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onsemi MC34063ADX
- Part No.:
- MC34063ADX
- Manufacturer:
- onsemi
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MC34063ADX.pdf
- Description:
- IC REG BUCK BOOST ADJ 1.5A 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,629
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Product details
Overview
MC34063ADX from Fairchild Semiconductor is a monolithic DC-DC switching regulator controller IC used for step-up, step-down, or inverting topologies. It integrates a temperature-compensated 1.24 V bandgap reference, oscillator with 100 Hz–100 kHz adjustable frequency, 1.5 A output switch, and current-limit sensing at 300 mV. It operates from 3.0 V to 40 V input and supports industrial power supply designs requiring compact, low-cost regulation.
For engineers reviewing the MC34063ADX datasheet, pinout, applications, or equivalent options, key selection considerations include its 1.5 A internal switch capability, 300 mV current-sense threshold, 1.24 V reference accuracy, oscillator timing control via external capacitor, and compatibility with SOP-8 PCB layout constraints.
Technical Context
The MC34063ADX implements a fixed-frequency, current-mode control architecture using an internal oscillator with charge/discharge currents (31 µA/190 µA typ.) to set switching frequency. Its comparator compares sensed current against a 300 mV threshold to enable cycle-by-cycle current limiting.
It features a dual-transistor output stage (Q1/Q2) with pulsed 1.5 A collector current capability and saturation voltages of 0.7 V (VCE(SAT)2) under 1.0 A drive. The 1.24 V reference exhibits ±3 mV line regulation over 3–40 V VCC.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.0 V to 40 V - supports wide-input industrial and automotive battery-fed supplies |
| Output Switch Current | 1.5 A - enables direct drive of external inductor without external transistor in low-to-mid power converters |
| Current Sense Threshold | 300 mV - sets precise overcurrent limit with minimal power loss in sense resistor |
| Reference Voltage | 1.24 V ±3 mV - provides stable feedback for accurate output voltage regulation |
| Oscillator Frequency Range | 100 Hz to 100 kHz - allows trade-off between efficiency, size, and EMI via external timing capacitor |
| Operating Temperature | 0°C to +70°C - rated for commercial-grade ambient operation |
| Package | 8-SOP (SOIC-8) - surface-mount package compatible with automated assembly and space-constrained layouts |
Pinout & Package
MC34063ADX is housed in an 8-pin SOIC (Small Outline Integrated Circuit) package per JEDEC MS-012, 0.150-inch narrow body, with 1.27 mm lead pitch. Pin 1 is marked by beveled edge or dot indicator.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (SW) | Switch Collector | High-current output node connected to inductor in boost/buck/invert topologies |
| 2 (GND) | Ground Reference | Power and signal return for internal circuitry and current-sense resistor |
| 3 (VCC) | Supply Input | Primary power rail; powers internal logic, oscillator, and driver stages |
| 4 (CT) | Oscillator Timing | Connects external timing capacitor to set switching frequency via charge/discharge current ratio |
| 5 (ISENSE) | Current Limit Sense | Monitors voltage drop across external sense resistor to trigger current limiting at 300 mV |
| 6 (OUT) | Driver Output | Drives external NPN transistor base in high-current configurations; open-collector output |
| 7 (COMP) | Comparator Inverting Input | Feedback node for error amplifier; connects to resistor divider from regulated output |
| 8 (VREF) | Internal Reference Output | Provides 1.24 V reference for feedback network; requires bypass capacitor for stability |
Key Features
| Feature | Design Value |
|---|---|
| Adjustable switching frequency | Set precisely from 100 Hz to 100 kHz using single external capacitor - enables optimization for efficiency vs. magnetics size |
| Integrated 1.5 A switch | Eliminates need for external power transistor in ≤5 W DC-DC designs - reduces BOM count and layout area |
| 300 mV current-limit threshold | Minimizes sense-resistor power loss and thermal drift - improves accuracy and thermal margin |
| 1.24 V ±3 mV reference | Enables stable output regulation across input and load variations without external trimming |
| Short-circuit protection | Automatic foldback via current-sense comparator - prevents device damage during output faults |
Applications
| Battery-Powered Portable Equipment | Industrial 24 V DC Power Conversion |
|---|---|
Use Scenario: Generating 5 V or 12 V from single or dual alkaline/NiMH cells in handheld meters or sensors. IC Role / Device Role / Timing Role: Primary DC-DC controller implementing step-up topology with fixed-frequency current-mode control. Use Value: Enables >85% efficiency at 100–500 mA loads while maintaining regulation down to 1.8 V input. | Use Scenario: Converting unregulated 24 V industrial bus to isolated 5 V for microcontroller and I/O rails. IC Role / Device Role / Timing Role: Core controller in non-isolated buck or inverting configuration driving discrete MOSFET or bipolar switch. Use Value: Delivers stable output with <±2% line/load regulation using only passive components and no transformer. |
| Automotive Accessory Power Supplies | Legacy System Voltage Translation |
Use Scenario: Deriving 5 V or 3.3 V from vehicle battery (9–16 V) for infotainment USB ports or CAN transceivers. IC Role / Device Role / Timing Role: Step-down controller with built-in current limiting to survive load dump and cold-crank conditions. Use Value: Withstands 40 V transients and maintains regulation during 6 V cranking dips without external protection. | Use Scenario: Replacing obsolete linear regulators (e.g., 7805) in legacy equipment where heat dissipation is critical. IC Role / Device Role / Timing Role: Efficient switching alternative to linear regulation in fixed-voltage point-of-load applications. Use Value: Reduces power loss by >70% compared to linear solution at 500 mA, eliminating heatsink requirement. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar SMPS controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MC34063AP | DIP-8 package; same electrical specs but through-hole mounting; higher thermal resistance (1 W vs. 0.8 W PD) | Suitable for prototyping or low-volume through-hole assemblies; not for automated SMT production | Select MC34063AP only when DIP-8 footprint and manual soldering are required |
| LM2574N-5.0 | Fixed 5 V output; integrated 0.5 A switch; no external timing capacitor needed; wider input range (4–40 V) | Limited to step-down only; lacks inverting/boost capability; simpler design but less topology flexibility | Choose LM2574N-5.0 for cost-sensitive 5 V buck-only applications where programmability is unnecessary |
Compared with MC34063AP and LM2574N-5.0, the MC34063ADX offers full topology flexibility (buck/boost/invert), adjustable output voltage, and surface-mount compatibility - making it optimal for space-constrained, multi-rail, or variable-output designs where layout density and functional adaptability are prioritized.
