onsemi MC7905ACTG

Overview

MC7905ACTG from onsemi is a fixed-output negative voltage regulator delivering −5.0 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 operates with input voltages down to −35 V, maintains ±2% output tolerance over 0°C to +125°C, and achieves 70 dB ripple rejection at 120 Hz - ideal for dual-rail op-amp biasing and MECL logic systems.

For engineers reviewing the MC7905ACTG datasheet, pinout, applications, or equivalent options, key selection criteria include dropout voltage (1.3 V at 1.0 A), junction-to-case thermal resistance (5.0°C/W), output noise (40 µV_RMS, 10 Hz–100 kHz), and TO-220 package compatibility with standard heatsinking solutions.

Technical Context

The MC7905ACTG implements a monolithic PNP pass transistor architecture with integrated protection circuitry: current-limiting folds back under overload, thermal shutdown activates at +150°C junction temperature, and safe-area compensation dynamically reduces short-circuit current as V_CE increases. Its internal bias network draws only 4.4 mA typical input current and exhibits −1.0 mV/°C average temperature coefficient.

Designed for fixed-voltage regulation without external components, it requires no feedback resistors and supports stable operation with ≥0.33 µF input and ≥1.0 µF output capacitors. Ripple rejection degrades above 1 kHz but remains ≥40 dB up to 10 kHz, making it suitable for post-filter regulation in switched-mode supply outputs.

Key Specifications

Pinout & Package

MC7905ACTG uses the TO-220 package (Case 221AB), with heatsink surface electrically connected to Pin 2 (Input). The device has three terminals: Pin 1 (Ground), Pin 2 (Input), Pin 3 (Output).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC7905CTG and LM7905CT, the MC7905ACTG delivers tighter output regulation (±2%), superior ripple suppression (70 dB), and lower dropout (1.3 V), making it optimal for noise-sensitive analog systems where thermal margin and long-term stability are critical.

Availability

MC7905ACTG is available at Aetrix Electronics and suitable for industrial sensor interfaces, dual-rail op-amp supplies, and MECL logic systems requiring stable component supply with full RoHS compliance and traceable lot control.

Supply support for MC7905ACTG 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 was designed as a robust, drop-in complement to the MC7800 positive regulator family - targeting high-reliability linear regulation in harsh environments where thermal resilience and fault tolerance are essential.

FAQ

What is the maximum input voltage rating for MC7905ACTG?

The MC7905ACTG supports a maximum input voltage of −35 Vdc for output voltages between −5.0 V and −18 V. Exceeding this rating risks permanent damage, even briefly. For −24 V output variants, the absolute maximum is −40 Vdc - always verify against the specific variant's datasheet section "Maximum Ratings" before design-in.

Does MC7905ACTG require input and output capacitors?

Yes - MC7905ACTG requires a minimum 0.33 µF input capacitor (tantalum or low-ESR ceramic) and a 1.0 µF output capacitor for stability, especially with long trace lengths or large load capacitance. Omitting these can cause oscillation or poor transient response. The datasheet specifies capacitor ESR < 0.7 Ω for reliable operation.

Can MC7905ACTG be used as a constant current source?

Yes - MC7905ACTG can configure as a constant current source by connecting a resistor between output and ground, leveraging its precise −5.0 V reference. With R = 25 Ω, it delivers ~200 mA (IO ≈ 5.0 V / R + 4.3 mA quiescent current). This topology appears in Figure 8 of the official datasheet and is validated for low-noise biasing applications.

What is the thermal resistance and heatsinking requirement for MC7905ACTG?

MC7905ACTG has θ_JC = 5.0°C/W and θ_JA = 65°C/W (TO-220, no heatsink). To sustain 1.0 A at +25°C ambient, junction temperature must stay ≤ +150°C. With 10 V differential (e.g., −15 V in, −5 V out), power dissipation is 10 W - requiring a heatsink with θ_SA ≤ 9.5°C/W to keep T_J ≤ 145°C.

Is MC7905ACTG pin-compatible with older MC7905C variants?

Yes - MC7905ACTG uses the identical TO-220 package (Case 221AB) and pinout (Pin 1: Ground, Pin 2: Input, Pin 3: Output) as MC7905C and MC7905CTG. The only functional difference is tighter ±2% output tolerance versus ±4%, enabling direct replacement in existing designs without layout changes.