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Texas Instruments LM2598S-3.3
- Part No.:
- LM2598S-3.3
- Manufacturer:
- Texas Instruments
- Package:
- TO-263-8, D2PAK (7 Leads + Tab), TO-263CA
- Datasheet:
-
LM2598S-3.3.pdf
- Description:
- IC REG BUCK 3.3V 1A TO263
- Quantity:
- Payment:
- Shipping:
Inventory:4,516
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Product details
Overview
LM2598S-3.3 from Texas Instruments is a monolithic 150 kHz step-down (buck) switching voltage regulator IC delivering a fixed 3.3 V output at up to 1 A, with ±4% output voltage tolerance over line and load, 4.5–40 V input range, and integrated thermal shutdown and current limiting. It serves as a high-efficiency primary DC-DC converter in industrial power supplies and embedded system rails.
For engineers reviewing the LM2598S-3.3 datasheet, LM2598S-3.3 pinout, LM2598S-3.3 application, or LM2598S-3.3 equivalent, key selection criteria include its fixed 3.3 V output, 150 kHz internal oscillator, TO-220/DDPAK package options, soft-start/shutdown control, and out-of-regulation flag functionality - all critical for stable, compact, single-rail buck conversion without external feedback resistors.
Technical Context
The LM2598S-3.3 implements a fixed-frequency current-mode buck topology with an internal 150 kHz oscillator, enabling predictable EMI filtering and use of standard off-the-shelf inductors. Its two-stage current limit and thermal shutdown provide fault protection during overload or ambient overheating.
It integrates soft-start via the SS/SD pin (2 V threshold), an error flag with delay timing (1.25 V delay threshold), and a dedicated FLAG pin that asserts low when output drops below 92–98% of nominal - supporting system-level power monitoring and sequencing without external comparators.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3 V ±4% over full line/load/temperature range - eliminates need for external feedback divider and ensures rail stability for 3.3 V logic and I/O. |
| Max Output Current | 1 A continuous - supports microcontroller cores, FPGAs, and peripheral ICs requiring moderate power at 3.3 V. |
| Input Voltage Range | 4.5 V to 40 V - enables direct regulation from unregulated 5 V, 12 V, 24 V, or 36 V sources without pre-regulation. |
| Switching Frequency | 150 kHz fixed - allows use of low-cost, high-saturation-current inductors (e.g., 68 µH L30 series) and simplifies EMI filter design. |
| Efficiency | 78% at VIN = 12 V, IOUT = 1 A - reduces thermal load vs. linear regulators and supports operation without heatsink below 50°C ambient. |
| Quiescent Current | 85 µA in shutdown - enables ultra-low-power standby modes in battery-backed or energy-conscious systems. |
| Protection Features | Thermal shutdown, peak current limit (1.2–2.6 A), and out-of-regulation flag - provides autonomous fault response without external supervision circuitry. |
Pinout & Package
LM2598S-3.3 is available in a 7-pin DDPAK (surface-mount) package with exposed thermal pad, optimized for high-power density PCB layouts and improved thermal performance versus through-hole alternatives.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Input Power Supply | Accepts 4.5–40 V DC; requires local 120 µF low-ESR input capacitor to suppress switching transients. |
| OUT | Switched Output Node | Drives external catch diode and inductor; connects to LC filter output; not directly regulated - feedback is internal. |
| GND | Power Ground | Common return for input/output paths and internal control circuitry; must be low-inductance connection to thermal pad. |
| FB | Feedback Input | Not used in fixed-output LM2598S-3.3; internally connected to output; leave unconnected per datasheet. |
| SD/SS | Shutdown/Soft-start Control | Pulled low (<0.6 V) disables regulator; pulled high (>2 V) initiates soft-start; 85 µA standby current when grounded. |
| FLAG | Error Flag Output | Open-collector output asserting low when VOUT falls outside 92–98% window; sinks ≥3 mA for direct MCU interrupt or LED drive. |
| DELAY | Flag Delay Timing | Connects to 0.1 µF capacitor to ground to set flag assertion delay (≈100 ms typical); sets system fault response latency. |
Key Features
| Feature | Design Value |
|---|---|
| Fixed 3.3 V Output | Eliminates external resistor network, reduces BOM count, and guarantees ±4% accuracy across temperature and load without calibration. |
| Integrated Soft-start | Prevents inrush current and output overshoot during power-up by ramping duty cycle from zero over ~10 ms (controlled by SD/SS pin). |
| Dedicated Error Flag with Delay | Enables reliable power-good signaling and fault logging by delaying flag assertion until dropout persists beyond user-set time (via DELAY capacitor). |
| Thermal Shutdown + Two-Stage Current Limit | First-stage current limit protects switch under transient overload; second-stage thermal cutoff prevents permanent damage during sustained fault conditions. |
| DDPAK Package Thermal Performance | Junction-to-ambient θJA as low as 20°C/W with double-sided copper - supports 1 A operation without heatsink in compact industrial PCBs. |
Applications
| Industrial PLC I/O Power | Embedded Microcontroller Core Rail |
|---|---|
Use Scenario: Providing isolated 3.3 V power to digital I/O modules in programmable logic controllers operating from 24 V DC field buses. IC Role / Device Role / Timing Role: Primary buck regulator converting 24 V bus to clean, regulated 3.3 V for FPGA configuration, level-shifting buffers, and optocoupler drivers. Use Value: Delivers 1 A at 78% efficiency with no heatsink required below 50°C ambient, reducing board area and thermal management complexity. | Use Scenario: Generating main supply rail for ARM Cortex-M or RISC-V microcontrollers in edge sensor nodes powered by 12 V wall adapters or PoE injectors. IC Role / Device Role / Timing Role: Single-chip step-down converter supplying core logic voltage with integrated soft-start and power-good flag for safe boot sequencing. Use Value: Fixed 3.3 V output and FLAG pin enable deterministic startup and fault detection - critical for firmware integrity and remote diagnostics. |
