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onsemi MC33166THG
- Part No.:
- MC33166THG
- Manufacturer:
- onsemi
- Package:
- TO-220-5 Formed Leads
- Datasheet:
-
MC33166THG.pdf
- Description:
- IC REG BUCK BST ADJ 3.3A TO220-5
- Quantity:
- Payment:
- Shipping:
Inventory:1,064
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Product details
Overview
MC33166THG from onsemi is a monolithic fixed-frequency voltage-mode switching regulator IC designed for step-down, voltage-inverting, and cost-effective step-up DC-DC converter applications. It integrates a 3.0 A output switch, 72 kHz oscillator, precision 5.05 V ±2% reference, latching PWM controller, and thermal/UVLO/current-limit protection. It operates from 7.5 V to 40 V input and delivers regulated outputs in automotive, industrial, and embedded power supplies.
For engineers reviewing the MC33166THG datasheet, pinout, applications, or equivalent options, key selection criteria include its −40°C to +85°C operating temperature range, TO-220-5 (Case 314B) package with heatsink-connected Pin 3, 95% max duty cycle, cycle-by-cycle current limiting at 4.3 A typ, and standby current of 36 µA - all critical for reliable high-current offline or battery-fed converters.
Technical Context
The MC33166THG implements voltage-mode 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 (62–79 kHz over temperature) that drives a latch-based PWM comparator, enabling precise duty-cycle control up to 95%.
Protection is implemented via three independent circuits: undervoltage lockout with 5.9 V startup threshold and 0.9 V hysteresis, cycle-by-cycle current sensing referenced to an internal 0.1 Ω sense resistor, and thermal shutdown activating at ~170°C junction temperature - all integrated without external components.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 7.5 V to 40 V - supports wide-range industrial and automotive battery inputs without pre-regulation |
| Output Switch Current | 3.0 A continuous, 4.3 A typical current limit - enables ≥25 W step-down or inverting converters with minimal external FETs |
| Oscillator Frequency | 72 kHz nominal (62–79 kHz over temp) - balances EMI suppression and magnetics size for cost-sensitive designs |
| Reference Voltage | 5.05 V ±2% at 25°C - provides stable feedback threshold for 5.0 V output without external divider |
| Duty Cycle Range | 0% to 95% - allows deep step-down (e.g., 40 V → 5 V) and high-efficiency inverting configurations |
| Standby Supply Current | 36 µA at 12 V - enables low-power sleep modes in battery-backed systems |
| Operating Temperature | −40°C to +85°C - qualified for under-hood automotive and industrial ambient environments |
Pinout & Package
MC33166THG is housed in a Pb-free 5-lead TO-220 package (Case 314B), with the metal tab thermally and electrically connected to Pin 3 (Ground). The package supports vertical mounting and requires heatsinking for >1.5 A continuous operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 (Comp) | Compensation Node | Connects to RC network (RF, CF) for loop stability - sets phase margin and transient response |
| Pin 2 (VFB) | Voltage Feedback Input | Monitors output via resistive divider; clamping below 150 mV enables 36 µA standby mode |
| Pin 3 (GND) | Power Ground / Heatsink | Common return for internal circuits and thermal path - must be low-impedance connection to PCB copper pour |
| Pin 4 (VCC) | Power Supply Input | Accepts 7.5–40 V; powers internal circuitry and enables UVLO when ≥5.9 V |
| Pin 5 (SW) | Switch Output Collector | Drives external inductor/diode; rated for 40 V VCEO, −1.5 V to +VIN swing in inverting mode |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 3.0 A switch | Eliminates need for external power transistor in ≤25 W converters, reducing BOM count and layout complexity |
| Fixed 72 kHz oscillator | Enables predictable EMI filtering and consistent magnetics design without timing component tolerance sensitivity |
| 5.05 V ±2% reference | Permits direct 5.0 V regulation with <±0.05% line regulation (tested 8–36 V), minimizing output drift across input range |
| Cycle-by-cycle current limit | Protects against short-circuit and overload without foldback - maintains 4.3 A peak limit across −40°C to +85°C |
| Undervoltage lockout with hysteresis | Prevents erratic startup by holding output disabled until VCC exceeds 5.9 V, then releasing only after dropping to ≤5.0 V |
Applications
| Automotive Body Control Module | Industrial PLC I/O Power |
|---|---|
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 switching regulator providing isolated, ripple-controlled 5.0 V rail with thermal fault protection during load dump events. Use Value: Delivers 3.0 A continuous output with 82.8% efficiency at 12 V→5 V/3 A, meeting AEC-Q100 ambient requirements without derating. | Use Scenario: Generating −12 V auxiliary supply from 24 V DC bus for analog signal conditioning and op-amp biasing in programmable logic controller backplanes. IC Role / Device Role / Timing Role: Voltage-inverting regulator configured per Figure 23, using internal 5.05 V reference to regulate negative output via ground-referenced feedback. Use Value: Achieves ±0.017% load regulation and 81.2% efficiency at 12 V→−12 V/1.0 A, with emitter swing limited to −1.5 V to ensure safe bipolar transistor operation. |
| Off-line AC-DC Preconverter | Brushed DC Motor Speed Control |
Use Scenario: Serving as post-regulator in multi-output offline power supplies (e.g., 24 V preconverter feeding multiple MC33166THG rails). IC Role / Device Role / Timing Role: Secondary-side fixed-frequency buck controller delivering independently regulated +5 V, +12 V, and −12 V outputs with <±1.9% cross-regulation. Use Value: Enables triple-output design with 83.3% total efficiency and <50 mVpp ripple on main 5 V rail, leveraging shared transformer turns ratio and synchronous feedback. | Use Scenario: Controlling speed of 18 V brushed motors in portable tools using EMF-sensing feedback for closed-loop RPM regulation. IC Role / Device Role / Timing Role: PWM generator with variable duty cycle driven by motor back-EMF voltage applied to VFB pin, replacing dedicated motor driver ICs. Use Value: Provides ±1% low-speed line regulation (12–24 V input) and eliminates need for external current-sense amplifiers or H-bridge drivers. |
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 core architecture but rated for 0°C to +70°C; D2PAK package with lower RθJA (70°C/W vs. 65°C/W) and tape-and-reel packaging | Preferred for commercial-grade, surface-mount production where thermal performance and automated assembly are prioritized | Select when ambient temperature stays within 0–70°C and PCB space constraints favor SMT over through-hole |
| LM2596-5.0 | 3.0 A buck-only regulator with 150 kHz switching, integrated diode, and different compensation scheme; no inverting capability | Limited to step-down only; lacks UVLO hysteresis and cycle-by-cycle current limiting - relies on foldback protection | Choose for simpler 5 V point-of-load designs where inverting or wide-temp operation is unnecessary |
Compared with MC34166D2TR4G, MC33166THG offers extended temperature range and through-hole mechanical robustness; compared with LM2596-5.0, it provides inverting topology support, tighter reference accuracy (±2% vs. ±4%), and superior fault coverage - making it suitable for mission-critical industrial and automotive subsystems.