Availability
MC34063ADX is available at Aetrix Electronics and suitable for battery-powered portable equipment, industrial 24 V DC power conversion, and automotive accessory power supplies requiring stable component supply and long-term manufacturability.
Supply support for MC34063ADX 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
Fairchild Semiconductor was a U.S.-based analog and power IC manufacturer acquired by ON Semiconductor in 2016; known for rugged, cost-optimized power management solutions.
The MC34063A product line was designed for general-purpose, low-to-mid power DC-DC conversion in commercial applications where simplicity, reliability, and minimal external component count were essential.
FAQ
What is the maximum output current achievable with MC34063ADX without external transistors?
The MC34063ADX integrates a 1.5 A output switch, enabling up to 1.5 A peak switch current. Practical continuous output current depends on topology, input/output voltage, duty cycle, and thermal management. At typical 5 V output from 12 V input in buck mode, sustained output current is ~750 mA with adequate PCB copper area. Exceeding this requires external transistor drive via pin 6 (OUT).
Does MC34063ADX support inverting (negative output) DC-DC conversion?
Yes, MC34063ADX supports inverting topology as confirmed in its official description and application circuits. In this configuration, the switch (pin 1) drives the inductor to ground, and the output capacitor is referenced to ground with polarity reversed, generating a negative regulated voltage. External diode and capacitor placement follows standard inverting converter layout rules.
What is the purpose of the COMP pin (pin 7) on MC34063ADX?
The COMP pin (pin 7) is the inverting input of the internal error amplifier. It connects to the feedback resistor divider from the regulated output. The amplifier compares this voltage against the 1.24 V internal reference (pin 8) and adjusts the duty cycle to maintain regulation. Stability requires proper compensation network (typically RC) between COMP and VREF.
Can MC34063ADX operate from a 3.3 V input supply?
No, MC34063ADX has a minimum input voltage of 3.0 V, but reliable startup and regulation require VCC ≥ 3.3 V under load. At exactly 3.3 V, marginal operation may occur due to internal voltage drops and oscillator startup thresholds. For robust 3.3 V input designs, use MC33063AD (−40°C to +85°C) or verify startup behavior per Figure 6 in the datasheet.
How is switching frequency set on MC34063ADX?
Switching frequency is set by an external timing capacitor (CT) connected to pin 4 (CT). The oscillator uses internal charge (31 µA typ.) and discharge (190 µA typ.) currents; frequency ≈ 1/(2.4 × CT × RDISCHARGE/RCHARGE) - simplified to f ≈ 460 kHz × (1 µF / CT) for typical values. A 470 pF capacitor yields ~100 kHz.
MC34063ADX Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Function:
- Step-Up, Step-Down
- Output Configuration:
- Positive or Negative
- Topology:
- Buck, Boost
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 1.24V
- Voltage - Output (Max):
- 40V (Switch)
- Current - Output:
- 1.5A (Switch)
- Frequency - Switching:
- 100Hz ~ 100kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
MC34063ADX FAQ
1.How can I place an order for MC34063ADX through Aetrix?
Please submit a Request for Quotation (RFQ) for MC34063ADX 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 MC34063ADX reliable?
The price and inventory of MC34063ADX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC34063ADX is usually 5 days.
3.What payment methods are accepted for MC34063ADX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC34063ADX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC34063ADX?
MC34063ADX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC34063ADX 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 MC34063ADX?
For technical support, including MC34063ADX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC34063ADX requirements.
6.How does Aetrix verify that MC34063ADX is sourced from the original manufacturer or authorized distributors?
All MC34063ADX 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 MC34063ADX meets industry standards.
7.What is the process for return or replacement of MC34063ADX?
All MC34063ADX units undergo pre-shipment inspection (PSI). If there is an issue with MC34063ADX, 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 MC34063ADX part is unused and in its original packaging.
Return procedure for MC34063ADX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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