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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Voltage Regulators - DC DC Switching Regulators

onsemi MC33166D2TR4

Name: MC33166D2TR4
Brand: onsemi
SKU: MC33166D2TR4
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MC33166D2TR4

Manufacturer:: onsemi

Category:: Voltage Regulators - DC DC Switching Regulators

Package:: TO-263-6, D2PAK (5 Leads + Tab), TO-263BA

Datasheet:: MC33166D2TR4.pdf

Description:: IC REG BUCK BST ADJ 3.3A D2PAK-5

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Product details

Overview

MC33166D2TR4 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 3.3–6.0 A cycle-by-cycle current-limited output switch. Operates from 7.5 V to 40 V input and delivers up to 3.0 A output in D2PAK package - used in automotive power supplies and industrial DC-DC modules.

For engineers reviewing the MC33166D2TR4 datasheet, pinout, applications, or equivalent options, key selection criteria include its −40°C to +85°C operating range, internal thermal shutdown, undervoltage lockout with 0.9 V hysteresis, standby mode (36 µA ICC), and compatibility with standard flyback/boost/inverting topologies using external inductors and Schottky rectifiers.

Technical Context

The MC33166D2TR4 implements voltage-mode control with a fixed 72 kHz oscillator (62–79 kHz over temperature) and a latching PWM comparator that accepts the error amplifier output and oscillator ramp. Its internal 5.05 V reference feeds the non-inverting input of the error amplifier, which features 80 dB open-loop gain and 600 kHz unity-gain bandwidth.

Cycle-by-cycle current limiting triggers at 3.3–6.0 A (typ. 4.3 A), while undervoltage lockout activates at 5.9 V (±0.4 V) with 0.9 V hysteresis. Thermal shutdown engages at ~170°C, and standby mode reduces supply current to 36 µA when compensation pin voltage drops below 0.15 V.

Key Specifications

Parameter	Value and Actual Design Meaning
Oscillator Frequency	72 kHz nominal (62–79 kHz over −40°C to +85°C); sets minimum external component count and defines switching loss vs. size trade-off.
Reference Voltage	5.05 V ±2% at +25°C; enables precise 5.0 V output without external divider; compensates for 1% cable drop.
Output Switch Current Limit	3.3–6.0 A (typ. 4.3 A); provides cycle-by-cycle protection against inductor saturation or short-circuit faults.
Input Voltage Range	7.5 V to 40 V; supports 12 V/24 V automotive and industrial bus rails with margin for transients.
Operating Temperature	−40°C to +85°C ambient; qualified for under-hood automotive and harsh industrial environments.
Standby Supply Current	36 µA at 12 V; achieved by clamping compensation pin < 0.15 V; enables low-power sleep modes.
Undervoltage Lockout	Startup at 5.9 V ±0.4 V with 0.9 V hysteresis; prevents erratic startup during brownout conditions.

Pinout & Package

D2PAK (TO-263) surface-mount package (Case 936A), thermally enhanced with heatsink tab electrically connected to Pin 3 (GND). Moisture Sensitivity Level (MSL) = 1. Pb-free compliant.

Pin/Terminal	Circuit Role	Design Meaning
Pin 1: Compensation	Error amplifier output / loop compensation node	Connects RC network (RF, CF) for stability; soft-start implemented via 100 µA pull-up current source.
Pin 2: Switch Output	Collector of internal NPN power transistor	Drives external inductor; rated for 40 V max V_CE; requires Schottky rectifier (e.g., 1N5822) for fast recovery.
Pin 3: Ground	Power and signal reference ground	Heatsink tab connection point; must be low-impedance path to minimize thermal resistance (θ_JC = 5.0°C/W).
Pin 4: V_CC	Power supply input	Accepts 7.5–40 V; powers internal circuitry; UVLO monitors this rail; decoupling capacitor required.
Pin 5: Feedback	Error amplifier inverting input	Compares output voltage (via resistor divider) against internal 5.05 V reference; threshold = 4.95–5.15 V.

