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onsemi MC34166D2TR4
- Part No.:
- MC34166D2TR4
- Manufacturer:
- onsemi
- Package:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Datasheet:
-
MC34166D2TR4.pdf
- Description:
- IC REG BUCK BST ADJ 3.3A D2PAK-5
- Quantity:
- Payment:
- Shipping:
Inventory:4,268
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Product details
Overview
MC34166D2TR4 from onsemi is a fixed-frequency voltage-mode switching regulator IC designed for step-down, voltage-inverting, and step-up/down dc-dc converter applications. It integrates a 72 kHz oscillator, 5.05 V ±2% reference, latching PWM, high-gain error amplifier, and 3.0 A output switch, operating from 7.5 V to 40 V input with cycle-by-cycle current limiting and thermal shutdown. It delivers stable 5.05 V output without external resistor divider in basic step-down configurations.
For engineers reviewing the MC34166D2TR4 datasheet, pinout, applications, or equivalent options, key selection considerations include its D2PAK surface-mount package, 0–95% duty cycle range, undervoltage lockout (5.9 V startup with 0.9 V hysteresis), standby mode reducing supply current to 36 µA, and compatibility with Schottky rectifiers like 1N5822 in high-efficiency flyback topologies.
Technical Context
The MC34166D2TR4 implements voltage-mode control using an internal 72 kHz oscillator with fixed charge/discharge thresholds (4.1 V/2.3 V) and a latching PWM comparator that compares the error amplifier output against the oscillator ramp. Its error amplifier features 80 dB open-loop gain and 600 kHz unity-gain bandwidth, with non-inverting input tied internally to the 5.05 V reference-no external feedback pin required for 5.05 V output.
Cycle-by-cycle current limiting monitors switch conduction via an internal trimmed sense resistor, resetting the PWM latch when peak current reaches 4.3 A (typical). Undervoltage lockout ensures reliable start-up only above 5.9 V with 0.9 V hysteresis, while thermal shutdown activates at ~170°C to disable the output switch-complementing external heatsinking requirements for continuous 3.0 A operation in D2PAK.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Oscillator Frequency | 72 kHz nominal; enables compact magnetics and predictable EMI profile in step-down/inverting converters. |
| Reference Voltage | 5.05 V ±2% at +25°C; allows precise 5.0 V output with built-in 50 mV headroom to compensate for cable drop. |
| Output Switch Current | 3.0 A continuous; supports up to 3.0 A load in step-down configuration with appropriate heatsinking. |
| Duty Cycle Range | 0% to 95%; accommodates wide input/output ratios in step-down (e.g., 12 V → 5 V) and inverting (e.g., 12 V → −12 V) designs. |
| UVLO Threshold | 5.9 V startup / 5.0 V turn-off (0.9 V hysteresis); prevents erratic operation during brown-out or soft-start conditions. |
| Standby Supply Current | 36 µA at 12 V; enables low-power sleep mode by clamping Pin 5 below 150 mV. |
| Operating Input Range | 7.5 V to 40 V; suitable for automotive battery (12 V/24 V), industrial 24 V rails, and offline pre-regulated supplies. |
Pinout & Package
The MC34166D2TR4 is housed in a Pb-free D2PAK (TO-263) surface-mount package (Case 936A), with the exposed metal tab electrically connected to Pin 3 (Ground) and thermally coupled to the PCB copper for enhanced heat dissipation. Thermal resistance is θJC = 5.0°C/W and θJA = 70°C/W (with 2.0 oz. copper).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 (Comp) | Compensation Node | Output of error amplifier; connects to RC network (RF/CF) for loop stability-critical for step-up/inverting topologies. |
| Pin 2 (Switch) | High-Current Switch Output | Collector of internal NPN transistor; drives external inductor/diode; rated for 40 V max and 3.0 A continuous. |
| Pin 3 (GND) | Power & Signal Ground | Common return for internal circuits and heatsink tab; must be low-impedance connection to minimize noise and thermal rise. |
| Pin 4 (VCC) | Power Supply Input | Primary power rail (7.5–40 V); powers internal circuitry and bias networks; requires local 330 µF bypass capacitor. |
