My Inquiry
My Account
Texas Instruments LM2577S-ADJ/NOPB
- Part No.:
- LM2577S-ADJ/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Datasheet:
-
LM2577S-ADJ/NOPB.pdf
- Description:
- IC REG BST FLYBACK ADJ 3A TO263
- Quantity:
- Payment:
- Shipping:
Inventory:240
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LM2577S-ADJ/NOPB from Texas Instruments is a monolithic step-up (boost) switching voltage regulator IC featuring an integrated 3.0A NPN power switch, 52 kHz fixed-frequency oscillator, current-mode control, and adjustable output voltage via external resistor divider. It operates from 3.5V to 40V input and delivers regulated output up to 60V in boost topology, commonly used in industrial power supplies and battery-powered instrumentation where compact, efficient DC-DC conversion is required.
For engineers reviewing the LM2577S-ADJ/NOPB datasheet, LM2577S-ADJ/NOPB pinout, LM2577S-ADJ/NOPB application, or LM2577S-ADJ/NOPB equivalent, key selection criteria include its TO-263-5 surface-mount package thermal performance (θJA = 37°C/W with 1 in² copper), 1.230V internal reference accuracy (±1.3% over temperature), soft-start function for in-rush current control, and current-limit protection with thermal shutdown.
Technical Context
The LM2577S-ADJ/NOPB implements current-mode control architecture, comparing sensed switch current against an error amplifier output to regulate duty cycle. Its 52 kHz oscillator enables predictable EMI filtering and simplifies magnetics design using standardized inductors like AIE L47–H150 series.
It integrates undervoltage lockout (2.70–3.15V threshold), thermal shutdown, and switch current limiting (3.0A typical, 6.0A absolute max). The adjustable version uses a precision 1.230V reference at the feedback pin, enabling output voltages from ~1.25V to 60V via external resistive divider.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.5V to 40V - supports wide-range unregulated inputs including 12V/24V industrial rails and multi-cell battery packs. |
| Output Voltage | Adjustable (≥1.25V) - set by external R1/R2 divider; reference voltage is 1.230V ±1.3% over full temperature range. |
| Switch Current Limit | 3.0A typical - defines maximum peak inductor current; requires external current limiting in boost configuration per datasheet guidance. |
| Oscillator Frequency | 52 kHz ±8% - fixed frequency enables consistent filter design and avoids audible noise; no external timing components needed. |
| Thermal Resistance θJA | 37°C/W - measured with 1 in² PCB copper area on TO-263-5 package, enabling 2.5W+ continuous dissipation at 25°C ambient. |
| Reference Voltage Accuracy | ±1.3% (1.214V–1.246V) - determines output regulation tolerance when using high-precision feedback resistors. |
| Soft-Start Current | 5.0 μA typical - charges external capacitor to ramp output voltage linearly, reducing input surge and preventing output overshoot. |
Pinout & Package
LM2577S-ADJ/NOPB is housed in a 5-lead TO-263 (S) surface-mount package (NS package code TS5B), with exposed thermal pad for enhanced heat dissipation. Pin 1 is Input (VIN), Pin 2 is Ground (GND), Pin 3 is Feedback (FB), Pin 4 is Output Switch (SW), and Pin 5 is Output (VOUT).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (VIN) | Input Supply | Connects to unregulated DC source (3.5–40V); feeds internal bias circuitry and switch driver. |
| 2 (GND) | Power & Signal Ground | Common return for input, output, feedback, and internal circuits; must be low-impedance connection to minimize noise. |
| 3 (FB) | Feedback Input | Monitors output via resistor divider; compares to 1.230V reference to regulate duty cycle; high-impedance (100 nA bias). |
| 4 (SW) | Switch Collector | Drives external flyback diode and inductor; NPN collector node switching at 52 kHz; rated for 65V standoff. |
| 5 (VOUT) | Regulated Output | Provides filtered DC output; connects to output capacitor and load; not internally connected to SW or GND. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 3.0A NPN switch | Eliminates need for external transistor and drive circuitry; reduces BOM count and layout complexity in boost/flyback designs. |
| Current-mode control | Improves line and load transient response, enables inherent cycle-by-cycle current limiting, and simplifies loop compensation. |
| 52 kHz fixed-frequency oscillator | Enables predictable EMI spectrum and use of standard off-the-shelf inductors without custom magnetics design. |
| Soft-start function | Reduces in-rush current during startup by gradually increasing duty cycle, preventing input rail sag and output overshoot. |
| Undervoltage lockout (UVLO) | Disables operation below ~2.7V input, preventing erratic behavior during brown-out conditions and ensuring clean startup. |
Applications
| Industrial Power Supply | Battery-Powered Instrumentation |
|---|---|
|
Use Scenario: Generating stable +15V or +24V from a 9V or 12V lead-acid battery in portable test equipment. IC Role / Device Role / Timing Role: Step-up regulator controlling energy transfer via 52 kHz PWM to maintain regulated output under variable load and battery discharge. Use Value: Enables extended runtime from single battery while maintaining precise analog sensor supply voltage within ±1% tolerance. |
Use Scenario: Providing isolated +5V logic supply from a 3.7V Li-ion cell in handheld data loggers. IC Role / Device Role / Timing Role: Adjustable boost converter with soft-start, regulating output to 5.0V ±2% across 3.0–4.2V input range. Use Value: Delivers clean, low-noise 5V rail for microcontroller and ADC without requiring additional LDO post-regulation. |
| Automotive Aftermarket Lighting | Legacy System Voltage Booster |
|
Use Scenario: Driving white LED arrays from 12V vehicle bus in auxiliary lighting modules. IC Role / Device Role / Timing Role: Constant-voltage boost controller supplying up to 800 mA to LED string via external Schottky diode and inductor. Use Value: Maintains constant LED brightness across 9–16V input variation while meeting automotive thermal derating requirements. |
