My Inquiry
My Account
onsemi MC78M18CDT
- Part No.:
- MC78M18CDT
- Manufacturer:
- onsemi
- Package:
- TO-252-3, DPAK (2 Leads + Tab), SC-63
- Datasheet:
-
MC78M18CDT.pdf
- Description:
- IC REG LINEAR 18V 500MA DPAK
- Quantity:
- Payment:
- Shipping:
Inventory:4,059
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
MC78M18CDT from onsemi is a 500 mA, fixed +18 V positive voltage regulator in DPAK-3 (TO-252) package, featuring internal thermal shutdown, short-circuit current limiting, and safe-area compensation for rugged local on-card regulation. It delivers stable output under load currents up to 500 mA with ≤18.9 V variation across input range 21–33 V and operating junction temperature 0°C to +125°C.
For engineers reviewing the MC78M18CDT datasheet, pinout, applications, or equivalent options, this device is selected for industrial power supplies, embedded control rails, and automotive subsystems requiring reliable fixed-voltage regulation without external components.
Technical Context
The MC78M18CDT implements a monolithic three-terminal linear regulator architecture with an internal pass transistor thermally coupled to the die. Its safe-area compensation dynamically reduces short-circuit current as input-output differential increases, preventing second breakdown during fault conditions.
It operates with no external capacitors required for stability but recommends ≥0.33 µF input bypass for long trace or high-capacitance load scenarios. Dropout voltage remains fixed at 2.0 V typical across temperature and load, enabling predictable minimum input headroom design.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | +18 V nominal, ±0.7 V tolerance (17.3–18.7 V at 25°C), ensuring tight rail accuracy for analog and digital logic interfaces |
| Max Output Current | 500 mA continuous, supporting mid-power microcontrollers, sensors, and interface ICs without heatsinking in low-ambient environments |
| Input Voltage Range | 21–33 V DC, defining minimum startup headroom and maximum safe operating input for 24 V systems |
| Dropout Voltage | 2.0 V typical at 25°C, setting minimum VI = 20 V for full-load regulation - critical for battery-backed or unregulated supply designs |
| Ripple Rejection | 53 dB at 120 Hz (IO = 100 mA), suppressing line-frequency noise in AC/DC-derived supplies |
| Thermal Shutdown | Active at TJ ≥ +150°C, protecting against sustained overload or inadequate PCB copper area |
| Short-Circuit Limit | 350 mA typical at VI = 35 V, providing self-limiting fault behavior without external current sensing |
Pinout & Package
DPAK-3 (TO-252) package with exposed thermal pad (pin 2 connected to GND), optimized for surface-mount PCB thermal management using ≥2.0 oz copper pour.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Input | Unregulated DC input; requires ≥0.33 µF bypass capacitor mounted directly across pins 1–2 for stability with long traces |
| 2 | Ground | Common reference and thermal connection point; must be tied to large copper area for thermal dissipation |
| 3 | Output | Regulated +18 V output; supports up to 500 mA load with ≤360 mV load regulation error (5–500 mA) |
Key Features
| Feature | Design Value |
|---|---|
| No external components required | Stable operation with only optional input bypass - reduces BOM count and layout complexity for space-constrained boards |
| Internal thermal overload protection | Automatic shutdown at +150°C junction temperature, eliminating need for discrete thermal monitoring circuitry |
| Safe-area compensated pass transistor | Prevents secondary breakdown during output short by reducing current as VI–VO increases - enhances reliability in fault-prone environments |
| Pb-free DPAK-3 package | RoHS-compliant TO-252 footprint with exposed thermal pad, compatible with standard reflow profiles and IPC-A-610 Class 2/3 assembly |
Applications
| Industrial Power Supply | Automotive Body Control Module |
|---|---|
Use Scenario: Local regulation of 24 V vehicle battery to clean +18 V rail for window lift motor drivers and door lock actuators. IC Role / Device Role / Timing Role: Fixed-voltage linear regulator providing isolated, low-noise supply independent of battery transients. Use Value: Withstands load dump pulses up to 35 V input and maintains regulation during cold-crank dips due to 21 V min input requirement. | Use Scenario: Powering CAN transceiver bias and microcontroller I/O banks in body control units. IC Role / Device Role / Timing Role: Primary 18 V rail generator for analog front-end circuitry and level-shifting interfaces. Use Value: 53 dB ripple rejection suppresses alternator noise at 120 Hz, preserving signal integrity in CAN physical layer. |
| Embedded Sensor Hub | Test Equipment Power Rail |
Use Scenario: Regulating unregulated 24 V bench supply to power precision ADC references and op-amp signal chains. IC Role / Device Role / Timing Role: Low-noise local regulator delivering stable 18 V for analog signal conditioning stages. Use Value: 100 µV RMS output noise (10 Hz–100 kHz) minimizes added noise floor in high-resolution measurement paths. | Use Scenario: Generating auxiliary 18 V rail in programmable DC power supplies for DUT biasing. IC Role / Device Role / Timing Role: Secondary regulated output stage for user-configurable auxiliary outputs. Use Value: 500 mA output capability supports moderate-current DUTs while thermal shutdown prevents damage during overcurrent test faults. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar fixed-voltage linear regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MC78M18BDTRKG | −40°C to +125°C operating range vs. 0°C to +125°C; same electrical specs and DPAK-3 package | Required for automotive under-hood or industrial outdoor deployments with extended ambient extremes | Select when wide temperature qualification is mandatory - otherwise MC78M18CDT suffices for commercial/industrial indoor use |
| LM2940CT-18/NOPB | Lower dropout (0.5 V typ), higher quiescent current (10 mA max), TO-220 package, 1 A output rating | Better suited for low-headroom inputs or higher-current loads; requires heatsink for >500 mA | Choose LM2940CT-18/NOPB only if input voltage margin is <20 V or peak load exceeds 500 mA - not a drop-in replacement |
Compared with MC78M18BDTRKG, the MC78M18CDT offers identical regulation performance at lower cost for non-automotive applications; versus LM2940CT-18/NOPB, it trades higher dropout for lower quiescent current and simpler thermal design at 500 mA.
