My Inquiry
My Account
Texas Instruments LM2577SX-ADJ/NOPB
- Part No.:
- LM2577SX-ADJ/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Datasheet:
-
LM2577SX-ADJ/NOPB.pdf
- Description:
- IC REG BST FLYBACK ADJ 3A TO263
- Quantity:
- Payment:
- Shipping:
Inventory:928
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LM2577SX-ADJ/NOPB from Texas Instruments (formerly National Semiconductor) is a monolithic step-up (boost) switching voltage regulator IC featuring an integrated 3.0A NPN power switch, 52 kHz fixed-frequency oscillator, and adjustable output via external resistor divider. It operates from 3.5V to 40V input and delivers up to 60V output with current-mode control for stable transient response in compact DC-DC converters.
For engineers reviewing the LM2577SX-ADJ/NOPB datasheet, LM2577SX-ADJ/NOPB pinout, LM2577SX-ADJ/NOPB application, or LM2577SX-ADJ/NOPB equivalent, key selection criteria include its TO-263-5 (S) package thermal performance (θJA = 37°C/W with 1 in² copper), 1.230V ±1.3% reference voltage, soft-start function, and undervoltage lockout threshold of 2.70–3.15V.
Technical Context
The LM2577SX-ADJ/NOPB implements current-mode control architecture, where the internal error amplifier compares feedback voltage against a precision 1.230V reference and modulates switch duty cycle based on sensed inductor current. Its 52 kHz oscillator enables predictable EMI filtering and simplifies magnetics design using standardized inductors like AIE L47–H2200 series.
Thermal management is defined by its TO-263-5 package: junction-to-ambient thermal resistance drops to 37°C/W with ≥1 in² PCB copper area, supporting continuous 3.0A switch current at ambient temperatures up to +125°C. Protection includes thermal shutdown, current limiting (3.7–6.0A), and undervoltage lockout.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.5V to 40V - supports wide-range industrial and automotive battery inputs without pre-regulation |
| Output Voltage | Adjustable via R1/R2 divider; VOUT = 1.23V × (1 + R1/R2) - enables precise regulation from ~1.5V to 60V |
| Switch Current Limit | 3.7A min / 6.0A max - defines maximum sustainable inductor peak current in boost topology |
| Oscillator Frequency | 52 kHz ±8% - fixed frequency simplifies EMI filter design and enables use of low-cost, high-saturation inductors |
| Reference Voltage | 1.230V ±1.3% (min/max over temp) - sets output accuracy baseline; line regulation ≤0.5 mV over 3.5–40V input |
| Soft-Start Current | 5.0 µA typical - controls ramp rate of duty cycle at startup to limit inrush into output capacitor |
| UVLO Threshold | 2.70V to 3.15V - prevents erratic operation during brown-out; hysteresis ensures clean turn-on/turn-off |
Pinout & Package
LM2577SX-ADJ/NOPB uses the TO-263-5 (S) surface-mount package (NS Package Number TS5B), with exposed thermal pad for enhanced heat dissipation. The 5-pin layout supports standard boost converter implementation with minimal external components.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1: Input | Power input supply connection | Accepts 3.5–40V DC; requires local 0.1 µF ceramic bypass capacitor to ground |
| Pin 2: Ground | Power and signal reference node | Must be connected to low-impedance ground plane; ties to thermal pad for thermal conduction |
| Pin 3: Feedback | Resistor-divider input to error amplifier | Senses output voltage; sets regulated VOUT = 1.23V × (1 + R1/R2); high-impedance (100 nA bias) |
| Pin 4: Output | Collector of internal NPN switch | Drives external diode/inductor node; rated for 65V off-state and 3.0A continuous switch current |
| Pin 5: Compensation | Error amplifier output for loop stabilization | Connects RC/CC network to set pole-zero for stability; also part of soft-start timing circuit (CC ≥ 0.22 µF) |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 3.0A NPN switch | Eliminates need for external transistor; reduces BOM count and layout complexity in boost/flyback designs |
| Current-mode control | Provides inherent cycle-by-cycle current limiting and superior line/load transient rejection vs. voltage-mode |
