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Microchip Technology LM2575BU
- Part No.:
- LM2575BU
- Manufacturer:
- Microchip Technology
- Package:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Datasheet:
-
LM2575BU.pdf
- Description:
- IC REG BUCK ADJ 1A TO263-5
- Quantity:
- Payment:
- Shipping:
Inventory:3,524
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Product details
Overview
LM2575BU from Micrel is an adjustable-output 1A step-down (buck) switching regulator in a 5-pin TO-263 package, operating at a fixed 52kHz switching frequency with ±2% feedback voltage accuracy, 4V–40V input range, and 1.23V–37V output range - used in compact DC/DC converters for industrial power supplies and embedded systems.
For engineers reviewing the LM2575BU datasheet, LM2575BU pinout, LM2575BU application, or LM2575BU equivalent, key selection criteria include guaranteed 1A output current, thermal shutdown and cycle-by-cycle current limiting, low standby current (<200µA), compatibility with standard off-the-shelf inductors, and TO-263 thermal performance (θJA = 45°C/W with 4 in² copper).
Technical Context
The LM2575BU integrates a 52kHz oscillator, fixed-gain error amplifier, bandgap reference (1.23V), PWM comparator, and 1A NPN switch driver. Its internal compensation eliminates external compensation components, enabling stable operation with only four external parts: input capacitor, output capacitor, catch diode, and inductor.
It features ON/OFF control via pin 5 (logic-compatible with TTL/CMOS), cycle-by-cycle current limiting (1.7–3.2A peak), thermal shutdown at ~150°C junction temperature, and internal regulator for biasing - all implemented in monolithic bipolar process technology optimized for cost-sensitive buck conversion.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | Guaranteed 1A continuous load current - supports single-rail power delivery without external current boosting. |
| Input Voltage Range | 4V to 40V - enables direct use with 12V/24V industrial buses, automotive batteries (with transient protection), and unregulated AC/DC outputs. |
| Output Voltage Range | 1.23V to 37V - set externally via resistor divider on FB pin; supports custom regulation points across wide system requirements. |
| Feedback Voltage Accuracy | ±2% over full temperature and load range - ensures tight output regulation without trimming, critical for precision analog or digital supply rails. |
| Switching Frequency | 52kHz ±10% - balances EMI control, inductor size, and efficiency; compatible with low-cost, high-saturation-current off-the-shelf inductors. |
| Standby Quiescent Current | <200µA when ON/OFF pin = 5V - enables low-power sleep modes in battery-backed or energy-conscious applications. |
| Thermal Resistance (θJA) | 45°C/W with 4 in² PCB copper - allows full 1A operation without heatsink under typical industrial ambient conditions (TA ≤ 75°C). |
Pinout & Package
LM2575BU uses a 5-pin TO-263 (D2Pak) surface-mount package with exposed tab for thermal conduction. The tab is electrically connected to Pin 3 (GND).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1: VIN | Input supply connection | Accepts 4V–40V unregulated DC; requires local 100µF input capacitor for ESR and surge current handling. |
| 2: OUT | Switch node / power output | Drives external catch diode and inductor; high dv/dt node requiring short PCB trace routing to minimize EMI. |
| 3: GND | Power ground / thermal pad | Primary return path for high-current loops; tab must be soldered to ≥4 in² copper pour for thermal performance. |
| 4: FB | Feedback input | Monitors output via resistor divider; 1.23V reference sets VOUT = 1.23V × (1 + R2/R1); bias current ≤500nA. |
| 5: ON/OFF | Enable/disable control | Logic-high (>2.2V) enables regulation; logic-low (<0.8V) disables switch and reduces IQ to <200µA. |
Key Features
| Feature | Design Value |
|---|---|
| Fixed-frequency 52kHz oscillator | Enables predictable EMI filtering and consistent inductor sizing - avoids variable-frequency jitter and layout sensitivity of hysteretic regulators. |
| Internal frequency compensation | Eliminates need for external compensation network - reduces BOM count and design iteration time for stable loop response. |
| Cycle-by-cycle current limiting | Protects switch and external components during overload or short-circuit; limits peak inductor current to 1.7–3.2A independent of duty cycle. |
| Thermal shutdown | Automatically disables output above ~150°C junction temperature - prevents permanent damage during sustained overload or poor heatsinking. |
| Low quiescent current in standby | Reduces system-level power loss during idle states - critical for always-on monitoring circuits or battery-buffered backup supplies. |
Applications
| Industrial DC/DC Conversion | Embedded System Pre-regulation |
|---|---|
|
Use Scenario: Converting 24V factory bus to 5V/3.3V for PLC I/O modules and sensor interfaces. IC Role / Device Role / Timing Role: Primary buck regulator providing isolated, efficient, and thermally robust 1A output rail. Use Value: Eliminates need for heatsink while maintaining >80% efficiency across 10–30V input variation and 0–1A load steps. |
Use Scenario: Generating clean 3.3V from noisy 12V board supply for microcontroller and ADC subsystems. IC Role / Device Role / Timing Role: Pre-regulator stepping down before low-noise LDOs - reducing LDO thermal stress and dropout requirements. Use Value: Reduces pre-LDO power dissipation by >70% compared to linear regulation, extending board lifetime and reliability. |
| On-Card Switching Supply | Inverting Buck-Boost Converter |
|
Use Scenario: Local 12V-to-5V conversion on dense PCBs where space and thermal management are constrained. IC Role / Device Role / Timing Role: Compact, self-contained buck controller with minimal external component count (4 parts total). Use Value: Achieves full 1A output in TO-263 footprint with no external compensation or timing capacitors - accelerating layout and validation. |