| Pin 5 (FB) | Voltage Feedback Input | Inverting input of error amplifier; senses output via resistor divider; threshold is 5.05 V-no external reference needed for 5.05 V output. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 5.05 V Reference | Eliminates external reference IC; ±2% accuracy over temperature enables stable regulation without trimming. |
| Latching PWM Architecture | Prevents multiple pulses per cycle; ensures deterministic timing and simplifies EMI filtering in fixed-frequency designs. |
| Cycle-by-Cycle Current Limit | Protects switch under overload or short-circuit; resets each cycle-avoids thermal runaway during fault conditions. |
| Low-Power Standby Mode | Reduces ICC to 36 µA by pulling Pin 5 below 150 mV; enables energy-efficient idle states in battery-powered systems. |
| Thermal Shutdown Protection | Disables output at ~170°C junction temperature; safeguards device during transient overloads or inadequate heatsinking. |
Applications
| Automotive Body Control Module | Industrial Sensor Power Supply |
|---|---|
Use Scenario: Regulating 12 V battery input to stable 5.05 V for microcontroller, CAN transceiver, and analog sensor interfaces in door modules or lighting controllers. IC Role / Device Role / Timing Role: Primary step-down regulator providing tightly regulated 5.05 V rail with UVLO ensuring clean start-up after ignition cycling. Use Value: Delivers 3.0 A continuous output with <±0.05% line regulation and 82.8% efficiency-reducing thermal load versus linear regulators. | Use Scenario: Generating isolated negative voltage (−12 V) from 24 V industrial bus to power op-amps and ADC drivers in precision measurement front-ends. IC Role / Device Role / Timing Role: Voltage-inverting converter core with ground-referenced feedback enabling accurate −12 V output at 1.0 A. Use Value: Achieves ±0.017% load regulation and 81.2% efficiency using standard 1N5822 Schottky diode-eliminating need for dual-rail supplies. |
| Consumer Audio DC-DC Conversion | Medical Portable Device Power |
Use Scenario: Stepping down 19 V laptop adapter output to 5.05 V for USB charging ports and audio codec ICs in portable speakers. IC Role / Device Role / Timing Role: High-efficiency step-down controller with soft-start (via Pin 5 current source) preventing inrush into downstream capacitors. Use Value: 82.8% efficiency at 3.0 A reduces heat generation in compact enclosures; D2PAK package allows automated SMT assembly. | Use Scenario: Providing triple-output power (5.05 V/2.0 A, +12 V/300 mA, −12 V/100 mA) from 24 V input in handheld diagnostic equipment. IC Role / Device Role / Timing Role: Triple-output flyback controller using transformer-coupled secondaries-regulated primary controls all outputs via volt-turn ratio. Use Value: 83.3% total efficiency and <±1.5% cross-regulation enable compact, low-noise multi-rail design meeting IEC 60601 leakage limits. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switching regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MC33166D2TR4G | Wider operating ambient range (−40°C to +85°C) vs. MC34166D2TR4 (0°C to +70°C); identical electrical specs and pinout. | Suitable for extended-temperature industrial or automotive under-hood use where MC34166D2TR4's 0°C lower limit is insufficient. | Select MC33166D2TR4G when ambient temperature may fall below 0°C; otherwise MC34166D2TR4 offers cost advantage for commercial-grade applications. |
| LM2576-5.0 | Fixed 5.0 V output (not 5.05 V); 3.0 A switch but 52 kHz frequency; requires external diode and has no integrated current-sense resistor. | Better suited for simpler step-down designs where ±2% tolerance suffices and layout space allows discrete diode placement. | Choose LM2576-5.0 for legacy designs or cost-sensitive applications where 52 kHz EMI profile is preferred and external diode integration is acceptable. |
Compared with MC33166D2TR4G, the MC34166D2TR4 trades extended temperature range for lower cost in commercial environments; versus LM2576-5.0, it offers tighter reference accuracy, integrated current sensing, and higher oscillator frequency-reducing inductor size but requiring careful compensation in inverting topologies.