| 52 kHz fixed-frequency oscillator | Enables consistent EMI profile and compatibility with off-the-shelf inductors optimized for 50–60 kHz operation |
| Soft-start function | Prevents input surge and output overshoot during power-up by gradually increasing duty cycle via CC |
| Thermal shutdown & UVLO | Ensures safe operation under overload or low-input conditions without external protection circuitry |
Applications
| Portable Medical Instrument Power | Industrial Sensor Transmitter Supply |
|---|---|
|
Use Scenario: Battery-powered handheld blood glucose meters requiring stable 5V rail from single Li-ion cell (3.0–4.2V). IC Role / Device Role / Timing Role: Step-up regulator generating regulated 5V output with <50 mV load regulation across 10–200 mA load range. Use Value: Enables extended runtime via high efficiency (>80% at 5V/200mA) and eliminates need for dual-cell packs or linear regulators. |
Use Scenario: 4–20 mA loop-powered temperature transmitter needing isolated 12V auxiliary supply from 9–36V loop voltage. IC Role / Device Role / Timing Role: Primary boost stage feeding isolated flyback controller; provides clean, regulated 12V bias for op-amps and ADCs. Use Value: Delivers stable 12V at 150 mA with <20 mV line regulation over full input range-critical for sensor signal integrity. |
| Automotive Aftermarket Display Backlight | Legacy Industrial PLC I/O Module |
|
Use Scenario: 12V vehicle system powering white LED backlight (requiring ~24V @ 150 mA) for LCD dashboard display. IC Role / Device Role / Timing Role: Boost converter driving constant-current LED string via external MOSFET; configured for 24V output with R1/R2 divider. Use Value: Withstands cold-crank transients down to 3.5V and delivers 24V ±2% with 52 kHz switching-minimizing audible noise in cabin. |
Use Scenario: Retrofitting 24V DC-powered programmable logic controller with additional 15V analog input stage requiring low-noise supply. IC Role / Device Role / Timing Role: Non-isolated boost regulator supplying 15V/300 mA to precision op-amp front-end; uses standard AIE inductor L100. Use Value: Achieves <100 mVpp output ripple with 680 µF electrolytic output cap and meets EN 55022 Class B conducted EMI limits. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-up regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2577T-ADJ | TO-220-5 package; higher θJA (65°C/W); same electrical specs and pinout | Requires heatsink for >1.5A continuous output; less suitable for space-constrained SMT layouts | Select when through-hole assembly or manual prototyping is preferred; identical compensation and feedback design |
| TPS61088RHLR | 5-V to 12-V input; 2.2-MHz switching; integrated 12-A FET; smaller QFN package | Higher frequency enables smaller inductors/caps but increases EMI sensitivity; not drop-in compatible | Choose for modern, high-density designs needing >3A output; requires new loop compensation and layout validation |
Compared with LM2577T-ADJ, the LM2577SX-ADJ/NOPB offers superior thermal performance in SMT form factor; compared with TPS61088RHLR, it trades higher frequency and integration for proven ruggedness, lower EMI, and direct compatibility with legacy inductor libraries.
Availability
LM2577SX-ADJ/NOPB is available at Aetrix Electronics and suitable for industrial sensor transmitters, portable medical instruments, automotive display backlights, and legacy PLC I/O modules requiring stable component supply and long-term obsolescence support.
Supply support for LM2577SX-ADJ/NOPB 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 acquired National Semiconductor in 2011 and maintains full technical support, datasheets, and SPICE models for the SIMPLE SWITCHER® portfolio.
The LM2577 family was designed for cost-sensitive, robust DC-DC conversion in industrial, automotive, and instrumentation applications where reliability, wide input range, and minimal external components are critical.
FAQ
What is the maximum output voltage achievable with LM2577SX-ADJ/NOPB?
