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Texas Instruments LM2577T-ADJ
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- Part No.:
- LM2577T-ADJ
- Manufacturer:
- Texas Instruments
- Package:
- TO-220-5
- Datasheet:
-
LM2577T-ADJ.pdf
- Description:
- IC REG BST FLYBCK ADJ 3A TO220-5
- Quantity:
- Payment:
- Shipping:
Inventory:4,842
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Product details
Overview
LM2577T-ADJ from Texas Instruments is a monolithic step-up (boost) switching regulator IC featuring an integrated 3.0A NPN power switch, 52 kHz fixed-frequency oscillator, and adjustable output voltage via external resistor divider. It operates from 3.5V to 40V input, delivers up to 60V output, and includes current limiting, thermal shutdown, and undervoltage lockout. It is commonly used in battery-powered industrial sensors requiring regulated 5V/12V/24V rails from single-cell or multi-cell Li-ion or lead-acid sources.
For engineers reviewing the LM2577T-ADJ datasheet, LM2577T-ADJ pinout, LM2577T-ADJ application, or LM2577T-ADJ equivalent, key selection criteria include its adjustable feedback reference (1.230 V ±1.3%), 3.0A switch current rating, TO-220 (T) package thermal resistance (θJA = 65°C/W), and compatibility with standard flyback transformers and off-the-shelf inductors such as AIE L47–L680 series.
Technical Context
The LM2577T-ADJ implements current-mode control architecture with internal error amplifier (AVOL = 800 V/V, GM = 3700 μmho), soft-start circuitry (ISS = 5.0 μA), and fixed 52 kHz oscillator-no external timing components required. Its feedback pin accepts a resistive divider to set output voltage from ~1.23 V to 60 V, constrained by VOUT ≤ 10 × VIN(min).
It integrates protection functions including undervoltage lockout (2.90 V typical, 2.65–3.15 V range), thermal shutdown, and switch current limiting (3.7–6.0 A). The NPN switch exhibits VSAT = 0.5 V (typ) at 2.0 A and supports flyback and forward converter topologies beyond basic boost.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output topology | Adjustable step-up (boost) DC-DC converter; requires external diode, inductor, and capacitors. |
| Input voltage range | 3.5 V to 40 V; enables direct use with 5 V, 12 V, or 24 V industrial bus or battery inputs. |
| Feedback reference voltage | 1.230 V ±1.3% (min/max); sets output via R1/R2 divider; enables precise regulation across temperature. |
| Switch current rating | 3.0 A continuous (ISWITCH ≤ 3.0 A); limits peak inductor current to prevent saturation and ensure reliability. |
| Oscillator frequency | 52 kHz ±8% (42–62 kHz); fixed internal clock eliminates external timing component and simplifies layout. |
| Thermal resistance (θJA) | 65 °C/W for TO-220 (T) package; requires ≥1 in² copper pour for full 3.0 A operation at ambient ≤70 °C. |
| Protection features | Undervoltage lockout (2.65–3.15 V), thermal shutdown, and current limit-no external fault management needed. |
Pinout & Package
LM2577T-ADJ uses a 5-lead TO-220 (T) package (NS package number T05A/T05D), with the tab electrically connected to Pin 2 (Ground). Thermal performance relies on proper heatsinking of the metal tab.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1: Input | Power input | Connects to unregulated DC source (3.5–40 V); requires local 100 µF low-ESR capacitor. |
| Pin 2: Ground | Power and signal reference | Common return for input, output, feedback, and compensation; tied to metal tab for thermal conduction. |
| Pin 3: Feedback | Voltage sense input | Accepts resistor divider from output; regulates output by comparing to 1.230 V internal reference. |
| Pin 4: Output | Switch collector | Drives external diode/anode; connects to inductor; switches between VIN and open-circuit (65 V max). |
| Pin 5: Compensation | Error amplifier output | Provides access to internal transconductance amplifier output; used for loop stability compensation. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 3.0A NPN switch | Eliminates need for external high-current transistor; reduces BOM count and PCB footprint. |
