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Texas Instruments LM2585T-ADJ
- Part No.:
- LM2585T-ADJ
- Manufacturer:
- Texas Instruments
- Package:
- TO-220-5 Formed Leads
- Datasheet:
-
LM2585T-ADJ.pdf
- Description:
- IC REG BST FLYBCK ADJ 3A TO220-5
- Quantity:
- Payment:
- Shipping:
Inventory:2,568
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Product details
Overview
LM2585T-ADJ from Texas Instruments is a monolithic step-up (boost) and flyback DC-DC converter IC with an integrated 3-A, 65-V NPN power switch, 100-kHz fixed-frequency oscillator, current-mode control, and internal soft-start. It operates from 4 V to 40 V input, delivers adjustable output voltage via external resistor divider, and achieves ±4% system output voltage tolerance over line and load. It is used in industrial power supplies requiring isolated or non-isolated high-voltage boost conversion.
For engineers reviewing the LM2585T-ADJ datasheet, LM2585T-ADJ pinout, LM2585T-ADJ application, or LM2585T-ADJ equivalent, key selection criteria include its 3-A switch current rating, 65-V switch standoff voltage, 100-kHz switching frequency for compact magnetics, current-mode operation for transient response, and adjustable feedback reference of 1.23 V - all critical for stable wide-input boost/flyback design.
Technical Context
The LM2585T-ADJ implements current-mode PWM control: the error amplifier compares feedback voltage against a precise 1.230 V reference, and its output is compared to a ramp proportional to switch current to terminate each on-time cycle. This enables cycle-by-cycle current limiting, improved line/load regulation, and stable operation across wide input ranges.
Its internal 100-kHz oscillator drives the NPN output switch directly, eliminating need for external timing components. Protection includes undervoltage lockout (3.30 V threshold), thermal shutdown, and internal current limit (4 A typical), while soft-start reduces in-rush current by controlling the error amplifier's output ramp during startup.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4 V to 40 V - supports wide industrial input rails including 5 V, 12 V, 24 V, and 36 V systems without pre-regulation. |
| Switch Current Rating | 3 A continuous - defines maximum peak inductor current in boost mode; output current must be externally limited to prevent switch overstress. |
| Switch Standoff Voltage | 65 V - enables safe operation in flyback topologies with reflected output voltages up to 65 V at primary. |
| Switching Frequency | 100 kHz (±15 kHz) - allows use of standard, low-cost off-the-shelf inductors and transformers with predictable core loss and EMI profile. |
| Feedback Reference Voltage | 1.230 V (±2.5 mV) - sets precision output voltage via R1/R2 divider; enables any output ≥1.23 V with appropriate resistor ratio. |
| Output Voltage Tolerance | ±4% over full line/load/temperature - specifies total system-level accuracy including component drift and layout effects. |
| Soft-Start Current | 11.0 μA (typ) - controls ramp rate of error amplifier output to limit input surge and prevent output overshoot during startup. |
Pinout & Package
LM2585T-ADJ is available in TO-220 (NDH) and DDPAK/TO-263 (KTT) packages - both 5-pin thermally enhanced variants. The TO-220 variant uses vertical mounting with exposed tab for heatsink attachment; the DDPAK offers lower thermal resistance when mounted horizontally on PCB copper.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1: Input | Power input supply connection | Accepts 4–40 V DC; requires local ceramic bypass capacitor (≥100 nF) near pin for stability and EMI suppression. |
| Pin 2: Ground | Power and signal reference node | Must be low-impedance connection to main power ground plane; shared with feedback and compensation return paths. |
| Pin 3: Feedback | Error amplifier inverting input | Connects to resistor divider from output; senses voltage relative to 1.230 V reference to regulate output. |
| Pin 4: Compensation | Error amplifier output | External RC network here sets loop bandwidth and phase margin; critical for stability in varying load conditions. |
| Pin 5: Switch | Collector of internal NPN transistor | Drives external inductor (boost) or transformer primary (flyback); connects to catch diode anode in boost configuration. |
Key Features
| Feature | Design Value |
|---|---|
| Current-mode PWM control | Enables fast transient response, inherent cycle-by-cycle current limiting, and simplified loop compensation vs. voltage-mode. |
| Integrated 3-A/65-V NPN switch | Eliminates need for external high-voltage transistor and driver; reduces BOM count and layout complexity in boost/flyback designs. |
| 100-kHz fixed-frequency oscillator | Permits consistent EMI filtering design and use of standardized, cost-optimized magnetics without frequency variation. |
| Internal soft-start | Reduces in-rush current by linearly ramping error amplifier output, preventing input rail sag and output overshoot at startup. |
| Comprehensive protection suite | Includes undervoltage lockout (3.3 V), thermal shutdown, and current limit - ensures robust operation under fault conditions. |
Applications
| Industrial Boost Power Supply | Flyback Isolated Bias Supply |
|---|---|
|
Use Scenario: Generating 24 V from a 12 V battery-powered industrial controller with variable load and temperature. IC Role / Device Role / Timing Role: LM2585T-ADJ acts as the primary PWM controller and power switch in non-isolated boost topology, regulating output using feedback from output divider. Use Value: Delivers stable 24 V at up to 1.2 A with ±4% tolerance across −40°C to +125°C junction temperature, leveraging current-mode control for load-step immunity. |
Use Scenario: Providing isolated ±12 V and +5 V auxiliary rails for gate drivers and logic in a 400 V DC bus motor drive. IC Role / Device Role / Timing Role: LM2585T-ADJ serves as flyback controller driving transformer primary; secondary windings deliver multiple isolated outputs. Use Value: Enables single-chip multi-output isolation with 65 V switch rating supporting reflected voltages up to 60 V, meeting IEC 61800-5-1 creepage requirements. |
| Telecom Line-Powered Interface | Automotive LED Driver Supply |
|
Use Scenario: Converting 5 V USB-C PD input to 12 V for PoE-powered Ethernet PHY interface with surge immunity. IC Role / Device Role / Timing Role: LM2585T-ADJ configured as simple boost regulator; input filtered for EN 61000-4-5 compliance. Use Value: Achieves >80% efficiency at 600 mA load with 100-kHz switching, enabling compact 1210-size inductor and minimizing conducted EMI in sensitive comms circuits. |
