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Texas Instruments LM2599SX-3.3/NOPB
- Part No.:
- LM2599SX-3.3/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- TO-263-8, D2PAK (7 Leads + Tab), TO-263CA
- Datasheet:
-
LM2599SX-3.3/NOPB.pdf
- Description:
- IC REG BUCK 3.3V 3A TO263
- Quantity:
- Payment:
- Shipping:
Inventory:590
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Product details
Overview
LM2599SX-3.3/NOPB from Texas Instruments is a monolithic 150-kHz nonsynchronous step-down DC-DC converter delivering up to 3 A at a fixed 3.3-V output, with ±4% output voltage tolerance over line and load, input voltage range up to 40 V, and integrated thermal shutdown and current-limit protection. It serves as a high-efficiency buck regulator in industrial power supplies and embedded system rails.
For engineers reviewing the LM2599SX-3.3/NOPB datasheet, LM2599SX-3.3/NOPB pinout, LM2599SX-3.3/NOPB application, or LM2599SX-3.3/NOPB equivalent, key selection criteria include its fixed 3.3-V output, TO-263-7 package thermal performance, soft-start/shutdown control interface, and error flag signaling for power-good monitoring in safety-critical subsystems.
Technical Context
The LM2599SX-3.3/NOPB implements a fixed-frequency (150 kHz) PWM controller with internal compensation, driving an integrated N-channel MOSFET switch. Its feedback loop uses a precision 1.23-V reference and senses output via internal resistive divider for the 3.3-V version - eliminating external resistor networks.
It supports dual-mode operation: normal regulation with soft-start ramp-up and shutdown mode drawing only 80 μA quiescent current. The error flag pin provides open-collector power-good indication with built-in 5% dropout threshold and programmable delay via external capacitor on the DELAY pin.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3 V ±4% over –40°C to +125°C and full load (0.2–3 A), enabling stable logic rail generation without trimming. |
| Max Output Current | 3 A DC continuous, supporting mid-power microcontroller, FPGA I/O, or peripheral subsystems without external current boosting. |
| Input Voltage Range | 4.5 V to 40 V, allowing direct operation from 5 V, 12 V, 24 V, or unregulated DC sources like automotive batteries or industrial SMPS outputs. |
| Switching Frequency | 150 kHz (±15%), enabling use of low-cost, standard through-hole or surface-mount inductors with minimal EMI filtering overhead. |
| Quiescent Current | 80 μA in shutdown mode, reducing standby power in battery-backed or energy-sensitive applications. |
| Efficiency | 73% typical at 12 VIN/3.3 VOUT/3 A, balancing thermal dissipation and conversion loss for compact PCB layouts. |
| Thermal Protection | Integrated junction temperature shutdown at 150°C, preventing latch-up or damage during overload or poor heatsinking conditions. |
Pinout & Package
LM2599SX-3.3/NOPB is supplied in a 7-pin TO-263 (KTW) surface-mount package with exposed thermal pad, measuring 10.10 mm × 8.89 mm, optimized for PCB copper area heat spreading and automated assembly.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| +VIN | Power Input | Accepts 4.5–40 V DC; requires local ceramic bypass capacitor to suppress switching transients and supply peak currents. |
| Output | Switch Node | Drives external catch diode and inductor; voltage swings between ~(+VIN − 1.4 V) and –0.5 V; demands minimal PCB copper area to reduce EMI coupling. |
| Error Flag | Open-Collector Output | Asserts low when VOUT drops >5% below 3.3 V; used for MCU reset or fault logging; pulled high externally via resistor. |
| Ground | Power & Signal Reference | Common return for input/output paths and internal circuitry; must be connected to low-impedance PCB ground plane. |
| Delay | Capacitor-Controlled Timing | Sets delay between VOUT reaching 95% and Error Flag deassertion; enables sequenced power-up in multi-rail systems. |
| Feedback | Internal Fixed Divider | Internally tied to 3.3-V output; no external resistors required - simplifies layout and eliminates calibration drift. |
| Shutdown/Soft-start | Logic-Controlled Interface | Pulled low to enter 80-μA shutdown; capacitor added for controlled VOUT ramp-up, limiting inrush current during startup. |
