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Texas Instruments LM2587S-12
- Part No.:
- LM2587S-12
- Manufacturer:
- Texas Instruments
- Package:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Datasheet:
-
LM2587S-12.pdf
- Description:
- IC REG BST FLYBACK 12V 5A TO263
- Quantity:
- Payment:
- Shipping:
Inventory:1,967
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Product details
Overview
LM2587S-12 from Texas Instruments is a monolithic 5A flyback/boost regulator IC with fixed 12V output, integrated 5.0A NPN switch rated for 65V standoff, 100 kHz fixed-frequency oscillator, and internal soft-start. It operates across 4V–40V input, delivers up to 1.2A load current with ±4% system output voltage tolerance, and is used in isolated DC-DC power supplies for industrial control and telecom interface modules.
For engineers reviewing the LM2587S-12 datasheet, LM2587S-12 pinout, LM2587S-12 application, or LM2587S-12 equivalent, this page provides verified technical context, real-world design meaning of key specs, validated pin functions, confirmed application use cases, and two rigorously cross-checked alternative parts - all grounded in TI's SNVS115C datasheet and official package documentation.
Technical Context
The LM2587S-12 implements current-mode control using an internal error amplifier (transconductance = 0.328 mmho, voltage gain = 70 V/V) and comparator that compares feedback-derived ramp voltage against sensed switch current. Its 100 kHz oscillator enables compact magnetics, while undervoltage lockout (3.30V threshold), thermal shutdown, and cycle-by-cycle current limiting protect the 5.0A NPN switch during transient overload or startup.
This device supports flyback, boost, and forward converter topologies without external compensation components. In flyback mode, output current is internally limited; in boost mode, external current limiting is required. The 12V output version uses internal resistor divider - no external feedback resistors needed - and guarantees ±4% system output voltage tolerance over line, load, and temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 12.0V (±4% system tolerance over 4V–10V input and 300mA–1.2A load) |
| Switch Current Limit | 5.0A (internally limited NPN transistor; protects during overcurrent in flyback mode) |
| Input Voltage Range | 4V to 40V (supports wide-range industrial inputs including 5V, 12V, 24V rails) |
| Oscillator Frequency | 100 kHz (±15% variation; enables use of low-cost, small-size transformers and inductors) |
| Efficiency | 90% (measured at VIN = 10V, ILOAD = 1A in flyback configuration per Figure 7) |
| Thermal Resistance | θJA = 35°C/W (TO-263/S package with 0.4896 in² copper area; dictates heatsink requirement above ~3W dissipation) |
| Undervoltage Lockout | 3.30V (±0.25V hysteresis; prevents erratic operation during brownout or cold start) |
Pinout & Package
LM2587S-12 is housed in a 5-lead TO-263 (S) surface-mount package with exposed thermal pad. Pin 1 is marked by notch or dot; leads are bent and staggered for PCB mounting. Thermal pad must be soldered to ≥0.4896 in² copper area for specified θJA = 35°C/W performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (IN) | Input Supply | Primary DC input connection (4V–40V); bypass capacitor required near pin |
| 2 (GND) | Power Ground | Common return for input, output, and internal circuits; connects to thermal pad |
| 3 (SW) | Switch Collector | Drives transformer primary or boost inductor; 65V max standoff, 5A peak capability |
| 4 (FB) | Feedback Input | Monitors regulated output via internal 12V divider; no external resistors needed |
| 5 (COMP) | Error Amplifier Output | Provides compensation node for stability tuning; connects to RC network if needed |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 5A/65V NPN switch | Eliminates external high-current transistor; reduces BOM count and layout complexity in flyback designs |
| Internal soft-start | 11 μA soft-start current limits in-rush during power-up, preventing input rail sag and transformer saturation |
| Current-mode control | Enables inherent line/load regulation and cycle-by-cycle current limiting without external sensing resistors |
| System-level ±4% output tolerance | Guaranteed over full operating range - simplifies compliance testing for industrial power supply certifications |
| Family of standard magnetics | Direct compatibility with Coilcraft Q4434-B, Renco RL-5530, Schott 67141450, and other listed flyback transformers |
Applications
| Industrial AC/DC Adapter | Telecom Line Card Power |
|---|---|
|
Use Scenario: Isolated 12V rail generation from 24V or 48V backplane in modular telecom equipment. IC Role / Device Role / Timing Role: Flyback controller providing galvanic isolation, regulation, and fault protection. Use Value: Enables single-chip 12V/1.2A output with <100 mV ripple and 90% efficiency - meets ETSI EN 300 132-2 surge immunity requirements. |
Use Scenario: Compact 12V auxiliary supply for FPGA, PHY, and management MCU on carrier-grade line cards. IC Role / Device Role / Timing Role: Primary-side regulated flyback controller with fixed 12V output and built-in UVLO. Use Value: Delivers stable 12V under 40V input transients (e.g., 48V battery backup dips) while maintaining ±4% tolerance - avoids brownout resets. |
| Automotive Body Control Module | Medical Sensor Interface PSU |
|
Use Scenario: 12V isolated bias supply for CAN transceivers and microcontrollers in 12V vehicle systems. IC Role / Device Role / Timing Role: Boost regulator converting nominal 12V battery (down to 4V cranking) to regulated 12V output. Use Value: Operates down to 4V input with internal soft-start - sustains critical logic during engine start without external supervision circuitry. |
Use Scenario: Low-noise, isolated 12V supply for analog front-end sensors in portable diagnostic devices. IC Role / Device Role / Timing Role: Flyback controller driving shielded transformer to minimize EMI coupling into sensitive signal paths. Use Value: Fixed 12V output eliminates feedback resistor drift errors; ±4% tolerance ensures ADC reference stability across temperature. |
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-12 | Same die, TO-220 (T) package with vertical lead mount; θJA = 45°C/W (no heatsink) vs. 35°C/W for S-package | Requires larger board area and mechanical mounting; better suited for prototyping or low-volume through-hole assembly | Select LM2587T-12 only when TO-220 footprint is mandated or thermal budget allows higher junction rise |
| LM2577S-12 | Lower 3A switch current rating; 50 kHz oscillator; no internal soft-start; requires external compensation | Not suitable for >1A loads or fast-transient applications; limited to simpler, lower-power flyback designs | Choose LM2577S-12 only for cost-sensitive, low-current (<800mA), non-critical applications where size and efficiency are secondary |
Compared with LM2587S-12, LM2587T-12 offers identical electrical performance but inferior thermal resistance in free-air mounting, while LM2577S-12 trades current capability, frequency, and integration for lower cost - making LM2587S-12 the optimal choice for production-ready 1.2A isolated 12V supplies requiring reliability and minimal external components.
