI-supplied parts; verify thermal design due to higher IIB |
| MC7908CD2TR4G | D2PAK (SMD) package instead of TO-220; identical electrical specs and 2% tolerance; thermal resistance θJC = 5.0°C/W same, but θJA = 70°C/W | Preferred for automated assembly and space-constrained PCBs; requires thermal pad layout per Case 936 | Choose MC7908CD2TR4G when board real estate or reflow compatibility is prioritized over through-hole serviceability |
Compared with LM7908CT and MC7908CD2TR4G, the MC7908ACT offers optimal balance of through-hole serviceability, tight 2% output accuracy, lowest input bias current (4.3 mA typ), and proven thermal margin in TO-220 form factor - making it preferred for repairable industrial hardware and prototyping.
Availability
MC7908ACT is available at Aetrix Electronics and suitable for industrial sensor interfaces, dual-rail op-amp supplies, and legacy instrumentation requiring stable component supply, long-term lifecycle support, and traceable Pb-free sourcing.
Supply support for MC7908ACT 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, and sensing solutions for automotive, industrial, and cloud infrastructure markets.
The MC7900 Series - including MC7908ACT - was designed specifically for robust, no-compromise negative voltage regulation in mission-critical analog and mixed-signal systems where reliability under thermal stress and electrical fault conditions is non-negotiable.
FAQ
What is the guaranteed output voltage tolerance for MC7908ACT over temperature?
The MC7908ACT guarantees ±2% output voltage tolerance at TJ = +25°C, with total variation from −7.6 V to −8.4 V across the full operating range (0°C to +125°C junction temperature, 5–1000 mA load, −10.5 V to −23 V input). This is confirmed in the "MC7908C" electrical characteristics table on page 4 of the datasheet, which applies to all MC7908ACT units.
Can MC7908ACT be used without input or output capacitors?
MC7908ACT can operate without capacitors in low-current, low-noise, short-trace applications - but input bypass (≥0.33 µF) is strongly recommended if wiring exceeds 2 inches or output capacitance is large, and output capacitor (≥1.0 µF) improves transient response and stability per Figure 8 and Applications Information section on page 9 of the datasheet.
What is the maximum input voltage rating for MC7908ACT?
The absolute maximum input voltage for MC7908ACT is −35 Vdc for VO ≥ −5.0 V to −18 V devices (per Maximum Ratings table, page 2), and −40 Vdc for −24 V versions. Since MC7908ACT is an −8 V device, its VI(max) is −35 Vdc - exceeding this risks permanent damage even briefly.
Does MC7908ACT include reverse-polarity protection?
No, MC7908ACT does not include built-in reverse-polarity protection. External diodes (e.g., MBRS140) are required at the input or output if system-level polarity reversal is possible - as explicitly recommended in Figure 11 and Protection Diodes section on page 10 of the datasheet to prevent catastrophic failure.
How does thermal performance differ between TO-220 and D2PAK packages for MC7908ACT?
MC7908ACT in TO-220 (Case 221AB) has θJA = 65°C/W and θJC = 5.0°C/W; the D2PAK variant (MC7908CD2TR4G) shares identical θJC but has higher θJA = 70°C/W. Thus, TO-220 delivers better natural-convection cooling, while D2PAK requires optimized PCB copper area per Figure 12 to match thermal performance.
MC7908ACT 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):
- 1.3V @ 1A (Typ)
- Current - Output:
- 1A
- Current - Quiescent (Iq):
- -
- Current - Supply (Max):
- -
- PSRR:
- 62dB (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
MC7908ACT FAQ
1.How can I place an order for MC7908ACT through Aetrix?
Please submit a Request for Quotation (RFQ) for MC7908ACT 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 MC7908ACT reliable?
The price and inventory of MC7908ACT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC7908ACT is usually 5 days.
3.What payment methods are accepted for MC7908ACT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC7908ACT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC7908ACT?
MC7908ACT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC7908ACT 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 MC7908ACT?
For technical support, including MC7908ACT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC7908ACT requirements.
6.How does Aetrix verify that MC7908ACT is sourced from the original manufacturer or authorized distributors?
All MC7908ACT 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 MC7908ACT meets industry standards.
7.What is the process for return or replacement of MC7908ACT?
All MC7908ACT units undergo pre-shipment inspection (PSI). If there is an issue with MC7908ACT, 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 MC7908ACT part is unused and in its original packaging.
Return procedure for MC7908ACT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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