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Texas Instruments LM2598SX-ADJ
- Part No.:
- LM2598SX-ADJ
- Manufacturer:
- Texas Instruments
- Package:
- TO-263-8, D2PAK (7 Leads + Tab), TO-263CA
- Datasheet:
-
LM2598SX-ADJ.pdf
- Description:
- IC REG BUCK ADJ 1A TO263
- Quantity:
- Payment:
- Shipping:
Inventory:1,683
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Product details
Overview
LM2598SX-ADJ from Texas Instruments is a monolithic 150 kHz step-down (buck) switching regulator IC delivering up to 1A output current with adjustable output voltage from 1.2V to 37V (±4% tolerance over line and load), input voltage range up to 40V, and integrated soft-start/shutdown control. It serves as a primary DC-DC power conversion stage in industrial power supplies and embedded systems requiring high-efficiency regulation without external compensation.
For engineers reviewing the LM2598SX-ADJ datasheet, LM2598SX-ADJ pinout, LM2598SX-ADJ application, or LM2598SX-ADJ equivalent, key selection criteria include its fixed 150 kHz oscillator frequency, ±4% output voltage accuracy across temperature and load, thermal shutdown protection, 85 μA standby quiescent current, and compatibility with standard off-the-shelf inductors.
Technical Context
The LM2598SX-ADJ implements a current-mode buck topology with internal 150 kHz oscillator, two-stage current limiting, and thermal shutdown. Its feedback pin monitors output via external resistor divider, referencing a precise 1.230 V (±3.3% over temperature) internal bandgap reference.
It integrates soft-start via an internal 1.6 μA current source charging an external capacitor, and provides an error flag output with programmable delay. Shutdown is controlled by pulling the SD/SS pin below 0.6 V, reducing quiescent current to 85 μA typical.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 1 A continuous - supports full-load operation without derating at ambient ≤50°C in TO-220 or DDPAK packages without heatsink. |
| Input Voltage Range | 4.5 V to 40 V - enables direct regulation from 12 V, 24 V, or 36 V industrial rails without pre-regulation. |
| Output Voltage Range | 1.2 V to 37 V (adjustable) - set precisely using external R1/R2 divider; VFB = 1.230 V ±3.3% ensures stable regulation across temperature. |
| Switching Frequency | 150 kHz fixed - allows use of compact, low-cost standard inductors (e.g., 68–100 μH) while minimizing EMI filtering complexity. |
| Efficiency | 78% at VIN = 12 V, VOUT = 3 V, ILOAD = 1 A - delivers high conversion efficiency without synchronous rectification. |
| Quiescent Current | 85 μA in shutdown - enables ultra-low-power system sleep modes with minimal battery drain. |
| Thermal Protection | Internally limited junction temperature (TJ ≤ 150°C) - prevents damage during overload or poor heatsinking conditions. |
Pinout & Package
LM2598SX-ADJ is supplied in a 7-pin DDPAK (surface-mount) package with exposed thermal pad for enhanced heat dissipation. The package measures 10.16 mm × 8.89 mm × 4.57 mm (0.400″ × 0.350″ × 0.180″) and features a thermally optimized leadframe design.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (VIN) | Input Power Supply | Accepts 4.5–40 V DC; requires local 120 μF low-ESR input capacitor to suppress switching transients. |
| 2 (OUT) | Power Switch Output | Drives external catch diode and inductor; peak switch current up to 2.6 A under overload. |
| 3 (GND) | Power Ground | Common return for input, output, and internal circuitry; must be connected directly to thermal pad for optimal thermal performance. |
| 4 (FB) | Feedback Input | Monitors regulated output via resistor divider; 10 nA bias current enables high-resistance dividers with minimal error. |
| 5 (SD/SS) | Shutdown/Soft-start Control | Pull ≤0.6 V to disable regulator (85 μA IQ); apply rising voltage to initiate controlled soft-start ramp. |
| 6 (FLAG) | Error Flag Output | Open-collector output pulled low when VOUT drops below 92–98% of nominal; used for system fault detection. |
| 7 (DELAY) | Flag Delay Timing | Connects to 0.1 μF capacitor to set flag assertion delay; avoids false triggers during transient load steps. |
