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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Voltage Regulators - Linear, Low Drop Out (LDO) Regulators

onsemi MC7908CT

Name: MC7908CT
Brand: onsemi
SKU: MC7908CT
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MC7908CT

Manufacturer:: onsemi

Category:: Voltage Regulators - Linear, Low Drop Out (LDO) Regulators

Package:: TO-220-3

Datasheet:: MC7908CT.pdf

Description:: IC REG LINEAR -8V 1A TO220AB

Quantity:: RFQ Add To RFQ list

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Inventory:1,659

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Product details

Overview

MC7908CT from onsemi is a fixed-output negative linear 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).

For engineers reviewing the MC7908CT datasheet, pinout, applications, or equivalent options, key selection considerations include its −8 V fixed output, TO-220 package with heatsink-compatible Pin 2, dropout voltage of 1.3 V at 1 A, ripple rejection of 62 dB at 120 Hz, and compatibility with dual-rail op-amp supplies requiring matched negative rails.

Technical Context

The MC7908CT implements a monolithic bipolar pass transistor with integrated protection circuitry: thermal overload sensing triggers shutdown at +150°C junction temperature, while current limiting caps peak output at ~1.8 A under short-circuit conditions. Safe-area compensation dynamically reduces short-circuit current as V_IN−V_OUT increases, preventing second breakdown.

Its internal bias network draws 4.3–8.0 mA input current and exhibits −1.0 mV/°C average temperature coefficient over 0°C to +125°C. Output noise is 52 µV_RMS (10 Hz–100 kHz), and line regulation is specified at 12 mV (for −10.5 V ≤ V_IN ≤ −25 V, I_O = 100 mA) and 50 mV (same range, I_O = 500 mA).

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	−8.0 V nominal, −7.7 V to −8.3 V at +25°C; ensures precise negative rail generation for analog circuits.
Maximum Output Current	1.0 A continuous with adequate heatsinking; supports medium-power analog subsystems.
Dropout Voltage	1.3 V at 1.0 A and +25°C; defines minimum input-to-output differential needed for regulation.
Ripple Rejection	62 dB at 120 Hz and 20 mA load; suppresses AC ripple from rectified supplies in sensitive analog stages.
Thermal Resistance (Junction-to-Case)	5.0 °C/W; enables predictable thermal design when mounted to heatsink via Pin 2.
Operating Junction Temperature	0°C to +125°C; validated for industrial ambient environments without derating.
Output Noise	52 µV_RMS (10 Hz–100 kHz); low enough for precision op-amp biasing and sensor signal chains.

Pinout & Package

MC7908CT is supplied in TO-220 package (Case 221AB), with heatsink surface electrically connected to Pin 2. The package is Pb-free (G-suffix compatible) and rated for 15 W maximum power dissipation with infinite heatsink.

Pin/Terminal	Circuit Role	Design Meaning
Pin 1	Ground	Reference node for output voltage; must be tied to system common ground.
Pin 2	Input	Negative input terminal; connects to unregulated negative supply; heatsink mounting surface.
Pin 3	Output	Regulated −8.0 V output; requires 1.0 µF output capacitor for stability per datasheet recommendation.

Key Features

Feature	Design Value
No external components required	Enables drop-in replacement in legacy designs; eliminates BOM cost and layout area for feedback resistors or compensation networks.
Internal thermal overload protection	Automatically disables output above +150°C junction temperature, preventing permanent damage during transient overloads.
Internal short-circuit current limiting	Clamps output current to ~1.8 A under hard short, allowing safe fault recovery without external fusing.
Safe-area compensated pass transistor	Prevents secondary breakdown by reducing short-circuit current as V_IN−V_OUT rises - critical for high-differential-voltage operation.
2% output voltage tolerance option	MC7908CT offers ±4% tolerance; tighter 2% variants (e.g., MC7908ACTG) exist for precision applications.

Applications

Operational Amplifier Dual Supply	Industrial Sensor Signal Conditioning
Use Scenario: Powering ±15 V op-amp stages in data acquisition systems where matched positive/negative rails are essential. IC Role / Device Role / Timing Role: Provides stable −8 V rail paired with MC7808 for asymmetric dual supplies (e.g., ±8 V) in low-noise instrumentation. Use Value: 52 µV RMS output noise and 62 dB ripple rejection preserve SNR in amplifier front-ends without additional filtering.	Use Scenario: Biasing precision analog sensors (e.g., strain gauges, RTDs) requiring clean negative reference voltage. IC Role / Device Role / Timing Role: Delivers regulated −8 V to sensor excitation circuits and instrumentation amplifier negative supplies. Use Value: −1.0 mV/°C tempco ensures minimal drift in sensor bridge bias over 0–125°C operating range.
Legacy Industrial Control Logic	MECL-Compatible Negative Rail
Use Scenario: Replacing aging regulators in PLC I/O modules needing robust −8 V for level-shifting and interface ICs. IC Role / Device Role / Timing Role: Supplies −8 V to TTL-compatible interface logic and isolated gate drivers in motor control cabinets. Use Value: Internal short-circuit and thermal protection eliminate need for external fault management in harsh cabinet environments.	Use Scenario: Generating MECL-compliant negative supply rails in high-speed digital test equipment. IC Role / Device Role / Timing Role: Provides −8 V rail for ECL gate arrays and clock distribution ICs requiring tightly regulated negative bias. Use Value: 1.3 V dropout enables efficient operation from −9.3 V input, minimizing power loss in multi-rail backplanes.

Operational Amplifier Dual Supply

Industrial Sensor Signal Conditioning

Use Scenario: Powering ±15 V op-amp stages in data acquisition systems where matched positive/negative rails are essential.

