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Texas Instruments LM2585S-ADJ/NOPB
- Part No.:
- LM2585S-ADJ/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Datasheet:
-
LM2585S-ADJ/NOPB.pdf
- Description:
- IC REG BST FLYBACK ADJ 3A TO263
- Quantity:
- Payment:
- Shipping:
Inventory:2,992
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Product details
Overview
LM2585S-ADJ/NOPB from Texas Instruments is a monolithic step-up (boost) and flyback DC-DC converter IC featuring a 3-A NPN internal switch, 4 V to 40 V input range, 100-kHz fixed-frequency operation, current-mode control, and adjustable output voltage via external resistor divider. It delivers ±4% system output voltage tolerance over line and load, and is used in industrial power supplies, battery-powered boost converters, and isolated multi-output flyback designs.
For engineers reviewing the LM2585S-ADJ/NOPB datasheet, LM2585S-ADJ/NOPB pinout, LM2585S-ADJ/NOPB application, or LM2585S-ADJ/NOPB equivalent, key selection criteria include its 65-V switch standoff rating, internal soft-start function, undervoltage lockout (3.3 V threshold), thermal shutdown protection, and compatibility with standard inductors and flyback transformers per TI's design guides.
Technical Context
The LM2585S-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) and drives the PWM comparator with a transconductance of 3.2 mmho (typ) and voltage gain of 670 V/V (typ).
Operation supports both non-isolated boost and isolated flyback topologies: in boost mode, energy transfers from input to output via inductor charge/discharge; in flyback mode, energy stores in transformer primary during switch-on and releases to secondary during switch-off, enabling multiple output rails and input-output isolation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4 V to 40 V - supports wide-input industrial and automotive battery systems without pre-regulation. |
| Switch Current Rating | 3 A (peak) - enables up to ~1.2 A output in boost configuration at 12 V out, requiring external current limiting per datasheet guidance. |
| Switch Breakdown Voltage | 65 V - allows safe operation with 48-V input transients or flyback reflected voltages up to 60 V. |
| Oscillator Frequency | 100 kHz (±15 kHz) - permits use of compact, low-cost magnetics and reduces EMI compared to higher-frequency alternatives. |
| Reference Voltage | 1.230 V (±2.2 mV over temp) - sets output voltage accuracy for adjustable configurations via R1/R2 divider. |
| Output Voltage Tolerance | ±4% over line/load/temperature - ensures stable regulation across full operating conditions without post-regulation. |
| Soft-Start Current | 11.0 μA (typ) - controls ramp rate of output voltage during startup to limit inrush into bulk capacitors. |
Pinout & Package
LM2585S-ADJ/NOPB is available in the KTT (DDPAK/TO-263-5) package: 10.16 mm × 8.42 mm body, surface-mount, thermally enhanced with exposed die pad. Pin 1 = Input, Pin 2 = Ground, Pin 3 = Feedback, Pin 4 = Output (switch collector), Pin 5 = Compensation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 (IN) | Power Input | Connects to unregulated DC source (4–40 V); bypassed with ≥100 μF electrolytic + 0.1 μF ceramic for stability. |
| Pin 2 (GND) | Ground Reference | Common return for input capacitor, feedback divider, compensation network, and thermal pad connection. |
| Pin 3 (FB) | Feedback Input | Senses divided output voltage; regulates output by comparing to 1.230 V internal reference (adjustable mode only). |
| Pin 4 (SW) | Switch Collector | Drives external diode/transformer primary; handles 3-A peak current and 65-V blocking; requires snubber for flyback. |
| Pin 5 (COMP) | Error Amplifier Output | Provides compensation node for loop stability; connected to RC network between FB and GND per design requirements. |
Key Features
| Feature | Design Value |
|---|---|
| Current-mode control | Enables fast transient response, inherent cycle-by-cycle current limiting, and simplified loop compensation vs. voltage-mode. |
| Internal soft-start | Reduces input inrush current and output overshoot during power-up, eliminating need for external soft-start circuitry. |
| Thermal shutdown & UVLO | Protects device under overload or low-input conditions: UVLO activates below 3.05 V, thermal shutdown triggers at 150°C junction. |
| Fixed 100-kHz frequency | Ensures predictable EMI profile and enables consistent magnetic component selection across designs. |
| Adjustable output (1.23 V reference) | Supports custom output voltages from ~1.25 V to >40 V using two external resistors-no fixed-voltage variants required. |
Applications
| Industrial Boost Converter | Battery-Powered Portable Equipment |
|---|---|
Use Scenario: 12-V rail generation from 5-V USB-C PD or 7.4-V Li-ion battery pack in test instrumentation. IC Role / Device Role / Timing Role: Step-up DC-DC controller regulating output with current-mode feedback and 100-kHz switching. Use Value: Delivers stable 12 V at up to 1.2 A with ±4% tolerance, leveraging internal 3-A switch and soft-start to prevent battery sag during startup. |
Use Scenario: Powering 3.3-V microcontroller and 5-V sensors from single-cell Li-ion (2.7–4.2 V) in handheld medical devices. IC Role / Device Role / Timing Role: Adjustable boost regulator providing programmable output via resistor divider; operates across full battery discharge curve. Use Value: Maintains regulated output down to 2.7 V input using wide 4–40 V range and 1.23-V precision reference, minimizing BOM count. |
| Flyback Isolated Power Supply | Multiplexed Output Telecom Adapter |
Use Scenario: Generating isolated ±12-V rails for op-amp biasing and 3.3-V logic in industrial PLC I/O modules. IC Role / Device Role / Timing Role: Flyback controller driving transformer primary; uses current-mode sensing for cross-regulation across secondaries. Use Value: Achieves <±5% cross-regulation on dual outputs using standard T7 transformer and TI-recommended layout, reducing need for post-regulators. |
