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Texas Instruments LM2577T-12
- Part No.:
- LM2577T-12
- Manufacturer:
- Texas Instruments
- Package:
- TO-220-5
- Datasheet:
-
LM2577T-12.pdf
- Description:
- IC REG BST FLYBCK 12V 3A TO220-5
- Quantity:
- Payment:
- Shipping:
Inventory:1,945
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Product details
Overview
LM2577T-12 from Texas Instruments is a monolithic step-up (boost) switching voltage regulator with fixed 12 V output, integrated 3.0 A NPN switch, 52 kHz internal oscillator, and current-mode control architecture. It operates from 3.5 V to 40 V input, delivers up to 800 mA load current, and includes undervoltage lockout, thermal shutdown, and current limiting-used in industrial power supplies and battery-powered instrumentation where compact, low-component-count DC-DC conversion is required.
For engineers reviewing the LM2577T-12 datasheet, LM2577T-12 pinout, LM2577T-12 application, or LM2577T-12 equivalent, this page provides verified technical context, package-specific pin functions, real-world application mappings, and validated alternative options for boost converter design validation and BOM optimization.
Technical Context
The LM2577T-12 implements current-mode PWM control with a fixed 52 kHz oscillator, enabling stable regulation under varying line and load conditions. Its error amplifier compares feedback voltage against an internal 12 V reference (for -12 versions), generating a compensation signal that modulates switch duty cycle via peak-current sensing.
It integrates protection features including undervoltage lockout (2.7–3.1 V threshold), thermal shutdown, and switch current limiting (3.0 A typical, 3.7–6.0 A min/max). The NPN output switch withstands up to 65 V and exhibits 0.5–0.9 V saturation voltage at 2.0 A, supporting efficient flyback and boost topologies without external gate drivers.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 12 V ±0.4 V (min/max over temp and load), enabling direct replacement of linear regulators in 12 V rail generation. |
| Input Voltage Range | 3.5 V to 40 V - supports wide-range inputs including 5 V logic rails, 12 V batteries, and unregulated industrial supplies. |
| Switch Current Rating | 3.0 A continuous (6.0 A absolute max), defining maximum inductor peak current and limiting usable output power at low VIN. |
| Oscillator Frequency | 52 kHz (42–62 kHz over temp), setting minimum inductor size and EMI profile; fixed frequency simplifies filter design vs. variable-frequency controllers. |
| Efficiency | ≥80% at VIN = 5 V, ILOAD = 800 mA - enables thermally constrained designs without forced cooling in TO-220 packages. |
| Reference Voltage | 12 V internal (for -12 variant), eliminating external resistor divider and reducing component count versus adjustable versions. |
| Thermal Resistance (θJA) | 65 °C/W (TO-220 T package), requiring ≥1 in² copper pour for full 3.0 A operation at ambient ≤70 °C. |
Pinout & Package
LM2577T-12 is housed in a 5-lead TO-220 (T) package (NS package code T05A), with the tab electrically connected to Pin 2 (Ground). Thermal performance relies on mechanical mounting to heatsink or PCB copper area.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - Input | Power input to internal switch emitter | Connects to unregulated DC source (3.5–40 V); must be bypassed with low-ESR capacitor near pin. |
| 2 - Ground | Power and signal reference node | Tab-connected ground; requires low-inductance path to input/output capacitors and heatsink for thermal stability. |
| 3 - Feedback | Regulation sense input | Internally tied to 12 V reference; shorted directly to output for fixed-voltage operation (no external divider needed). |
| 4 - Output | Switch collector output | Drives external diode/anode; high dv/dt node requiring careful layout to minimize EMI and ringing. |
| 5 - Compensation | Error amplifier output | Used for loop compensation (RC network to ground); determines transient response and stability margin. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 3.0 A NPN switch | Eliminates need for external MOSFET and driver, reducing BOM count and board space in low-to-mid power boost converters. |
| Current-mode control | Provides inherent cycle-by-cycle current limiting, fast transient response, and simplified loop compensation vs. voltage-mode designs. |
| 52 kHz fixed-frequency oscillator | Enables predictable EMI filtering and consistent inductor sizing; avoids subharmonic oscillation issues seen in variable-frequency controllers. |
| Soft-start function | Reduces in-rush current during startup by gradually increasing duty cycle, preventing input supply sag and output overshoot. |
| Undervoltage lockout (UVLO) | Disables switching below ~2.7 V input, preventing erratic operation and protecting downstream circuitry during brownout conditions. |
Applications
| Industrial Sensor Power Supply | Portable Test Equipment |
|---|---|
|
Use Scenario: Powering 12 V analog front-end circuits (op-amps, ADCs, transducers) from single 9 V alkaline or Li-ion cells in handheld meters. IC Role / Device Role / Timing Role: Primary DC-DC boost regulator providing regulated 12 V rail with low-noise, high PSRR output for precision analog stages. Use Value: Enables extended battery life via >80% efficiency at 500 mA, while maintaining tight 12 V ±4% regulation across 6–10 V input range. |
Use Scenario: Generating isolated 12 V bias for op-amp rails and display backlight drivers in portable oscilloscopes and multimeters. IC Role / Device Role / Timing Role: Fixed-output boost controller driving coupled inductor/flyback transformer for galvanically isolated secondary winding. Use Value: Delivers clean 12 V output with <50 mV load/line regulation, minimizing measurement drift caused by supply variation. |
| Automotive Aftermarket Modules | Legacy Industrial Control Panels |
|
Use Scenario: Up-converting 12 V vehicle battery (9–16 V range) to stable 12 V for microcontroller peripherals and CAN transceivers in dash-mounted accessories. IC Role / Device Role / Timing Role: Input-tolerant boost regulator compensating for cold-crank voltage dips and alternator ripple. Use Value: UVLO prevents reset during cranking; 65 V switch rating handles load-dump transients up to 60 V without external clamping. |
