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Texas Instruments LM2585SX-12/NOPB
- Part No.:
- LM2585SX-12/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Datasheet:
-
LM2585SX-12/NOPB.pdf
- Description:
- IC REG BST FLYBACK 12V 3A TO263
- Quantity:
- Payment:
- Shipping:
Inventory:1,225
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Product details
Overview
LM2585SX-12/NOPB from Texas Instruments is a monolithic 4-V to 40-V input, 12-V fixed-output step-up (boost) and flyback DC-DC converter IC featuring a 3-A NPN internal switch, 100-kHz fixed-frequency current-mode control, ±4% system output voltage tolerance, and integrated soft-start. It operates in flyback, boost, or forward topologies for industrial power supplies and isolated auxiliary rails.
For engineers reviewing the LM2585SX-12/NOPB datasheet, LM2585SX-12/NOPB pinout, LM2585SX-12/NOPB application, or LM2585SX-12/NOPB equivalent, key selection criteria include input voltage range (4–40 V), output voltage accuracy (±4%), thermal performance in TO-263 package, current-mode stability, and compatibility with standard flyback transformers or boost inductors.
Technical Context
The LM2585SX-12/NOPB implements current-mode PWM control using an internal 100-kHz oscillator and cycle-by-cycle peak current limiting. Its error amplifier compares feedback voltage against a 12-V reference (internally trimmed), generating a compensation signal that modulates switch conduction time via a ramp-compare architecture.
It supports three primary topologies: boost (non-isolated step-up), flyback (isolated single/multi-output), and forward (isolated step-down). Protection includes undervoltage lockout (3.3 V threshold), thermal shutdown, and internal current limit (4–7 A typical), with switch sustaining voltage rated at 65 V and saturation voltage ≤0.9 V at 3 A.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4 V to 40 V - supports wide-range industrial, automotive, and telecom inputs without pre-regulation. |
| Output Voltage | Fixed 12 V ±4% - eliminates external feedback resistors; suitable for powering logic, analog circuitry, or gate drivers. |
| Switch Current Rating | 3 A continuous - enables up to ~0.8 A output in boost mode (efficiency-dependent); requires external current limiting for safe operation. |
| Switching Frequency | 100 kHz ±15% - permits use of compact magnetics while balancing EMI and efficiency trade-offs. |
| Reference Voltage | 12.0 V (min 11.4 V, max 12.6 V) - defines regulated output accuracy across line/load/temperature per test conditions in Figure 48. |
| UVLO Threshold | 3.30 V (min 3.05 V, max 3.75 V) - prevents erratic startup during brownout; hysteresis ensures clean turn-on above 3.75 V. |
| Efficiency | 93% at VIN = 10 V, IOUT = 0.6 A - measured in flyback configuration; higher than typical boost due to transformer coupling advantages. |
Pinout & Package
LM2585SX-12/NOPB is packaged in a 5-pin DDPAK/TO-263 (KTT) surface-mount package with exposed thermal pad (10.16 mm × 8.42 mm nominal body size), optimized for high-power dissipation in space-constrained designs.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| IN | Input Supply | Primary DC input connection; accepts 4–40 V; must be bypassed with low-ESR capacitor near pin. |
| SW | Switch Node | Collector of internal 3-A NPN transistor; connects to primary winding (flyback) or inductor (boost); handles 65-V transients. |
| GND | Power Ground | Common return for input, output, and internal circuits; tied to thermal pad for optimal heat transfer. |
| FB | Feedback Input | Monitors output via internal 12-V reference; not used in fixed-output version - internally connected to reference divider. |
| COMP | Compensation Output | Error amplifier output; connects to RC network for loop stability tuning in custom designs. |
Key Features
| Feature | Design Value |
|---|---|
| Current-mode control | Enables fast transient response and inherent line/load regulation without external compensation complexity. |
| Internal soft-start | Reduces in-rush current by gradually ramping peak switch current over ~10 ms, preventing input rail sag. |
| Thermal shutdown | Activates at 150°C junction temperature, latching off until cooldown - protects against sustained overload or poor heatsinking. |
| Undervoltage lockout | Disables switching below 3.05 V input, eliminating unstable operation during startup or brownout conditions. |
| Fixed 12-V output | Eliminates external feedback resistors, reducing BOM count and layout sensitivity while maintaining ±4% system tolerance. |
Applications
| Industrial Flyback Power Supply | Automotive Auxiliary Rail Generator |
|---|---|
Use Scenario: Isolated 12-V supply for PLC I/O modules requiring galvanic separation from 24-V field bus. IC Role / Device Role / Timing Role: Primary-side controller in flyback topology; regulates output via optocoupler feedback and transformer turns ratio. Use Value: Delivers stable 12 V at up to 0.8 A with ±4% tolerance across −40°C to +125°C ambient, meeting IEC 61000-4 immunity requirements. | Use Scenario: Boosting vehicle battery (9–16 V) to regulated 12 V for infotainment USB ports during cold-crank conditions. IC Role / Device Role / Timing Role: Step-up regulator with 100-kHz fixed-frequency operation; maintains regulation down to 4 V input during cranking. Use Value: Sustains 12-V output at 0.6 A with 93% efficiency at 10 V input, minimizing thermal stress in confined under-dash enclosures. |
| Telecom Line Card Bias Supply | Test Equipment Dual-Output Converter |
Use Scenario: Generating isolated ±12-V rails from a 48-V backplane for op-amp biasing in signal conditioning circuits. IC Role / Device Role / Timing Role: Flyback controller driving center-tapped transformer; regulates main 12-V output, with −12 V derived passively. Use Value: Achieves <100 mV load regulation and <20 mV line regulation per datasheet specs, ensuring precision analog performance. | Use Scenario: Compact benchtop instrument requiring isolated 12-V and 5-V outputs from a single 12-V input source. IC Role / Device Role / Timing Role: Dual-output flyback controller using T6 transformer (Coilcraft Q4438-B) per Table 1; manages cross-regulation via primary-side sensing. Use Value: Enables dual-rail generation with only one IC and standard off-the-shelf magnetics-reducing design cycle time and qualification effort. |
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 |
|---|---|---|---|
| LM2585T-12/NOPB | TO-220-5 package; higher θJA (65°C/W vs. 56°C/W); identical electrical specs. | Better suited for prototyping or low-volume through-hole assembly; requires larger PCB area and mechanical mounting. | Select when manual soldering, breadboarding, or heat sink attachment via screw is preferred over surface-mount thermal management. |
| LM2577-12 | Lower max input (40 V same), but 50-kHz switching (vs. 100 kHz); 3-A switch; no internal soft-start. | Optimized for lower EMI and higher efficiency at light loads; lacks soft-start, requiring external circuitry for in-rush control. | Choose for cost-sensitive, low-EMI applications where board space allows larger magnetics and soft-start can be added externally. |
Compared with LM2585SX-12/NOPB, the TO-220 variant offers mechanical flexibility but sacrifices thermal performance, while LM2577-12 trades higher-frequency operation for reduced EMI and simpler magnetics - both require revalidation of loop stability and transformer selection.