Availability
MC78M18CDT is available at Aetrix Electronics and suitable for industrial power supplies, automotive body control modules, and embedded sensor hubs requiring stable component supply with consistent lead times and volume pricing.
Supply support for MC78M18CDT 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 MC78Mxx series was designed as a half-current variant of the classic 78xx family to serve cost-sensitive, space-constrained applications needing robust local regulation without external components.
FAQ
What is the maximum input voltage for MC78M18CDT?
The MC78M18CDT supports a maximum input voltage of 35 V DC under normal operating conditions, with absolute maximum rating of 40 V for transient events such as load dump. Operation above 35 V risks exceeding safe-area limits and triggering thermal shutdown.
Does MC78M18CDT require an input bypass capacitor?
While the MC78M18CDT is stable without external capacitors, onsemi recommends a ≥0.33 µF low-ESR capacitor (e.g., tantalum or ceramic) placed directly across pins 1 (Input) and 2 (GND) when connected via long traces or driving large capacitive loads - this ensures stability and improves transient response.
What is the thermal resistance of MC78M18CDT in its DPAK-3 package?
The MC78M18CDT in DPAK-3 (Case 369C) has a junction-to-case thermal resistance (θJC) of 5.0°C/W and a junction-to-air thermal resistance (θJA) of 92°C/W with standard PCB mounting - effective thermal management requires ≥2.0 oz copper area connected to pin 2 (GND/thermal pad).
Can MC78M18CDT be used in automotive applications?
The MC78M18CDT is rated for 0°C to +125°C junction temperature and is not AEC-Q100 qualified. For automotive applications, use the NCV78M18BDTRKG or MC78M18BDTRKG variants, which are specified for −40°C to +125°C and meet automotive PPAP requirements.
What is the output voltage tolerance of MC78M18CDT over temperature and load?
The MC78M18CDT guarantees output voltage between 17.1 V and 18.9 V across full operating conditions (VI = 21–33 V, IO = 5–350 mA, TJ = 0–125°C), with typical 17.3–18.7 V at 25°C - meeting ±3.9% total variation for industrial-grade fixed-voltage regulation.
MC78M18CDT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-252-3, DPAK (2 Leads + Tab), SC-63
- Packaging:
- Tube
- Product Status:
- Obsolete
- Output Configuration:
- Positive
- Output Type:
- Fixed
- Number of Regulators:
- 1
- Voltage - Input (Max):
- 35V
- Voltage - Output (Min/Fixed):
- 18V
- Voltage - Output (Max):
- -
- Voltage Dropout (Max):
- -
- Current - Output:
- 500mA
- Current - Quiescent (Iq):
- -
- Current - Supply (Max):
- -
- PSRR:
- 70dB (120Hz)
- Control Features:
- -
- Protection Features:
- Over Temperature, Short Circuit
- Operating Temperature:
- 0°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DPAK
MC78M18CDT FAQ
1.How can I place an order for MC78M18CDT through Aetrix?
Please submit a Request for Quotation (RFQ) for MC78M18CDT 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 MC78M18CDT reliable?
The price and inventory of MC78M18CDT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC78M18CDT is usually 5 days.
3.What payment methods are accepted for MC78M18CDT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC78M18CDT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC78M18CDT?
MC78M18CDT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC78M18CDT 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 MC78M18CDT?
For technical support, including MC78M18CDT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC78M18CDT requirements.
6.How does Aetrix verify that MC78M18CDT is sourced from the original manufacturer or authorized distributors?
All MC78M18CDT 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 MC78M18CDT meets industry standards.
7.What is the process for return or replacement of MC78M18CDT?
All MC78M18CDT units undergo pre-shipment inspection (PSI). If there is an issue with MC78M18CDT, 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 MC78M18CDT part is unused and in its original packaging.
Return procedure for MC78M18CDT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
MC78M18CDT Tags
-
MIC5504-1.8YM5-TR
Microchip Technology
-
MIC5504-3.3YM5-TR
Microchip Technology
-
MIC5365-3.0YC5-TR
Microchip Technology
-
MIC5365-1.8YC5-TR
Microchip Technology
-
MIC5365-2.5YC5-TR
Microchip Technology
-
MIC5365-3.3YC5-TR
Microchip Technology
-
MIC5365-3.3YD5-TR
Microchip Technology
-
MIC5317-3.3YM5-TR
Microchip Technology
-
TLV1117LV33DCYR
Texas Instruments
-
MIC5317-3.3YMT-TZ
Microchip Technology
-
MIC5528-3.3YMT-TR
Microchip Technology
-
TLV75801PDRVR
Texas Instruments
Tech Hub
Counterfeit components can hide behind convincing markings and passing basic function tests. This engineering reference covers source traceability, external inspection, X-ray, XRF, electrical testing, …
A practical engineering and sourcing framework covering lifecycle verification, lifetime-buy calculations, replacement qualification, supplier checks and counterfeit-risk controls.
TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
