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onsemi MC33166TG
- Part No.:
- MC33166TG
- Manufacturer:
- onsemi
- Package:
- TO-220-5
- Datasheet:
-
MC33166TG.pdf
- Description:
- IC REG BUCK BST ADJ 3.3A TO220-5
- Quantity:
- Payment:
- Shipping:
Inventory:2,564
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Product details
Overview
MC33166TG from onsemi is a monolithic 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, high-gain error amplifier with 5.05 V ±2% reference, latching PWM controller, and 3.0 A output switch - enabling compact, low-component-count power supplies operating from 7.5 V to 40 V input in automotive and industrial environments.
For engineers reviewing the MC33166TG datasheet, pinout, applications, or equivalent options, key selection considerations include its −40°C to +85°C operating temperature range, cycle-by-cycle current limiting (4.3 A typ), undervoltage lockout with hysteresis (5.9 V startup / 0.9 V hysteresis), thermal shutdown, and standby mode reducing supply current to 36 µA.
Technical Context
The MC33166TG implements voltage-mode control using an internal 5.05 V reference and error amplifier with 80 dB open-loop gain and 600 kHz unity-gain bandwidth. Its oscillator delivers a fixed 72 kHz frequency via on-chip timing components, supporting up to 95% duty cycle with precise ramp-based PWM generation.
Protection architecture includes cycle-by-cycle current limiting triggered at 4.3 A (min 3.3 A), undervoltage lockout with 0.9 V hysteresis, and thermal shutdown activated near 170°C. The device operates in a 5-lead TO-220 package with heatsink tab electrically connected to Pin 3 (GND), enabling direct mounting to chassis ground for thermal management.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Oscillator Frequency | 72 kHz (fixed, internally trimmed; enables predictable EMI filtering and stable loop compensation) |
| Reference Voltage | 5.05 V ±2% (precision internal bandgap reference; sets nominal output without external divider) |
| Output Switch Current | 3.0 A continuous (supports ≥3 A load in step-down/inverting topologies; peak limit 4.3 A typical) |
| Input Voltage Range | 7.5 V to 40 V (covers 12 V/24 V automotive and industrial rails; UVLO prevents erratic start-up below 5.9 V) |
| Operating Temperature | −40°C to +85°C (qualified for extended industrial and automotive under-hood use) |
| Standby Supply Current | 36 µA at 12 V (achieved by clamping Pin 5 < 150 mV; enables ultra-low-power sleep modes) |
| Thermal Resistance θJC | 5.0°C/W (low junction-to-case resistance supports >3 W dissipation with minimal heatsink) |
Pinout & Package
MC33166TG uses a Pb-free 5-lead TO-220 package (Case 314B), with heatsink tab internally connected to Pin 3 (GND). Mounting the tab to chassis ground provides critical thermal path and EMI shielding.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 | Compensation | Output of error amplifier; connects to RC network (RF/CF) for loop stability tuning |
| Pin 2 | Switch Output | Collector of internal NPN power transistor; drives external inductor/diode in all topologies |
| Pin 3 | GND / Heatsink Tab | Power and signal ground reference; tab is electrically tied to this pin for thermal conduction |
| Pin 4 | VCC | Main power supply input (7.5–40 V); powers internal circuitry and oscillator |
| Pin 5 | Feedback | Inverting input of error amplifier; senses output via resistor divider to regulate 5.05 V reference |
Key Features
| Feature | Design Value |
|---|---|
| Fixed 72 kHz oscillator with on-chip timing | Eliminates external timing resistor/capacitor; ensures consistent switching frequency across temperature and supply |
| 5.05 V ±2% internal reference | Enables accurate 5 V output without feedback divider; compensates for typical 1% cable drop |
| 0% to 95% duty cycle range | Supports wide input-output ratios in step-down (VOUT < VIN) and inverting (VOUT = −VIN) configurations |
| Cycle-by-cycle current limiting | Protects switch during overload/short-circuit without latch-up; resets each cycle for fast recovery |
| Undervoltage lockout with hysteresis | Prevents unstable operation during brown-out; 0.9 V hysteresis avoids oscillation near threshold |
| Thermal shutdown at ~170°C | Defensive protection against sustained overtemperature; requires external heatsink for >2 W continuous dissipation |
Applications
| Automotive Body Control Module (BCM) | Industrial Programmable Logic Controller (PLC) I/O Power |
|---|---|
Use Scenario: Regulating 5 V rail from 12 V battery in vehicle door modules, lighting controllers, or seat position systems with load dumps up to 40 V. IC Role / Device Role / Timing Role: Primary step-down switching regulator controlling MOSFET gate drive; provides stable 5 V for microcontroller, CAN transceiver, and sensor interfaces. Use Value: Withstand 40 V transients, operate down to −40°C, and deliver 3 A continuously - meeting ISO 7637-2 pulse 5a requirements without external TVS. | Use Scenario: Generating isolated −12 V and +12 V auxiliary rails from 24 V DC industrial bus for analog signal conditioning and relay drivers. IC Role / Device Role / Timing Role: Voltage-inverting regulator (Figure 23) producing negative output; referenced to negative rail to maintain error amp functionality. Use Value: Eliminates need for dual-output transformer or separate inverter IC; achieves 81.2% efficiency at 1.0 A while maintaining ±0.017% load regulation. |
| Off-Line AC/DC Preconverter Stage | Brushed DC Motor Speed Control |
Use Scenario: 24 V intermediate bus generation from rectified AC line (via flyback preconverter) feeding multiple downstream MC33166TG-based point-of-load regulators. IC Role / Device Role / Timing Role: Post-regulator in distributed power architecture; accepts unregulated 24 V and delivers tightly regulated 5 V/3 A to sensitive digital loads. Use Value: Fixed 72 kHz frequency simplifies EMI filter design; 2% reference and 0.02% load regulation ensure stable MCU clocking and ADC reference accuracy. | Use Scenario: Closed-loop speed control of 12–24 V brushed motors in factory automation, using back-EMF sensing for RPM feedback. IC Role / Device Role / Timing Role: Step-down regulator modulating motor voltage; compensation pin (Pin 1) interfaced with EMF-sensing op-amp for analog feedback loop. Use Value: 95% max duty cycle enables full-speed operation at low input; cycle-by-cycle current limiting protects against stall currents up to 4.3 A. |
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 surface-mount package (Case 936A) | Preferred for commercial-grade, space-constrained PCBs; lacks extended temperature qualification | Select when ambient temperature stays within 0–70°C and SMT assembly is required |
| LM2596T-5.0 | 3 A buck regulator with 150 kHz switching, integrated diode, and different compensation scheme; no inverting capability | Limited to step-down only; simpler layout but no voltage inversion or step-up/down topology support | Choose for cost-sensitive 5 V step-down where inverting function is unnecessary and higher frequency is acceptable |
Compared with MC33166TG, MC34166D2TR4G offers identical regulation performance in a surface-mount package but sacrifices industrial temperature range, while LM2596T-5.0 simplifies design for basic buck conversion yet removes critical flexibility for inverting and multi-rail architectures.