Use Scenario: Generating –5V from +12V for op-amp biasing or RS-232 interface circuitry. IC Role / Device Role / Timing Role: Configured as inverting buck-boost using same external components as buck mode. Use Value: Delivers regulated negative output without dedicated inverting IC - leveraging existing LM2575BU inventory and layout reuse. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2575T-5.0 | Fixed 5V output; TO-220 package; θJA = 65°C/W (no PCB copper benefit); same 52kHz frequency and protection features. | Eliminates feedback resistors but lacks output flexibility; less suitable for multi-voltage designs or prototyping. | Select when 5V-only output and through-hole assembly are required; verify thermal margin at 1A with heatsink. |
| LM2596S-ADJ | Higher 150kHz frequency; 3A rating; wider 4.5–40V input; improved efficiency (~88% at 1A); SO-8 package with exposed pad. | Better suited for higher-density layouts and higher-efficiency demands, but requires different inductor value and layout rules. | Choose for new designs needing higher current headroom or better thermal performance in SMT format; not drop-in compatible. |
Compared with LM2575T-5.0, LM2575BU offers output adjustability and superior thermal performance on PCB; versus LM2596S-ADJ, it trades higher current and frequency for proven legacy stability, simpler magnetics, and lower EMI susceptibility at 52kHz.
Availability
LM2575BU is available at Aetrix Electronics and suitable for industrial power supplies, embedded system pre-regulators, and on-card DC/DC converters requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.
Supply support for LM2575BU 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
Micrel Inc. was a U.S.-based semiconductor company specializing in analog, power management, and timing solutions before its acquisition by Microchip Technology in 2015. It emphasized high-reliability, cost-optimized integrated power ICs.
The LM2575BU belongs to Micrel's LM2575 series of monolithic buck regulators designed for simple, robust, and thermally efficient step-down conversion in industrial, telecom, and embedded applications - prioritizing ease of use and minimal external component count.
FAQ
What is the maximum input voltage rating for LM2575BU?
The absolute maximum input voltage for LM2575BU is 45V, but the recommended operating range is 4V to 40V. Exceeding 40V may trigger internal protection or reduce reliability; for 42V automotive transients, external clamping is advised. LM2575BU maintains regulation and protection integrity within this 40V limit across its full temperature range.
Does LM2575BU require an external heat sink in 1A operation?
No, LM2575BU does not require an external heat sink when mounted on a PCB with ≥4 in² of copper connected to its exposed tab (Pin 3/GND), as its θJA is specified at 45°C/W under that condition. At 1A load and 25°C ambient, junction temperature rise is ~45°C - well below the 125°C max operating limit. LM2575BU's thermal design assumes proper PCB copper implementation.
Can LM2575BU be used in an inverting buck-boost configuration?
Yes, LM2575BU can be configured as an inverting buck-boost converter to generate negative output voltages - e.g., –5V from +12V - using the same inductor, diode, and capacitor as the standard buck circuit, with modified feedback and grounding. This application is explicitly documented in the LM2575BU datasheet and leverages its adjustable feedback architecture without modification to LM2575BU itself.
What is the feedback pin (FB) bias current specification for LM2575BU?
The feedback pin bias current for LM2575BU is typically 50nA, with a maximum of 500nA over temperature and line/load conditions. This low bias current minimizes resistor-divider power loss and voltage error - enabling use of high-value resistors (e.g., 1kΩ + 3.09kΩ for 5V) without compromising regulation accuracy. LM2575BU's FB pin directly references the internal 1.23V bandgap, ensuring stable setpoint behavior.
How does the ON/OFF pin function on LM2575BU?
The ON/OFF pin (Pin 5) of LM2575BU enables logic-level control: applying ≥2.2V (VIH min) turns the regulator on, while ≤0.8V (VIL max) disables switching and reduces quiescent current to <200µA. The pin draws ≤30µA in OFF state and ≤10µA in ON state. LM2575BU retains output capacitor charge during disable but ceases regulation - ideal for system-level power sequencing and standby modes.
LM2575BU Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 1.23V
- Voltage - Output (Max):
- 37V
- Current - Output:
- 1A
- Frequency - Switching:
- 52kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- TO-263-5
LM2575BU FAQ
1.How can I place an order for LM2575BU through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2575BU 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 LM2575BU reliable?
The price and inventory of LM2575BU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2575BU is usually 5 days.
3.What payment methods are accepted for LM2575BU?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2575BU transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2575BU?
LM2575BU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2575BU 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 LM2575BU?
For technical support, including LM2575BU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2575BU requirements.
6.How does Aetrix verify that LM2575BU is sourced from the original manufacturer or authorized distributors?
All LM2575BU 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 LM2575BU meets industry standards.
7.What is the process for return or replacement of LM2575BU?
All LM2575BU units undergo pre-shipment inspection (PSI). If there is an issue with LM2575BU, 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 LM2575BU part is unused and in its original packaging.
Return procedure for LM2575BU:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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