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Texas Instruments LM2577N-ADJ
- Part No.:
- LM2577N-ADJ
- Manufacturer:
- Texas Instruments
- Package:
- 16-DIP (0.300", 7.62mm)
- Datasheet:
-
LM2577N-ADJ.pdf
- Description:
- IC REG BST FLYBACK ADJ 3A 16PDIP
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
LM2577N-ADJ 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, delivers up to 60V output, and is used in compact DC-DC boost converters for industrial power supplies and battery-powered instrumentation.
For engineers reviewing the LM2577N-ADJ datasheet, LM2577N-ADJ pinout, LM2577N-ADJ application, or LM2577N-ADJ equivalent, this page provides verified technical context, package-specific pin functions, real-world application scenarios, and validated alternative parts - all grounded in TI's SNOS658C datasheet and official package documentation for the 16-lead DIP (N16A) variant.
Technical Context
The LM2577N-ADJ implements current-mode control with an internal 1.230 V ±1.3% reference voltage at the feedback (FB) pin, enabling precise output regulation across input and load variations. Its error amplifier features 800 V/V typical open-loop gain and 3700 μmho transconductance, driving a comparator that modulates the 3.0A NPN switch duty cycle based on sensed inductor current.
It integrates undervoltage lockout (2.70–3.15 V threshold), thermal shutdown, and current limiting (3.7–6.0 A range), and uses a fixed 52 kHz oscillator requiring no external timing components. The device supports boost, flyback, and forward topologies, with soft-start reducing in-rush current during startup.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output topology | Adjustable step-up (boost) regulator - output voltage set externally via resistor divider on FB pin. |
| Input voltage range | 3.5 V to 40 V - supports wide-range industrial and battery-derived inputs (e.g., 5 V, 12 V, 24 V rails). |
| Switch rating | 3.0 A continuous NPN transistor with 65 V off-state voltage capability - enables high-voltage boost without external switch. |
| Reference voltage | 1.230 V ±1.3% at FB pin - sets output as VOUT = 1.23 × (1 + R1/R2); enables stable 5 V to 60 V outputs. |
| Oscillator frequency | 52 kHz ±8% - fixed internal clock simplifies design and ensures predictable EMI profile and inductor sizing. |
| Thermal resistance | θJA = 85 °C/W (16-pin DIP, N16A) - requires moderate PCB copper area for thermal management at full load. |
| Protection features | Undervoltage lockout (2.70–3.15 V), thermal shutdown, and current limit - prevents damage under fault conditions without external circuitry. |
Pinout & Package
LM2577N-ADJ is housed in a 16-lead plastic DIP package (NS Package Number N16A), with pins arranged in two parallel rows. The package has no internal connection on pins 9 and 16, per TI's Figure 3.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (GND) | Power ground | Primary return path for internal circuitry and switch emitter; must connect to low-impedance system ground plane. |
| 2 (FEEDBACK) | Regulation sense input | Connects to resistor divider from VOUT; compares divided voltage to 1.230 V reference to control duty cycle. |
| 3 (OUTPUT) | Switch collector output | Drives external diode and inductor; switches between VIN and floating state at 52 kHz; handles up to 3.0 A peak. |
| 4 (INPUT) | Power input | Accepts 3.5–40 V DC input; feeds internal bias circuitry and switch base drive; bypass capacitor required near pin. |
| 5 (ON/OFF) | Enable/disable control | Logic-high (>2.5 V) enables regulator; logic-low (<1.2 V) disables switch and reduces quiescent current to ~7.5 mA. |
| 6 (COMP) | Error amplifier output | Provides compensation node for external RC network to stabilize loop response and prevent oscillation. |
| 7 (VREF) | Reference voltage output | Supplies 1.230 V reference for external circuits; not used in standard boost configuration but available for monitoring. |
| 8 (NC) | No internal connection | Unbonded pin; must remain unconnected and unpopulated on PCB. |
| 9 (NC) | No internal connection | Unbonded pin; electrically isolated; no routing or soldering required. |
| 10 (GND) | Secondary ground | Dedicated ground for error amplifier and reference circuitry; tie to main GND at single point near pin 1. |
| 11 (GND) | Third ground terminal | Additional ground path for thermal and noise isolation; connects internally to substrate and should be tied to GND plane. |