Use Scenario: Upgrading vintage 5V-only embedded systems to accept 12V input without redesigning power stage. IC Role / Device Role / Timing Role: Fixed-frequency boost regulator generating 5.0V from 12V rail using external R1/R2 feedback network. Use Value: Enables drop-in replacement of obsolete linear regulators with >80% efficiency and minimal board space impact. |
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 through-hole package; higher θJA (65°C/W); same electrical specs and pinout. | Suitable for prototyping or low-volume assemblies where manual soldering or heatsink mounting is preferred. | Select LM2577T-ADJ for breadboarding or thermal testing with clip-on heatsinks; LM2577S-ADJ/NOPB preferred for production SMT. |
| MC34063AP | 3.0A switch, 100 kHz oscillator, wider input range (3–40V), but lower reference accuracy (2.5V ±2%) and no integrated soft-start. | Used in cost-sensitive consumer electronics where ±2% output tolerance is acceptable and EMI filtering is less critical. | Choose MC34063AP only if 100 kHz operation and lower BOM cost outweigh need for soft-start and tighter reference tolerance. |
Compared with LM2577T-ADJ, LM2577S-ADJ/NOPB offers superior thermal performance in SMT layouts; compared with MC34063AP, it provides better output accuracy, built-in soft-start, and lower EMI due to fixed 52 kHz frequency-making it preferable for industrial and instrumentation applications demanding stability and reliability.
Availability
LM2577S-ADJ/NOPB is available at Aetrix Electronics and suitable for industrial power supplies, battery-powered instrumentation, automotive lighting modules, and legacy system upgrades requiring stable component supply and long-term manufacturability.
Supply support for LM2577S-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 is a global semiconductor leader specializing in analog and embedded processing technologies, with decades of expertise in power management ICs and industrial-grade reliability.
The LM2577 family was designed specifically for cost-effective, robust DC-DC boost, flyback, and forward converter applications in industrial, automotive, and instrumentation systems where simplicity, thermal resilience, and wide input range are critical.
FAQ
What is the maximum output voltage achievable with LM2577S-ADJ/NOPB?
The LM2577S-ADJ/NOPB supports output voltages up to 60V in boost configuration, limited by the 65V switch voltage rating and system-level constraints such as diode reverse voltage and capacitor ratings. The adjustable feedback architecture allows setting any output ≥1.25V using external resistors, with practical upper limits governed by external component selection and thermal management.
Does LM2577S-ADJ/NOPB require an external diode, and what type is recommended?
Yes, LM2577S-ADJ/NOPB requires an external flyback diode connected between the SW and VOUT pins. A Schottky diode with ≥60V PIV rating and ≥3A average current capability is recommended-such as the SB560 or MBR360-to minimize conduction loss and ensure fast recovery during 52 kHz switching.
How does the soft-start function operate in LM2577S-ADJ/NOPB?
The LM2577S-ADJ/NOPB implements soft-start by sourcing a constant 5.0 μA current into an external capacitor on the feedback pin, gradually raising the FB voltage and thus ramping the output voltage linearly. This prevents in-rush current spikes and output overshoot during startup, especially critical when driving large output capacitors or sensitive downstream loads.
Can LM2577S-ADJ/NOPB be used in flyback or forward converter topologies?
Yes, LM2577S-ADJ/NOPB is explicitly designed for flyback and forward converter configurations per its datasheet. In those topologies, the internal current limit becomes active and protects the switch, unlike in boost mode where external current limiting is required. Transformer-coupled designs enable isolated outputs and higher power density than basic boost.
What is the thermal performance difference between LM2577S-ADJ/NOPB and LM2577T-ADJ?
LM2577S-ADJ/NOPB in TO-263-5 achieves θJA = 37°C/W with 1 in² PCB copper, while LM2577T-ADJ in TO-220-5 has θJA = 65°C/W. This means LM2577S-ADJ/NOPB can dissipate ~70% more power at the same junction-to-ambient temperature rise, making it significantly more suitable for high-current or thermally constrained SMT applications.
LM2577S-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:
- Tube
- 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)
LM2577S-ADJ/NOPB FAQ
1.How can I place an order for LM2577S-ADJ/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2577S-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 LM2577S-ADJ/NOPB reliable?
The price and inventory of LM2577S-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 LM2577S-ADJ/NOPB is usually 5 days.
3.What payment methods are accepted for LM2577S-ADJ/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2577S-ADJ/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2577S-ADJ/NOPB?
LM2577S-ADJ/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2577S-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 LM2577S-ADJ/NOPB?
For technical support, including LM2577S-ADJ/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2577S-ADJ/NOPB requirements.
6.How does Aetrix verify that LM2577S-ADJ/NOPB is sourced from the original manufacturer or authorized distributors?
All LM2577S-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 LM2577S-ADJ/NOPB meets industry standards.
7.What is the process for return or replacement of LM2577S-ADJ/NOPB?
All LM2577S-ADJ/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2577S-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 LM2577S-ADJ/NOPB part is unused and in its original packaging.
Return procedure for LM2577S-ADJ/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM2577S-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…
