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Microchip Technology MIC2171BU
- Part No.:
- MIC2171BU
- Manufacturer:
- Microchip Technology
- Package:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Datasheet:
-
MIC2171BU.pdf
- Description:
- IC REG BUCK BST ADJ 2.5A TO263-5
- Quantity:
- Payment:
- Shipping:
Inventory:1,342
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Product details
Overview
MIC2171BU from Microchip Technology is a 100 kHz current-mode PWM controller IC with an integrated 65V/2.5A NPN power switch, designed for step-up, step-down, inverting, Cuk, and isolated flyback/forward topologies. It operates from 3V to 40V input, delivers up to 50W with external switch, and features internal cycle-by-cycle current limiting and 7 mA quiescent current - ideal for battery-powered handheld instruments and laptop auxiliary supplies.
For engineers reviewing the MIC2171BU datasheet, MIC2171BU pinout, MIC2171BU application, or MIC2171BU equivalent, key selection criteria include its 2.5A peak switch rating, 1.24V feedback reference, TO-263-5 package thermal performance (θJA = 45°C/W), duty cycle programmability up to 95%, and compatibility with LT1171/LM2577 socket footprints.
Technical Context
The MIC2171BU implements fixed-frequency (88–112 kHz) current-mode control using an internal 1.24V bandgap reference and transconductance error amplifier (gm = 3.0–6.0 µA/mV). Its floating switch architecture enables topology flexibility without external high-side drivers.
It integrates anti-saturation circuitry to extend usable duty cycle, employs internal 2.3V bias regulation, and supports soft-start and current-limit tailoring via the COMP pin - all while maintaining stable operation across –40°C to +85°C ambient temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Rating | 65V VBR, 2.5A peak - supports off-line boost converters up to 50W with external switch |
| Input Voltage Range | 3.0V to 40V - enables direct operation from single Li-ion to 24V industrial rails |
| Oscillator Frequency | 88–112 kHz (typ. 100 kHz) - twice LM2577 frequency, allowing smaller magnetics |
| Feedback Reference | 1.240V ±24 mV - sets output voltage accuracy via external resistor divider (R1/R2) |
| Quiescent Current | 7–9 mA - ensures >100-hour runtime in 200mA battery systems |
| Max Duty Cycle | 80–95% - accommodates wide input/output ratios in flyback and forward designs |
| Thermal Resistance | θJA = 45°C/W (TO-263-5) - requires ≥2 in² copper pour for 1.3W dissipation at 70°C ambient |
Pinout & Package
Package: 5-pin TO-263 (SMD), tab-connected to GND, rated for –40°C to +85°C ambient operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - COMP | Error amplifier output | Transconductance node for loop compensation, soft-start capacitor connection, or current limit clamping |
| 2 - FB | Inverting input of error amplifier | Connects to mid-point of R1/R2 divider; senses output voltage against 1.24V reference |
| 3 - GND | Power and signal ground | Must tie directly to input capacitor ground - single-point grounding critical for noise immunity |
| 4 - SW | Collector of internal NPN switch | Drives external inductor/transformer primary; withstands 65V transient during flyback reset |
| 5 - IN | Supply input | Accepts 3–40V DC; powers internal bias circuits and switch driver; no external bootstrap needed |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 65V/2.5A NPN switch | Eliminates external transistor in ≤50W boost/flyback designs; reduces BOM count by 3–5 components |
| Current-mode control | Removes right-half-plane zero in boost transfer function; simplifies compensation with single-pole RC network |
| Internal cycle-by-cycle current limit | Prevents switch failure during overload or short-circuit; no external sense resistor required |
| Anti-saturation diode | Enables >90% duty cycle operation by clearing base-collector charge; avoids switching delay in high-VIN/low-VOUT cases |
| TO-220/TO-263 socket compatibility | Direct drop-in replacement for LT1171/LM2577 in legacy designs; no PCB rework needed |
Applications
| Laptop Auxiliary Power Supply | Battery-Powered Handheld Instrument |
|---|---|
Use Scenario: Generating 12V/250mA from 5V USB-C or single-cell Li-ion input in portable test equipment. IC Role / Device Role / Timing Role: Primary PWM controller and power switch in non-isolated boost converter; regulates output via FB pin feedback. Use Value: 7 mA quiescent current extends battery life; 100 kHz switching allows compact 15 µH inductor and low-profile capacitors. |
Use Scenario: Providing regulated 5V/500mA output from 4–6V battery pack in digital multimeter or oscilloscope probe. IC Role / Device Role / Timing Role: Flyback controller with transformer isolation; SW pin drives primary winding; COMP pin enables voltage clamping for leakage inductance protection. Use Value: 65V switch rating handles reflected flyback spikes; TO-263 package supports automated SMT assembly and thermal relief on 2 in² copper. |
| Off-Line 50W Boost Converter | Predriver for High-Power SMPS |
Use Scenario: Stepping up 24V industrial rail to 48V bus for PoE++ or motor control interface. IC Role / Device Role / Timing Role: Main controller in discontinuous conduction mode (DCM) boost stage; FB pin monitors output; SW pin drives external MOSFET via gate driver. Use Value: Internal 2.5A switch handles startup surge; external switch option scales power beyond 50W; 95% max duty cycle supports wide VIN/VOUT ratios. |
Use Scenario: Driving gate of 100V/10A external MOSFET in high-current buck converter for server VRM or LED driver. IC Role / Device Role / Timing Role: Current-mode predriver - COMP pin sources error signal to external gate driver; SW pin unused or left open. Use Value: Transconductance COMP output provides precise current-proportional drive signal; eliminates need for separate current-sense amplifier and error amp. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switching regulator controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2577T-12/NOPB | Fixed 12V output, no adjustable FB pin; 3A switch; 52 kHz oscillator; TO-220 only | Limited to fixed-output boost; no flyback/forward support; lower frequency increases inductor size | Select when fixed 12V output suffices and board space allows larger magnetics |
| LT1171CT#PBF | 50 kHz oscillator; 4A switch; wider 3–60V input; no anti-saturation; SO-8 and TO-220 packages | Lower switching frequency; higher peak current but less thermal margin in TO-263 footprint | Choose for higher current demand where 50 kHz operation is acceptable and layout accommodates larger heat spread |
Compared with LM2577T-12/NOPB and LT1171CT#PBF, the MIC2171BU offers higher switching frequency (100 kHz vs. ≤52 kHz), adjustable output via FB pin, integrated anti-saturation, and TO-263 packaging - enabling smaller passive components, broader topology support, and automated assembly in space-constrained battery-powered systems.