| Medical Instrument Front-End Power | Automotive Body Control Module (BCM) |
Use Scenario: Powering analog front-end (AFE) circuits and ADC references in portable diagnostic devices using 9 V or 12 V Li-ion packs. IC Role / Device Role / Timing Role: High-efficiency pre-regulator feeding low-noise LDOs; FLAG output triggers battery-low alerts when input sags near dropout. Use Value: 150 kHz switching frequency avoids sensitive audio/ECG bands; ±4% output tolerance ensures accurate sensor biasing and reference stability. | Use Scenario: Converting 12 V vehicle battery voltage to 3.3 V for CAN transceivers, EEPROM, and wake-up logic in body control units. IC Role / Device Role / Timing Role: Robust buck regulator surviving load-dump (40 V) and cold-crank (4.5 V) conditions while maintaining regulated output and flagging faults. Use Value: 4.5–40 V input range and thermal/current protection ensure AEC-Q100-compatible operation without external supervision circuitry. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2596S-3.3 | Same pinout, 150 kHz, but lower max current (3 A vs. 1 A); higher quiescent current (5 mA vs. 85 µA in shutdown). | Better suited for higher-current loads; less optimal for low-power standby due to higher IQ. | Select LM2596S-3.3 only if >1 A output or higher input voltage margin (up to 45 V) is required. |
| TPS54302DDCR | 3.5–28 V input, 3 A, 2.5 MHz switching, integrated MOSFETs; no FLAG pin; requires external feedback. | Enables smaller magnetics and faster transient response; lacks built-in fault flag and fixed-output simplicity. | Choose TPS54302DDCR for space-constrained designs needing >1 A or higher frequency, but accept added design complexity. |
Compared with LM2596S-3.3 and TPS54302DDCR, the LM2598S-3.3 offers unique value in fixed-output simplicity, integrated FLAG/delay, and ultra-low shutdown current - making it optimal for cost-sensitive, thermally constrained, or fault-aware 1 A buck applications where layout simplicity and supervisory features outweigh raw current or frequency specs.
Availability
LM2598S-3.3 is available at Aetrix Electronics and suitable for industrial PLCs, embedded microcontroller power rails, medical instrumentation, and automotive body control modules requiring stable component supply and long-term manufacturability.
Supply support for LM2598S-3.3 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 LM2598S-3.3 belongs to TI's SIMPLE SWITCHER® family - designed specifically for ease-of-use, minimal external component count, and robust operation in industrial, automotive, and medical power supply applications.
FAQ
What is the maximum input voltage rating for the LM2598S-3.3?
The LM2598S-3.3 has an absolute maximum input voltage rating of 45 V, but its recommended operating input voltage range is 4.5 V to 40 V. Exceeding 40 V may trigger internal protection or reduce reliability; operation at 40 V is validated per datasheet test conditions and supports common 36 V industrial and automotive inputs.
Does the LM2598S-3.3 require external feedback resistors?
No, the LM2598S-3.3 does not require external feedback resistors. As a fixed-output variant, its 3.3 V regulation is implemented internally; the FB pin is unused and must be left unconnected per the official Texas Instruments datasheet for LM2598S-3.3.
How does the FLAG pin on the LM2598S-3.3 function in practice?
The FLAG pin on the LM2598S-3.3 is an open-collector output that pulls low when the regulated output falls outside 92–98% of nominal (i.e., below 3.04 V or above 3.24 V). It includes an internal delay controlled by the DELAY pin capacitor, allowing configurable fault-holdoff time before assertion - enabling reliable power-good signaling in the LM2598S-3.3.
Can the LM2598S-3.3 operate without a heatsink?
Yes, the LM2598S-3.3 can operate without an external heatsink when mounted in its DDPAK package on a PCB with ≥2.5 in² of 1 oz. copper on one side (θJA ≈ 30°C/W) or ≥3 in² on the component side plus ≥16 in² on the opposite side (θJA ≈ 20°C/W), provided ambient temperature stays below 50°C and input voltage is ≤24 V - verified in TI's thermal models for LM2598S-3.3.
What inductor value is recommended for the LM2598S-3.3 at 12 V input and 1 A load?
For the LM2598S-3.3 operating at VIN = 12 V and ILOAD = 1 A, Texas Instruments specifies a 68 µH inductor (L30 series) as the standard value. This is confirmed in the "Fixed Output Voltage Versions" design procedure and Quick Design Component Selection Table for 3.3 V output in the LM2598S-3.3 datasheet.
LM2598S-3.3 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:
- 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:
- 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-3.3 FAQ
1.How can I place an order for LM2598S-3.3 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2598S-3.3 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-3.3 reliable?
The price and inventory of LM2598S-3.3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2598S-3.3 is usually 5 days.
3.What payment methods are accepted for LM2598S-3.3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2598S-3.3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2598S-3.3?
LM2598S-3.3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2598S-3.3 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-3.3?
For technical support, including LM2598S-3.3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2598S-3.3 requirements.
6.How does Aetrix verify that LM2598S-3.3 is sourced from the original manufacturer or authorized distributors?
All LM2598S-3.3 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-3.3 meets industry standards.
7.What is the process for return or replacement of LM2598S-3.3?
All LM2598S-3.3 units undergo pre-shipment inspection (PSI). If there is an issue with LM2598S-3.3, 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-3.3 part is unused and in its original packaging.
Return procedure for LM2598S-3.3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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