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onsemi MC34063AD
- Part No.:
- MC34063AD
- Manufacturer:
- onsemi
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MC34063AD.pdf
- Description:
- IC REG BUCK BOOST ADJ 1.5A 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,054
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Product details
Overview
MC34063AD from Fairchild Semiconductor is a monolithic DC-DC switching regulator controller IC supporting step-up, step-down, and inverting topologies. It features 3.0–40V input range, 1.5A internal switch current, adjustable output voltage, 100Hz–100kHz oscillator frequency, and integrated temperature-compensated 1.24V reference. It is used in low-cost power supply designs for industrial sensors and portable instrumentation.
For engineers reviewing the MC34063AD datasheet, pinout, applications, or equivalent options, key selection considerations include its fixed 8-pin SOIC package, internal switch saturation voltage (0.45–0.70V at 1.0A), current-limit sense threshold (250–350mV), and compatibility with external timing capacitor-based frequency control.
Technical Context
The MC34063AD integrates a bandgap reference, oscillator with charge/discharge current ratio (5.2–7.5), comparator with 1.21–1.29V threshold, and Darlington output switch. Its oscillator frequency is set by an external capacitor and internal 22–42µA charging/140–260µA discharging currents.
It operates as a current-mode controller: the switch is turned off when sensed current exceeds the 250–350mV limit across the sense resistor. The duty cycle is controlled via feedback to the comparator's inverting input, enabling stable regulation across input and load variations.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.0 V to 40 V - Supports wide-input industrial and automotive battery-derived supplies without pre-regulation. |
| Output Switch Current | 1.5 A - Enables up to ~12W DC-DC conversion without external transistors in step-down or inverting configurations. |
| Oscillator Frequency Range | 100 Hz to 100 kHz - Set by external timing capacitor; lower frequencies reduce EMI and enable high-efficiency operation at light loads. |
| Current Sense Threshold | 250–350 mV - Defines overcurrent trip point; determines minimum sense resistor value (e.g., 0.22Ω for ~1.1A limit). |
| Reference Voltage | 1.21–1.29 V - Precision bandgap reference used for feedback divider; sets output voltage accuracy in adjustable configurations. |
| Supply Current (ICC) | 5 mA - Quiescent current at VCC = 5–40 V; enables low-power standby operation in battery-powered systems. |
| Switch Saturation Voltage | 0.45–0.70 V at 1.0 A - Low VCE(SAT)2 reduces conduction loss in driver-collector mode, improving efficiency in step-up/inverting designs. |
Pinout & Package
MC34063AD is housed in an 8-lead SOIC (JEDEC MS-012, .150" narrow body) package with 1.27 mm lead pitch and surface-mount footprint.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (SW) | Switch Collector | High-current output node of internal Darlington transistor; connects to inductor in step-up or to ground in step-down. |
| 2 (GND) | Ground Reference | Power and signal ground return for oscillator, comparator, and switch emitter. |
| 3 (VCC) | Supply Input | Primary power input (3–40 V); powers internal circuitry and charges timing capacitor. |
| 4 (C.T.) | Timing Capacitor | Connects external capacitor to set oscillator frequency via internal charge/discharge currents. |
| 5 (Ipk SENSE) | Current Limit Sense | Inputs voltage drop across external sense resistor; triggers switch turn-off when ≥250–350 mV. |
| 6 (COMP) | Comparator Inverting Input | Feedback node for output voltage regulation; connected to resistor divider from output. |
| 7 (VOUT) | Driver Collector | Open-collector driver output; used to drive external PNP transistor in higher-current configurations. |
| 8 (REF) | Internal Reference Output | Provides 1.24 V reference for feedback divider; requires no external components for basic operation. |
Key Features
| Feature | Design Value |
|---|---|
| Adjustable Output Topology | Supports step-down, step-up, and inverting configurations using same IC-reduces BOM count and design reuse effort. |
| Integrated 1.24 V Reference | Eliminates need for external reference IC; enables precise output regulation with only two feedback resistors. |
| Short-Circuit Protection | Automatic current limiting via Ipk SENSE pin prevents device damage during output faults or startup overload. |
| Low Standby Current | 5 mA ICC allows efficient operation in always-on systems such as remote sensors or metering interfaces. |
| Temperature-Compensated Bandgap | Reference drift ≤±5 mV over 0°C to +70°C ensures stable output voltage across operating range. |
Applications
| Industrial Sensor Power Supply | Portable Instrumentation DC-DC |
|---|---|
Use Scenario: Powering 3.3V or 5V logic and analog circuitry in loop-powered 4–20mA field transmitters. IC Role / Device Role / Timing Role: Step-down DC-DC controller generating regulated output from 12–24V loop supply. Use Value: Internal 1.5A switch eliminates external MOSFET, reducing component count and PCB area in space-constrained enclosures. | Use Scenario: Generating ±5V rails from a single 9V alkaline battery in handheld multimeters or data loggers. IC Role / Device Role / Timing Role: Inverting regulator producing negative rail while step-down section powers microcontroller core. Use Value: Single-chip dual-rail generation avoids separate charge pumps or isolated converters, lowering cost and EMI. |
| Automotive Body Control Module | Legacy Industrial PLC I/O Interface |
Use Scenario: Providing isolated 5V supply for CAN transceiver and microcontroller in 12V vehicle subsystems. IC Role / Device Role / Timing Role: Step-up controller boosting battery voltage to maintain regulation during cold-crank dips below 6V. Use Value: Wide 3–40V input range ensures continuous operation during cranking transients without brownout reset. | Use Scenario: Converting unregulated 24V DC from DIN-rail power supply into stable 5V for TTL-level digital I/O buffers. IC Role / Device Role / Timing Role: Step-down regulator with external sense resistor for programmable current limiting on each I/O channel. Use Value: Adjustable current limit (via sense resistor) protects outputs against shorted field wiring without requiring fuse replacement. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar SMPS controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2574N-5.0 | Fixed 5V output; no adjustable topology; 0.5A switch; requires external diode and inductor. | Limited to step-down only; no inverting or boost capability; simpler layout but less flexible. | Choose LM2574N-5.0 for cost-sensitive, fixed-output 5V applications where topology flexibility is unnecessary. |
| TPS54202DR | 2A synchronous buck controller; 4.5–28V input; integrated FETs; 500kHz switching; requires external compensation. | Higher efficiency and smaller solution size, but incompatible pinout and design flow; not drop-in. | Choose TPS54202DR for higher-efficiency, higher-frequency designs where board space and thermal performance are critical. |
Compared with LM2574N-5.0 and TPS54202DR, the MC34063AD offers unique topology versatility and internal switch integration at lower cost, though with lower switching frequency and efficiency-making it optimal for legacy-compatible, multi-rail, or low-BOM-count designs.