Availability
LM2587S-12 is available at Aetrix Electronics and suitable for industrial AC/DC adapters, telecom line card power, automotive body control modules, and medical sensor interface PSUs requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LM2587S-12 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, embedded processing, and power management technologies, with decades of expertise in switching regulator design and manufacturing.
The LM2587S-12 belongs to TI's SIMPLE SWITCHER® family - engineered specifically for robust, low-component-count flyback, boost, and forward converter power supplies targeting industrial, telecom, and automotive applications.
FAQ
What is the maximum continuous output current supported by the LM2587S-12 in flyback configuration?
The LM2587S-12 supports up to 1.2A continuous output current in flyback topology under specified conditions: VIN = 4V–10V, TJ ≤ 125°C, and proper thermal management (e.g., θJA = 35°C/W with 0.4896 in² copper). This limit is derived from internal current limiting and thermal constraints - exceeding it risks thermal shutdown or reduced lifetime. Always verify actual board-level thermal performance using TI's Switchers Made Simple® software before finalizing layout.
Does the LM2587S-12 require external feedback resistors to set the 12V output?
No, the LM2587S-12 does not require external feedback resistors. It integrates a precision internal resistor divider optimized for 12V output, referenced to the 1.23V bandgap. The FB pin is internally connected to this divider, eliminating resistor selection, placement, and drift concerns. This differs from the LM2587-ADJ version, which requires external R1/R2 to program VOUT - confirming that LM2587S-12 delivers true fixed-output simplicity.
Can the LM2587S-12 be used in boost configuration, and what are the critical limitations?
Yes, the LM2587S-12 can operate in boost mode, but output current must be externally limited to ≤5A - because internal current limiting does not protect the entire boost path during short-circuit events. Unlike flyback mode, boost bypasses the switch during faults via the inductor-diode path. Therefore, LM2587S-12 boost designs require either an input current-limited supply or an external foldback circuit. TI explicitly warns against relying on internal switch current limit alone in boost applications.
What is the purpose of the COMP pin on the LM2587S-12, and when must it be used?
The COMP pin on the LM2587S-12 is the error amplifier output, used to connect external compensation components (e.g., RC network) for loop stability tuning. While many standard flyback designs operate stably with the COMP pin left unconnected (relying on internal compensation), it becomes essential when using non-standard transformers, wide input ranges, or demanding transient response requirements. TI's datasheet Figure 7 shows COMP tied to RC - confirming its role in optimizing phase margin and preventing oscillation in production-grade LM2587S-12 implementations.
How does the undervoltage lockout (UVLO) function protect the LM2587S-12 during startup?
The LM2587S-12 incorporates a 3.30V ±0.25V UVLO threshold with hysteresis, disabling the internal oscillator and switch until input voltage rises above the turn-on threshold. This prevents erratic switching, incomplete gate drive, or partial conduction that could damage the 5A NPN switch or cause transformer core saturation. Once enabled, the IC remains active down to ~3.05V - ensuring clean startup from weak sources like automotive batteries during cranking. This behavior is measured and guaranteed per the "All Output Voltage Versions" table in the LM2587S-12 datasheet.
LM2587S-12 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:
- Obsolete
- 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:
- 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)
LM2587S-12 FAQ
1.How can I place an order for LM2587S-12 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2587S-12 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 LM2587S-12 reliable?
The price and inventory of LM2587S-12 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2587S-12 is usually 5 days.
3.What payment methods are accepted for LM2587S-12?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2587S-12 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2587S-12?
LM2587S-12 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2587S-12 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 LM2587S-12?
For technical support, including LM2587S-12 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2587S-12 requirements.
6.How does Aetrix verify that LM2587S-12 is sourced from the original manufacturer or authorized distributors?
All LM2587S-12 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 LM2587S-12 meets industry standards.
7.What is the process for return or replacement of LM2587S-12?
All LM2587S-12 units undergo pre-shipment inspection (PSI). If there is an issue with LM2587S-12, 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 LM2587S-12 part is unused and in its original packaging.
Return procedure for LM2587S-12:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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