Use Scenario: Driving high-brightness LED strings from 12 V automotive battery with cold-crank down to 6 V. IC Role / Device Role / Timing Role: LM2585T-ADJ functions as constant-current boost controller, with current sense resistor replacing feedback divider. Use Value: Maintains LED brightness during 6–16 V input transients using current-mode control and 3-A switch, avoiding dropout during cranking events. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar boost/flyback regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2577T-ADJ | Lower 3-A switch rating, 40-V max switch voltage, no internal soft-start; 50-kHz switching frequency. | Suitable only for lower-output-voltage boost (≤24 V) and low-power flyback; requires larger magnetics and external soft-start circuit. | Choose LM2577T-ADJ only if 50-kHz EMI profile or legacy design compatibility is required; not recommended for new 65-V-referenced designs. |
| TPS40210DGQ | External MOSFET controller (no integrated switch), 1.2-MHz programmable frequency, higher efficiency at light loads. | Requires external high-side N-channel MOSFET and driver; supports wider VIN (4.5–52 V) but increases BOM and layout complexity. | Choose TPS40210DGQ for >2 A output at >36 V output or when synchronous rectification and ultra-low quiescent current are needed. |
Compared with LM2577T-ADJ and TPS40210DGQ, LM2585T-ADJ uniquely balances integration (built-in 3-A/65-V NPN), fixed 100-kHz timing, and proven flyback capability - making it optimal for cost-sensitive, thermally constrained industrial boost and isolated bias supply designs where simplicity and reliability outweigh ultra-high efficiency or programmability.
Availability
LM2585T-ADJ is available at Aetrix Electronics and suitable for industrial power supplies, telecom interface modules, and automotive LED driver systems requiring stable component supply and long-term manufacturability.
Supply support for LM2585T-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 company headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and personal electronics markets.
The LM2585 series was designed specifically for cost-effective, wide-input-voltage flyback, boost, and forward converter applications - targeting engineers needing minimal external components and proven reliability in harsh environments.
FAQ
What is the maximum output voltage achievable with LM2585T-ADJ?
The LM2585T-ADJ does not impose an intrinsic upper limit on output voltage; it is determined by external components and layout. In boost configuration, practical limits arise from switch voltage rating (65 V max), diode reverse voltage, and transformer insulation in flyback. For example, with proper 100-V diode and 1:1 transformer, outputs up to 60 V are routinely achieved. Always verify reflected voltage and derate accordingly per TI SNVS120G Section 6.1.
Can LM2585T-ADJ be used in a synchronous rectifier configuration?
No, LM2585T-ADJ is not compatible with synchronous rectification. Its internal NPN switch and control architecture are optimized for diode-based rectification in boost and flyback topologies. Synchronous operation would require external MOSFET gate drive timing aligned with switch off-time - a function not provided by the LM2585T-ADJ. Use dedicated controllers like TPS40210 or LM5116 for synchronous designs.
What is the purpose of the compensation pin (Pin 4) on LM2585T-ADJ?
The compensation pin (Pin 4) is the output of the internal error amplifier. An external RC network connected between this pin and ground sets the dominant pole and zero of the control loop, directly determining phase margin and transient response. TI recommends starting with a 10-nF capacitor and 10-kΩ resistor (per Figure 48 in SNVS120G), then adjusting based on load-step testing and output ripple measurements.
Does LM2585T-ADJ support adjustable switching frequency?
No, LM2585T-ADJ has a fixed 100-kHz internal oscillator - frequency cannot be adjusted externally. This simplifies design and EMI filtering but means designers must select magnetics rated for 100 kHz. For variable-frequency operation, consider TI's UC384x family or newer controllers like LM5122, which offer programmable frequency and synchronization capability.
How does LM2585T-ADJ handle short-circuit protection?
LM2585T-ADJ employs foldback current limiting during short-circuit events: when output voltage collapses below ~1.15 V, the oscillator frequency drops from 100 kHz to 25 kHz (short-circuit frequency), reducing power dissipation and enabling safe hiccup-mode operation. This behavior is specified in Electrical Characteristics Table 6.9 and protects both the IC and external components without requiring external circuitry.
LM2585T-ADJ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- TO-220-5 Formed Leads
- Packaging:
- Tube
- Product Status:
- Obsolete
- 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:
- Through Hole
- Supplier Device Package:
- TO-220-5
LM2585T-ADJ FAQ
1.How can I place an order for LM2585T-ADJ through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2585T-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 LM2585T-ADJ reliable?
The price and inventory of LM2585T-ADJ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2585T-ADJ is usually 5 days.
3.What payment methods are accepted for LM2585T-ADJ?
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Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2585T-ADJ?
LM2585T-ADJ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2585T-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 LM2585T-ADJ?
For technical support, including LM2585T-ADJ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2585T-ADJ requirements.
6.How does Aetrix verify that LM2585T-ADJ is sourced from the original manufacturer or authorized distributors?
All LM2585T-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 LM2585T-ADJ meets industry standards.
7.What is the process for return or replacement of LM2585T-ADJ?
All LM2585T-ADJ units undergo pre-shipment inspection (PSI). If there is an issue with LM2585T-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 LM2585T-ADJ part is unused and in its original packaging.
Return procedure for LM2585T-ADJ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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