onsemi MC79M05BDT

Overview

MC79M05BDT from onsemi is a fixed-output, 500 mA negative voltage linear regulator in DPAK-3 (DT) package, delivering −5.0 V ±4% output with dropout voltage of 1.1 V at 500 mA and thermal shutdown protection. It operates across −40 °C to +125 °C and is used in industrial power supplies, analog sensor biasing, and legacy RS-232 interface rails requiring stable negative supply.

For engineers reviewing the MC79M05BDT datasheet, pinout, applications, or equivalent options, key selection considerations include its −5.0 V output tolerance, DPAK thermal resistance (θ_JA = 92 °C/W), input voltage range (−35 V max), ripple rejection (54–66 dB at 120 Hz), and safe-area compensated output transistor for robust short-circuit handling.

Technical Context

The MC79M05BDT implements a monolithic PNP pass transistor with internal current limiting, thermal shutdown, and safe-area compensation-enabling reliable operation under overload and transient conditions without external components. Its architecture supports fixed −5.0 V regulation with no need for feedback resistors or compensation networks.

Designed for negative rail generation, it requires a minimum input-to-output differential of 1.1 V (typical) and maintains output stability with ≥0.33 μF input and ≥1.0 μF output capacitance. Input bias current is 4.3–8.0 mA, and output noise is 40 μV_RMS (10 Hz–100 kHz).

Key Specifications

Pinout & Package

DPAK-3 (Case 369C) surface-mount package with exposed thermal pad; footprint dimensions 6.10 × 6.54 × 2.28 mm, lead pitch 2.29 mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM79M05CDT and MC79M05CDTRKG, the MC79M05BDT offers superior low-temperature operation, tighter output tolerance, and lower dropout-making it the preferred choice for demanding industrial and automotive-adjacent applications where reliability across extreme ambient conditions is mandatory.

Availability

MC79M05BDT is available at Aetrix Electronics and suitable for industrial power supplies, analog sensor biasing, and legacy RS-232 interface rails requiring stable component supply and long-term design continuity.

Supply support for MC79M05BDT 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 industrial, automotive, and cloud infrastructure markets.

The MC79M05BDT belongs to the MC79M00 series of negative voltage regulators-designed specifically to complement the MC78M00 positive regulators and provide robust, drop-in replacements for legacy 79xx family designs in space-constrained surface-mount applications.

FAQ

What is the maximum input voltage rating for the MC79M05BDT?

The MC79M05BDT has an absolute maximum input voltage rating of −35 V DC. Exceeding this value risks permanent device damage. For reliable operation, the input should remain at least 1.1 V more negative than the output (i.e., ≤ −6.1 V) under all load and ripple conditions, per the datasheet's recommended margin.

Does the MC79M05BDT require external capacitors, and if so, what values are recommended?

Yes-the MC79M05BDT requires both input and output capacitors for stability and transient performance. A minimum 0.33 μF ceramic or tantalum capacitor is recommended at the input pin, placed as close as possible to the device. A minimum 1.0 μF capacitor (aluminum electrolytic or tantalum) is required at the output. Larger values improve ripple rejection and load transient response.

Is the MC79M05BDT pin-compatible with older TO-220 versions like MC79M05BT?

No-the MC79M05BDT uses the DPAK-3 (Case 369C) surface-mount package with pinout Ground–Input–Output, while the TO-220 MC79M05BT uses a through-hole package with pinout Output–Ground–Input. The pin assignments and physical footprints are incompatible; PCB redesign is required for migration.

What thermal performance can be expected from the MC79M05BDT in a standard 2 oz. copper PCB layout?

In a standard PCB layout with 2 oz. copper and a 10 mm × 10 mm thermal pad connected to internal ground planes, the MC79M05BDT achieves θ_JA ≈ 45–55 °C/W-significantly better than the 92 °C/W free-air rating. At 500 mA and 25 °C ambient, junction temperature rise would be ~25–28 °C, well within the −40 °C to +150 °C operating range.

How does the MC79M05BDT handle short-circuit conditions?

The MC79M05BDT incorporates internal short-circuit current limiting that clamps output current to approximately 600 mA (typical) during a hard short. Combined with thermal shutdown (triggering at ~150 °C), this provides dual-layer protection. After fault removal, the device auto-recovers without latch-up or manual reset.