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Texas Instruments LM2599SX-ADJ
- Part No.:
- LM2599SX-ADJ
- Manufacturer:
- Texas Instruments
- Package:
- TO-263-8, D2PAK (7 Leads + Tab), TO-263CA
- Datasheet:
-
LM2599SX-ADJ.pdf
- Description:
- IC REG BUCK ADJ 3A TO263
- Quantity:
- Payment:
- Shipping:
Inventory:2,589
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Product details
Overview
LM2599SX-ADJ from Texas Instruments is a monolithic step-down (buck) switching voltage regulator IC delivering up to 3A output current with adjustable output voltage from 1.2V to 37V, ±4% tolerance over line and load, operating at a fixed 150 kHz switching frequency, and featuring thermal shutdown, current limiting, and an error flag output - used in high-efficiency DC/DC conversion for industrial power supplies and embedded systems.
For engineers reviewing the LM2599SX-ADJ datasheet, LM2599SX-ADJ pinout, LM2599SX-ADJ application, or LM2599SX-ADJ equivalent, key selection considerations include its 40V max input voltage, 80 μA standby quiescent current, feedback reference voltage of 1.230 V, integrated soft-start/shutdown control, and TO-263-7 surface-mount package thermal performance.
Technical Context
The LM2599SX-ADJ implements a current-mode PWM buck topology with internal 150 kHz oscillator, two-stage current limit protection, and built-in thermal shutdown. Its feedback loop uses a precision 1.230 V reference applied to the FB pin, enabling output programming via external resistor divider.
It integrates soft-start via the SS/SD pin (2 V threshold), error flag assertion when output drops below 92–98% of nominal, and delay timing controlled by an external capacitor on the DELAY pin. The device operates across −40°C to +125°C junction temperature with internally compensated control loop.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | Ensured 3 A continuous - supports high-power loads without external current boosting. |
| Input Voltage Range | 4.5 V to 40 V - compatible with 5 V, 12 V, 24 V, and 36 V industrial bus rails. |
| Output Voltage Range | 1.2 V to 37 V (adjustable) - set precisely using external R1/R2 divider per VOUT = 1.23 × (1 + R2/R1). |
| Feedback Reference | 1.230 V ±0.037 V - defines regulation accuracy and sets minimum output voltage floor. |
| Switching Frequency | 150 kHz (±15%) - enables use of standard, low-cost off-the-shelf inductors (e.g., 33–68 μH). |
| Quiescent Current | 80 μA in shutdown - minimizes system standby power loss in battery-backed applications. |
| Thermal Resistance | θJA = 20°C/W (TO-263 on double-sided PCB w/ 16 in² copper) - enables 3 A operation without external heatsink under typical layout. |
Pinout & Package
LM2599SX-ADJ is housed in a 7-lead TO-263 (KTW) surface-mount package with exposed thermal pad. Pin 1 is marked by tab notch; pin numbering follows standard counterclockwise sequence starting from tab side.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| IN | Input Power Supply | Accepts 4.5–40 V DC; requires local 470 μF low-ESR input capacitor for stability. |
| OUT | Switched Output Node | Drives external catch diode and inductor; high di/dt node requiring short PCB traces. |
| GND | Power Ground | Common return for input/output capacitors, inductor, and feedback network; must be low-impedance plane. |
| FB | Feedback Input | Senses output via resistor divider; 10 nA bias current allows high-value resistors to minimize divider power loss. |
| SS/SD | Soft-Start / Shutdown Control | Pulled low (≤0.6 V) disables regulator; pulled high (≥2 V) initiates 2 ms soft-start ramp. |
| FLAG | Error Flag Output | Open-collector active-low signal asserting when output drops >4% below target (e.g., overload or dropout). |
| DELAY | Flag Delay Timing | Connects to 0.1 μF capacitor to ground to set flag assertion delay (≈10 ms typical). |
Key Features
| Feature | Design Value |
|---|---|
| Integrated Soft-Start | 2 ms output voltage ramp prevents inrush current and stabilizes downstream LDOs or microcontrollers. |
| Out-of-Regulation Flag | Dedicated open-drain FLAG pin with programmable delay ensures reliable fault detection before system reset. |
| Two-Stage Current Limit | Peak switch current limit (3.4–6.9 A) plus foldback protects against short-circuit while maintaining startup capability. |
| Low Standby IQ | 80 μA shutdown current enables multi-day battery operation in always-on monitoring systems. |
| Thermal Shutdown | Activates at +150°C junction temperature and auto-recovers after cooldown - prevents permanent damage during overload. |
Applications
| Industrial Power Supply | Embedded System Pre-Regulator |
|---|---|
Use Scenario: Converting 24 V factory bus to 5 V/3.3 V for PLC I/O modules and sensor interfaces. IC Role / Device Role: Primary non-isolated buck converter delivering regulated 5 V @ 3 A with ripple <100 mV. Use Value: Eliminates need for external current-sense amplifiers or discrete MOSFET drivers due to integrated 3 A switch and current limiting. | Use Scenario: Providing clean 3.3 V rail to ARM Cortex-M7 MCU and DDR3 memory in edge gateway hardware. IC Role / Device Role: Efficient pre-regulator stepping down 12 V intermediate rail to reduce heat dissipation before final LDO stage. Use Value: Achieves 73% efficiency at 12 V → 3 V / 3 A, cutting thermal load vs. linear solution by >8 W. |
| Positive-to-Negative Converter | Test Equipment Power Module |
Use Scenario: Generating −12 V from +24 V supply in analog front-end circuitry for op-amp biasing. IC Role / Device Role: Configured in inverting buck-boost topology using external inductor and diode. Use Value: Leverages same 150 kHz frequency and feedback architecture as buck mode - simplifies design reuse and BOM consolidation. | Use Scenario: Programmable 1.2–30 V output module in benchtop power supply with digital control interface. IC Role / Device Role: Core adjustable regulator with DAC-driven feedback divider enabling precise voltage setting. Use Value: 1.230 V reference tolerance (±3%) and 10 nA FB bias enable 0.1% output resolution with 16-bit DAC and precision resistors. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2596SX-ADJ | Lower 3 A current rating, 150 kHz frequency, no FLAG/DELAY pins, higher dropout voltage. | Lacks error flag and programmable delay; less suitable for safety-monitored systems. | Choose when cost sensitivity outweighs fault reporting needs and full 3 A load is not required. |
| MP1584EN-LF-Z | 4 A rated, 1.5 MHz switching, smaller 8-pin SOIC package, no integrated FLAG output. | Higher frequency enables smaller magnetics but increases EMI filtering complexity; no native fault signaling. | Prefer for space-constrained designs where board area is critical and external fault monitoring is acceptable. |
Compared with LM2596SX-ADJ, LM2599SX-ADJ adds robust fault detection and tighter output tolerance; versus MP1584EN-LF-Z, it trades higher-frequency efficiency for proven industrial reliability, larger thermal margin, and integrated diagnostics - making it preferred for long-lifecycle, maintenance-sensitive equipment.