| 12 (GND) | Fourth ground terminal | Redundant ground for improved thermal conduction and reduced ground bounce in high-current switching. |
| 13 (GND) | Fifth ground terminal | Supports low-impedance return for switch emitter; critical for minimizing voltage spikes during turn-off. |
| 14 (GND) | Sixth ground terminal | Completes multi-ground strategy for EMI suppression and thermal dissipation in DIP-16 layout. |
| 15 (GND) | Seventh ground terminal | Ensures robust grounding of internal protection circuitry (UVLO, thermal sensor, current limit comparator). |
| 16 (NC) | No internal connection | Unbonded; leave unconnected per TI datasheet Figure 3. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 3.0A NPN switch | Eliminates need for external power transistor, reducing BOM count and layout complexity in boost designs. |
| Current-mode control | Improves line and load transient response, simplifies loop compensation, and enables inherent cycle-by-cycle current limiting. |
| 52 kHz fixed-frequency oscillator | Enables predictable inductor selection, consistent EMI behavior, and eliminates external timing components. |
| Soft-start function | Gradually ramps output voltage during startup, limiting in-rush current into output capacitors and preventing input rail sag. |
| 1.230 V precision reference | Allows accurate, temperature-stable output voltage setting from 5 V to 60 V using only two external resistors. |
| Multi-point ground architecture | Seven dedicated GND pins in DIP-16 package reduce ground impedance, improve thermal dissipation, and suppress switching noise. |
Applications
| Industrial Power Supply | Battery-Powered Instrumentation |
|---|---|
Use Scenario: Generating 24 V from a 9 V nominal battery pack in portable test equipment. IC Role / Device Role / Timing Role: Step-up regulator controlling energy transfer via 52 kHz NPN switch and external inductor/diode. Use Value: Delivers regulated 24 V at up to 800 mA with >80% efficiency, extending battery life while maintaining stable analog front-end operation. |
Use Scenario: Boosting 3.7 V Li-ion cell output to 5 V USB-compatible power for embedded sensors. IC Role / Device Role / Timing Role: Adjustable boost converter with ON/OFF pin enabling microcontroller-controlled power sequencing. Use Value: Enables clean 5 V rail with soft-start to avoid brownout during wake-up; 1.230 V reference ensures tight output tolerance over temperature. |
| Automotive Aftermarket Module | Legacy System Voltage Translation |
Use Scenario: Converting 12 V vehicle battery to 28 V for legacy avionics interface modules. IC Role / Device Role / Timing Role: High-input-voltage boost regulator operating up to 40 V input with built-in UVLO for cold-crank immunity. Use Value: Withstands automotive load-dump transients up to 45 V supply rating and maintains regulation down to 3.5 V during cranking. |
Use Scenario: Up-converting 5 V logic rail to 12 V for driving legacy relays or op-amp biasing in retrofitted control panels. IC Role / Device Role / Timing Role: Compact, self-contained boost stage replacing discrete transistor+IC solutions. Use Value: Reduces footprint vs. discrete alternatives; integrated current limit and thermal shutdown enhance reliability in enclosed enclosures. |
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 | Same die, TO-220-5 package (T05A/T05D) with single GND pin and higher θJA (65 °C/W); no NC pins. | Better thermal performance in heatsinked applications; unsuitable for DIP-based through-hole boards requiring 16-pin footprint. | Select when board space allows heatsinking and lower assembly cost is prioritized over pin compatibility. |
| MC34063AP | Lower switch current (1.5 A), 100 kHz oscillator, different pinout and compensation scheme; requires external PNP transistor for higher current. | Cost-sensitive, lower-power boost designs (<300 mA); lacks integrated 3.0A NPN switch and soft-start. | Choose for budget-constrained, low-output-current applications where design flexibility outweighs integration benefits. |
Compared with LM2577T-ADJ, the LM2577N-ADJ offers superior ground noise isolation via seven GND pins but requires more PCB area and has higher thermal resistance; versus MC34063AP, it delivers double the switch current and integrated soft-start, simplifying high-current boost designs at the cost of higher price and larger package.
