onsemi MC7809ECDTXM

Overview

MC7809ECDTXM from ON Semiconductor (formerly Fairchild) is a fixed-output, 3-terminal positive voltage regulator delivering 9 V at up to 1 A output current in TO-252 (D-PAK) surface-mount package. It integrates thermal overload protection, short-circuit protection, and safe operating area (SOA) protection for robust operation in industrial power supplies and embedded systems requiring stable +9 V rail generation.

For engineers reviewing the MC7809ECDTXM datasheet, pinout, applications, or equivalent options, key selection considerations include dropout voltage (2 V @ 1 A), line regulation (≤10 mV over VI = 11–30 V), load regulation (≤11 mV over IO = 5 mA–1.5 A), output voltage tolerance (±4%), and operating temperature range (–40°C to +125°C).

Technical Context

The MC7809ECDTXM implements a monolithic series pass regulator architecture with internal error amplifier, reference voltage, current limiting, thermal shutdown, and SOA protection circuitry. Its design centers on fixed-voltage regulation without external feedback components, relying on precision bandgap reference and trimmed resistor networks to maintain output stability across temperature and load.

It operates as a linear regulator requiring minimum input-to-output differential of 2 V under full load, supports capacitor-stabilized operation with standard 0.33 µF input and 0.1 µF output ceramic capacitors, and exhibits typical ripple rejection of 65 dB at 120 Hz - enabling use in noise-sensitive analog subsystems when paired with adequate input filtering.

Key Specifications

Pinout & Package

MC7809ECDTXM is housed in a TO-252-3 (D-PAK) surface-mount package with exposed thermal pad for enhanced heat dissipation. The package meets JEDEC MO-263 standards and is optimized for automated assembly and thermal performance in high-density PCB layouts.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar fixed-output linear regulator applications.

Compared with LM7809CDT/NOPB and UA7809CKCS, the MC7809ECDTXM offers optimal balance of SMT compatibility, thermal robustness (150°C max TJ), and cost-effective ±4% tolerance - making it preferred for new industrial and automotive PCB designs where TO-252 footprint and reliability under thermal stress are prioritized.

Availability

MC7809ECDTXM is available at Aetrix Electronics and suitable for industrial power supplies, automotive body electronics, and embedded system power management requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for MC7809ECDTXM 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

ON Semiconductor (formerly Fairchild Semiconductor) is a global supplier of energy-efficient semiconductor solutions, specializing in power management, analog, and discrete devices for automotive, industrial, and consumer markets.

The MC78XXE series - including MC7809ECDTXM - was designed specifically for cost-sensitive, high-reliability linear regulation in space-constrained applications where integrated protection and TO-252 thermal performance are essential.

FAQ

What is the maximum input voltage rating for MC7809ECDTXM?

The absolute maximum input voltage for MC7809ECDTXM is 35 V, as specified in the Absolute Maximum Ratings table. Operation above this level risks permanent device damage. For reliable continuous operation, input voltage should remain within 11 V to 30 V - ensuring sufficient headroom above the 9 V output while staying well below the 35 V stress limit. This range accommodates typical 12 V and 24 V system rails with ripple and transients.

Does MC7809ECDTXM require external capacitors, and if so, what values are recommended?

Yes, MC7809ECDTXM requires external capacitors for stability and transient response. A 0.33 µF ceramic capacitor is recommended at the input pin (Pin 1), placed as close as possible to minimize lead inductance. A 0.1 µF ceramic capacitor is required at the output pin (Pin 3) to suppress high-frequency oscillations and improve load step response. These values are validated in the official MC78XXE datasheet test circuits and are critical for preventing instability under varying load conditions.

Can MC7809ECDTXM be used in automotive applications, and what qualifications does it meet?

MC7809ECDTXM is rated for operation from –40°C to +125°C junction temperature and features built-in thermal shutdown, short-circuit protection, and SOA protection - making it suitable for non-safety-critical automotive body electronics such as lighting controls and comfort modules. While it is not AEC-Q100 qualified, its robust protection architecture and wide temperature range align with many Tier-2 automotive subsystem requirements where qualification is not mandated but reliability is essential.

How does the dropout voltage of MC7809ECDTXM affect system design?

The dropout voltage of MC7809ECDTXM is 2 V at 1 A and +25°C, meaning the input voltage must remain at least 2 V above 9 V (i.e., ≥11 V) under full load to maintain regulation. This directly impacts upstream power stage selection - for example, requiring a 12 V nominal supply with sufficient headroom during brownout or ripple valleys. Designers must verify worst-case dropout across temperature and load, as it increases slightly at higher junction temperatures.

Is MC7809ECDTXM pin-compatible with other MC78XXE variants like MC7805ECDTXM or MC7812ECDTXM?

Yes, all MC78XXE series regulators - including MC7809ECDTXM, MC7805ECDTXM, and MC7812ECDTXM - share identical TO-252-3 (D-PAK) pinout: Pin 1 = Input, Pin 2 = GND, Pin 3 = Output. This allows direct substitution in the same footprint when changing output voltage requirements, provided input voltage and thermal design accommodate the new variant's dropout and power dissipation characteristics.