Use Scenario: Replacing aging linear regulators in PLC I/O modules powered from 24 V DC bus, where heat dissipation limits upgrade paths. IC Role / Device Role / Timing Role: High-efficiency step-up converter supplying 12 V logic rails from 5 V backplane, reducing thermal load on chassis. Use Value: Cuts power loss by >65% vs. 78L12 linear regulator at 500 mA, allowing retrofit into existing enclosures without heatsink modification. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar boost regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2577S-12 | Same silicon, TO-263 surface-mount package (θJA = 37 °C/W with 1 in² copper), no through-hole leads. | Suitable for automated SMT assembly and higher-density layouts; requires thermal pad soldering and reflow profile validation. | Select when board space, assembly method, or thermal management favors SMT over through-hole TO-220. |
| LM2587T-12 | Higher 5 A switch rating, 100 kHz oscillator, improved efficiency (≥85%), but larger die and different compensation behavior. | Better suited for higher-power (>1 A) or lower-profile designs; not drop-in due to differing pinout and loop compensation requirements. | Choose for new designs needing higher output current or tighter regulation; avoid for LM2577T-12 drop-in replacement. |
Compared with LM2577S-12, the LM2577T-12 offers identical electrical performance but requires manual or wave-solder assembly and delivers higher thermal resistance; compared with LM2587T-12, it trades lower cost and proven legacy compatibility for reduced current capability and efficiency.
Availability
LM2577T-12 is available at Aetrix Electronics and suitable for industrial sensor power supplies, portable test equipment, and automotive aftermarket modules requiring stable component supply with long-term lifecycle support.
Supply support for LM2577T-12 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
Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management ICs, with decades of heritage in switching regulator innovation.
The LM2577 product line was designed for cost-sensitive, medium-power DC-DC conversion in industrial, automotive, and instrumentation applications-emphasizing simplicity, reliability, and minimal external component count.
FAQ
What is the maximum output current achievable with LM2577T-12 in a standard TO-220 layout?
The LM2577T-12 supports up to 800 mA continuous output current when mounted on a PCB with ≥1 in² copper pour and ambient temperature ≤70 °C. This limit derives from its 3.0 A switch rating, thermal resistance (θJA = 65 °C/W), and typical 80% efficiency at 5 V input. Exceeding 800 mA risks thermal shutdown or reduced regulation accuracy without enhanced heatsinking.
Can LM2577T-12 be used in flyback or forward converter topologies?
Yes, the LM2577T-12 is explicitly qualified for flyback and forward converter applications per its datasheet. Its integrated NPN switch, current-mode control, and 65 V breakdown voltage enable safe operation in isolated topologies. External transformer turns ratio and feedback configuration must match the target output voltage and isolation requirements.
Does LM2577T-12 require an external feedback resistor divider?
No. The LM2577T-12 has an internal 12 V reference connected to the Feedback pin; for fixed 12 V operation, the Feedback pin is shorted directly to the output. Only the adjustable version (LM2577T-ADJ) requires external resistors to set output voltage.
What is the purpose of the Compensation pin (Pin 5) on LM2577T-12?
The Compensation pin (Pin 5) is the output of the internal error amplifier. An RC network (typically 10 kΩ + 100 nF) is connected between this pin and ground to stabilize the control loop, prevent oscillation, and optimize transient response. Incorrect compensation can cause output instability or excessive overshoot during load steps.
How does the undervoltage lockout (UVLO) function protect LM2577T-12 during startup?
The LM2577T-12 disables switching until input voltage exceeds ~2.9 V (typical), with hysteresis ensuring clean turn-on above 3.1 V and turn-off below 2.7 V. This prevents erratic operation, output voltage collapse, or excessive switch stress during low-input conditions such as battery discharge or power-up sequencing delays.
LM2577T-12 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- TO-220-5
- Packaging:
- Tube
- Product Status:
- Obsolete
- Function:
- Step-Up, Step-Up/Step-Down
- Output Configuration:
- Positive or Negative
- Topology:
- Boost, Flyback, Forward Converter
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3.5V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 12V
- Voltage - Output (Max):
- -
- Current - Output:
- 3A (Switch)
- Frequency - Switching:
- 52kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-220-5
LM2577T-12 FAQ
1.How can I place an order for LM2577T-12 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2577T-12 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 LM2577T-12 reliable?
The price and inventory of LM2577T-12 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2577T-12 is usually 5 days.
3.What payment methods are accepted for LM2577T-12?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2577T-12 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2577T-12?
LM2577T-12 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2577T-12 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 LM2577T-12?
For technical support, including LM2577T-12 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2577T-12 requirements.
6.How does Aetrix verify that LM2577T-12 is sourced from the original manufacturer or authorized distributors?
All LM2577T-12 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 LM2577T-12 meets industry standards.
7.What is the process for return or replacement of LM2577T-12?
All LM2577T-12 units undergo pre-shipment inspection (PSI). If there is an issue with LM2577T-12, 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 LM2577T-12 part is unused and in its original packaging.
Return procedure for LM2577T-12:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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