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Texas Instruments LM2585T-3.3/NOPB
- Part No.:
- LM2585T-3.3/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- TO-220-5 Formed Leads
- Datasheet:
-
LM2585T-3.3/NOPB.pdf
- Description:
- IC REG BST FLYBACK 3.3V TO220-5
- Quantity:
- Payment:
- Shipping:
Inventory:4,604
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Product details
Overview
LM2585T-3.3/NOPB from Texas Instruments is a monolithic step-up (boost) and flyback DC-DC converter IC featuring a 3-A NPN internal switch, 100-kHz fixed-frequency operation, ±4% system output voltage tolerance, and 4 V to 40 V input range - designed for compact, cost-effective isolated or non-isolated power supplies in industrial control and telecom infrastructure.
For engineers reviewing the LM2585T-3.3/NOPB datasheet, LM2585T-3.3/NOPB pinout, LM2585T-3.3/NOPB application, or LM2585T-3.3/NOPB equivalent, key selection considerations include its 3.3-V fixed output, thermal shutdown protection, current-mode control architecture, soft-start function, and compatibility with standard flyback transformers and boost inductors per TI's design guides.
Technical Context
The LM2585T-3.3/NOPB implements current-mode control with cycle-by-cycle current limiting, using an internal 100-kHz oscillator to drive the 3-A NPN switch. Its error amplifier compares feedback from the 3.3-V output against a precision 3.3-V reference (±1.5% over temperature), generating a compensation signal that modulates duty cycle via peak-current sensing.
Operation supports both boost and flyback topologies: in boost mode, it regulates output > VIN using external inductor/diode; in flyback mode, it enables multiple outputs with transformer isolation, leveraging the same 3-A switch and integrated undervoltage lockout (3.3 V threshold), thermal shutdown, and soft-start (11 µA start-up current).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3 V ±4% over line/load/temperature - ensures stable logic supply without external feedback resistors. |
| Input Voltage Range | 4 V to 40 V - supports wide-input industrial rails, automotive battery transients, and distributed power architectures. |
| Switch Current Rating | 3 A continuous - enables up to ~1.2 A output at 3.3 V in boost configuration (with external current limiting). |
| Switching Frequency | 100 kHz ±15% - allows use of small, standardized magnetics while balancing EMI and efficiency trade-offs. |
| Oscillator Accuracy | ±15% over temperature - sufficient for stable regulation without requiring external timing components. |
| Reference Voltage | 3.3 V ±1.5% at feedback pin - defines output accuracy baseline; measured directly at FB pin under specified conditions. |
| Soft-Start Current | 11 µA typical - controls ramp rate of output voltage during startup to limit inrush into bulk capacitors. |
Pinout & Package
LM2585T-3.3/NOPB is packaged in a 5-pin TO-220 (NDH) with exposed tab for thermal dissipation. Pin 1 = Input, Pin 2 = Ground, Pin 3 = Feedback, Pin 4 = Output Switch, Pin 5 = Compensation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 (IN) | Power Input | Accepts 4–40 V DC; connects to input capacitor and current-sense path for UVLO and supply current monitoring. |
| Pin 2 (GND) | Ground Reference | Common return for internal circuitry, switch emitter, and feedback network; requires low-inductance PCB connection. |
| Pin 3 (FB) | Feedback Input | Monitors regulated output via resistive divider (not required for fixed 3.3-V version); internally tied to 3.3-V reference. |
| Pin 4 (SW) | Switch Collector | Drives external diode/transformer primary; sustains up to 65 V; carries full switch current (3 A max). |
| Pin 5 (COMP) | Error Amplifier Output | Provides compensation node for loop stability; connects to RC network to set bandwidth and phase margin. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 3-A NPN Switch | Eliminates need for external high-current transistor; rated for 65-V blocking and 0.65-V saturation at 3 A. |
| Current-Mode Control | Enables fast transient response, inherent cycle-by-cycle current limiting, and simplified loop compensation. |
| Internal Soft-Start | Reduces input inrush current by gradually ramping COMP voltage; prevents overshoot and stress on input capacitors. |
| Thermal Shutdown & UVLO | Protects device under overload or low-input conditions: shuts down below 3.3 V input and above 150°C junction temp. |
| Fixed 3.3-V Output | Removes external resistor divider; simplifies BOM and layout for standard logic supply generation. |
Applications
| Industrial Sensor Power Supply | Telecom Line Card Boost |
|---|---|
|
Use Scenario: Powering 3.3-V RS-485 transceivers and analog front-ends from a 5-V or 12-V backplane rail in harsh industrial environments. IC Role / Device Role / Timing Role: Step-up regulator providing isolated 3.3-V rail with tight tolerance and transient immunity. Use Value: Delivers ±4% output stability across −40°C to +125°C junction temperature, reducing need for post-regulation LDOs. |
Use Scenario: Generating 3.3-V auxiliary power for FPGA configuration and management circuits on telecom line cards with 48-V input. IC Role / Device Role / Timing Role: Flyback converter enabling galvanic isolation and multiple secondary outputs from single primary winding. Use Value: Supports transformer-based multi-output designs (e.g., ±12 V + 3.3 V) using TI-recommended T7 family parts, minimizing component count. |
| Automotive Body Control Module | Legacy Equipment Voltage Upgrade |
|
Use Scenario: Upgrading 5-V microcontroller subsystems to 3.3-V operation in body control modules powered by 12-V battery with load dump transients. IC Role / Device Role / Timing Role: Robust boost regulator handling 40-V input surges while maintaining clean 3.3-V output. Use Value: Withstands 45-V absolute max input and includes undervoltage lockout (3.3 V threshold), preventing brownout operation during cranking. |
Use Scenario: Retrofitting legacy 5-V embedded systems to support modern 3.3-V peripherals without redesigning main power stage. IC Role / Device Role / Timing Role: Simple boost converter replacing linear regulators to improve efficiency and reduce thermal load. Use Value: Achieves >76% efficiency at 5-V input/0.3-A load, cutting power loss by >60% versus 78L05-based solutions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-up/flyback converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2585T-5.0/NOPB | Fixed 5-V output; identical pinout, package, and topology support; reference voltage 5.0 V ±1.5%. | Suitable where 5-V logic or interface rails are required instead of 3.3 V; no change to transformer/inductor selection needed. | Select when system requires 5-V output; shares same layout, thermal design, and external component guidelines. |
| LM2587T-3.3/NOPB | Same family, but optimized for higher efficiency in flyback mode; includes enhanced transformer drive capability and tighter reference tolerance (±1.2%). | Better suited for multi-output isolated supplies with stringent cross-regulation requirements; not recommended for simple boost. | Prefer for new flyback designs demanding improved load regulation; not drop-in compatible due to different compensation behavior. |
Compared with LM2585T-3.3/NOPB, the LM2585T-5.0/NOPB offers identical mechanical and thermal design but targets 5-V systems, while the LM2587T-3.3/NOPB improves flyback performance at the cost of reduced boost-mode flexibility - making the original optimal for cost-sensitive, single-rail 3.3-V boost applications.