Availability
LM2585SX-12/NOPB is available at Aetrix Electronics and suitable for industrial automation power supplies, automotive auxiliary systems, and telecom line card biasing requiring stable component supply and long-term manufacturability.
Supply support for LM2585SX-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 company headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, personal electronics, and communications markets.
The LM2585 series was designed specifically for cost-effective, low-component-count flyback, boost, and forward converter applications - targeting engineers needing reliable, thermally robust DC-DC conversion without complex controller ICs or external MOSFETs.
FAQ
What is the maximum output current achievable with LM2585SX-12/NOPB in boost configuration?
The LM2585SX-12/NOPB does not internally limit output current in boost mode. While its 3-A switch supports peak currents up to 7 A, continuous output current depends on input voltage, efficiency, and thermal design. At VIN = 10 V and 93% efficiency, it delivers ~0.6 A at 12 V. External current limiting is mandatory to prevent switch damage - refer to Section 6.9 and Figure 15 in the LM2585SX-12/NOPB datasheet for implementation guidance.
Can LM2585SX-12/NOPB be used in a non-isolated boost configuration?
Yes, LM2585SX-12/NOPB is explicitly validated for non-isolated boost operation per Figure 15 and Section 7.3.1. It requires an external inductor, Schottky diode, and output capacitor. The fixed 12-V output eliminates feedback resistors, simplifying layout. However, input ripple current is high - use ≥100 μF low-ESR input capacitance and ensure proper thermal management on the DDPAK thermal pad.
What is the purpose of the COMP pin on LM2585SX-12/NOPB, and how should it be configured?
The COMP pin is the error amplifier output and serves as the control node for loop compensation. In fixed-output versions like LM2585SX-12/NOPB, it is not internally connected to feedback and must be externally compensated with an RC network (e.g., 1–10 nF capacitor + 1–10 kΩ resistor to GND) to ensure stability across line/load/temperature. Incorrect compensation causes oscillation or poor transient response - TI's Application Report SLVA057 provides design equations and Bode plot guidance specific to LM2585SX-12/NOPB.
Does LM2585SX-12/NOPB support synchronous rectification?
No, LM2585SX-12/NOPB does not support synchronous rectification. It drives an external diode (e.g., MBR20100CT) in boost or flyback configurations. The internal NPN switch and control architecture are optimized for diode-based topologies. For synchronous operation, consider TI's TPS40210 or LM5122 controllers, which provide gate drive outputs for external MOSFETs - LM2585SX-12/NOPB remains ideal for cost-sensitive, diode-rectified designs.
How does the thermal performance of LM2585SX-12/NOPB compare between KTT (DDPAK) and NDH (TO-220) packages?
LM2585SX-12/NOPB in KTT (DDPAK/TO-263) achieves 56°C/W junction-to-ambient thermal resistance with minimal copper (0.136 in²), versus 65°C/W for NDH (TO-220) under identical conditions. With 0.4896 in² copper, KTT improves to 35°C/W - enabling ~25% higher continuous power before thermal shutdown. This makes LM2585SX-12/NOPB preferable for high-density, surface-mount industrial designs where thermal headroom is critical.
LM2585SX-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:
- Tape & Reel (TR)
- 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):
- 12V
- 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)
LM2585SX-12/NOPB FAQ
1.How can I place an order for LM2585SX-12/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2585SX-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 LM2585SX-12/NOPB reliable?
The price and inventory of LM2585SX-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 LM2585SX-12/NOPB is usually 5 days.
3.What payment methods are accepted for LM2585SX-12/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2585SX-12/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2585SX-12/NOPB?
LM2585SX-12/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2585SX-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 LM2585SX-12/NOPB?
For technical support, including LM2585SX-12/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2585SX-12/NOPB requirements.
6.How does Aetrix verify that LM2585SX-12/NOPB is sourced from the original manufacturer or authorized distributors?
All LM2585SX-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 LM2585SX-12/NOPB meets industry standards.
7.What is the process for return or replacement of LM2585SX-12/NOPB?
All LM2585SX-12/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2585SX-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 LM2585SX-12/NOPB part is unused and in its original packaging.
Return procedure for LM2585SX-12/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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