Availability
MC33166TG is available at Aetrix Electronics and suitable for automotive body electronics, industrial PLC power supplies, off-line preconverters, and brushed motor control systems requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for MC33166TG 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 leader delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.
The MC33166TG belongs to onsemi's legacy high-voltage switching regulator product line, engineered for robust, low-cost DC-DC conversion in harsh environments where reliability, thermal resilience, and topology flexibility are critical.
FAQ
What is the maximum input voltage rating for the MC33166TG?
The MC33166TG has an absolute maximum power supply input voltage (VCC) of 40 V, with recommended operating range from 7.5 V to 40 V. This allows direct use in 12 V and 24 V automotive and industrial systems, including transient conditions per ISO 7637-2. Exceeding 40 V risks permanent damage to the internal switch and oscillator circuitry. The device incorporates undervoltage lockout to prevent operation below 5.9 V, ensuring clean start-up behavior.
Does the MC33166TG support voltage-inverting converter topologies?
Yes, the MC33166TG is explicitly designed to support voltage-inverting configurations, as documented in Figure 23 of the datasheet. It achieves this by re-referencing the IC ground pin to the negative output rail, which reverses the error amplifier inputs while maintaining regulation of the −12 V output. The device delivers 1.0 A at −12 V with 81.2% efficiency and ±0.017% load regulation - confirming functional validation in inverting mode. No external level-shifting circuitry is required beyond the grounding rearrangement.
What is the purpose of Pin 5 (Feedback) on the MC33166TG?
Pin 5 is the inverting input of the internal error amplifier and serves as the voltage feedback node for closed-loop regulation. It compares the scaled output voltage (via external resistor divider) against the internal 5.05 V reference. When used without a divider, the MC33166TG regulates to exactly 5.05 V. Adding R1/R2 enables programmable outputs (e.g., 12 V or −12 V). The pin accepts voltages from −1.0 V to +7.0 V and exhibits 0.15 µA typical input bias current - critical for minimizing divider resistor thermal noise and power loss.
How does the standby mode function on the MC33166TG?
Standby mode on the MC33166TG is activated by pulling Pin 1 (Compensation) below 150 mV, which disables the internal oscillator and PWM latch, reducing total supply current to 36 µA at 12 V. This state maintains regulation readiness while minimizing quiescent consumption - ideal for battery-backed systems or sleep-wake architectures. Recovery is immediate upon releasing Pin 1 above threshold; no reset sequence or delay is required. The feature is fully characterized across temperature and supply voltage in Figure 11 of the datasheet.
Can the MC33166TG be used in step-up (boost) converter designs?
Yes, the MC33166TG can be used in step-up applications, though not as a standalone boost controller. As shown in Figure 21, it functions as the PWM controller driving an external MOSFET (e.g., MTP3055EL) in a step-up/down configuration. This hybrid approach leverages the MC33166TG's oscillator, error amplifier, and current-limiting while offloading high-voltage switching to the external FET. The datasheet confirms 28 V/0.6 A output at 82.8% efficiency, validating practical boost capability when paired with appropriate external components.
MC33166TG Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- TO-220-5
- 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
MC33166TG FAQ
1.How can I place an order for MC33166TG through Aetrix?
Please submit a Request for Quotation (RFQ) for MC33166TG 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 MC33166TG reliable?
The price and inventory of MC33166TG are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC33166TG is usually 5 days.
3.What payment methods are accepted for MC33166TG?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC33166TG transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC33166TG?
MC33166TG orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC33166TG 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 MC33166TG?
For technical support, including MC33166TG datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC33166TG requirements.
6.How does Aetrix verify that MC33166TG is sourced from the original manufacturer or authorized distributors?
All MC33166TG 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 MC33166TG meets industry standards.
7.What is the process for return or replacement of MC33166TG?
All MC33166TG units undergo pre-shipment inspection (PSI). If there is an issue with MC33166TG, 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 MC33166TG part is unused and in its original packaging.
Return procedure for MC33166TG:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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