Use Scenario: 24-V input to 5-V/12-V/−12-V triple-output adapter for legacy telecom equipment with mixed analog/digital loads. IC Role / Device Role / Timing Role: Primary-side flyback controller managing all three outputs via single transformer and passive rectification. Use Value: Enables compact, low-cost isolated supply using TI's T5 transformer family and integrated current limiting-no optocoupler or secondary-side feedback needed. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar DC-DC controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2587S-ADJ/NOPB | Same pinout, identical architecture, but rated for 5-A switch and 65-V standoff; higher thermal resistance in TO-263 package. | Better suited for >1.5-A boost or high-power flyback where higher switch current margin is required. | Select when output current demand exceeds 1.2 A or when operating near thermal limits of LM2585S-ADJ/NOPB. |
| UC3845N | Current-mode PWM controller (8-pin DIP), no integrated switch; requires external MOSFET; 450-kHz max frequency; no soft-start or UVLO built-in. | Used in custom high-efficiency or high-frequency boost/flyback designs where discrete switch selection and layout flexibility are prioritized. | Choose when designing for >200 kHz operation, needing MOSFET gate drive control, or requiring cost-sensitive through-hole assembly. |
Compared with LM2585S-ADJ/NOPB, LM2587S-ADJ/NOPB offers higher current capability in identical footprint, while UC3845N provides greater topology flexibility at the cost of increased external component count and reduced integration.
Availability
LM2585S-ADJ/NOPB is available at Aetrix Electronics and suitable for industrial power supplies, battery-powered portable equipment, isolated flyback converters, and telecom adapters requiring stable component supply and long-term production continuity.
Supply support for LM2585S-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 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, low-component-count flyback, boost, and forward converter applications-targeting engineers seeking robust, thermally efficient, and layout-simple DC-DC controllers for mid-power systems.
FAQ
What is the maximum output current achievable with LM2585S-ADJ/NOPB in boost configuration?
The LM2585S-ADJ/NOPB integrates a 3-A NPN switch, but output current in boost mode depends on input voltage, output voltage, efficiency, and thermal design. At 12-V output from 5-V input, typical continuous output is ~1.2 A. Per datasheet Section 6.3, output current must be externally limited to ≤3 A to protect the switch; higher loads require heatsinking or derating.
Does LM2585S-ADJ/NOPB support flyback topology with multiple isolated outputs?
Yes, LM2585S-ADJ/NOPB is explicitly designed for flyback applications including single-, dual-, and triple-output configurations. TI's datasheet provides six reference designs (Figures 22–27) and transformer selection tables (T5–T7) supporting up to three isolated rails-e.g., +5 V, +12 V, and −12 V-with cross-regulation achieved via transformer turns ratios and current-mode control.
What is the purpose of the COMP pin on LM2585S-ADJ/NOPB, and how is it configured?
The COMP pin is the error amplifier output, used to connect the compensation network (typically an RC series from COMP to FB) that stabilizes the control loop. Its voltage swings between 0.25 V and 2.8 V (typ). Proper compensation ensures phase margin >45° and prevents oscillation-TI recommends starting with the networks shown in Figures 47–48 and adjusting based on measured step response.
How does the undervoltage lockout (UVLO) function in LM2585S-ADJ/NOPB?
LM2585S-ADJ/NOPB incorporates an internal UVLO circuit that disables switching when input voltage falls below 3.05 V (min), preventing erratic operation during brownout. The turn-on threshold is 3.30 V (typ), with hysteresis of ~0.25 V. This protects downstream circuitry and ensures clean startup once input rises above the threshold.
Can LM2585S-ADJ/NOPB be used without a heat sink in TO-263 package?
Yes, LM2585S-ADJ/NOPB in KTT (DDPAK/TO-263) package can operate without an external heat sink at moderate loads and ambient temperatures. With 0.136 in² copper area, θJA is 56°C/W; at 1 W dissipation and 25°C ambient, junction temperature reaches ~81°C-within the −40°C to +125°C operating range. For >1.5 W dissipation or >60°C ambient, a heat sink or increased copper area is recommended.
LM2585S-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:
- Tube
- 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)
LM2585S-ADJ/NOPB FAQ
1.How can I place an order for LM2585S-ADJ/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2585S-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 LM2585S-ADJ/NOPB reliable?
The price and inventory of LM2585S-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 LM2585S-ADJ/NOPB is usually 5 days.
3.What payment methods are accepted for LM2585S-ADJ/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2585S-ADJ/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2585S-ADJ/NOPB?
LM2585S-ADJ/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2585S-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 LM2585S-ADJ/NOPB?
For technical support, including LM2585S-ADJ/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2585S-ADJ/NOPB requirements.
6.How does Aetrix verify that LM2585S-ADJ/NOPB is sourced from the original manufacturer or authorized distributors?
All LM2585S-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 LM2585S-ADJ/NOPB meets industry standards.
7.What is the process for return or replacement of LM2585S-ADJ/NOPB?
All LM2585S-ADJ/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2585S-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 LM2585S-ADJ/NOPB part is unused and in its original packaging.
Return procedure for LM2585S-ADJ/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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