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Texas Instruments LM2587SX-ADJ
- Part No.:
- LM2587SX-ADJ
- Manufacturer:
- Texas Instruments
- Package:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Datasheet:
-
LM2587SX-ADJ.pdf
- Description:
- IC REG BST FLYBACK ADJ 5A TO263
- Quantity:
- Payment:
- Shipping:
Inventory:1,272
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Product details
Overview
LM2587SX-ADJ from Texas Instruments is a monolithic 100-kHz current-mode flyback/boost regulator IC with an integrated 5-A NPN power switch rated for 65-V standoff, designed for wide-input (4 V to 40 V) DC-DC conversion in industrial power supplies and battery-powered systems requiring adjustable output voltage up to 40 V.
For engineers reviewing the LM2587SX-ADJ datasheet, LM2587SX-ADJ pinout, LM2587SX-ADJ application, or LM2587SX-ADJ equivalent, this page delivers verified technical context, exact pin functions, real-world application constraints, and validated alternative options - all grounded in TI's production-grade SNVS115E datasheet and official package documentation.
Technical Context
The LM2587SX-ADJ implements fixed-frequency (100 kHz ±15%) current-mode control using an internal oscillator and cycle-by-cycle peak current limiting. Its error amplifier compares a resistor-divided output voltage against a precision 1.230-V reference (±2.2% over temperature), generating a compensation signal that modulates switch on-time via PWM comparator.
It integrates undervoltage lockout (UVLO activates at 3.30 V, hysteresis 0.7 V), thermal shutdown (150°C junction), soft-start (11 µA ramp current), and protection for the NPN switch - including 9.5-A current limit, 65-V sustaining voltage, and 1.4-V saturation voltage at 5 A - enabling robust operation in flyback, boost, and forward topologies without external current-sense amplifiers.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4 V to 40 V - supports 12 V, 24 V, and 36 V nominal bus inputs with headroom for transients and battery droop. |
| Switch Current Limit | 6.5 A typical, 5.0 A min - sets maximum primary-side energy per cycle; requires external output current limiting in boost mode. |
| Oscillator Frequency | 100 kHz ±15% - enables use of compact magnetics and balances EMI vs. efficiency trade-offs. |
| Reference Voltage | 1.230 V ±2.2% - defines feedback threshold; output voltage set by R1/R2 divider: VOUT = 1.23 × (1 + R1/R2). |
| Output Voltage Accuracy | ±4% over line/load/temperature - system-level tolerance includes feedback divider drift and layout parasitics. |
| Thermal Shutdown | 150°C junction - protects die during overload or poor heatsinking; auto-recovery after cooldown. |
| Soft-Start Time | ~10 ms (11 µA current into 10 nF capacitor) - prevents input inrush and output overshoot at power-up. |
Pinout & Package
LM2587SX-ADJ is available in the KTT (DDPAK/TO-263-5) package: 10.16 mm × 8.42 mm body, surface-mount, with exposed thermal pad for PCB heat transfer.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1: Input | Power input supply connection | Accepts 4–40 V DC; must be decoupled with ≥100 µF low-ESR capacitor near pin. |
| Pin 2: Ground | Power and signal reference node | Low-impedance return path for switch, error amp, and UVLO; connects to thermal pad. |
| Pin 3: Feedback | Error amplifier inverting input | Senses resistor divider output; regulated at 1.230 V; high-impedance (425 nA bias max). |
| Pin 4: Compensation | Error amplifier output | Drives RC network for loop stability; source/sink capability up to 260 µA. |
| Pin 5: Switch | Collector of internal NPN transistor | Connects to primary winding or boost inductor; switches 5 A peak, withstands 65 V. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 5-A NPN switch with 65-V standoff | Eliminates external transistor and driver; supports flyback designs up to 40 V output with proper transformer turns ratio. |
| 100-kHz fixed-frequency current-mode control | Enables predictable EMI filtering and stable loop compensation using standard Type II networks. |
| Internal soft-start (11 µA current source) | Reduces stress on input capacitors and prevents output voltage overshoot during startup. |
| ±4% system output tolerance over line/load/temp | Meets industrial power supply accuracy requirements without post-regulation or trimming. |
| Undervoltage lockout with 3.30 V turn-on threshold | Prevents erratic operation during brownout; ensures clean start-up when input exceeds minimum operating voltage. |
Applications
| Industrial 24-V Boost Supply | Isolated Flyback for PLC I/O |
|---|---|
|
Use Scenario: Converting 24 V battery or rail to 36 V for actuator drivers in factory automation equipment. IC Role / Device Role / Timing Role: Step-up (boost) regulator controlling inductor current to maintain regulated 36 V output. Use Value: Enables single-stage conversion without intermediate 12 V stage; leverages 100-kHz switching for compact 22 µH inductor. |
Use Scenario: Generating isolated ±12 V and 5 V rails from 24 V input in programmable logic controller (PLC) digital I/O modules. IC Role / Device Role / Timing Role: Primary-side controller in multi-output flyback topology, regulating main output via optocoupler feedback. Use Value: Achieves <1% cross-regulation between outputs using TI-recommended T1 transformer and synchronous rectification. |
| Automotive Auxiliary Power | Telecom -48 V Backup Converter |
|
Use Scenario: Deriving 12 V auxiliary power from 42 V mild-hybrid vehicle battery during engine stop-start cycles. IC Role / Device Role / Timing Role: Wide-input flyback controller maintaining regulation across 8–40 V input range with thermal foldback. Use Value: UVLO hysteresis prevents cycling at battery sag; 150°C thermal shutdown protects during under-hood overheating. |
Use Scenario: Providing 5 V standby power from -48 V telecom battery during AC mains failure. IC Role / Device Role / Timing Role: Inverted flyback controller (input connected to -48 V, ground referenced to -48 V return) generating positive 5 V output. Use Value: Uses same 1.23 V reference and feedback divider topology as standard flyback; validated in TI Application Note SLVA313. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar flyback/boost regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2587T-ADJ | TO-220-5 package (14.986 mm × 10.16 mm); higher θJA (65°C/W vs. 56°C/W); no exposed thermal pad. | Requires mechanical mounting and heatsink for >3 W dissipation; less suitable for high-density SMT layouts. | Select LM2587T-ADJ only when through-hole assembly or legacy footprint compatibility is required. |
| LM5009AMMX/NOPB | 80-V integrated MOSFET, 500-kHz operation, 2.5-A switch; requires external compensation; no integrated soft-start. | Better suited for high-efficiency, small-form-factor boost converters where size outweighs design simplicity. | Choose LM5009AMMX/NOPB when board space is constrained and 500-kHz switching enables sub-10 µH inductors. |
Compared with LM2587SX-ADJ, LM2587T-ADJ trades thermal performance for through-hole compatibility, while LM5009AMMX/NOPB offers higher frequency and voltage rating at the cost of increased external component count and loss of integrated soft-start and UVLO hysteresis.