Availability
LM2599SX-ADJ is available at Aetrix Electronics and suitable for industrial power supplies, embedded system pre-regulators, test equipment power modules, and positive-to-negative converters requiring stable component supply, long-term lifecycle support, and consistent parametric performance across temperature and load.
Supply support for LM2599SX-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 specializing in analog, embedded processing, and power management technologies, with decades of expertise in high-reliability power conversion ICs.
The LM2599 series belongs to TI's SIMPLE SWITCHER® portfolio - designed specifically for ease-of-use, minimal external component count, and rugged operation in industrial, automotive, and telecom power systems.
FAQ
What is the maximum input voltage rating for LM2599SX-ADJ?
The absolute maximum input voltage for LM2599SX-ADJ is 45 V, but the recommended operating range is 4.5 V to 40 V. Exceeding 40 V may trigger internal overvoltage protection or reduce reliability. The device maintains regulation and protection features across this full range, including thermal shutdown and current limiting at elevated input conditions. Always verify derating curves in the SNVS123C datasheet for sustained operation near limits.
How do I calculate the output voltage setting resistors for LM2599SX-ADJ?
Use the formula VOUT = 1.23 × (1 + R2/R1), where R1 connects from FB to GND and R2 from OUT to FB. Select R1 ≈ 1 kΩ (1% tolerance) for stability; then solve for R2. For example, for 12 V output: R2 = 1 kΩ × ((12 / 1.23) − 1) ≈ 8.74 kΩ - use 8.66 kΩ (1%) for closest match. LM2599SX-ADJ's 10 nA FB bias current minimizes resistor-divider error, supporting high-value resistors to reduce power loss.
Does LM2599SX-ADJ require an external compensation network?
No, LM2599SX-ADJ includes internal frequency compensation - no external compensation components are needed. The device is optimized for standard output capacitor ESR ranges (e.g., aluminum electrolytic or solid tantalum). Adding external compensation may destabilize the loop. Layout best practices (short FB trace, grounded thermal pad, localized input/output caps) are sufficient for stable operation per TI's Application Report SLVA001.
What thermal performance can I expect from LM2599SX-ADJ in TO-263 package?
In a standard double-sided PCB layout with 3 in² copper on the LM2599SX-ADJ side and 16 in² on the opposite side, θJA is 20°C/W. At 3 A output with 12 V input → 5 V output (73% efficiency), power dissipation is ~2.3 W - resulting in ~46°C rise above ambient. With 25°C ambient, junction temperature reaches ~71°C, well below the 150°C limit. No external heatsink is required under these conditions.
Can LM2599SX-ADJ be used in a negative-output configuration?
Yes, LM2599SX-ADJ supports inverting buck-boost topology to generate negative outputs. Configure the IN pin as ground reference, connect the inductor between OUT and the negative rail, and route the catch diode accordingly. Feedback must be referenced to the negative output. The LM2599SX-ADJ's wide 1.2–37 V adjustment range and robust current limit make it suitable for such applications, as confirmed in TI's Application Note SLVA001 Section 5.2.
LM2599SX-ADJ 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:
- Obsolete
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4.5V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 1.23V
- Voltage - Output (Max):
- 37V
- 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-ADJ FAQ
1.How can I place an order for LM2599SX-ADJ through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2599SX-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 LM2599SX-ADJ reliable?
The price and inventory of LM2599SX-ADJ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2599SX-ADJ is usually 5 days.
3.What payment methods are accepted for LM2599SX-ADJ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2599SX-ADJ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2599SX-ADJ?
LM2599SX-ADJ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2599SX-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 LM2599SX-ADJ?
For technical support, including LM2599SX-ADJ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2599SX-ADJ requirements.
6.How does Aetrix verify that LM2599SX-ADJ is sourced from the original manufacturer or authorized distributors?
All LM2599SX-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 LM2599SX-ADJ meets industry standards.
7.What is the process for return or replacement of LM2599SX-ADJ?
All LM2599SX-ADJ units undergo pre-shipment inspection (PSI). If there is an issue with LM2599SX-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 LM2599SX-ADJ part is unused and in its original packaging.
Return procedure for LM2599SX-ADJ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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