Key Features

Feature	Design Value
Fixed-frequency oscillator with on-chip timing	72 kHz operation eliminates external timing components; stable across temperature and line variations.
Internal precision reference	5.05 V ±2% reference enables accurate 5.0 V output without trimming; reduces BOM cost and calibration effort.
Cycle-by-cycle current limiting	Real-time peak-current detection protects switch during overload or short-circuit without external sense resistor.
Undervoltage lockout with hysteresis	5.9 V startup + 0.9 V hysteresis prevents oscillation near threshold; ensures clean power-on sequencing.
Low-power standby mode	36 µA quiescent current at 12 V enables energy-efficient idle states in battery-backed systems.

Applications

Automotive Power Supply	Industrial DC-DC Module
Use Scenario: Regulating 12 V battery input to stable 5.0 V for engine control unit (ECU) microcontrollers and sensors. IC Role / Device Role / Timing Role: Primary switching controller implementing step-down topology with external inductor and Schottky diode. Use Value: −40°C to +85°C rating ensures reliability under hood; 72 kHz switching balances EMI and efficiency; integrated UVLO prevents ECU reset during cranking.	Use Scenario: Generating isolated −12 V rail from 24 V industrial bus for analog front-end op-amps and ADC references. IC Role / Device Role / Timing Role: Core controller in voltage-inverting configuration per Figure 23, with ground pin tied to negative output. Use Value: Internal 5.05 V reference and error amplifier enable precise regulation; cycle-by-cycle current limit protects against field-wiring shorts.
Off-Line Preconverter Stage	Triple-Output Distributed Power
Use Scenario: AC/DC pre-regulation stage stepping down rectified line voltage to 24 V for downstream MC33166-based post-regulators. IC Role / Device Role / Timing Role: Fixed-frequency controller driving self-oscillating flyback transformer (T2) in Figure 28. Use Value: 40 V max V_CC accommodates rectified 24 VAC; 72 kHz frequency simplifies transformer design and EMI filtering.	Use Scenario: Single-input, multi-rail power system delivering +5.05 V/2.0 A, +12 V/300 mA, and −12 V/100 mA from 24 V input. IC Role / Device Role / Timing Role: Primary controller in triple-output flyback with center-tapped secondary windings (Figure 25). Use Value: 5.05 V reference ensures tight main rail accuracy; duty cycle range (0–95%) supports wide output voltage ratios across secondaries.

Automotive Power Supply

Industrial DC-DC Module

Use Scenario: Regulating 12 V battery input to stable 5.0 V for engine control unit (ECU) microcontrollers and sensors.

IC Role / Device Role / Timing Role: Primary switching controller implementing step-down topology with external inductor and Schottky diode.

Use Value: −40°C to +85°C rating ensures reliability under hood; 72 kHz switching balances EMI and efficiency; integrated UVLO prevents ECU reset during cranking.

Use Scenario: Generating isolated −12 V rail from 24 V industrial bus for analog front-end op-amps and ADC references.

IC Role / Device Role / Timing Role: Core controller in voltage-inverting configuration per Figure 23, with ground pin tied to negative output.

Use Value: Internal 5.05 V reference and error amplifier enable precise regulation; cycle-by-cycle current limit protects against field-wiring shorts.

Off-Line Preconverter Stage

Triple-Output Distributed Power

Use Scenario: AC/DC pre-regulation stage stepping down rectified line voltage to 24 V for downstream MC33166-based post-regulators.

IC Role / Device Role / Timing Role: Fixed-frequency controller driving self-oscillating flyback transformer (T2) in Figure 28.

Use Value: 40 V max V_CC accommodates rectified 24 VAC; 72 kHz frequency simplifies transformer design and EMI filtering.

Use Scenario: Single-input, multi-rail power system delivering +5.05 V/2.0 A, +12 V/300 mA, and −12 V/100 mA from 24 V input.

IC Role / Device Role / Timing Role: Primary controller in triple-output flyback with center-tapped secondary windings (Figure 25).

Use Value: 5.05 V reference ensures tight main rail accuracy; duty cycle range (0–95%) supports wide output voltage ratios across secondaries.

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 die, but rated for 0°C to +70°C ambient; identical electrical specs and pinout.	Suitable for commercial-grade systems; not qualified for extended automotive temperature range.	Select MC33166D2TR4 for −40°C to +85°C operation; choose MC34166D2TR4G only if ambient stays within 0–70°C.
LM2576-5.0	Fixed 5.0 V output (non-adjustable); 52 kHz switching; higher quiescent current (5.5 mA); no standby mode.	Lacks voltage-inverting capability; limited to step-down only; simpler layout but less topology flexibility.	Use LM2576-5.0 for cost-sensitive, single-rail 5 V applications where temperature range and topology flexibility are secondary.

