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onsemi MC34166D2TG
- Part No.:
- MC34166D2TG
- Manufacturer:
- onsemi
- Package:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Datasheet:
-
MC34166D2TG.pdf
- Description:
- IC REG BUCK BST ADJ 3.3A D2PAK-5
- Quantity:
- Payment:
- Shipping:
Inventory:2,319
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Product details
Overview
MC34166D2TG 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, low-component-count power supplies in automotive and industrial systems.
For engineers reviewing the MC34166D2TG datasheet, pinout, applications, or equivalent options, key selection criteria include input voltage range (7.5–40 V), duty cycle control (0–95%), standby current (36 µA), undervoltage lockout (5.9 V startup with 0.9 V hysteresis), and D2PAK surface-mount package compatibility with high-power thermal management.
Technical Context
The MC34166D2TG 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 uses an internal current source and external timing capacitor CT to generate a stable 72 kHz ramp signal with 4.1 V/2.3 V thresholds.
Current protection operates via cycle-by-cycle sensing of switch collector current through an internal resistor, comparing it to a 4.3 A typical threshold. The latch-based PWM ensures single-pulse metering per clock cycle, while undervoltage lockout disables operation below 5.9 V with 0.9 V hysteresis to prevent erratic startup.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Output Current | 3.0 A continuous - supports up to 3 A load in step-down configuration without external boost transistor |
| Oscillator Frequency | 72 kHz fixed - enables predictable EMI filtering and consistent inductor sizing across designs |
| Reference Voltage | 5.05 V ±2% - provides accurate feedback threshold for 5.0 V output regulation with built-in cable-drop compensation |
| Duty Cycle Range | 0% to 95% - allows wide input-to-output voltage ratios in buck and inverting topologies |
| Input Voltage Range | 7.5 V to 40 V - accommodates 12 V and 24 V automotive and industrial rails with margin |
| Standby Supply Current | 36 µA at 12 V - enables low-power sleep mode by clamping COMP pin below 0.15 V |
| UVLO Threshold | 5.9 V startup with 0.9 V hysteresis - prevents oscillation near turn-on and ensures robust power sequencing |
Pinout & Package
MC34166D2TG is housed in a Pb-free D2PAK (TO-263) surface-mount package (Case 936A), with the heatsink tab electrically connected to Pin 3 (GND). Thermal resistance is θJC = 5.0 °C/W and θJA = 70 °C/W at +25°C ambient.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 (COMP) | Compensation Node | Output of error amplifier; connects to RC network for loop stability - clamping below 0.15 V enables 36 µA standby mode |
| Pin 2 (VFB) | Voltage Feedback Input | Inverting input of error amp; compares output voltage divider against 5.05 V reference to regulate VO |
| Pin 3 (GND) | Power & Signal Ground | Common return for internal circuits and heatsink tab - must be low-impedance connection for thermal and noise performance |
| Pin 4 (VCC) | Power Supply Input | Primary supply rail (7.5–40 V); powers internal circuitry and drives gate of integrated NPN switch |
| Pin 5 (SW) | Switch Collector Output | High-current NPN collector node; connects to inductor in buck topology or emitter in inverting configuration |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 3.0 A NPN Switch | Eliminates need for external pass transistor in ≤3 A buck converters, reducing BOM count and layout area |
| Fixed 72 kHz Oscillator | Enables consistent magnetic design and predictable EMI signature without external timing components |
| 5.05 V ±2% Reference | Provides factory-trimmed accuracy for stable 5.0 V output without external trimming resistors |
| Cycle-by-Cycle Current Limit | Protects switch under overload or short-circuit by disabling conduction each cycle above ~4.3 A peak |
| Thermal Shutdown | Disables output at ~170°C junction temperature to prevent permanent damage during sustained overloads |
| Undervoltage Lockout | Ensures full functionality before enabling switch - prevents brownout-induced instability during power ramp-up |
Applications
| Automotive Body Control Module | Industrial PLC I/O Power Supply |
|---|---|
Use Scenario: Regulating 12 V battery input to stable 5.0 V for microcontroller, CAN transceiver, and sensor interfaces in door modules or lighting controllers. IC Role / Device Role / Timing Role: Primary step-down DC-DC controller managing power sequencing, current limiting, and thermal safety. Use Value: Delivers 3.0 A at 82.8% efficiency with line/load regulation < ±0.05%, meeting automotive transient and reliability requirements. |
Use Scenario: Generating isolated 5 V, 12 V, and −12 V rails from 24 V DC bus in programmable logic controller backplanes. IC Role / Device Role / Timing Role: Core switching controller in triple-output flyback-derived topology with shared transformer coupling. Use Value: Enables compact multi-rail design with 83.3% total efficiency and auxiliary regulation < ±1.9% across load variations. |
| Negative Voltage Inverter for Op-Amp Bias | Off-Line AC-DC Preconverter Stage |
Use Scenario: Converting +12 V to −12 V for dual-supply op-amps and analog front-ends in test equipment and data acquisition systems. IC Role / Device Role / Timing Role: Voltage-inverting regulator using emitter-referenced ground configuration to enable negative output generation. Use Value: Achieves −12 V/1.0 A with 81.2% efficiency and < ±0.017% load regulation, eliminating need for dedicated inverting ICs. |
