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Texas Instruments LM2598S-ADJ
- Part No.:
- LM2598S-ADJ
- Manufacturer:
- Texas Instruments
- Package:
- TO-263-8, D2PAK (7 Leads + Tab), TO-263CA
- Datasheet:
-
LM2598S-ADJ.pdf
- Description:
- IC REG BUCK ADJ 1A TO263
- Quantity:
- Payment:
- Shipping:
Inventory:4,709
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Product details
Overview
LM2598S-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), operating from 4.5V to 40V input, and featuring internal soft-start, shutdown control, and out-of-regulation error flag - used in industrial power supplies requiring compact, high-efficiency DC-DC conversion.
For engineers reviewing the LM2598S-ADJ datasheet, LM2598S-ADJ pinout, LM2598S-ADJ application, or LM2598S-ADJ equivalent, key selection considerations 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 LM2598S-ADJ implements a current-mode PWM buck topology with internal 150 kHz oscillator, two-stage current limiting, and integrated power switch. It uses feedback from an external resistor divider to regulate output voltage via a 1.230 V ±2.7% reference at the FB pin.
Its control architecture includes soft-start initiated by charging an external capacitor on the SS/SD pin, delay-controlled flag assertion for undervoltage detection, and thermal shutdown activation above +150°C junction temperature - all without requiring external compensation components.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 1 A maximum continuous - supports single-rail loads such as microcontroller cores or analog subsystems without external current boosting. |
| Input Voltage Range | 4.5 V to 40 V - enables direct operation from 12 V, 24 V, or 36 V industrial bus rails with margin for transients. |
| Output Voltage Range | 1.2 V to 37 V (adjustable) - set precisely using external R1/R2 divider; 1.230 V ±2.7% FB reference ensures tight regulation. |
| Switching Frequency | 150 kHz fixed - allows use of low-cost, small-footprint magnetic components while avoiding AM radio band interference. |
| Efficiency | 78% typical at VIN = 12 V, VOUT = 3 V, IOUT = 1 A - balances thermal performance and EMI in space-constrained designs. |
| Quiescent Current | 85 μA in shutdown - minimizes battery drain in always-on or low-power standby systems. |
| Thermal Protection | Internal thermal shutdown at +150°C junction - prevents damage during overload or poor heatsinking conditions. |
Pinout & Package
LM2598S-ADJ is housed in a 7-pin DDPAK (TO-263) surface-mount package with exposed thermal pad for enhanced heat dissipation; θJA = 20°C/W with double-sided PCB copper pour per TI datasheet SNVS125C.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Input supply connection | Accepts 4.5–40 V DC; requires local 120 μF low-ESR input capacitor near pin for stability. |
| OUT | Switch node / power output | Drives external catch diode and inductor; high dv/dt node requiring short, wide traces. |
| GND | Power and signal ground | Common return for internal switch, feedback, and error circuits; must connect to thermal pad. |
| FB | Feedback input | Senses output via resistor divider; 10 nA bias current enables high-value resistors for low quiescent loss. |
| SS/SD | Soft-start / shutdown control | Pulled low to disable regulator (85 μA IQ); pulled high to initiate soft-start via external capacitor ramp. |
| FLAG | Error flag output | Open-collector active-low signal asserting when output drops below 92–98% of nominal value. |
| DELAY | Flag delay timing | Connects to 0.1 μF capacitor to set flag assertion delay (typically ~10 ms) after startup or fault. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 1A power switch | Eliminates need for external MOSFET and gate driver; reduces BOM count and layout complexity. |
| Fixed 150 kHz oscillator | Enables predictable EMI filtering and consistent inductor sizing across designs without frequency drift. |
| Adjustable output (1.2–37 V) | Supports custom rail generation (e.g., 3.3 V, 15 V, 24 V) using only two precision resistors - no variant stocking required. |
| Out-of-regulation flag with delay | Provides reliable system-level fault signaling with user-configurable hold-off time to avoid false triggers during transients. |
| Thermal shutdown + current limit | Two-stage current limiting and automatic thermal recovery enable robust operation under sustained overload or ambient extremes. |
Applications
| Industrial PLC Power Supply | Test Equipment Auxiliary Rail |
|---|---|
Use Scenario: Generating isolated 15 V/1 A auxiliary supply from 24 V backplane in programmable logic controller modules. IC Role / Device Role / Timing Role: Primary buck regulator controlling power delivery to analog I/O circuitry and communication interfaces. Use Value: Delivers stable 15 V output with ±4% accuracy across −25°C to +125°C ambient, eliminating need for post-regulation LDOs. | Use Scenario: Providing clean 5 V/1 A bias rail for DMM front-end amplifiers and ADC references in portable test gear. IC Role / Device Role / Timing Role: High-efficiency pre-regulator stepping down 9 V battery or 12 V adapter input before linear regulation. Use Value: Achieves 78% efficiency at 12 V → 5 V conversion, extending battery life while maintaining <100 mVpp ripple with standard 68 μH inductor. |
| LED Driver Bias Supply | Motor Control Logic Power |
Use Scenario: Creating 3.3 V/1 A logic supply for LED driver ICs and current-sense amplifiers in architectural lighting systems. IC Role / Device Role / Timing Role: Buck converter supplying digital control and analog sensing circuitry adjacent to high-current LED strings. Use Value: Maintains regulation during 40 V load-dump transients on vehicle-derived 24 V inputs, supported by 45 V absolute max VIN rating. | Use Scenario: Powering gate drivers and MCU peripherals in 24 V BLDC motor controllers where space and thermal headroom are constrained. IC Role / Device Role / Timing Role: Compact, thermally robust DC-DC stage replacing discrete buck solutions with higher assembly cost. Use Value: Exposed DDPAK thermal pad enables 20°C/W θJA with double-sided copper, allowing full 1 A load at +70°C ambient without heatsink. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2596S-ADJ | Same 150 kHz frequency and 1 A rating, but lower 37 V max VIN (vs. 40 V), no FLAG/DELAY pins, and 1.235 V FB reference. | Lacks error flag and delay functionality; suitable only where supervisory signaling is unnecessary. | Choose LM2596S-ADJ for cost-sensitive, non-critical applications omitting fault reporting. |
| MP1584EN-LF-Z | Higher 1.5 MHz switching frequency, 3 A rating, 4.5–28 V input, but requires external compensation and lacks integrated flag/delay. | Better suited for ultra-compact designs needing smaller inductors, but demands more design effort and offers no built-in fault signaling. | Select MP1584EN-LF-Z when board area is critical and system-level monitoring replaces FLAG functionality. |
Compared with LM2596S-ADJ, LM2598S-ADJ provides fault visibility and wider input range; versus MP1584EN-LF-Z, it trades higher-frequency size reduction for plug-and-play reliability and integrated protection - making LM2598S-ADJ optimal for industrial systems prioritizing robustness over miniaturization.