| 52 kHz fixed-frequency oscillator | Enables predictable EMI profile and simplifies filter design; no external RC network required. |
| Soft-start function | Reduces inrush current during startup by gradually increasing duty cycle; prevents input rail sag and stress on input caps. |
| Current-mode control | Improves line and load transient response and inherent cycle-by-cycle current limiting for robust short-circuit protection. |
| Adjustable output (1.23 V reference) | Supports wide output range (≥1.23 V up to 60 V) using two external resistors-ideal for custom voltage rails. |
Applications
| Industrial Sensor Power Supply | Automotive Auxiliary Rail Generator |
|---|---|
|
Use Scenario: Powering 12 V analog sensor modules from a 5 V microcontroller supply in factory automation PLC I/O cards. IC Role / Device Role / Timing Role: Step-up regulator generating stable 12 V output; provides isolated, low-noise bias for op-amps and ADC references. Use Value: Eliminates need for separate 12 V wall adapter; maintains regulation across 4.5–5.5 V input variation and 10–500 mA load steps. |
Use Scenario: Generating 24 V auxiliary rail from vehicle 12 V battery for CAN transceiver bias and EEPROM programming voltage. IC Role / Device Role / Timing Role: Boost converter operating in discontinuous conduction mode; handles cold-crank dips down to 6 V input. Use Value: Delivers 24 V @ 200 mA with <50 mV load regulation and built-in UVLO prevents erratic behavior below 7 V battery. |
| Portable Medical Instrument Battery Booster | Legacy RS-232 Level Shifter Supply |
|
Use Scenario: Extending runtime of handheld pulse oximeters using single-cell Li-ion (3.0–4.2 V) to power 3.3 V MCU and 5 V analog front-end. IC Role / Device Role / Timing Role: Adjustable boost regulator configured for 5.0 V output; synchronized with MCU sleep/wake cycles via enable pin. Use Value: Achieves >80% efficiency at 300 mA load; soft-start prevents voltage droop during MCU wake-up events. |
Use Scenario: Providing ±12 V RS-232 driver supply from 3.3 V or 5 V logic rails in embedded serial gateways. IC Role / Device Role / Timing Role: Primary boost stage feeding charge-pump inverter; supplies +12 V to MAX232-type drivers. Use Value: Enables true RS-232 compliance without external transformer; supports 115.2 kbps data rates with <1% output ripple. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-up regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2577S-ADJ | TO-263 surface-mount package (θJA = 37°C/W with 1 in² copper); identical electrical specs and pinout mapping. | Better thermal performance in space-constrained PCBs; requires reflow-compatible layout and no through-hole mounting. | Select when board area is limited and thermal headroom must be maximized without external heatsink. |
| LM2587-ADJ | Higher 5 A switch rating, 100 kHz oscillator, and improved efficiency (>85% at 1 A); different pinout and compensation requirements. | Supports higher output power and tighter regulation in compact designs; not drop-in compatible due to pin rearrangement. | Choose for new designs needing >3 A output or lower EMI; redesign PCB and recalculate compensation network. |
Compared with LM2577S-ADJ, the LM2577T-ADJ offers lower assembly cost and simpler thermal management via screw-mount heatsinks, while LM2587-ADJ enables higher power density and efficiency at the expense of layout redesign and revised stability tuning.
Availability
LM2577T-ADJ is available at Aetrix Electronics and suitable for industrial sensor power supplies, automotive auxiliary rail generation, portable medical instrument battery boosters, and legacy RS-232 level shifter supplies requiring stable component supply and long-term manufacturability.
Supply support for LM2577T-ADJ 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 expertise in switching regulator design and manufacturing.
The LM2577 family was engineered for cost-sensitive, medium-power DC-DC conversion in industrial, automotive, and instrumentation applications where simplicity, reliability, and minimal external component count are critical.