Availability
MC34063AD is available at Aetrix Electronics and suitable for industrial sensor power supplies, portable instrumentation DC-DC conversion, and automotive body control modules requiring stable component supply and long-term sourcing continuity.
Supply support for MC34063AD 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 semiconductor company specializing in power management, analog, and discrete devices before its acquisition by ON Semiconductor in 2016.
The MC34063A product line was designed for cost-effective, flexible DC-DC conversion in resource-constrained embedded systems-emphasizing topology adaptability, minimal external components, and robust operation across industrial temperature ranges.
FAQ
What is the maximum output current achievable with MC34063AD in a step-down configuration?
The MC34063AD supports up to 1.5A peak switch current internally. In a practical step-down design, continuous output current is limited by thermal dissipation and external component ratings. With proper heatsinking and optimized layout, 750–1000mA is reliably achievable. For higher currents, the MC34063AD can drive an external transistor via pin 7 (VOUT), extending capability beyond its internal switch limits. Always verify thermal performance using the 0.8W SOIC power dissipation rating.
Can MC34063AD be used for negative voltage generation?
Yes, the MC34063AD supports inverting topology natively. When configured as an inverting regulator, it generates a negative output voltage referenced to system ground-for example, −5V from a +12V input. This requires specific inductor, diode, and capacitor placement per the standard inverting schematic. The internal switch, reference, and current-sense architecture are fully compatible with this mode without modification.
What is the purpose of the C.T. (pin 4) terminal on MC34063AD?
The C.T. (Timing Capacitor) terminal on MC34063AD connects to an external capacitor that sets the oscillator frequency. Internal 22–42µA charging and 140–260µA discharging currents create a sawtooth waveform across this capacitor, determining switching frequency between 100Hz and 100kHz. Selecting capacitor value allows designers to optimize for efficiency, size, or EMI-e.g., 470pF yields ~50kHz, while 0.01µF yields ~1kHz.
Does MC34063AD require an external reference voltage?
No, the MC34063AD includes an internal temperature-compensated 1.24V bandgap reference (pin 8). This reference is used directly by the error comparator (pin 6) and eliminates the need for external reference ICs. In standard configurations, only two resistors form a voltage divider from the output to pin 6, comparing against the internal reference to regulate output voltage precisely.
How does the current limit function work on MC34063AD?
The MC34063AD implements current limiting via the Ipk SENSE pin (pin 5). An external sense resistor placed between the switch emitter and ground develops a voltage proportional to load current. When this voltage reaches 250–350mV, the internal comparator disables the switch, terminating the current pulse. This cycle-by-cycle limiting protects both the IC and external components during overload or short-circuit conditions without requiring additional circuitry.
MC34063AD Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- 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):
- 1.25V
- Voltage - Output (Max):
- 40V (Switch)
- Current - Output:
- 1.5A (Switch)
- Frequency - Switching:
- 100kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
MC34063AD FAQ
1.How can I place an order for MC34063AD through Aetrix?
Please submit a Request for Quotation (RFQ) for MC34063AD 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 MC34063AD reliable?
The price and inventory of MC34063AD are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC34063AD is usually 5 days.
3.What payment methods are accepted for MC34063AD?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC34063AD transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC34063AD?
MC34063AD orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC34063AD 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 MC34063AD?
For technical support, including MC34063AD datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC34063AD requirements.
6.How does Aetrix verify that MC34063AD is sourced from the original manufacturer or authorized distributors?
All MC34063AD 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 MC34063AD meets industry standards.
7.What is the process for return or replacement of MC34063AD?
All MC34063AD units undergo pre-shipment inspection (PSI). If there is an issue with MC34063AD, 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 MC34063AD part is unused and in its original packaging.
Return procedure for MC34063AD:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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