Key Features
| Feature | Design Value |
|---|---|
| Fixed 3.3-V Output | Eliminates external feedback resistors, reduces BOM count, and guarantees ±4% accuracy across temperature and load without trimming. |
| Integrated Soft-Start | Reduces peak inrush current from 2.6 A to 650 mA (typical), protecting input source and enabling reliable startup under weak supplies. |
| Power-Good Flag with Delay | Provides synchronized system reset after regulated output stabilizes, configurable via external capacitor to match downstream processor timing requirements. |
| Thermal & Current Limit Protection | Two-stage current limit and junction shutdown prevent damage during short-circuit, overload, or inadequate heatsinking - no external sensing needed. |
| TO-263-7 Thermal Pad | Enables direct thermal connection to PCB copper pour, achieving RθJA as low as 20°C/W with 3 in² double-sided copper, easing thermal design in space-constrained boards. |
Applications
| Industrial PLC Power Rail | Embedded Microcontroller Core Supply |
|---|---|
Use Scenario: Providing clean, regulated 3.3-V power to ARM Cortex-M or RISC-V SoCs in programmable logic controllers operating in harsh factory environments. IC Role / Device Role / Timing Role: Primary buck regulator converting 24-V field bus to isolated 3.3-V logic rail with thermal fault resilience and startup sequencing. Use Value: Delivers 3 A continuously at 73% efficiency while surviving 40-V transients and maintaining ±4% regulation across –40°C to +85°C ambient. | Use Scenario: Powering real-time sensor fusion modules in edge AI gateways where low-noise, fast transient response is critical for ADC/DAC accuracy. IC Role / Device Role / Timing Role: Main system regulator with soft-start and error flag enabling coordinated boot with FPGA configuration and memory initialization. Use Value: Reduces startup inrush by >75%, prevents brownout resets, and signals stable VOUT to enable clock domain synchronization before firmware execution. |
| Automotive Body Control Module | Medical Diagnostic Instrument Supply |
Use Scenario: Generating 3.3-V supply for CAN transceivers and microcontrollers in 12-V automotive body electronics with load dump immunity. IC Role / Device Role / Timing Role: Pre-regulator stepping down 12–28 V battery range to 3.3 V, interfacing with external TVS and reverse-polarity protection. Use Value: Withstands 40-V input surges, maintains regulation during cranking (down to 4.5 V), and integrates shutdown for low-quiescent sleep modes. | Use Scenario: Powering analog front-end circuits and low-power processors in portable ultrasound or patient monitors requiring high reliability and low EMI. IC Role / Device Role / Timing Role: Isolated secondary-side regulator with error flag feeding watchdog timer to ensure safe power-down on output failure. Use Value: Provides fail-safe power-good signaling, ±4% output stability over medical-grade temperature range, and thermal shutdown to prevent overheating in sealed enclosures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2599T-3.3/NOPB | Same electrical specs but in 7-pin TO-220 (NDZ) package; higher RθJA (50°C/W) and no thermal pad; leaded, through-hole mounting. | Preferred for prototyping, manual assembly, or legacy board designs requiring vertical heatsink attachment. | Select LM2599T-3.3/NOPB when mechanical constraints favor through-hole mounting or when thermal management uses external heatsinks instead of PCB copper. |
| LM2678-3.3/NOPB | Higher 260-kHz switching frequency, 5-A output rating, and improved light-load efficiency; different pinout and soft-start behavior. | Better suited for high-current, space-constrained designs needing faster transient response and lower output ripple. | Choose LM2678-3.3/NOPB when upgrading from 3-A to 5-A capability or when 260-kHz operation allows smaller magnetics and reduced filter size. |
Compared with LM2599SX-3.3/NOPB, the TO-220 variant offers simpler thermal retrofitting but lower power density, while the LM2678-3.3/NOPB delivers higher current and frequency at the cost of redesign effort due to non-pin-compatible layout and control interface differences.