FAQ
What is the minimum input voltage required for stable operation of the LM2577T-ADJ?
The LM2577T-ADJ requires a minimum input voltage of 3.5 V to maintain regulation and avoid undervoltage lockout. Its UVLO threshold is 2.90 V typical (2.65–3.15 V range), and operation below 3.5 V may cause intermittent dropout or failure to start. For reliable boost operation, ensure VIN remains ≥3.5 V under worst-case load and temperature conditions. The LM2577T-ADJ datasheet specifies this as an absolute operating limit-not a recommended design margin.
Can the LM2577T-ADJ be used in flyback or forward converter topologies?
Yes, the LM2577T-ADJ supports flyback and forward converter configurations per its official TI datasheet (SNOS658C). Its internal NPN switch, current-mode control, and protection circuitry are explicitly validated for these topologies. When used in flyback mode, output current is internally limited; in boost mode, external inductor current limiting is required. The LM2577T-ADJ block diagram and application hints confirm dual-mode capability with appropriate transformer and snubber design.
What is the maximum achievable output voltage with the LM2577T-ADJ?
The LM2577T-ADJ supports output voltages up to 60 V, as specified in its Absolute Maximum Ratings and Operating Ratings tables. However, practical output is constrained by VOUT ≤ 10 × VIN(min) and the 65 V switch voltage rating. For example, with VIN(min) = 5 V, maximum regulated output is 50 V. Exceeding 60 V risks switch breakdown; always verify VSWITCH = VOUT + VF (diode forward drop) stays ≤65 V. The LM2577T-ADJ reference design in Figure 10 validates outputs up to 28 V.
How does the soft-start function of the LM2577T-ADJ reduce in-rush current?
The LM2577T-ADJ implements soft-start by linearly ramping the internal error amplifier's output voltage (at Pin 5, Compensation), which directly controls peak switch current. This limits initial duty cycle and inductor charging rate, preventing abrupt current surges into output capacitors. Measured ISS = 5.0 μA (typ) charges the external compensation capacitor slowly, extending startup time to ~1–5 ms depending on CCOMP. This protects input sources and avoids tripping upstream fuses-critical in battery-powered LM2577T-ADJ applications.
Is the LM2577T-ADJ pin-compatible with the LM2577N-ADJ or LM2577M-ADJ variants?
No-the LM2577T-ADJ (TO-220) is not pin-compatible with LM2577N-ADJ (16-pin DIP) or LM2577M-ADJ (24-pin surface-mount), despite identical functional pin names. Pin counts, spacing, and terminal assignments differ: T-package has 5 leads; N-package has 16 pins with unused terminals; M-package has 24 pins with internal routing variations. Substitution requires full PCB redesign. Only LM2577S-ADJ (TO-263) shares identical 5-pin functional mapping and can be considered a direct surface-mount alternative to the LM2577T-ADJ.
LM2577T-ADJ 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
- Topology:
- Boost, Flyback, Forward Converter
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3.5V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 1.23V
- Voltage - Output (Max):
- 60V (Switch)
- 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-ADJ FAQ
1.How can I place an order for LM2577T-ADJ through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2577T-ADJ 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-ADJ reliable?
The price and inventory of LM2577T-ADJ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2577T-ADJ is usually 5 days.
3.What payment methods are accepted for LM2577T-ADJ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2577T-ADJ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2577T-ADJ?
LM2577T-ADJ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2577T-ADJ 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-ADJ?
For technical support, including LM2577T-ADJ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2577T-ADJ requirements.
6.How does Aetrix verify that LM2577T-ADJ is sourced from the original manufacturer or authorized distributors?
All LM2577T-ADJ 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-ADJ meets industry standards.
7.What is the process for return or replacement of LM2577T-ADJ?
All LM2577T-ADJ units undergo pre-shipment inspection (PSI). If there is an issue with LM2577T-ADJ, 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-ADJ part is unused and in its original packaging.
Return procedure for LM2577T-ADJ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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