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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Voltage Regulators - DC DC Switching Regulators

Texas Instruments LM2585S-3.3/NOPB

Name: LM2585S-3.3/NOPB
Brand: Texas Instruments
SKU: LM2585S-3.3/NOPB
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: LM2585S-3.3/NOPB

Manufacturer:: Texas Instruments

Category:: Voltage Regulators - DC DC Switching Regulators

Package:: TO-263-6, D2PAK (5 Leads + Tab), TO-263BA

Datasheet:: LM2585S-3.3/NOPB.pdf

Description:: IC REG BST FLYBACK 3.3V 3A TO263

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Product details

Overview

LM2585S-3.3/NOPB from Texas Instruments is a monolithic 3-A step-up (boost) and flyback DC-DC converter IC with fixed 3.3-V output, 4-V to 40-V input range, 100-kHz fixed-frequency operation, NPN internal switch rated for 65-V standoff, and ±4% system output voltage tolerance over line and load. It serves as the core controller in isolated or non-isolated high-efficiency power supplies for industrial sensors and embedded systems requiring stable low-noise 3.3-V rails.

For engineers reviewing the LM2585S-3.3/NOPB datasheet, LM2585S-3.3/NOPB pinout, LM2585S-3.3/NOPB application, or LM2585S-3.3/NOPB equivalent, key selection criteria include its 3-A integrated NPN switch capability, current-mode control architecture for transient response, soft-start function to limit in-rush, and compatibility with standard flyback transformers and boost inductors per TI's design guides.

Technical Context

The LM2585S-3.3/NOPB implements current-mode control with an internal 100-kHz oscillator, error amplifier with 1.193 mmho transconductance and 260 V/V gain, and cycle-by-cycle current limiting. Its feedback pin references a trimmed 3.3-V internal bandgap, enabling precise regulation without external resistive dividers.

Operation supports both boost and flyback topologies: in boost mode, it regulates output voltage > VIN using external inductor/diode; in flyback mode, it drives a transformer primary with energy transfer to secondary windings, supporting single- or multi-output isolation. Undervoltage lockout activates below 3.3 V, and thermal shutdown protects at 150°C junction temperature.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	Fixed 3.3 V ±4% over full line/load/temperature range - eliminates need for external feedback divider and ensures stable logic supply for microcontrollers or FPGAs.
Input Voltage Range	4 V to 40 V - supports wide-range industrial inputs including 5-V, 12-V, 24-V, and 36-V bus systems without pre-regulation.
Switch Current Rating	3 A continuous - enables up to ~1.2 A output at 3.3 V in boost configuration (accounting for efficiency), sufficient for powering multiple digital loads.
Oscillator Frequency	100 kHz (±15%) - allows use of compact, low-cost magnetics while maintaining EMI manageability in space-constrained designs.
Reference Voltage	3.3 V at FB pin (3.242–3.358 V min/max) - defines regulation setpoint with tight tolerance, directly tied to internal bandgap and used by error amplifier for closed-loop control.
UVLO Threshold	3.30 V (3.05–3.75 V) - prevents erratic startup during brownout conditions and ensures reliable enablement only when input meets minimum operational requirement.
Efficiency	76% at VIN = 5 V, ILOAD = 0.3 A - reflects real-world performance in low-input, moderate-load boost applications typical in battery-powered instrumentation.

Pinout & Package

LM2585S-3.3/NOPB is packaged in a 5-pin DDPAK/TO-263 (KTT) thermally enhanced surface-mount package measuring 10.16 mm × 8.42 mm, optimized for PCB heat spreading and high-current switching applications.

Pin/Terminal	Circuit Role	Design Meaning
IN	Input Supply	Primary DC input connection (4–40 V); must be decoupled with low-ESR capacitor near pin to stabilize switching loop.
SW	Switch Node	Collector of internal 3-A NPN transistor; connects to inductor (boost) or transformer primary (flyback); requires careful layout to minimize ringing.
GND	Power Ground	Common return for input, output, and internal circuitry; must tie to large copper pour for thermal and noise control.
FB	Feedback Input	Senses regulated output via direct connection (for 3.3-V version); internal reference compares this to 3.3 V to adjust duty cycle.
COMP	Error Amplifier Output	Provides compensation node for external RC network to stabilize control loop; sets bandwidth and phase margin.