Key Features
| Feature | Design Value |
|---|---|
| Internal Frequency Compensation | Eliminates need for external compensation network - simplifies design and improves stability across all operating conditions. |
| Two-Stage Current Limit | First stage limits peak switch current to ≥1.15 A; second stage reduces frequency under severe overload - protects MOSFET and inductor. |
| Programmable Error Flag Delay | External capacitor on DELAY pin sets flag assertion time - prevents nuisance triggering during startup or load transients. |
| Low Standby Quiescent Current | 85 μA typical in shutdown - extends battery life in portable or always-on applications. |
| Thermal Shutdown with Hysteresis | Shuts down at TJ = 150°C; restarts after ~15°C cooldown - prevents thermal runaway while allowing safe recovery. |
Applications
| Industrial Power Supplies | Embedded System Pre-Regulators |
|---|---|
Use Scenario: Converting 24 V factory bus voltage to 5 V or 12 V for PLC I/O modules and sensor interfaces. IC Role / Device Role / Timing Role: Primary non-isolated buck converter providing stable, efficient intermediate rail with built-in fault signaling. Use Value: Eliminates need for external current-sense or thermal monitoring circuits due to integrated two-stage current limit and thermal shutdown. | Use Scenario: Generating clean 3.3 V supply for microcontrollers and FPGAs from higher-voltage battery or adapter inputs. IC Role / Device Role / Timing Role: Step-down regulator with soft-start ensuring controlled power-up sequencing and avoiding inrush-induced brownouts. Use Value: 1.230 V feedback reference and ±4% output tolerance guarantee reliable logic-level compliance across temperature and load variation. |
| On-Card DC-DC Conversion | Positive-to-Negative Inverting Supplies |
Use Scenario: Local regulation on dense PCBs where space constraints prohibit discrete buck controllers with external MOSFETs. IC Role / Device Role / Timing Role: Integrated switcher delivering 1 A output in compact DDPAK footprint with minimal external components. Use Value: Fixed 150 kHz frequency enables predictable EMI filtering and consistent inductor sizing across designs. | Use Scenario: Generating −5 V or −12 V rails for op-amp biasing or analog signal conditioning using inverting buck-boost topology. IC Role / Device Role / Timing Role: Adjustable-output buck controller reconfigured as inverting regulator via standard application circuit (Figure 29). Use Value: Wide 1.2–37 V output range and precise feedback reference support accurate negative rail generation without additional regulators. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2596SX-ADJ | Same 150 kHz frequency and 1 A rating, but lower max input voltage (40 V vs. 40 V), identical feedback reference (1.23 V), and slightly lower efficiency (75% vs. 78% at 3 V out). | Identical pinout and application circuitry; suitable for cost-sensitive designs where thermal margin is less constrained. | Select LM2596SX-ADJ if board space and BOM cost are prioritized over peak efficiency and thermal headroom. |
| TPS54202DRCT | Higher switching frequency (480 kHz), smaller solution size, 2 A rating, but requires external compensation and lacks integrated error flag/delay functions. | Designed for compact, high-density layouts; not drop-in compatible due to different pinout, control architecture, and feature set. | Choose TPS54202DRCT only when upgrading to higher frequency and current capability justifies redesign effort and added component count. |
Compared with LM2596SX-ADJ, LM2598SX-ADJ offers marginally better efficiency and identical functionality; compared with TPS54202DRCT, it trades higher integration and simpler layout for lower frequency and current capability-making LM2598SX-ADJ optimal for robust, low-risk industrial power stages.
Availability
LM2598SX-ADJ is available at Aetrix Electronics and suitable for industrial power supplies, embedded system pre-regulators, and on-card DC-DC conversion requiring stable component supply, long-term lifecycle support, and proven reliability in harsh environments.