Compared with MC34166D2TR4G, the MC33166D2TR4 offers extended temperature qualification critical for automotive use, while LM2576-5.0 trades topology versatility and low-power standby for lower BOM count and simplified design - making it suitable only for basic step-down needs.

Availability

MC33166D2TR4 is available at Aetrix Electronics and suitable for automotive power supplies, industrial DC-DC modules, off-line preconverters, and multi-output distributed power systems requiring stable component supply across extended temperature ranges.

Supply support for MC33166D2TR4 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 focused on energy-efficient innovation for automotive, industrial, cloud, and IoT applications.

The MC33166 series was engineered for robust, low-component-count dc-dc conversion in demanding environments - emphasizing thermal resilience, wide input range, and topology flexibility across step-down, inverting, and step-up/down configurations.

FAQ

What is the maximum input voltage supported by the MC33166D2TR4?

The MC33166D2TR4 supports a maximum power supply input voltage (V_CC) of 40 V, as specified in the Absolute Maximum Ratings table. This allows direct operation from 24 V industrial buses or 12 V automotive systems with transient margin. Exceeding 40 V risks permanent damage. The device also features undervoltage lockout that disables operation below ~5.9 V to prevent unstable startup.

Does the MC33166D2TR4 require an external feedback resistor divider for 5.0 V output?

No - the MC33166D2TR4 provides a factory-trimmed 5.05 V ±2% internal reference, enabling precise 5.0 V output without any external resistor divider. This is explicitly stated in the datasheet's Features section and confirmed in Figure 14 and Application Note Figure 19. An external divider is only needed if the target output voltage exceeds 5.05 V.

What package type and thermal characteristics does the MC33166D2TR4 use?

The MC33166D2TR4 uses the D2PAK (TO-263) surface-mount package (Case 936A), with the metal tab electrically connected to Pin 3 (GND) for heatsinking. Its thermal resistance is θ_JC = 5.0°C/W and θ_JA = 70°C/W (at +25°C ambient on standard PCB). MSL rating is Level 1, indicating unlimited floor life at ≤30°C/60% RH.

Can the MC33166D2TR4 be used in voltage-inverting configurations?

Yes - the MC33166D2TR4 is explicitly designed for voltage-inverting applications, as detailed in Figure 23 and Section "Voltage-Inverting Converter". It achieves this by connecting the IC's ground pin to the negative output rail, reversing error amplifier polarity while maintaining regulation via the internal 5.05 V reference. A Schottky rectifier (e.g., 1N5822) is mandatory for efficiency.

What is the purpose of the Compensation pin (Pin 1) on the MC33166D2TR4?

Pin 1 (Compensation) is the output of the internal error amplifier and serves as the loop compensation node. It connects to an external RC network (R_F, C_F) to stabilize the feedback loop across operating conditions. It also hosts a 100 µA pull-up current source used for soft-start - charging an external capacitor to gradually ramp the output voltage and limit inrush current.

MC33166D2TR4 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:: -40°C ~ 85°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: D2PAK-5

MC33166D2TR4 FAQ

1.How can I place an order for MC33166D2TR4 through Aetrix?

Please submit a Request for Quotation (RFQ) for MC33166D2TR4 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 MC33166D2TR4 reliable?

The price and inventory of MC33166D2TR4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC33166D2TR4 is usually 5 days.

3.What payment methods are accepted for MC33166D2TR4?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC33166D2TR4 transactions.

Note: Certain payment methods may incur a processing fee.

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MC33166D2TR4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MC33166D2TR4 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 MC33166D2TR4?

For technical support, including MC33166D2TR4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC33166D2TR4 requirements.

6.How does Aetrix verify that MC33166D2TR4 is sourced from the original manufacturer or authorized distributors?

All MC33166D2TR4 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 MC33166D2TR4 meets industry standards.

7.What is the process for return or replacement of MC33166D2TR4?

All MC33166D2TR4 units undergo pre-shipment inspection (PSI). If there is an issue with MC33166D2TR4, 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 MC33166D2TR4 part is unused and in its original packaging.

Return procedure for MC33166D2TR4:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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