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Texas Instruments LM2585SX-ADJ/NOPB
- Part No.:
- LM2585SX-ADJ/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Datasheet:
-
LM2585SX-ADJ/NOPB.pdf
- Description:
- IC REG BST FLYBACK ADJ 3A TO263
- Quantity:
- Payment:
- Shipping:
Inventory:1,121
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Product details
Overview
LM2585SX-ADJ/NOPB from Texas Instruments is a monolithic step-up (boost) and flyback DC-DC converter IC with adjustable output voltage, featuring a 3-A NPN internal switch rated for 65-V standoff, 100-kHz fixed-frequency operation, current-mode control, and ±4% system output voltage tolerance over line and load. It enables compact, cost-effective power conversion in industrial and automotive auxiliary supplies.
For engineers reviewing the LM2585SX-ADJ/NOPB datasheet, LM2585SX-ADJ/NOPB pinout, LM2585SX-ADJ/NOPB application, or LM2585SX-ADJ/NOPB equivalent, key selection criteria include input voltage range (4 V to 40 V), internal soft-start function, undervoltage lockout (3.3 V threshold), thermal shutdown protection, and compatibility with standard flyback transformers and boost inductors.
Technical Context
The LM2585SX-ADJ/NOPB implements current-mode control using an internal 100-kHz oscillator and cycle-by-cycle peak current limiting. Its error amplifier compares feedback voltage against a precise 1.230-V reference (±1.5 mV line regulation), driving a transconductance stage (3.2 mmho typical) that modulates switch duty cycle via PWM comparator.
Operation supports both boost and flyback topologies: in boost mode, energy transfers from input inductor to output capacitor during switch off-time; in flyback mode, energy stores in transformer primary during on-time and delivers to secondary during off-time, enabling isolated or multiple-output designs without external optocoupler compensation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4 V to 40 V - supports wide-range industrial inputs including 12 V, 24 V, and 36 V nominal rails. |
| Switch Current Limit | 3 A - sets maximum peak inductor/primary current; requires external output current limiting in boost configuration. |
| Switch Sustaining Voltage | 65 V - enables safe operation with 48 V input systems and transient surges up to 60 V. |
| Oscillator Frequency | 100 kHz (±15 kHz) - permits use of low-cost, standardized magnetics and reduces EMI filtering complexity. |
| Reference Voltage | 1.230 V ±1.5 mV - defines adjustable output via resistor divider; enables precise VOUT = 1.23 × (1 + R1/R2). |
| Output Voltage Tolerance | ±4% over line/load/temp - ensures stable regulation across full operating conditions without post-regulation. |
| Soft Start Current | 11.0 μA typical - controls ramp rate of internal compensation node to limit in-rush current at startup. |
Pinout & Package
LM2585SX-ADJ/NOPB is packaged in a 5-pin DDPAK/TO-263 (KTT) surface-mount package with exposed thermal pad (10.16 mm × 8.42 mm body size), optimized for high-power dissipation in space-constrained PCB layouts.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Input Supply | Connects to unregulated DC input (4–40 V); bypassed externally with ≥100 μF electrolytic capacitor. |
| GND | Power Ground | Common return for input/output capacitors, transformer secondary, and IC substrate; ties to thermal pad. |
| SW | Switch Node | Drives transformer primary or boost inductor; connects to cathode of catch diode in boost topology. |
| FB | Feedback Input | Monitors output voltage via resistor divider; regulates VOUT by maintaining 1.230 V at this pin. |
| COMP | Compensation Output | Error amplifier output; connected to RC network for loop stability tuning in flyback/boost configurations. |
Key Features
| Feature | Design Value |
|---|---|
| Current-mode control | Enables fast transient response, inherent cycle-by-cycle current limiting, and simplified loop compensation. |
| Internal soft-start | Reduces input in-rush current and prevents output overshoot during power-up without external components. |
| Thermal shutdown & UVLO | Protects device under overload or low-input conditions; UVLO activates below 3.05 V, deactivates above 3.75 V. |
| 3-A NPN switch | Eliminates need for external high-current transistor; saturation voltage ≤0.65 V at 3 A simplifies thermal design. |
| Adjustable output | Supports any output voltage ≥1.23 V via two-resistor feedback network-no fixed-voltage variants required. |
Applications
| Industrial 24-V Boost Supply | Automotive Auxiliary Rail |
|---|---|
|
Use Scenario: Generating 36 V from a 24-V battery bus to power sensors and actuators in harsh environments. IC Role / Device Role: Step-up regulator controlling peak inductor current to maintain regulated 36-V output. Use Value: Enables single-stage conversion without intermediate buck-boost stages; 93% efficiency at 0.6 A load minimizes heat generation. |
Use Scenario: Providing isolated 5 V and −12 V rails from a 12-V vehicle battery for infotainment and CAN transceivers. IC Role / Device Role: Flyback controller regulating dual outputs using transformer-coupled secondary windings. Use Value: Achieves ±4% output tolerance across temperature and load without optocoupler feedback; supports transformer families listed in TI's design guides. |
| Telecom Line-Powered Interface | Programmable Lab Power Module |
|
Use Scenario: Deriving 48 V from a 12-V PoE midspan supply to drive remote Ethernet switches. IC Role / Device Role: High-voltage boost converter with 65-V switch rating handling 40-V input transients. Use Value: Withstands 45-V absolute max input and 60-V switch voltage limits; soft-start prevents tripping upstream current limiters. |
Use Scenario: Building a benchtop power supply with user-selectable 3.3 V to 24 V output via front-panel potentiometer. IC Role / Device Role: Adjustable-output DC-DC core where FB pin connects to variable resistor divider. Use Value: 1.230-V reference with ±1.5 mV line regulation ensures <0.1% output drift across input range-critical for calibration-grade outputs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-up and flyback regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2587SX-ADJ/NOPB | Higher 5-A switch current, same 100-kHz frequency and pinout; requires larger heatsinking at full load. | Better suited for >3 A continuous output in boost mode; not recommended for flyback due to lack of transformer-specific layout guidance. | Select when output current exceeds 3 A and board area allows additional thermal management. |
| UCC38C43D | Current-mode PWM controller (external MOSFET driver), no integrated switch; 1-MHz max frequency, wider VDD range (10–30 V). | Requires external N-channel MOSFET and gate driver; supports higher efficiency and higher-frequency designs but increases BOM count. | Choose for designs needing >100-kHz switching, lower quiescent current (<2 mA), or discrete FET optimization. |
Compared with LM2587SX-ADJ/NOPB, the LM2585SX-ADJ/NOPB offers lower cost and simpler layout for ≤3 A loads; versus UCC38C43D, it trades flexibility for integration-eliminating gate drive design effort but fixing switch voltage/current capability.