Key Features

Feature	Design Value
Integrated 3-A NPN Switch	Eliminates external transistor and driver, reducing BOM count and board area while maintaining 65-V blocking capability for robustness against voltage spikes.
Current-Mode Control	Enables fast transient response to load steps and inherent cycle-by-cycle current limiting, simplifying overcurrent protection design in variable-load systems.
Internal Soft-Start	Gradually ramps peak switch current at startup to limit in-rush into output capacitors-critical for preventing input rail collapse in multi-rail systems.
Thermal Shutdown & UVLO	Automatically disables switching under overtemperature (>150°C) or undervoltage (<3.05 V) conditions, protecting both IC and downstream circuitry without external supervision.
System-Level ±4% Tolerance	Guarantees final output accuracy across all operating conditions-reducing need for post-regulation LDOs in cost-sensitive industrial applications.

Applications

Industrial Sensor Power Supply	Isolated PLC I/O Module
Use Scenario: Powering 3.3-V analog front-end and microcontroller in a 24-V field-mounted pressure sensor with limited PCB space and no external cooling. IC Role / Device Role / Timing Role: Primary DC-DC controller implementing non-isolated boost topology to generate clean, regulated 3.3-V rail from 24-V supply. Use Value: Delivers 76% efficiency at light load and maintains ±4% output accuracy across −40°C to +85°C ambient, ensuring ADC reference stability and MCU reliability.	Use Scenario: Generating isolated ±12-V and 5-V rails in a programmable logic controller (PLC) I/O module powered from 24-V DC bus. IC Role / Device Role / Timing Role: Flyback controller driving transformer primary; regulates multiple secondary outputs via coupled winding design. Use Value: Enables single-chip solution for triple-output isolation with <1.4-A max 3.3-V output (per Table 1), reducing component count versus discrete controllers.
Automotive Body Control Unit	Medical Portable Diagnostic Device
Use Scenario: Providing 3.3-V logic supply in a body control module where input voltage varies from 6 V (cranking) to 16 V (charging). IC Role / Device Role / Timing Role: Step-up regulator compensating for low-battery dropout while maintaining constant output for CAN transceiver and MCU. Use Value: UVLO threshold of 3.3 V ensures controlled disable below safe operating voltage; 100-kHz switching avoids AM radio band interference.	Use Scenario: Powering low-noise analog signal chain and ARM Cortex-M4 in handheld ultrasound probe operating from single-cell Li-ion (3.0–4.2 V). IC Role / Device Role / Timing Role: Boost converter elevating battery voltage to stable 3.3-V rail; soft-start prevents audible coil whine during power-on. Use Value: Internal 3.3-V reference and current-mode control deliver <50 mV load regulation, preserving SNR in sensitive analog acquisition paths.

Industrial Sensor Power Supply

Isolated PLC I/O Module

Use Scenario: Powering 3.3-V analog front-end and microcontroller in a 24-V field-mounted pressure sensor with limited PCB space and no external cooling.

IC Role / Device Role / Timing Role: Primary DC-DC controller implementing non-isolated boost topology to generate clean, regulated 3.3-V rail from 24-V supply.

Use Value: Delivers 76% efficiency at light load and maintains ±4% output accuracy across −40°C to +85°C ambient, ensuring ADC reference stability and MCU reliability.

Use Scenario: Generating isolated ±12-V and 5-V rails in a programmable logic controller (PLC) I/O module powered from 24-V DC bus.

IC Role / Device Role / Timing Role: Flyback controller driving transformer primary; regulates multiple secondary outputs via coupled winding design.

Use Value: Enables single-chip solution for triple-output isolation with <1.4-A max 3.3-V output (per Table 1), reducing component count versus discrete controllers.

Automotive Body Control Unit

Medical Portable Diagnostic Device

Use Scenario: Providing 3.3-V logic supply in a body control module where input voltage varies from 6 V (cranking) to 16 V (charging).

IC Role / Device Role / Timing Role: Step-up regulator compensating for low-battery dropout while maintaining constant output for CAN transceiver and MCU.

Use Value: UVLO threshold of 3.3 V ensures controlled disable below safe operating voltage; 100-kHz switching avoids AM radio band interference.

Use Scenario: Powering low-noise analog signal chain and ARM Cortex-M4 in handheld ultrasound probe operating from single-cell Li-ion (3.0–4.2 V).

IC Role / Device Role / Timing Role: Boost converter elevating battery voltage to stable 3.3-V rail; soft-start prevents audible coil whine during power-on.

Use Value: Internal 3.3-V reference and current-mode control deliver <50 mV load regulation, preserving SNR in sensitive analog acquisition paths.