Availability
LM2585T-3.3/NOPB is available at Aetrix Electronics and suitable for industrial sensor power supplies, telecom line card boost converters, automotive body control modules, and legacy equipment voltage upgrades requiring stable component supply and long-term manufacturability.
Supply support for LM2585T-3.3/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 company specializing in analog and embedded processing technologies, with leadership in power management ICs for industrial, automotive, and communications markets.
The LM2585 series was developed to simplify isolated and non-isolated DC-DC conversion for cost-sensitive, medium-power applications - emphasizing minimal external components, robust protection, and broad topology support (boost, flyback, forward).
FAQ
What topology does the LM2585T-3.3/NOPB support?
The LM2585T-3.3/NOPB supports boost (step-up), flyback, and forward converter topologies. Its internal 3-A NPN switch, current-mode control, and 100-kHz oscillator enable flexible implementation - with boost used for non-isolated >VIN outputs, and flyback for isolated or multiple-output designs. The datasheet provides verified reference circuits for all three configurations.
Does the LM2585T-3.3/NOPB require external feedback resistors?
No, the LM2585T-3.3/NOPB has an internally trimmed 3.3-V reference and fixed feedback network, eliminating external resistors. Pin 3 (FB) is internally connected to the reference; external dividers are only needed for adjustable versions. This reduces BOM count and improves output accuracy stability.
What is the maximum output current achievable with LM2585T-3.3/NOPB in boost mode?
In boost configuration, LM2585T-3.3/NOPB delivers up to ~1.2 A at 3.3 V with proper thermal management and external current limiting - since output current is not internally limited in boost mode. The 3-A switch rating and 65-V standoff allow safe operation, but output current must be externally constrained to prevent switch overstress.
How does the soft-start function operate in LM2585T-3.3/NOPB?
The LM2585T-3.3/NOPB uses a 11-µA internal current source to charge the compensation (COMP) pin capacitor, gradually increasing duty cycle during startup. This limits inrush current into output capacitors and prevents output overshoot - critical for protecting downstream logic and minimizing input supply stress.
Is LM2585T-3.3/NOPB RoHS compliant and lead-free?
Yes, LM2585T-3.3/NOPB is RoHS compliant and lead-free, as indicated by the "/NOPB" suffix per Texas Instruments' packaging nomenclature. It meets JEDEC J-STD-020 moisture sensitivity level 3 and is qualified for lead-free reflow soldering per IPC/JEDEC J-STD-020 standards.
LM2585T-3.3/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- TO-220-5 Formed Leads
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Up, Step-Up/Step-Down
- Output Configuration:
- Positive
- Topology:
- Boost, Flyback, Forward Converter
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 3.3V
- Voltage - Output (Max):
- -
- Current - Output:
- 3A (Switch)
- Frequency - Switching:
- 100kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-220-5
LM2585T-3.3/NOPB FAQ
1.How can I place an order for LM2585T-3.3/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2585T-3.3/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 LM2585T-3.3/NOPB reliable?
The price and inventory of LM2585T-3.3/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2585T-3.3/NOPB is usually 5 days.
3.What payment methods are accepted for LM2585T-3.3/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2585T-3.3/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2585T-3.3/NOPB?
LM2585T-3.3/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2585T-3.3/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 LM2585T-3.3/NOPB?
For technical support, including LM2585T-3.3/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2585T-3.3/NOPB requirements.
6.How does Aetrix verify that LM2585T-3.3/NOPB is sourced from the original manufacturer or authorized distributors?
All LM2585T-3.3/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 LM2585T-3.3/NOPB meets industry standards.
7.What is the process for return or replacement of LM2585T-3.3/NOPB?
All LM2585T-3.3/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2585T-3.3/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 LM2585T-3.3/NOPB part is unused and in its original packaging.
Return procedure for LM2585T-3.3/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM2585T-3.3/NOPB Tags
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