Availability
MC34166D2TR4 is available at Aetrix Electronics and suitable for automotive body electronics, industrial sensor power supplies, consumer audio DC-DC conversion, and medical portable device power requiring stable component supply and long-term production continuity.
Supply support for MC34166D2TR4 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 MC34166 series belongs to onsemi's legacy monolithic switching regulator product line, engineered for cost-effective, high-reliability dc-dc conversion in step-down, inverting, and step-up/down topologies with minimal external components.
FAQ
What is the maximum output current capability of the MC34166D2TR4 in a step-down configuration?
The MC34166D2TR4 supports up to 3.0 A continuous output current in step-down applications when properly heatsinked on a 2.0 oz. copper PCB with ≥25 mm of copper length per Figure 29. Peak switch current is limited to 4.3 A (typical), and sustained operation above 2.5 A requires thermal validation per ambient conditions and layout. The MC34166D2TR4 datasheet specifies 3.0 A as the guaranteed continuous rating under defined thermal conditions.
Does the MC34166D2TR4 require external components to generate a 5.05 V output?
No-the MC34166D2TR4 provides a precise 5.05 V output without any external resistor divider because its internal reference is connected directly to the non-inverting input of the error amplifier and is not pinned out. Only external compensation (RF/CF), input/output capacitors, inductor, and Schottky diode are required for basic step-down operation. The MC34166D2TR4 simplifies design by eliminating feedback resistor selection for nominal 5.05 V regulation.
How does the MC34166D2TR4 implement undervoltage lockout, and what are its thresholds?
The MC34166D2TR4 incorporates an internal undervoltage lockout (UVLO) comparator monitoring VCC against the 5.05 V reference. It enables the output stage when VCC rises above 5.9 V (typical) and disables it when VCC falls below 5.0 V (typical), providing 0.9 V hysteresis. This prevents erratic switching during power-up or brown-out events. The MC34166D2TR4 UVLO behavior is fully specified across temperature and ensures robust start-up in automotive and industrial environments.
Can the MC34166D2TR4 be used in voltage-inverting configurations, and what design modifications are needed?
Yes-the MC34166D2TR4 is explicitly designed for voltage-inverting applications. To implement inversion (e.g., +12 V → −12 V), the IC's ground pin (Pin 3) must be connected to the negative output rail, reversing the error amplifier's effective inputs. This keeps the switch emitter within its −1.5 V limit relative to ground and allows regulation of the inverted output. The MC34166D2TR4 application circuit in Figure 23 demonstrates this configuration with verified 81.2% efficiency and ±0.017% load regulation.
What package type and thermal characteristics apply to the MC34166D2TR4?
The MC34166D2TR4 uses the D2PAK (TO-263) surface-mount package (Case 936A), with the exposed metal tab electrically and thermally connected to Pin 3 (GND). Its thermal resistance is θJC = 5.0°C/W and θJA = 70°C/W when mounted on 2.0 oz. copper with ≥25 mm trace length (per Figure 29). The MC34166D2TR4's MSL level is 1, supporting standard reflow profiles without baking.
MC34166D2TR4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- 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):
- 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:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- D2PAK-5
MC34166D2TR4 FAQ
1.How can I place an order for MC34166D2TR4 through Aetrix?
Please submit a Request for Quotation (RFQ) for MC34166D2TR4 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 MC34166D2TR4 reliable?
The price and inventory of MC34166D2TR4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC34166D2TR4 is usually 5 days.
3.What payment methods are accepted for MC34166D2TR4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC34166D2TR4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC34166D2TR4?
MC34166D2TR4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC34166D2TR4 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 MC34166D2TR4?
For technical support, including MC34166D2TR4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC34166D2TR4 requirements.
6.How does Aetrix verify that MC34166D2TR4 is sourced from the original manufacturer or authorized distributors?
All MC34166D2TR4 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 MC34166D2TR4 meets industry standards.
7.What is the process for return or replacement of MC34166D2TR4?
All MC34166D2TR4 units undergo pre-shipment inspection (PSI). If there is an issue with MC34166D2TR4, 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 MC34166D2TR4 part is unused and in its original packaging.
Return procedure for MC34166D2TR4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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