Equivalent & Alternatives

The following parts are listed as comparable options for similar step-up/flyback regulator applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
LM2587S-3.3/NOPB	Same pinout and 3.3-V output, but includes integrated diode and higher 5-A switch rating; larger thermal footprint (TO-220-5).	Better suited for higher-output-current boost designs (>1.2 A) where board space allows TO-220 mounting and heat sinking.	Select LM2587S-3.3/NOPB when output current exceeds 1.2 A or when integrated diode simplifies layout; verify thermal derating at full load.
TPS61088RHLR	5.5-V max input, 12-A switch, 2.5-MHz operation; requires external feedback divider; no flyback support.	Optimized for compact, high-efficiency boost from Li-ion or USB-PD sources-not suitable for 24-V+ or isolated flyback use.	Choose TPS61088RHLR only for low-input, high-current portable applications; LM2585S-3.3/NOPB remains preferred for wide-VIN industrial/flyback needs.

Compared with LM2587S-3.3/NOPB, LM2585S-3.3/NOPB offers smaller DDPAK footprint and lower quiescent current (11 mA vs. 15 mA), while TPS61088RHLR trades wide-VIN capability for ultra-high switching frequency and current density-making LM2585S-3.3/NOPB the optimal choice for ruggedized 4–40-V systems requiring flyback flexibility.

Availability

LM2585S-3.3/NOPB is available at Aetrix Electronics and suitable for industrial sensor power supplies, PLC I/O modules, automotive body control units, and portable medical diagnostics requiring stable component supply and long-term manufacturability.

Supply support for LM2585S-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 headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and personal electronics markets since 1930.

The LM2585 series was designed specifically for cost-effective, low-component-count flyback, boost, and forward converter power supplies targeting industrial automation, test equipment, and distributed power architectures.

FAQ

What topology does LM2585S-3.3/NOPB support?

The LM2585S-3.3/NOPB supports both step-up (boost) and flyback converter topologies. In boost mode, it uses an external inductor and diode to generate output voltages greater than input; in flyback mode, it drives a transformer primary to provide isolated outputs. It does not support buck or forward-topology configurations without external modifications beyond datasheet guidance.

Does LM2585S-3.3/NOPB require external feedback resistors?

No, LM2585S-3.3/NOPB has an internally trimmed 3.3-V reference connected directly to the FB pin, eliminating the need for external feedback resistors. The FB pin is connected to the output in standard boost or flyback configurations, enabling fixed 3.3-V regulation without resistor networks or trimming.

What is the maximum output current achievable with LM2585S-3.3/NOPB?

LM2585S-3.3/NOPB features a 3-A internal NPN switch, but maximum sustainable output current depends on topology and efficiency. In boost configuration at VIN = 5 V, it delivers up to ~1.2 A at 3.3 V (76% efficiency). In flyback mode with proper transformer selection (e.g., Coilcraft S6000-A), it supports up to 1.4 A on the 3.3-V winding per TI's Figure 22 design example.

Can LM2585S-3.3/NOPB operate from a 3.5-V input?

No-LM2585S-3.3/NOPB has a minimum recommended input voltage of 4 V and an undervoltage lockout threshold of 3.30 V (3.05–3.75 V). At 3.5 V, the device may not start or may exhibit unstable operation; operation below 4 V violates recommended ratings and risks failure to regulate or repeated UVLO cycling.

How is thermal performance managed in LM2585S-3.3/NOPB?

LM2585S-3.3/NOPB uses a DDPAK/TO-263 (KTT) package with RθJA = 56°C/W on minimal copper and 26°C/W with 1.0064 in² copper area. Thermal shutdown activates at 150°C junction temperature. Designers must calculate power dissipation (PD ≈ (VIN × IIN) − (VOUT × IOUT)) and ensure PD × RθJA + TA ≤ 125°C to maintain continuous operation within the −40°C to +125°C junction range.

LM2585S-3.3/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

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:: Surface Mount

Supplier Device Package:: TO-263 (DDPAK-5)

LM2585S-3.3/NOPB FAQ

1.How can I place an order for LM2585S-3.3/NOPB through Aetrix?

Please submit a Request for Quotation (RFQ) for LM2585S-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 LM2585S-3.3/NOPB reliable?

The price and inventory of LM2585S-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 LM2585S-3.3/NOPB is usually 5 days.

3.What payment methods are accepted for LM2585S-3.3/NOPB?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2585S-3.3/NOPB transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for LM2585S-3.3/NOPB?

LM2585S-3.3/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your LM2585S-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 LM2585S-3.3/NOPB?

For technical support, including LM2585S-3.3/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2585S-3.3/NOPB requirements.

6.How does Aetrix verify that LM2585S-3.3/NOPB is sourced from the original manufacturer or authorized distributors?

All LM2585S-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 LM2585S-3.3/NOPB meets industry standards.

7.What is the process for return or replacement of LM2585S-3.3/NOPB?

All LM2585S-3.3/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2585S-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 LM2585S-3.3/NOPB part is unused and in its original packaging.

Return procedure for LM2585S-3.3/NOPB:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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