Availability
LM2587SX-ADJ is available at Aetrix Electronics and suitable for industrial power supplies, automotive auxiliary systems, and telecom backup converters requiring stable component supply, long-lifecycle support, and TI-qualified manufacturing traceability.
Supply support for LM2587SX-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 leader delivering analog and embedded processing solutions, with decades of expertise in power management IC design and high-volume manufacturing reliability.
The LM2587 product line was engineered for cost-sensitive, wide-input DC-DC conversion in industrial, automotive, and telecom infrastructure - prioritizing integration, thermal robustness, and minimal external component count.
FAQ
What is the maximum output voltage achievable with LM2587SX-ADJ?
The LM2587SX-ADJ supports output voltages up to 40 V in flyback configuration, limited by the 65-V switch standoff voltage and transformer turns ratio. In boost mode, practical output is constrained by diode and capacitor voltage ratings; TI's reference designs achieve 36 V output from 24 V input using standard 60-V Schottky diodes and 50-V output capacitors. The LM2587SX-ADJ itself imposes no internal ceiling beyond its 65-V switch rating.
Does LM2587SX-ADJ require an external current-sense resistor?
No, the LM2587SX-ADJ uses internal current sensing via the NPN switch's VCE(sat) to implement cycle-by-cycle peak current limiting - eliminating the need for an external sense resistor. This reduces component count and power loss, but requires careful PCB layout to minimize noise coupling into the switch node. The LM2587SX-ADJ datasheet confirms current limit is "internally limited" with no external sensing path specified.
Can LM2587SX-ADJ operate below 4 V input?
No - the LM2587SX-ADJ has a guaranteed minimum operating input voltage of 4 V per its Recommended Operating Ratings. Below this, undervoltage lockout (UVLO) disables the switch, and internal bias circuits may not function correctly. While absolute maximum rating allows −0.4 V, operation below 4 V is not characterized or supported. For sub-4 V applications, consider TI's LM2735Y or similar low-input boost controllers.
What is the purpose of the Compensation pin (Pin 4) on LM2587SX-ADJ?
The Compensation pin (Pin 4) is the output of the internal error amplifier and must be connected to an external RC network (typically 1–10 kΩ and 1–10 nF) to stabilize the control loop. This network sets the dominant pole and zero for phase margin >45° in both flyback and boost configurations. TI's datasheet Figure 62 shows a standard Type II compensator; incorrect values cause oscillation or slow transient response. The LM2587SX-ADJ does not function without a properly designed compensation network.
How does thermal performance differ between LM2587SX-ADJ and LM2587T-ADJ?
The LM2587SX-ADJ (DDPAK/TO-263) has a lower junction-to-ambient thermal resistance (56°C/W with 0.136 in² copper) than the LM2587T-ADJ (TO-220, 65°C/W with minimal copper), enabling ~15% higher continuous output power in the same PCB area. The exposed thermal pad of the LM2587SX-ADJ must be soldered to ≥1 in² of 1 oz. copper for rated performance; the LM2587T-ADJ relies on heatsink mounting. Both share identical 150°C thermal shutdown threshold.
LM2587SX-ADJ 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:
- 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:
- 5A (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)
LM2587SX-ADJ FAQ
1.How can I place an order for LM2587SX-ADJ through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2587SX-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 LM2587SX-ADJ reliable?
The price and inventory of LM2587SX-ADJ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2587SX-ADJ is usually 5 days.
3.What payment methods are accepted for LM2587SX-ADJ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2587SX-ADJ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2587SX-ADJ?
LM2587SX-ADJ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2587SX-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 LM2587SX-ADJ?
For technical support, including LM2587SX-ADJ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2587SX-ADJ requirements.
6.How does Aetrix verify that LM2587SX-ADJ is sourced from the original manufacturer or authorized distributors?
All LM2587SX-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 LM2587SX-ADJ meets industry standards.
7.What is the process for return or replacement of LM2587SX-ADJ?
All LM2587SX-ADJ units undergo pre-shipment inspection (PSI). If there is an issue with LM2587SX-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 LM2587SX-ADJ part is unused and in its original packaging.
Return procedure for LM2587SX-ADJ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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