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Texas Instruments LM2577S-12/NOPB
- Part No.:
- LM2577S-12/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Datasheet:
-
LM2577S-12/NOPB.pdf
- Description:
- IC REG BST FLYBACK 12V 3A TO263
- Quantity:
- Payment:
- Shipping:
Inventory:1,870
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Product details
Overview
LM2577S-12/NOPB 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 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, battery-powered instrumentation, and distributed DC-DC conversion.
For engineers reviewing the LM2577S-12/NOPB datasheet, LM2577S-12/NOPB pinout, LM2577S-12/NOPB application, or LM2577S-12/NOPB equivalent, key selection criteria include its TO-263-5 surface-mount package, 12 V ±4% output tolerance over temperature and load, 37°C/W junction-to-ambient thermal resistance with 1 in² copper, and compatibility with standard off-the-shelf boost inductors (e.g., AIE L47–L680 series).
Technical Context
The LM2577S-12/NOPB implements current-mode control using an internal error amplifier (transconductance = 370 μmho, gain = 80 V/V), reference voltage (12.0 V at feedback pin), and comparator that terminates switch-on time based on sensed inductor current. Its 52 kHz fixed-frequency oscillator eliminates external timing components and enables predictable EMI filtering.
It integrates protection circuitry including undervoltage lockout (2.70–3.15 V threshold), thermal shutdown, and switch current limiting (3.0 A typical, 3.7–6.0 A min/max). The device supports boost, flyback, and forward topologies but requires external diode, inductor, and input/output capacitors per Figure 8 of SNOS658C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 12.0 V (11.40–12.60 V over full temp/load range); eliminates need for external feedback resistors. |
| Input Voltage Range | 3.5 V to 40 V; supports wide-range battery inputs (e.g., 4×AA, 12 V lead-acid, 24 V industrial rails). |
| Switch Current Limit | 3.0 A typical (3.7–6.0 A min/max); defines maximum peak inductor current and sets practical output power ceiling (~10 W at 12 V). |
| Oscillator Frequency | 52 kHz (42–62 kHz over temp); enables use of low-cost, high-saturation-current inductors and reduces EMI filter complexity. |
| Thermal Resistance θJA | 37°C/W with 1 in² PCB copper; determines max continuous output power before thermal shutdown (≈5.4 W @ TJ = 125°C, TA = 50°C). |
| Efficiency | 80% typical at 5 VIN, 800 mA load; reflects conduction and switching losses in integrated NPN switch and external diode/inductor. |
| Undervoltage Lockout | 2.70–3.15 V threshold; prevents erratic startup and ensures stable operation during brownout or cold-cranking conditions. |
Pinout & Package
LM2577S-12/NOPB uses the TO-263-5 (TS5B) surface-mount package: thermally enhanced 5-pin D2PAK variant with exposed metal tab for heatsinking. Pin 1 is Input (VIN), Pin 2 is Ground (GND), Pin 3 is Feedback (FB), Pin 4 is Output Switch (SW), Pin 5 is Output (VOUT). The tab is electrically connected to Pin 2 (GND).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (VIN) | Input supply connection | Accepts 3.5–40 V DC; must be bypassed with ≥100 μF low-ESR capacitor near pin to suppress ripple and support peak switch current. |
| 2 (GND) | Power and signal ground reference | Common return for internal circuits, switch emitter, and thermal pad; requires low-impedance PCB plane connection for stability and thermal performance. |
| 3 (FB) | Feedback input | Internally tied to 12 V reference; shorted directly to VOUT for fixed-output operation-no external resistor divider needed. |
| 4 (SW) | NPN collector output switch | Drives external boost diode and inductor; switches at 52 kHz; must be routed with minimal loop area to reduce EMI and voltage spikes. |
| 5 (VOUT) | Regulated output | Delivers 12 V to load; requires ≥680 μF electrolytic output capacitor (per Figure 8) to limit ripple and sustain transient loads. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 3.0 A NPN switch | Reduces BOM count by eliminating external transistor; rated for 65 V standoff, enabling 12 V output from ≤40 V input with margin. |
| Current-mode control | Provides inherent cycle-by-cycle current limiting, improves line/load transient response, and simplifies loop compensation vs. voltage-mode designs. |
| Soft-start function | Internal 5 μA current source ramps compensation pin voltage, limiting inrush current during startup and preventing output overshoot. |
| 52 kHz fixed-frequency oscillator | Eliminates external timing components; enables predictable EMI spectrum placement and simplifies filter design for conducted emissions compliance. |
| Thermal shutdown + UVLO | Protects against sustained overload, poor heatsinking, or low-input conditions-prevents latch-up or silicon damage without external circuitry. |
Applications
| Industrial Sensor Power Supply | Portable Test Equipment |
|---|---|
|
Use Scenario: Powering 12 V analog front-end circuits (op-amps, ADCs, transducers) from a single 9 V alkaline or Li-ion cell in handheld meters. IC Role / Device Role / Timing Role: Step-up regulator providing regulated 12 V rail; 52 kHz switching frequency allows compact LC filter design. Use Value: Enables high-precision analog measurement without requiring dual-supply rails or bulky transformers-extends battery life via 80% efficiency at mid-load. |
Use Scenario: Generating stable 12 V for microcontroller peripherals (LCD backlight, SD card interface, USB PHY) in field-deployable diagnostic tools. IC Role / Device Role / Timing Role: Primary DC-DC converter in battery-backed system; current-mode control maintains regulation during rapid load transients (e.g., LCD turn-on). Use Value: Integrated protection prevents field failure due to accidental short-circuit or low-battery brownout-reduces need for external supervision ICs. |
| Automotive Accessory Module | Distributed Control Node |
|
Use Scenario: Providing isolated 12 V supply for CAN transceiver and microcontroller in body-control modules powered from vehicle 12 V battery (9–16 V nominal, down to 6 V during cranking). IC Role / Device Role / Timing Role: Input-stage boost regulator ensuring stable 12 V output during cold-crank events; UVLO prevents malfunction below 2.7 V. Use Value: Maintains CAN communication integrity across full automotive voltage range without external pre-regulator-reduces system cost and footprint. |
