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Texas Instruments LM2594N-3.3
- Part No.:
- LM2594N-3.3
- Manufacturer:
- Texas Instruments
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
LM2594N-3.3.pdf
- Description:
- IC REG BUCK 3.3V 500MA 8PDIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,608
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Product details
Overview
LM2594N-3.3 from Texas Instruments is a monolithic nonsynchronous step-down (buck) DC-DC switching regulator delivering 3.3 V at up to 0.5 A, with 150-kHz fixed-frequency operation, ±4% output voltage tolerance over line and load, and input voltage support up to 40 V. It serves as a primary on-board power supply for microcontrollers, sensors, and logic circuits in industrial control and embedded systems.
For engineers reviewing the LM2594N-3.3 datasheet, LM2594N-3.3 pinout, LM2594N-3.3 application, or LM2594N-3.3 equivalent, key selection considerations include its PDIP-8 package, TTL-compatible ON/OFF control, 85 μA standby current, thermal shutdown protection, and requirement for only four external components - making it suitable for cost-sensitive, space-constrained, and thermally demanding designs.
Technical Context
The LM2594N-3.3 integrates a PWM controller, power switch, oscillator, error amplifier, and thermal/current protection circuitry in a single PDIP-8 package. Its fixed 3.3-V output eliminates external feedback resistors, and internal frequency compensation enables stable operation with standard off-the-shelf inductors and capacitors.
It operates in continuous conduction mode across typical loads (0.1–0.5 A), features undervoltage lockout via the ON/OFF pin (1.3 V threshold), and supports delayed start-up and inverting configurations. The internal switch exhibits 1.1 V saturation voltage at 0.5 A, limiting conduction loss while requiring careful thermal management due to 95 °C/W junction-to-ambient resistance in PDIP.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3 V ±4% over full line/load/temperature range - ensures reliable logic-level rail without trimming. |
| Max Output Current | 0.5 A DC - sufficient for powering MCU cores, peripherals, and small sensor arrays without external boost stages. |
| Input Voltage Range | 4.5 V to 40 V - supports wide-input industrial supplies, battery stacks, and unregulated wall adapters. |
| Switching Frequency | 150 kHz (±15%) - enables use of low-cost, high-saturation-current inductors and reduces EMI filtering complexity. |
| Standby Quiescent Current | 85 μA - allows low-power sleep modes in battery-backed systems without significant drain. |
| Thermal Protection | Internal thermal shutdown - prevents damage during sustained overload or poor heatsinking in PDIP package. |
| Current Limit | 0.8 A peak - provides robust short-circuit protection while allowing margin for startup surges. |
| Efficiency | 80% at 12 VIN/0.5 A - balances conversion loss and component count for non-ultra-low-power applications. |
Pinout & Package
LM2594N-3.3 is supplied in an 8-pin plastic dual in-line package (PDIP), with 9.81 mm × 6.35 mm body size and through-hole mounting. Thermal performance is characterized at RθJA = 95 °C/W on JEDEC-standard 4-layer board.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3 | No Connection | Internally unconnected; must be soldered to PCB ground plane for mechanical stability and thermal transfer. |
| 4 | Feedback | Not used in fixed 3.3-V version; left open or tied to ground per design guidelines - no external resistor network required. |
| 5 | ON/OFF | TTL-compatible shutdown control: <1.3 V = ON, >1.3 V = OFF; draws ≤15 μA when active, enabling low-power sequencing. |
| 6 | Ground | Main power and signal reference; requires low-impedance connection to minimize noise coupling into feedback path. |
| 7 | +VIN | Primary input supply (4.5–40 V); requires local 68-μF tantalum bypass capacitor to handle high di/dt switching currents. |
| 8 | Output | Switch node - connects to catch diode anode and inductor; high dv/dt demands minimal PCB copper area to reduce EMI. |
Key Features
| Feature | Design Value |
|---|---|
| Fixed-output architecture | Eliminates external feedback resistors - reduces BOM count, layout sensitivity, and calibration risk for 3.3-V rail generation. |
| Integrated thermal shutdown | Automatically disables switching above safe junction temperature - protects device and system during airflow loss or ambient rise. |
| TTL-compatible ON/OFF control | Enables direct interfacing with microcontroller GPIOs or logic supervisors without level-shifting circuitry. |
| Self-compensated loop | Requires no external compensation components - simplifies design validation and improves production yield consistency. |
| Standard inductor compatibility | Works with widely available 100–150 μH shielded drum-core inductors - avoids proprietary magnetics and long lead times. |
| Two-stage current limiting | Provides soft-foldback under overload - maintains regulation longer than hard-limit designs before entering hiccup mode. |
Applications
| Industrial PLC I/O Module | Embedded Sensor Node |
|---|---|
|
Use Scenario: Powering isolated digital I/O drivers, analog front-end ADCs, and RS-485 transceivers from a 24-V field bus. IC Role / Device Role / Timing Role: Primary buck regulator generating clean 3.3-V logic rail; handles transient load steps from solenoid actuation and communication bursts. Use Value: Delivers 0.5-A peak current with ±4% regulation across -40°C to +125°C ambient, ensuring deterministic timing for real-time I/O sampling and protocol compliance. |