Supply support for LM2598SX-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 solutions, with decades of expertise in switching regulator design and manufacturing.
The LM2598 series was engineered specifically for cost-effective, high-reliability buck conversion in industrial, automotive, and telecom infrastructure applications-emphasizing ease of use, thermal robustness, and minimal external component count.
FAQ
What is the maximum input voltage rating for the LM2598SX-ADJ?
The absolute maximum input voltage for the LM2598SX-ADJ is 45 V, but the recommended operating range is 4.5 V to 40 V per the datasheet's Operating Conditions table. Exceeding 40 V may compromise long-term reliability and is not guaranteed to meet electrical specifications. The LM2598SX-ADJ maintains full 1 A output capability across this 40 V range when properly heatsinked.
How do I set the output voltage for the LM2598SX-ADJ?
The LM2598SX-ADJ output voltage is set using two external resistors (R1 and R2) forming a voltage divider from VOUT to GND, with the FB pin connected to their junction. The formula is VOUT = 1.23 V × (1 + R2/R1). For best stability, select R1 ≈ 1 kΩ (1% tolerance), then calculate R2 accordingly - e.g., for 12 V output, R2 = 8.75 kΩ. The LM2598SX-ADJ's 10 nA feedback bias current minimizes divider error.
Does the LM2598SX-ADJ require external compensation components?
No, the LM2598SX-ADJ includes fully internal frequency compensation, eliminating the need for external capacitors or resistors in the compensation network. This simplifies design, reduces bill-of-materials cost, and ensures stable operation across all valid input voltages, output voltages, and load conditions without tuning. The internal compensation is optimized for standard inductor values (e.g., 68–100 μH) and output capacitors (e.g., 120–220 μF).
What thermal considerations apply to the LM2598SX-ADJ in DDPAK package?
The LM2598SX-ADJ in DDPAK (KTW0007B) achieves θJA = 20°C/W when mounted on a double-sided PCB with 3 in² copper on the device side and 16 in² on the opposite side. With minimal copper (0.5 in²), θJA rises to 50°C/W. The device includes thermal shutdown at 150°C junction temperature and automatically recovers after cooling by ~15°C. For 1 A continuous load at 40 V input, ensure ≥2 in² of 1 oz. copper connected to the thermal pad to avoid exceeding TJ = 125°C.
Can the LM2598SX-ADJ be used in a positive-to-negative inverting configuration?
Yes, the LM2598SX-ADJ supports positive-to-negative inverting operation using the standard buck-boost topology shown in Figure 29 of the datasheet. In this configuration, the output voltage magnitude is set by the same R1/R2 divider, with polarity inverted. The LM2598SX-ADJ's wide 1.2–37 V adjustable range and robust current limiting make it suitable for generating stable negative rails such as −5 V or −12 V, provided the external diode, inductor, and capacitor ratings are selected per the inverting design guidelines.
LM2598SX-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):
- 1.2V
- Voltage - Output (Max):
- 37V
- Current - Output:
- 1A
- 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)
LM2598SX-ADJ FAQ
1.How can I place an order for LM2598SX-ADJ through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2598SX-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 LM2598SX-ADJ reliable?
The price and inventory of LM2598SX-ADJ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2598SX-ADJ is usually 5 days.
3.What payment methods are accepted for LM2598SX-ADJ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2598SX-ADJ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2598SX-ADJ?
LM2598SX-ADJ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2598SX-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 LM2598SX-ADJ?
For technical support, including LM2598SX-ADJ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2598SX-ADJ requirements.
6.How does Aetrix verify that LM2598SX-ADJ is sourced from the original manufacturer or authorized distributors?
All LM2598SX-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 LM2598SX-ADJ meets industry standards.
7.What is the process for return or replacement of LM2598SX-ADJ?
All LM2598SX-ADJ units undergo pre-shipment inspection (PSI). If there is an issue with LM2598SX-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 LM2598SX-ADJ part is unused and in its original packaging.
Return procedure for LM2598SX-ADJ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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