Use Scenario: Local 12 V power for remote I/O modules in factory automation systems fed from 24 V DC backbone. IC Role / Device Role / Timing Role: Distributed point-of-load regulator; TO-263 package enables direct mounting to heatsink or copper pour for reliable 5+ W operation. Use Value: Eliminates need for centralized 12 V supply and long, lossy distribution traces-improves voltage regulation at load and simplifies system wiring. |
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-12/NOPB | Same die, TO-220-5 through-hole package; θJA = 65°C/W (no thermal pad); higher thermal resistance limits continuous output power. | Suitable for prototyping or low-power (<3 W), non-automated assembly where manual soldering is preferred. | Select LM2577T-12/NOPB only when board space permits larger footprint and thermal management relies on heatsink mounting rather than PCB copper. |
| LM2577M-12/NOPB | Same die, 24-pin surface-mount SOIC package; no exposed thermal pad; θJA = 100°C/W-significantly lower power handling capability. | Applicable only in ultra-low-power, space-constrained designs where <1.5 W output is sufficient and thermal performance is secondary. | Choose LM2577M-12/NOPB only if PCB layout constraints prohibit D2PAK mounting and thermal derating is acceptable. |
Compared with LM2577T-12/NOPB and LM2577M-12/NOPB, the LM2577S-12/NOPB offers optimal thermal performance (37°C/W) and power density for production SMT designs-enabling 5+ W continuous output without external heatsinks while maintaining identical electrical behavior and pin compatibility within the LM2577 family.
Availability
LM2577S-12/NOPB is available at Aetrix Electronics and suitable for industrial sensor power supplies, portable test equipment, and automotive accessory modules requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for LM2577S-12/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, embedded processing, and power management technologies with over 50 years of innovation in power conversion ICs.
The LM2577 product line delivers cost-effective, easy-to-use step-up regulators targeting industrial, automotive, and consumer applications where simplicity, reliability, and wide input range are critical.
FAQ
What is the maximum continuous output current supported by LM2577S-12/NOPB?
The LM2577S-12/NOPB supports up to 800 mA continuous output current under typical conditions (5 V input, 25°C ambient, 1 in² PCB copper). Actual current depends on input voltage, ambient temperature, and thermal layout-derate to ~500 mA at 40 V input or 50°C ambient to maintain junction temperature below 125°C. The internal 3.0 A switch current limit sets the absolute peak, but sustained current is thermally constrained.
Does LM2577S-12/NOPB require external feedback resistors?
No. The LM2577S-12/NOPB has an internally trimmed 12 V reference connected to the FB pin. For fixed 12 V operation, the FB pin is directly connected to the VOUT pin-no external resistors are required. This simplifies design, improves accuracy (±4% over temp/load), and eliminates resistor tolerance and drift errors inherent in adjustable versions.
Can LM2577S-12/NOPB be used in flyback or forward converter topologies?
Yes. The LM2577S-12/NOPB is explicitly designed for boost, flyback, and forward converter applications per its datasheet (SNOS658C). In flyback mode, it drives the primary winding with the SW pin while the secondary provides isolated output; in forward mode, it controls the main switch with reset winding management. External transformer selection and snubber design are required per topology.
What is the recommended minimum output capacitance for LM2577S-12/NOPB?
The datasheet specifies a minimum 680 μF electrolytic capacitor (e.g., Sprague 673D, 20 V rating) at the VOUT pin for stable operation and low ripple. Lower values increase output voltage ripple and may cause instability under dynamic load. Use low-ESR types and place the capacitor as close as possible to the VOUT and GND pins to minimize loop inductance.
How does the soft-start function operate in LM2577S-12/NOPB?
The LM2577S-12/NOPB incorporates an internal 5 μA soft-start current source that charges the compensation (COMP) pin capacitor, gradually increasing duty cycle at startup. This limits inrush current into the output capacitor, prevents output overshoot, and avoids triggering input supply current limits-critical for battery-powered and shared-rail systems.
LM2577S-12/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:
- 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:
- Surface Mount
- Supplier Device Package:
- TO-263 (DDPAK-5)
LM2577S-12/NOPB FAQ
1.How can I place an order for LM2577S-12/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2577S-12/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-12/NOPB reliable?
The price and inventory of LM2577S-12/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-12/NOPB is usually 5 days.
3.What payment methods are accepted for LM2577S-12/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2577S-12/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2577S-12/NOPB?
LM2577S-12/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2577S-12/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-12/NOPB?
For technical support, including LM2577S-12/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2577S-12/NOPB requirements.
6.How does Aetrix verify that LM2577S-12/NOPB is sourced from the original manufacturer or authorized distributors?
All LM2577S-12/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-12/NOPB meets industry standards.
7.What is the process for return or replacement of LM2577S-12/NOPB?
All LM2577S-12/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2577S-12/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-12/NOPB part is unused and in its original packaging.
Return procedure for LM2577S-12/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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