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onsemi MC33166D2T
- Part No.:
- MC33166D2T
- Manufacturer:
- onsemi
- Package:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Datasheet:
-
MC33166D2T.pdf
- Description:
- IC REG BUCK BST ADJ 3.3A D2PAK-5
- Quantity:
- Payment:
- Shipping:
Inventory:1,074
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Product details
Overview
MC33166D2T from onsemi is a fixed-frequency voltage-mode switching regulator IC designed for step-down, inverting, and step-up/down dc-dc converter topologies. It integrates a 3.0 A output switch, 72 kHz oscillator, precision 5.05 V ±2% reference, cycle-by-cycle current limiting, and thermal shutdown - enabling compact, high-efficiency power supplies operating from 7.5 V to 40 V input. It is widely used in automotive and industrial embedded power rails.
For engineers reviewing the MC33166D2T datasheet, pinout, applications, or equivalent options, key selection considerations include its D2PAK (Case 936A) surface-mount package, −40°C to +85°C operating temperature range, 36 µA standby current, and compatibility with inverting/step-down configurations requiring minimal external components.
Technical Context
The MC33166D2T implements voltage-mode PWM control using an internal error amplifier with 80 dB open-loop gain and 600 kHz unity-gain bandwidth, referenced to a trimmed 5.05 V bandgap. Its oscillator generates a fixed 72 kHz ramp with 95% max duty cycle, driving a latch-based PWM comparator that prevents multiple pulses per cycle.
Protection architecture includes undervoltage lockout (5.9 V startup threshold with 0.9 V hysteresis), cycle-by-cycle current limiting (typ. 4.3 A threshold), and thermal shutdown at ~170°C. The device supports low-power standby mode via Pin 5 clamping below 150 mV, reducing ICC to 36 µA at 12 V supply.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Oscillator Frequency | 72 kHz nominal; enables predictable EMI filtering and stable loop compensation in flyback and buck topologies. |
| Reference Voltage | 5.05 V ±2% at 25°C; provides accurate output regulation without external resistor divider for 5.0 V systems. |
| Output Switch Current | 3.0 A continuous; supports up to 3 A load in step-down configuration with proper heatsinking (θJC = 5.0°C/W). |
| Input Voltage Range | 7.5 V to 40 V; suitable for 12 V/24 V automotive and industrial bus applications with transient tolerance. |
| Standby Supply Current | 36 µA at 12 V; enables ultra-low quiescent power during system sleep modes. |
| Operating Temperature | −40°C to +85°C; qualified for under-hood automotive and wide-temperature industrial environments. |
| Thermal Shutdown | Activates at ~170°C junction; protects against thermal runaway but requires external heatsink for >1 W dissipation. |
Pinout & Package
D2PAK (Case 936A) surface-mount package with exposed thermal pad connected to Pin 3 (GND); moisture sensitivity level (MSL) = 1; Pb-free compliant.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 | Compensation (Comp) | Output of error amplifier; connects to RC network for loop stability tuning in all topologies. |
| Pin 2 | Switch Output (SW) | Collector of internal NPN power transistor; drives external inductor/diode in buck/inverting configurations. |
| Pin 3 | Ground (GND) | Power and signal ground reference; thermally tied to exposed pad for heat dissipation. |
| Pin 4 | Supply Input (VCC) | Primary power input (7.5–40 V); powers internal circuitry and bias networks. |
| Pin 5 | Feedback (FB) | Inverting input of error amplifier; senses regulated output via resistor divider to maintain 5.05 V reference. |
Key Features
| Feature | Design Value |
|---|---|
| Fixed 72 kHz oscillator | Enables consistent EMI profile and simplifies filter design without external timing components. |
| Internal 5.05 V ±2% reference | Eliminates need for external voltage divider in 5.0 V output designs, improving accuracy and reducing BOM count. |
| 95% max duty cycle | Supports high step-down ratios (e.g., 24 V → 3.3 V) while maintaining controllable minimum off-time. |
| Cycle-by-cycle current limiting | Provides robust short-circuit protection without external sensing resistors or delay circuits. |
| Undervoltage lockout with hysteresis | Prevents erratic startup by enforcing clean 5.9 V turn-on and 5.0 V turn-off thresholds. |
Applications
| Automotive Body Control Module (BCM) | Industrial PLC I/O Power Rail |
|---|---|
Use Scenario: Regulating 5.0 V microcontroller supply from noisy 12 V vehicle battery with load dumps up to 40 V. IC Role / Device Role / Timing Role: Primary step-down controller with integrated switch, reference, and protection - replacing discrete MOSFET + controller solutions. Use Value: Achieves 82.8% efficiency at 3.0 A load while surviving automotive transients and operating across −40°C to +85°C. | Use Scenario: Generating isolated −12 V rail for analog sensor interfaces in programmable logic controllers. IC Role / Device Role / Timing Role: Inverting regulator core with external Schottky diode and inductor; uses internal 5.05 V reference to set precise negative output. Use Value: Delivers 1.0 A at −12 V with only 3.0 mV line regulation and 81.2% efficiency - eliminating need for dual-output transformer designs. |
| Off-line AC-DC Preconverter | Brushed DC Motor Speed Control |
Use Scenario: 24 V intermediate bus generation from rectified AC line using self-oscillating flyback preconverter. IC Role / Device Role / Timing Role: Fixed-frequency PWM controller driving external MOSFET in discontinuous conduction mode; regulates via optocoupler feedback. Use Value: Enables 90% efficient, isolated 125 W preconversion with no external timing capacitor - leveraging internal 72 kHz oscillator stability. | Use Scenario: Variable-speed control of 18 V brushed motor using EMF-sensing feedback for closed-loop RPM regulation. IC Role / Device Role / Timing Role: Step-down regulator modulating average motor voltage; FB pin monitors back-EMF through RC network for speed stabilization. Use Value: Maintains ±1% speed accuracy across 12–24 V input range without Hall sensors or encoder hardware. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switching regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MC34166D2TR4G | Same silicon, but rated for 0°C to +70°C ambient; identical electrical specs and pinout. | Not qualified for extended temperature automotive or industrial use; limited to commercial-grade systems. | Select MC34166D2TR4G only if ambient operating range stays within 0–70°C and cost is primary constraint. |