Availability
LM2598S-ADJ is available at Aetrix Electronics and suitable for industrial PLCs, test equipment power supplies, LED driver bias rails, and motor control logic power requiring stable component supply and long-term manufacturability.
Supply support for LM2598S-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 LM2598 series belongs to TI's SIMPLE SWITCHER® portfolio - designed specifically for engineers needing easy-to-use, application-ready buck regulators with minimal external components and proven thermal performance in harsh environments.
FAQ
What is the minimum input voltage required for stable operation of the LM2598S-ADJ?
The LM2598S-ADJ requires a minimum input voltage of 4.5 V to maintain regulation across its full output range. Below this threshold, the internal circuitry cannot sustain switching action or feedback control, resulting in dropout. This specification is confirmed in the Operating Conditions table of TI's SNVS125C datasheet, where VIN ≥ 4.5 V is defined for all versions including LM2598S-ADJ.
Can the LM2598S-ADJ be used to generate a 3.3 V output, and what resistor values are recommended?
Yes, the LM2598S-ADJ can generate 3.3 V using an external resistor divider on the FB pin. With a 1.230 V reference, R1 = 1 kΩ and R2 = 1.7 kΩ (1% tolerance) yields 3.3 V output. TI's Application Information section confirms this configuration achieves ±4% accuracy over line and load, and recommends locating both resistors close to the IC to minimize noise coupling.
Does the LM2598S-ADJ require an external compensation network?
No, the LM2598S-ADJ includes internal frequency compensation and operates stably with standard external components (inductor, catch diode, input/output capacitors) as specified in TI's Figure 24 test circuit. The datasheet explicitly states "internal frequency compensation†" and provides no provision or recommendation for external compensation - simplifying design and reducing component count.
How does the FLAG pin function in the LM2598S-ADJ, and what is its electrical behavior?
The FLAG pin is an open-collector output that pulls low when the regulated output falls below 92–98% of its nominal value. Its saturation voltage is ≤0.3 V at 3 mA sink current, and it features an external delay capacitor (typically 0.1 μF on DELAY pin) to prevent false triggering during startup or transient dips. This behavior is documented in the FLAG/DELAY CONTROL section of the SNVS125C datasheet.
What thermal performance can be expected from the LM2598S-ADJ in a DDPAK package without a heatsink?
In the DDPAK (KTW0007B) package with proper PCB layout - including soldering the thermal pad to ≥3 in² of 1 oz. copper on the component side and ≥16 in² on the opposite side - the LM2598S-ADJ achieves θJA = 20°C/W. At 1 A load and 12 V input, this allows full-rated operation up to +70°C ambient without additional heatsinking, as verified in TI's thermal model and Application Information section.
LM2598S-ADJ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- TO-263-8, D2PAK (7 Leads + Tab), TO-263CA
- Packaging:
- Tube
- 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)
LM2598S-ADJ FAQ
1.How can I place an order for LM2598S-ADJ through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2598S-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 LM2598S-ADJ reliable?
The price and inventory of LM2598S-ADJ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2598S-ADJ is usually 5 days.
3.What payment methods are accepted for LM2598S-ADJ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2598S-ADJ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2598S-ADJ?
LM2598S-ADJ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2598S-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 LM2598S-ADJ?
For technical support, including LM2598S-ADJ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2598S-ADJ requirements.
6.How does Aetrix verify that LM2598S-ADJ is sourced from the original manufacturer or authorized distributors?
All LM2598S-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 LM2598S-ADJ meets industry standards.
7.What is the process for return or replacement of LM2598S-ADJ?
All LM2598S-ADJ units undergo pre-shipment inspection (PSI). If there is an issue with LM2598S-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 LM2598S-ADJ part is unused and in its original packaging.
Return procedure for LM2598S-ADJ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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