Availability
MC33166THG is available at Aetrix Electronics and suitable for automotive body electronics, industrial PLC power rails, off-line AC-DC preconverters, and brushed motor control systems requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for MC33166THG 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 is a global semiconductor manufacturer specializing in energy-efficient silicon solutions for automotive, industrial, cloud, medical, and IoT applications, with leadership in power management and analog ICs.
The MC33166 series was engineered for rugged, low-component-count DC-DC conversion in harsh environments - targeting automotive sub-systems, industrial controls, and cost-sensitive embedded power where reliability across −40°C to +85°C is mandatory.
FAQ
What is the maximum output current capability of the MC33166THG?
The MC33166THG features an integrated 3.0 A output switch with a typical current limit threshold of 4.3 A. In step-down configuration at 12 V input and 5 V output, it delivers 3.0 A continuously with 82.8% efficiency and 10 mVpp ripple. Actual current depends on thermal design: with proper heatsinking (e.g., AAVID 5903B), full 3.0 A is sustainable at +85°C ambient; derating is required above 1.5 A without heatsink due to 65°C/W junction-to-ambient thermal resistance in TO-220 package.
Can the MC33166THG be used in voltage-inverting applications?
Yes, the MC33166THG is explicitly designed for voltage-inverting topologies, as confirmed in the datasheet's Introduction and Figure 23. It achieves regulated negative outputs (e.g., −12 V/1.0 A) by re-referencing the IC ground pin to the negative output rail, which reverses the error amplifier polarity while preserving the 5.05 V reference. This configuration delivers ±0.017% load regulation and 81.2% efficiency, with the switch emitter limited to −1.5 V relative to the IC ground pin - a key constraint addressed by the ground-referencing technique.
What is the purpose of the 150 mV threshold on the Compensation (Pin 1) pin?
The 150 mV threshold on Pin 1 (Comp) is the activation level for the MC33166THG's low-power standby mode. When the voltage at Pin 1 drops below 150 mV, internal circuitry enters standby, reducing supply current from ~31 mA to 36 µA at 12 V VCC. This feature enables energy-saving sleep states in battery-powered systems. The threshold is not a regulation point but a control signal - it is typically implemented using a transistor or logic-level switch pulling Pin 1 toward ground, as shown in Figure 16 of the datasheet.
How does the MC33166THG implement undervoltage lockout?
The MC33166THG implements undervoltage lockout (UVLO) by monitoring VCC with an internal comparator referenced to the 5.05 V bandgap. Startup occurs when VCC rises above 5.9 V (typical), and the device remains enabled until VCC falls to ≤5.0 V (5.9 V − 0.9 V hysteresis), preventing oscillation near the threshold. This ensures clean power-on sequencing and avoids erratic switching during brownout conditions. The UVLO circuit is fully integrated - no external components are needed - and operates across the full −40°C to +85°C temperature range with specified hysteresis stability.
Is the MC33166THG pin-compatible with the MC34166 series?
Yes, the MC33166THG is functionally and pin-compatible with the MC34166 series, sharing identical pinout (TO-220-5), electrical specifications, block diagram, and application circuits. The primary difference is operating temperature range: MC33166THG is rated for −40°C to +85°C, while MC34166 is rated for 0°C to +70°C. Both use the same 72 kHz oscillator, 5.05 V reference, and protection features. Designers may substitute MC33166THG into MC34166 designs for extended temperature operation without layout changes, provided thermal margins are verified at −40°C and +85°C.
MC33166THG Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-220-5 Formed Leads
- 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:
- Through Hole
- Supplier Device Package:
- TO-220-5 Horizontal
MC33166THG FAQ
1.How can I place an order for MC33166THG through Aetrix?
Please submit a Request for Quotation (RFQ) for MC33166THG 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 MC33166THG reliable?
The price and inventory of MC33166THG are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC33166THG is usually 5 days.
3.What payment methods are accepted for MC33166THG?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC33166THG transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC33166THG?
MC33166THG orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC33166THG 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 MC33166THG?
For technical support, including MC33166THG datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC33166THG requirements.
6.How does Aetrix verify that MC33166THG is sourced from the original manufacturer or authorized distributors?
All MC33166THG 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 MC33166THG meets industry standards.
7.What is the process for return or replacement of MC33166THG?
All MC33166THG units undergo pre-shipment inspection (PSI). If there is an issue with MC33166THG, 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 MC33166THG part is unused and in its original packaging.
Return procedure for MC33166THG:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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