| LM2596S-5.0 | 3.0 A buck-only regulator; fixed 5.0 V output; 150 kHz switching; no inverting capability; no internal current sense resistor. | Cannot implement voltage-inverting or step-up/down topologies; lacks cycle-by-cycle current limiting and UVLO hysteresis. | Choose LM2596S-5.0 for simple 5 V buck conversion where topology flexibility and extended temp range are not required. |
Compared with MC34166D2TR4G, the MC33166D2T offers guaranteed operation down to −40°C - critical for automotive under-hood use - while both share identical D2PAK packaging and functional behavior. Versus LM2596S-5.0, the MC33166D2T provides broader topology support, tighter reference accuracy (±2% vs ±4%), and integrated protection features absent in the LM2596.
Availability
MC33166D2T is available at Aetrix Electronics and suitable for automotive body electronics, industrial PLC power supplies, and off-line preconverter designs requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for MC33166D2T 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 (Nasdaq: ON) is a global semiconductor manufacturer delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.
The MC33166 series belongs to onsemi's legacy analog power management portfolio, engineered specifically for cost-sensitive, high-reliability dc-dc conversion in harsh environments - emphasizing integration, thermal robustness, and topology versatility.
FAQ
What is the maximum output current capability of the MC33166D2T in step-down configuration?
The MC33166D2T supports up to 3.0 A continuous output current in step-down configuration when properly heatsinked. Its internal switch has a typical current limit threshold of 4.3 A, and thermal performance is constrained by θJC = 5.0°C/W. At 3 A load with 12 V input, efficiency reaches 82.8%, and junction temperature must remain below 150°C - requiring PCB copper area or external heatsink per Figure 29.
Can the MC33166D2T be used in voltage-inverting applications, and what is required?
Yes, the MC33166D2T is explicitly designed for voltage-inverting topologies. To implement −12 V/1.0 A output, the IC's ground pin (Pin 3) must be connected to the negative output rail - reversing error amplifier polarity and keeping the switch emitter within −1.5 V limit. Figure 23 shows the required layout, including external Schottky diode (1N5822), inductor, and feedback resistor network.
Does the MC33166D2T require an external timing capacitor?
No, the MC33166D2T does not require an external timing capacitor. Its 72 kHz oscillator is fully internal, using trimmed current sources and on-chip capacitance. This eliminates timing component variability and improves production consistency - unlike many competing regulators that rely on external RC networks for frequency setting.
What is the purpose of Pin 5 (FB) and how is output voltage set?
Pin 5 is the feedback input to the error amplifier's inverting terminal. For 5.0 V output, no external divider is needed - the internal 5.05 V reference directly regulates the output. To set higher voltages (e.g., 12 V), connect R1 and R2 as a resistor divider between VO and GND, with R2 to Pin 5. The formula is VOUT = 5.05 × (1 + R1/R2), as confirmed in Figure 14 and Section 7.
Is the MC33166D2T pin-compatible with the MC34166D2T?
Yes, the MC33166D2T and MC34166D2T are pin-compatible and functionally identical in electrical behavior and pinout. The sole difference is operating temperature range: MC33166D2T is rated for −40°C to +85°C, while MC34166D2T is rated for 0°C to +70°C. Both use the same D2PAK package (Case 936A) and share identical marking suffix "D2T".
MC33166D2T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- 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):
- 7.5V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 5.05V
- Voltage - Output (Max):
- 40V (Switch)
- Current - Output:
- 3.3A (Switch)
- Frequency - Switching:
- 72kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- D2PAK-5
MC33166D2T FAQ
1.How can I place an order for MC33166D2T through Aetrix?
Please submit a Request for Quotation (RFQ) for MC33166D2T 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 MC33166D2T reliable?
The price and inventory of MC33166D2T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC33166D2T is usually 5 days.
3.What payment methods are accepted for MC33166D2T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC33166D2T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC33166D2T?
MC33166D2T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC33166D2T 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 MC33166D2T?
For technical support, including MC33166D2T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC33166D2T requirements.
6.How does Aetrix verify that MC33166D2T is sourced from the original manufacturer or authorized distributors?
All MC33166D2T 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 MC33166D2T meets industry standards.
7.What is the process for return or replacement of MC33166D2T?
All MC33166D2T units undergo pre-shipment inspection (PSI). If there is an issue with MC33166D2T, 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 MC33166D2T part is unused and in its original packaging.
Return procedure for MC33166D2T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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