onsemi MC7912CD2TR4

Overview

MC7912CD2TR4 from onsemi is a fixed-output negative voltage regulator delivering −12 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 −14.5 V to −27 V with ≤120 mV load regulation (5–1000 mA) and ≤240 mV line regulation.

For engineers reviewing the MC7912CD2TR4 datasheet, pinout, applications, or equivalent options, key selection criteria include its D2PAK (Case 936) package with heatsink-connected Pin 2, −12 V ±5% output tolerance at 0°C to +125°C, 1.3 V dropout at 1.0 A, 61 dB ripple rejection at 120 Hz, and compatibility with dual-rail op-amp supplies and MECL system biasing.

Technical Context

The MC7912CD2TR4 implements a monolithic bipolar pass transistor architecture with integrated protection circuitry: thermal overload sensing triggers shutdown before junction temperature exceeds +150°C, while current limiting caps peak output at ~1.8 A and safe-area compensation dynamically reduces short-circuit current as V_IN−V_OUT increases. Its internal bias network draws 4.4 mA typical input current and exhibits −1.0 mV/°C average temperature coefficient over 0°C to +125°C.

Designed for fixed-voltage negative regulation, it operates without external capacitors in low-noise, low-current applications but mandates ≥0.33 µF input and ≥1.0 µF output bypassing for stability under high ripple or transient loads. Ripple rejection degrades above 1 kHz, falling to ~40 dB at 10 kHz, and noise voltage is specified at 75 µV_RMS (10 Hz–100 kHz).

Key Specifications

Pinout & Package

D2PAK (Case 936) package with exposed heatsink pad (Terminal 4) electrically connected to Pin 2 (Input). Requires PCB copper area for thermal management per Figure 12 in datasheet.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC7912CTG and LM337MDT-12/NOPB, the MC7912CD2TR4 offers optimal balance of SMT manufacturability, thermal performance in D2PAK, and zero-component simplicity for fixed −12 V applications - making it preferred for volume production of industrial analog subsystems.

Availability

MC7912CD2TR4 is available at Aetrix Electronics and suitable for industrial sensor signal conditioning, operational amplifier dual supplies, and legacy analog test equipment requiring stable component supply and long-term lifecycle support.

Supply support for MC7912CD2TR4 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 sensor solutions for automotive, industrial, and cloud infrastructure markets.

The MC7900 Series was designed as a complementary negative-voltage counterpart to the MC7800 positive regulators, targeting robust, low-cost linear regulation in industrial control, instrumentation, and legacy system upgrades where fixed output and high reliability are essential.

FAQ

What is the maximum input voltage rating for the MC7912CD2TR4?

The MC7912CD2TR4 has a maximum input voltage rating of −40 Vdc for devices rated at −24 V output, but for the −12 V version specifically, the datasheet specifies −35 Vdc absolute maximum input voltage under normal operating conditions. Exceeding this risks permanent damage due to junction breakdown or thermal runaway, even with heatsinking.

Does the MC7912CD2TR4 require input and output capacitors for stable operation?

Yes, the MC7912CD2TR4 requires a minimum 0.33 µF input capacitor and 1.0 µF output capacitor for stability, especially when located more than a few centimeters from the main power filter or driving capacitive loads. These values are specified in the Standard Application section of the datasheet and prevent oscillation and poor transient response.

How does the thermal shutdown feature operate in the MC7912CD2TR4?

The MC7912CD2TR4 incorporates a thermal shutdown circuit that disables the output pass transistor when the junction temperature reaches approximately +150°C. Recovery occurs automatically once the die cools below the hysteresis threshold (~140°C), enabling fault-tolerant operation in overload or inadequate heatsink scenarios without latch-up.

Can the MC7912CD2TR4 be used in parallel to increase output current?

No, the MC7912CD2TR4 is not designed for parallel operation. Its output voltage tolerance (±5%) and lack of current-sharing features mean paralleling units will cause unequal current distribution, thermal imbalance, and potential device failure. For higher current, use a single higher-rated regulator or an external pass transistor configuration as shown in Figure 9 of the datasheet.

What is the purpose of the heatsink-connected Pin 2 in the D2PAK package of the MC7912CD2TR4?

In the MC7912CD2TR4's D2PAK (Case 936) package, Pin 2 (Input) is internally bonded to the exposed metal tab (Terminal 4), which serves as the primary thermal path. This design requires the PCB copper pour connected to Pin 2 to act as both the input net and heatsink - ensuring efficient conduction of up to 15 W of power dissipation away from the silicon die.