Use Scenario: Stepping down rectified AC line to 24 V intermediate bus in cost-sensitive offline SMPS for consumer appliances. IC Role / Device Role / Timing Role: High-voltage pre-regulator operating at 50 kHz self-oscillating frequency with transformer isolation. Use Value: Supports 125 W total output with 90% efficiency and inherent isolation - extends safe operating area beyond 40 V input limit via transformer coupling. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switching regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MC33166D2TG | Wider operating ambient range (−40°C to +85°C vs. MC34166D2TG's 0°C to +70°C); identical electrical specs and pinout | Suitable for extended-temperature industrial or automotive under-hood use where MC34166D2TG's 0°C minimum is insufficient | Select MC33166D2TG when ambient temperature may fall below 0°C; otherwise MC34166D2TG offers same performance at lower cost |
| LM2576HVSX-5.0/NOPB | 5 A switch current, 52 kHz frequency, integrated diode, different pinout and compensation scheme; requires external diode in MC34166D2TG | Better suited for higher-current (>3 A) or lower-EMI (<52 kHz) applications; not drop-in compatible due to pinout and feedback architecture differences | Choose LM2576HVSX-5.0/NOPB only when >3 A output or simplified layout (integrated diode) is required - redesign needed |
Compared with MC33166D2TG, MC34166D2TG trades extended temperature range for cost optimization in commercial-grade applications; versus LM2576HVSX-5.0/NOPB, it offers higher switching frequency and lower quiescent current but requires external Schottky diode and more careful loop compensation.
Availability
MC34166D2TG is available at Aetrix Electronics and suitable for automotive body electronics, industrial PLC power supplies, and test equipment requiring stable component supply with long-term manufacturability and Pb-free compliance.
Supply support for MC34166D2TG 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, sensors, and connectivity solutions for automotive, industrial, and cloud infrastructure markets.
The MC34166 series was engineered for cost-sensitive, high-reliability DC-DC conversion in automotive and industrial environments - emphasizing minimal external components, integrated protection, and rugged thermal performance in TO-220 and D2PAK packages.
FAQ
What is the maximum output current capability of the MC34166D2TG in a step-down configuration?
The MC34166D2TG supports up to 3.0 A continuous output current in step-down operation, as confirmed by its 3.0 A switch rating and validated in Figure 19 test results (3.0 A load at 82.8% efficiency). Peak switch current is limited to 4.3 A typical via cycle-by-cycle protection, ensuring safe operation under transient overloads without external current-sense components.
Does the MC34166D2TG require an external timing capacitor to operate?
No, the MC34166D2TG does not require an external timing capacitor - its 72 kHz oscillator is fully internal, using a trimmed current source and on-chip capacitor. This eliminates timing component variability and simplifies design versus adjustable-frequency controllers, though external compensation components (RF, CF) remain necessary for loop stability.
Can the MC34166D2TG generate negative output voltages?
Yes, the MC34166D2TG can generate negative outputs using the voltage-inverting configuration shown in Figure 23. By connecting the IC's GND pin to the negative output rail, the internal reference and error amplifier are repurposed to regulate −12 V at 1.0 A with 81.2% efficiency and < ±0.017% load regulation - verified in datasheet testing.
What thermal management is required for the MC34166D2TG in a 3 A application?
At 3 A output in step-down mode, the MC34166D2TG dissipates ~2.5 W (calculated from Vsat ≈ 1.8 V and duty cycle). With θJA = 70 °C/W, a 40 mm × 40 mm 2-oz copper pad reduces junction-to-ambient resistance to ~40 °C/W (per Figure 29), limiting ΔT to ~100°C - requiring a heatsink or forced air if ambient exceeds +50°C to maintain TJ < +150°C.
Is the MC34166D2TG pin-compatible with the MC33166D2TG?
Yes, the MC34166D2TG and MC33166D2TG share identical pinout, package (D2PAK), and electrical specifications - differing only in guaranteed operating ambient temperature range (0°C to +70°C vs. −40°C to +85°C). No PCB changes are required when substituting MC33166D2TG for extended-temperature operation.
MC34166D2TG 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:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- D2PAK-5
MC34166D2TG FAQ
1.How can I place an order for MC34166D2TG through Aetrix?
Please submit a Request for Quotation (RFQ) for MC34166D2TG 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 MC34166D2TG reliable?
The price and inventory of MC34166D2TG are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC34166D2TG is usually 5 days.
3.What payment methods are accepted for MC34166D2TG?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC34166D2TG transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC34166D2TG?
MC34166D2TG orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC34166D2TG 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 MC34166D2TG?
For technical support, including MC34166D2TG datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC34166D2TG requirements.
6.How does Aetrix verify that MC34166D2TG is sourced from the original manufacturer or authorized distributors?
All MC34166D2TG 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 MC34166D2TG meets industry standards.
7.What is the process for return or replacement of MC34166D2TG?
All MC34166D2TG units undergo pre-shipment inspection (PSI). If there is an issue with MC34166D2TG, 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 MC34166D2TG part is unused and in its original packaging.
Return procedure for MC34166D2TG:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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