Availability
LM2585SX-ADJ/NOPB is available at Aetrix Electronics and suitable for industrial automation, automotive auxiliary power, telecom interface, and programmable lab equipment requiring stable component supply and long-term manufacturability.
Supply support for LM2585SX-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 broad industrial market support.
The LM2585 series was designed specifically for cost-sensitive, medium-power flyback and boost converter applications where integration, reliability, and ease of use outweigh the need for ultra-high efficiency or ultra-low quiescent current.
FAQ
What is the maximum output voltage achievable with LM2585SX-ADJ/NOPB?
The LM2585SX-ADJ/NOPB has no intrinsic upper limit on output voltage-the adjustable feedback architecture allows any VOUT ≥1.23 V, constrained only by external component ratings (e.g., transformer insulation, output capacitor voltage rating, and diode PIV). In practice, designs up to 100 V have been validated using appropriate magnetics and layout.
Does LM2585SX-ADJ/NOPB require an external diode in boost configuration?
Yes, LM2585SX-ADJ/NOPB requires an external Schottky or fast-recovery diode connected between the SW pin and output capacitor in boost topology. The diode must withstand ≥65 V reverse voltage and conduct ≥3 A peak current; TI recommends 100-V, 5-A Schottky diodes such as SS510 or MBRB25100CT.
Can LM2585SX-ADJ/NOPB be used in flyback mode without optocoupler feedback?
Yes, LM2585SX-ADJ/NOPB supports primary-side sensing in flyback mode using the transformer auxiliary winding and resistor divider on the FB pin. This eliminates the need for optocouplers or TL431 references, reducing cost and improving reliability-TI provides design examples with ±4% output tolerance using this method.
What thermal considerations apply to LM2585SX-ADJ/NOPB in TO-263 package?
The LM2585SX-ADJ/NOPB in KTT (DDPAK/TO-263) package has RθJA = 56°C/W with minimal copper and 26°C/W with 1.0064 in² of 1 oz. copper. For 3-A operation at 40 V input/12 V output, junction temperature rise can exceed 100°C-TI recommends ≥4 cm² thermal pad area, soldered to inner ground plane, and optional small heatsink for ambient >50°C.
How does the soft-start function operate in LM2585SX-ADJ/NOPB?
The LM2585SX-ADJ/NOPB integrates a 11.0 μA current source into the COMP pin that charges an external capacitor, gradually increasing the error amplifier output voltage and thus ramping up duty cycle. This limits in-rush current and prevents output overshoot-no external timer circuitry is needed, and start-up time is set solely by the COMP capacitor value.
LM2585SX-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:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Up, Step-Up/Step-Down
- Output Configuration:
- Positive
- Topology:
- Boost, Flyback, Forward Converter
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 1.23V
- Voltage - Output (Max):
- 60V
- 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)
LM2585SX-ADJ/NOPB FAQ
1.How can I place an order for LM2585SX-ADJ/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2585SX-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 LM2585SX-ADJ/NOPB reliable?
The price and inventory of LM2585SX-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 LM2585SX-ADJ/NOPB is usually 5 days.
3.What payment methods are accepted for LM2585SX-ADJ/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2585SX-ADJ/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2585SX-ADJ/NOPB?
LM2585SX-ADJ/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2585SX-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 LM2585SX-ADJ/NOPB?
For technical support, including LM2585SX-ADJ/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2585SX-ADJ/NOPB requirements.
6.How does Aetrix verify that LM2585SX-ADJ/NOPB is sourced from the original manufacturer or authorized distributors?
All LM2585SX-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 LM2585SX-ADJ/NOPB meets industry standards.
7.What is the process for return or replacement of LM2585SX-ADJ/NOPB?
All LM2585SX-ADJ/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2585SX-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 LM2585SX-ADJ/NOPB part is unused and in its original packaging.
Return procedure for LM2585SX-ADJ/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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