Availability
MIC2171BU is available at Aetrix Electronics and suitable for laptop auxiliary power supplies, battery-operated handheld instruments, and off-line 50W boost converters requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.
Supply support for MIC2171BU 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
Microchip Technology is a global semiconductor company specializing in microcontrollers, analog devices, and power management ICs, with design centers across the Americas, Europe, and Asia.
The MIC2171BU belongs to Microchip's legacy high-voltage switching regulator controller product line, engineered for robustness in portable, industrial, and off-line power conversion where integration, thermal efficiency, and topology flexibility are critical.
FAQ
What is the maximum output power achievable with MIC2171BU in boost configuration?
The MIC2171BU supports up to 50W output in boost topology when used with an external power switch. With its internal 2.5A/65V NPN switch, typical applications deliver ≤25W continuously - verified by thermal calculations showing 1.3W total dissipation at 70°C ambient with proper TO-263 copper pour. Exceeding this requires external MOSFET drive via the COMP pin.
Can MIC2171BU be used in flyback topology with transformer isolation?
Yes, MIC2171BU is explicitly validated for flyback operation per its datasheet Typical Application Circuits and Section 5.6. Its floating switch architecture and 65V VBR rating accommodate reflected voltage spikes. Designers must add a voltage clipper (D1/R4/C3) if transformer leakage inductance exceeds safe limits to prevent second breakdown of the internal switch.
What is the purpose of the COMP pin on MIC2171BU, and how is it used in practice?
The COMP pin on MIC2171BU is the output of a transconductance-type error amplifier. It serves three key functions: (1) loop compensation via RC network to GND or FB, (2) soft-start control using a diode-capacitor network, and (3) current limit adjustment via external voltage clamp. Its high output impedance enables easy external clamping without loading the amplifier.
Does MIC2171BU require an external bootstrap capacitor for high-side drive?
No, MIC2171BU does not require an external bootstrap capacitor. Its internal NPN power switch uses grounded-emitter configuration with collector output (SW pin), eliminating the need for high-side floating supply. The internal 2.3V bias regulator powers all control circuitry directly from the IN pin, supporting operation down to 2.7V input.
How does MIC2171BU differ from LM2577 in terms of frequency and efficiency?
MIC2171BU operates at 100 kHz - twice the 52 kHz frequency of LM2577 - enabling ~40% smaller inductors and output capacitors. Its current-mode architecture also improves line regulation (0.6%/V vs. LM2577's ~1.5%/V) and eliminates the need for slope compensation, reducing component count and improving transient response in variable-input applications.
MIC2171BU Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Packaging:
- Tube
- Product Status:
- Obsolete
- Function:
- Step-Up, Step-Down, Step-Up/Step-Down
- Output Configuration:
- Positive or Negative, Isolation Capable
- Topology:
- Buck, Boost, Cuk, Flyback, Forward Converter
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- -
- Voltage - Output (Max):
- 65V (Switch)
- Current - Output:
- 2.5A (Switch)
- Frequency - Switching:
- 100kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- TO-263-5
MIC2171BU FAQ
1.How can I place an order for MIC2171BU through Aetrix?
Please submit a Request for Quotation (RFQ) for MIC2171BU 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 MIC2171BU reliable?
The price and inventory of MIC2171BU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MIC2171BU is usually 5 days.
3.What payment methods are accepted for MIC2171BU?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MIC2171BU transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MIC2171BU?
MIC2171BU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MIC2171BU 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 MIC2171BU?
For technical support, including MIC2171BU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MIC2171BU requirements.
6.How does Aetrix verify that MIC2171BU is sourced from the original manufacturer or authorized distributors?
All MIC2171BU 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 MIC2171BU meets industry standards.
7.What is the process for return or replacement of MIC2171BU?
All MIC2171BU units undergo pre-shipment inspection (PSI). If there is an issue with MIC2171BU, 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 MIC2171BU part is unused and in its original packaging.
Return procedure for MIC2171BU:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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