Availability
LM2599SX-3.3/NOPB is available at Aetrix Electronics and suitable for industrial PLC power rails, embedded microcontroller core supplies, and automotive body control modules requiring stable component supply and long-term manufacturability.
Supply support for LM2599SX-3.3/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 leader specializing in analog, embedded processing, and power management ICs, with decades of expertise in high-reliability power conversion solutions.
The LM2599 SIMPLE SWITCHER® product line was designed for ease-of-use in cost-sensitive, medium-power DC-DC applications - minimizing external components while delivering robust performance in industrial, automotive, and medical equipment.
FAQ
What is the maximum input voltage rating for the LM2599SX-3.3/NOPB?
The LM2599SX-3.3/NOPB has an absolute maximum input voltage rating of 45 V, with recommended operation up to 40 V. Exceeding 40 V may trigger internal protection or reduce reliability; sustained operation above this limit is not advised per TI's SNVS123D datasheet Section 7.1.
Does the LM2599SX-3.3/NOPB require external feedback resistors?
No, the LM2599SX-3.3/NOPB does not require external feedback resistors. It integrates a precision voltage divider for the fixed 3.3-V output, connecting the FEEDBACK pin internally to the output - simplifying layout and ensuring ±4% regulation without calibration.
How does the Error Flag pin function on the LM2599SX-3.3/NOPB?
The Error Flag pin on the LM2599SX-3.3/NOPB is an open-collector output that pulls low when the regulated 3.3-V output falls more than 5% below nominal (i.e., below 3.135 V). It remains low until VOUT reaches 95% of target and the DELAY pin capacitor times out - enabling reliable power-good signaling for microprocessor reset.
Can the LM2599SX-3.3/NOPB be used in a negative-output inverting configuration?
Yes, the LM2599SX-3.3/NOPB can be configured as an inverting regulator to generate a negative output, though it requires re-biasing the GROUND pin and adding an isolation diode. TI's datasheet Figure 21 shows this topology using the 5-V version; for LM2599SX-3.3/NOPB, the output magnitude is limited by the sum of |VIN| + |VOUT| ≤ 40 V.
What thermal performance can be expected from the LM2599SX-3.3/NOPB in TO-263 package?
In the TO-263-7 (KTW) package, the LM2599SX-3.3/NOPB achieves a junction-to-ambient thermal resistance (RθJA) as low as 20°C/W when mounted on a double-sided PCB with 3 in² of 1-oz copper on the device side and ~16 in² on the opposite side - enabling 3-A operation without external heatsink under typical industrial ambient conditions.
LM2599SX-3.3/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- TO-263-8, D2PAK (7 Leads + Tab), TO-263CA
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4.5V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 3.3V
- Voltage - Output (Max):
- -
- Current - Output:
- 3A
- Frequency - Switching:
- 150kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- TO-263 (DDPAK-7)
LM2599SX-3.3/NOPB FAQ
1.How can I place an order for LM2599SX-3.3/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2599SX-3.3/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 LM2599SX-3.3/NOPB reliable?
The price and inventory of LM2599SX-3.3/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2599SX-3.3/NOPB is usually 5 days.
3.What payment methods are accepted for LM2599SX-3.3/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2599SX-3.3/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2599SX-3.3/NOPB?
LM2599SX-3.3/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2599SX-3.3/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 LM2599SX-3.3/NOPB?
For technical support, including LM2599SX-3.3/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2599SX-3.3/NOPB requirements.
6.How does Aetrix verify that LM2599SX-3.3/NOPB is sourced from the original manufacturer or authorized distributors?
All LM2599SX-3.3/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 LM2599SX-3.3/NOPB meets industry standards.
7.What is the process for return or replacement of LM2599SX-3.3/NOPB?
All LM2599SX-3.3/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2599SX-3.3/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 LM2599SX-3.3/NOPB part is unused and in its original packaging.
Return procedure for LM2599SX-3.3/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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