IC Role / Device Role / Timing Role: Provides stable −8 V rail paired with MC7808 for asymmetric dual supplies (e.g., ±8 V) in low-noise instrumentation.

Use Value: 52 µV RMS output noise and 62 dB ripple rejection preserve SNR in amplifier front-ends without additional filtering.

Use Scenario: Biasing precision analog sensors (e.g., strain gauges, RTDs) requiring clean negative reference voltage.

IC Role / Device Role / Timing Role: Delivers regulated −8 V to sensor excitation circuits and instrumentation amplifier negative supplies.

Use Value: −1.0 mV/°C tempco ensures minimal drift in sensor bridge bias over 0–125°C operating range.

Legacy Industrial Control Logic

MECL-Compatible Negative Rail

Use Scenario: Replacing aging regulators in PLC I/O modules needing robust −8 V for level-shifting and interface ICs.

IC Role / Device Role / Timing Role: Supplies −8 V to TTL-compatible interface logic and isolated gate drivers in motor control cabinets.

Use Value: Internal short-circuit and thermal protection eliminate need for external fault management in harsh cabinet environments.

Use Scenario: Generating MECL-compliant negative supply rails in high-speed digital test equipment.

IC Role / Device Role / Timing Role: Provides −8 V rail for ECL gate arrays and clock distribution ICs requiring tightly regulated negative bias.

Use Value: 1.3 V dropout enables efficient operation from −9.3 V input, minimizing power loss in multi-rail backplanes.

Equivalent & Alternatives

The following parts are listed as comparable options for similar negative voltage regulation applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
LM337T	Adjustable output (−1.25 V to −37 V); requires two external resistors; higher quiescent current (5.5 mA typ).	Used where programmable or non-standard negative voltages (e.g., −7.5 V, −10 V) are needed.	Select LM337T only if adjustable output is required; MC7908CT saves BOM cost and layout space for fixed −8 V.
MC7908CD2TR4G	D2PAK (TO-263) package; identical electrical specs; lower thermal resistance to PCB (JA ≈ 70°C/W vs. 65°C/W for TO-220).	Preferred for automated SMT assembly and higher power density layouts where heatsink mounting is impractical.	Choose MC7908CD2TR4G for surface-mount production; MC7908CT remains optimal for through-hole prototyping and heatsink-integrated designs.

Compared with LM337T and MC7908CD2TR4G, the MC7908CT delivers fixed −8 V with zero external components in a through-hole TO-220 package optimized for mechanical heatsinking - making it ideal for industrial repair, legacy board replacement, and thermally demanding linear regulation tasks.

Availability

MC7908CT is available at Aetrix Electronics and suitable for industrial control systems, analog instrumentation, and legacy embedded power supplies requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for MC7908CT 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 sensor solutions for automotive, industrial, and cloud infrastructure markets.

The MC7900 Series was designed specifically to complement the MC7800 positive regulators, providing rugged, fixed-output negative voltage regulation for dual-rail analog systems and legacy industrial electronics.

FAQ

What is the output voltage tolerance of the MC7908CT?

The MC7908CT has a guaranteed output voltage range of −7.6 V to −8.4 V under specified conditions (−10.5 V ≤ V_IN ≤ −23 V, 5 mA ≤ I_O ≤ 1.0 A, P ≤ 15 W, 0°C ≤ T_J ≤ +125°C). This corresponds to ±5% tolerance, consistent with the "C" grade designation in the MC7900 series nomenclature.

Can the MC7908CT be used without input and output capacitors?

The MC7908CT can operate without external capacitors in low-current, low-noise applications with short interconnects. However, the datasheet recommends a 0.33 µF input capacitor (low-ESR tantalum/mylar) when connected via long wires to the filter, and a 1.0 µF output capacitor for stability and improved transient response - both are strongly advised for production use.

What is the maximum input voltage the MC7908CT can withstand?

The MC7908CT has an absolute maximum input voltage rating of −35 V for output voltages between −5.0 V and −18 V. Since the MC7908CT is rated for −8 V output, its maximum allowable input voltage is −35 V DC. Exceeding this risks permanent device failure.

How does thermal shutdown work in the MC7908CT?

The MC7908CT incorporates a junction temperature sensor that disables the pass transistor when T_J reaches +150°C. Once the die cools below the hysteresis threshold (~135°C), regulation resumes automatically. This protects against sustained overloads, poor heatsinking, or ambient temperature excursions without requiring external circuitry.

Is the MC7908CT pin-compatible with other MC7900-series regulators?

Yes - all MC7900-series regulators (e.g., MC7905CT, MC7912CT, MC7915CT) share identical TO-220 pinout (Pin 1: Ground, Pin 2: Input, Pin 3: Output) and package footprint. This allows direct substitution across output voltages (−5 V to −24 V) in existing layouts, provided input voltage and thermal design accommodate the new V_OUT and dropout requirements.

MC7908CT 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

MC7908CT FAQ

1.How can I place an order for MC7908CT through Aetrix?

Please submit a Request for Quotation (RFQ) for MC7908CT 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 MC7908CT reliable?

The price and inventory of MC7908CT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC7908CT is usually 5 days.

3.What payment methods are accepted for MC7908CT?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC7908CT transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MC7908CT?

MC7908CT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MC7908CT 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 MC7908CT?

For technical support, including MC7908CT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC7908CT requirements.

6.How does Aetrix verify that MC7908CT is sourced from the original manufacturer or authorized distributors?

All MC7908CT 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 MC7908CT meets industry standards.

7.What is the process for return or replacement of MC7908CT?

All MC7908CT units undergo pre-shipment inspection (PSI). If there is an issue with MC7908CT, 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 MC7908CT part is unused and in its original packaging.

Return procedure for MC7908CT:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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