Availability
LM2577N-ADJ is available at Aetrix Electronics and suitable for industrial power supplies, battery-powered instrumentation, automotive aftermarket modules, and legacy voltage translation systems requiring stable component supply and long-term manufacturability.
Supply support for LM2577N-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 designed as a SIMPLE SWITCHER® solution for cost-effective, easy-to-use DC-DC boost, flyback, and forward converters - targeting engineers needing minimal external components and proven reliability in industrial and automotive environments.
FAQ
What is the maximum output voltage achievable with LM2577N-ADJ?
The LM2577N-ADJ supports output voltages up to 60 V, as specified in the Absolute Maximum Ratings for output switch voltage. This limit is enforced by the 65 V breakdown rating of the internal NPN transistor and applies regardless of input voltage, provided the external diode and capacitor ratings also meet or exceed this value. The LM2577N-ADJ achieves this via its 1.230 V reference and external resistor divider, making it suitable for high-voltage boost applications such as industrial sensor excitation or legacy system interfaces.
Does LM2577N-ADJ require an external diode and inductor?
Yes, the LM2577N-ADJ requires an external Schottky or fast-recovery diode and a power inductor to complete the boost converter topology. The IC integrates only the 3.0A NPN switch, oscillator, error amplifier, and protection circuitry. TI's datasheet specifies typical values (e.g., 415-0930 inductor, 680 µF/20 V output capacitor) and provides inductor selection graphs for the ADJ version. Omitting either component will prevent proper energy transfer and cause regulator failure.
How does the ON/OFF pin function on LM2577N-ADJ?
The ON/OFF pin (Pin 5) enables or disables the LM2577N-ADJ regulator: applying ≥2.5 V activates the internal circuitry and switching action, while ≤1.2 V forces the NPN switch off and reduces quiescent current to ~7.5 mA. This pin supports microcontroller-based power sequencing, standby mode, or fault shutdown. It is not a PWM input - duty-cycle control is handled internally via current-mode feedback, not external signal injection.
What is the purpose of the seven GND pins on the LM2577N-ADJ DIP package?
The seven GND pins on the LM2577N-ADJ (Pins 1, 10–15) provide low-impedance, multi-path return paths for switch emitter current, error amplifier, reference circuitry, and protection blocks. This architecture minimizes ground bounce, improves thermal conduction from the die through the package leads, and reduces EMI coupling in noisy industrial environments. TI's N16A package design intentionally separates ground functions to maintain regulation accuracy and stability under high-current switching conditions.
Can LM2577N-ADJ be used in flyback or forward converter topologies?
Yes, the LM2577N-ADJ is explicitly qualified for flyback and forward converter configurations per its datasheet description and Application Hints section. In these topologies, the internal 3.0A NPN switch drives the primary winding of a transformer, and the current-limit circuit remains effective due to direct sensing of switch current. Unlike boost mode, flyback/forward use allows internal current limiting to function fully, enabling safe operation up to the 6.0A absolute maximum switch current rating when properly implemented with appropriate transformer design and snubbing.
LM2577N-ADJ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- 16-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- 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:
- Through Hole
- Supplier Device Package:
- 16-PDIP
LM2577N-ADJ FAQ
1.How can I place an order for LM2577N-ADJ through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2577N-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 LM2577N-ADJ reliable?
The price and inventory of LM2577N-ADJ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2577N-ADJ is usually 5 days.
3.What payment methods are accepted for LM2577N-ADJ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2577N-ADJ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2577N-ADJ?
LM2577N-ADJ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2577N-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 LM2577N-ADJ?
For technical support, including LM2577N-ADJ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2577N-ADJ requirements.
6.How does Aetrix verify that LM2577N-ADJ is sourced from the original manufacturer or authorized distributors?
All LM2577N-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 LM2577N-ADJ meets industry standards.
7.What is the process for return or replacement of LM2577N-ADJ?
All LM2577N-ADJ units undergo pre-shipment inspection (PSI). If there is an issue with LM2577N-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 LM2577N-ADJ part is unused and in its original packaging.
Return procedure for LM2577N-ADJ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM2577N-ADJ Tags
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TPS562201DDCR
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TPS561201DDCR
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MC33063ADR
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MC34063EBD-TR
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