The LM2577SX-ADJ/NOPB supports output voltages up to 60V, as specified in its Absolute Maximum Ratings for output switch voltage. This limit is enforced by the internal NPN transistor's 65V breakdown rating and must be respected regardless of feedback resistor values. For reliable operation, output should remain ≤60V under all load, line, and temperature conditions.
Can LM2577SX-ADJ/NOPB operate from a 3.3V input source?
No - the LM2577SX-ADJ/NOPB has a minimum input voltage of 3.5V per its Operating Ratings. At 3.3V, the device will activate undervoltage lockout and disable switching. For 3.3V input applications, consider alternative boost regulators such as the TPS6123x series or redesign the input stage to ensure ≥3.5V under worst-case conditions.
What is the purpose of the Compensation pin (Pin 5) on LM2577SX-ADJ/NOPB?
The Compensation pin (Pin 5) serves two functions: it is the output of the internal error amplifier for loop stabilization (via RC/CC network), and it forms the soft-start timing node. A capacitor ≥0.22 µF between this pin and ground controls both the closed-loop bandwidth and the startup ramp rate, preventing output overshoot and input inrush current.
How does the thermal performance of LM2577SX-ADJ/NOPB compare to the TO-220 version?
The LM2577SX-ADJ/NOPB in TO-263-5 achieves θJA = 37°C/W with 1 in² PCB copper, versus 65°C/W for the TO-220 version. This 43% lower thermal resistance allows the S-package to sustain higher continuous output current without a heatsink - up to 3.0A at +125°C ambient - making it preferable for compact, high-power-density designs.
Is LM2577SX-ADJ/NOPB RoHS compliant and lead-free?
Yes - the /NOPB suffix explicitly indicates "No Lead (Pb)-Free" compliance per JEDEC J-STD-609. LM2577SX-ADJ/NOPB meets RoHS Directive 2011/65/EU and is manufactured with lead-free terminations and halogen-free molding compound, suitable for modern automated assembly processes.
LM2577SX-ADJ/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Up, Step-Up/Step-Down
- Output Configuration:
- Positive or Negative
- 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:
- Surface Mount
- Supplier Device Package:
- TO-263 (DDPAK-5)
LM2577SX-ADJ/NOPB FAQ
1.How can I place an order for LM2577SX-ADJ/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2577SX-ADJ/NOPB 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 LM2577SX-ADJ/NOPB reliable?
The price and inventory of LM2577SX-ADJ/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2577SX-ADJ/NOPB is usually 5 days.
3.What payment methods are accepted for LM2577SX-ADJ/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2577SX-ADJ/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2577SX-ADJ/NOPB?
LM2577SX-ADJ/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2577SX-ADJ/NOPB 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 LM2577SX-ADJ/NOPB?
For technical support, including LM2577SX-ADJ/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2577SX-ADJ/NOPB requirements.
6.How does Aetrix verify that LM2577SX-ADJ/NOPB is sourced from the original manufacturer or authorized distributors?
All LM2577SX-ADJ/NOPB 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 LM2577SX-ADJ/NOPB meets industry standards.
7.What is the process for return or replacement of LM2577SX-ADJ/NOPB?
All LM2577SX-ADJ/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2577SX-ADJ/NOPB, 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 LM2577SX-ADJ/NOPB part is unused and in its original packaging.
Return procedure for LM2577SX-ADJ/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM2577SX-ADJ/NOPB Tags
-
TPS562201DDCR
Texas Instruments
-
MC34063ABD-TR
STMicroelectronics
-
TPS561201DDCR
Texas Instruments
-
MC33063ADR
Texas Instruments
-
MC34063ADR
Texas Instruments
-
TPS560200DBVR
Texas Instruments
-
AP3012KTR-G1
Diodes Incorporated
-
TLV61048DBVR
Texas Instruments
-
AZ34063UMTR-G1
Diodes Incorporated
-
TPS562200DDCR
Texas Instruments
-
AP62300TWU-7
Diodes Incorporated
-
MC34063EBD-TR
STMicroelectronics
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