Use Scenario: Supplying ultra-low-noise 3.3-V rail to MEMS accelerometers, temperature sensors, and BLE SoCs in battery-powered condition monitoring nodes. IC Role / Device Role / Timing Role: Main system regulator with shutdown control synchronized to sensor acquisition cycles to minimize average current draw. Use Value: Achieves 85 μA standby current and fast wake-up (<100 μs), extending battery life while maintaining precise sensor biasing and clock domain integrity. |
| Medical Point-of-Care Device | Automotive Body Control Module |
|
Use Scenario: Generating regulated 3.3-V supply for touch-screen controllers, optical sensors, and data logging microcontrollers in portable diagnostic tools. IC Role / Device Role / Timing Role: Safety-redundant power stage - paired with linear post-regulator to meet IEC 60601 ripple and fault-isolation requirements. Use Value: Internal thermal shutdown and current limit prevent thermal runaway during extended operation in sealed enclosures, supporting Class II medical certification paths. |
Use Scenario: Providing 3.3-V rail for CAN transceivers, LIN gateways, and microcontroller peripherals in 12-V automotive subsystems. IC Role / Device Role / Timing Role: Pre-regulator stepping down noisy 12-V battery rail prior to LDO conditioning - reduces heat dissipation and improves PSRR. Use Value: Withstands 40-V load-dump transients (with external clamping) and maintains regulation during cold-crank (4.5 V), ensuring uninterrupted CAN frame transmission. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2594MX-3.3 | SOIC-8 surface-mount variant with RθJA = 150 °C/W - higher thermal resistance but smaller footprint. | Suitable for automated assembly and compact PCBs where thermal derating is acceptable below 300 mA. | Select when board space is constrained and thermal margin can be managed via copper pour or airflow. |
| LM2594HV-3.3 | Supports 60-V max input (vs. 40 V), same PDIP-8 package and pinout - identical functionality except extended VIN range. | Required for 48-V industrial buses or PoE-powered equipment where input may exceed 40 V during surge conditions. | Choose when input voltage exceeds 40 V; otherwise, LM2594N-3.3 offers lower cost and same performance at ≤40 V. |
Compared with LM2594MX-3.3, LM2594N-3.3 delivers better thermal performance in through-hole layouts but requires manual soldering; compared with LM2594HV-3.3, it trades input voltage headroom for lower cost and qualification maturity in 40-V systems.
Availability
LM2594N-3.3 is available at Aetrix Electronics and suitable for industrial automation, embedded sensor systems, and medical instrumentation requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.
Supply support for LM2594N-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 ICs, with decades of expertise in switching regulator design and manufacturing reliability.
The LM2594xx series was engineered as a robust, low-BOM-count SIMPLE SWITCHER® solution for cost-sensitive, thermally challenging, and high-reliability DC-DC conversion in industrial and automotive environments.
FAQ
What is the maximum input voltage rating for LM2594N-3.3?
The LM2594N-3.3 has an absolute maximum input voltage of 45 V, with recommended operating range from 4.5 V to 40 V. Exceeding 40 V risks violating recommended conditions and may trigger thermal shutdown or reduce long-term reliability - for 60-V operation, use LM2594HV-3.3 instead. The LM2594N-3.3 datasheet specifies 40 V as the upper limit for continuous operation.
Does LM2594N-3.3 require external feedback resistors?
No, LM2594N-3.3 is a fixed-output variant with internal resistor divider set to 3.3 V, so no external feedback resistors are needed. Pin 4 (Feedback) is unused and should be left open or grounded per TI layout guidelines. This simplifies design and eliminates resistor tolerance drift effects - unlike the adjustable LM2594ADJ, the LM2594N-3.3 delivers factory-trimmed regulation without user configuration.
Can LM2594N-3.3 be used in an inverting (positive-to-negative) configuration?
Yes, LM2594N-3.3 supports inverting regulator topologies by reconfiguring ground and feedback connections, as documented in TI's SNVS118F datasheet Figure 8-5. However, the output polarity becomes negative, and maximum |VIN| + |VOUT| must not exceed 40 V. The LM2594N-3.3 itself remains unchanged - only external component arrangement differs, and ON/OFF control requires level shifting due to floating ground.
What is the thermal resistance (RθJA) of LM2594N-3.3 in PDIP package?
The LM2594N-3.3 in PDIP-8 package has a junction-to-ambient thermal resistance of 95 °C/W, measured on a JEDEC-standard 4-layer board. This value assumes adequate copper pour on the ground pin and proper soldering of pins 1–3 for thermal conduction. Derating is required above 70°C ambient to maintain TJ ≤ 125°C - the LM2594N-3.3 thermal shutdown activates at ~150°C junction temperature.
Is LM2594N-3.3 RoHS compliant and halogen-free?
Yes, LM2594N-3.3 is RoHS compliant and halogen-free per Texas Instruments' official product change notices and packaging documentation. TI confirms lead-free matte tin plating on PDIP leads and compliance with JEDEC J-STD-020 moisture sensitivity level (MSL) 1 for through-hole assembly. Full compliance data is available in TI's Q100 qualification reports for the LM2594xx family.
LM2594N-3.3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- 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:
- 500mA
- Frequency - Switching:
- 150kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
LM2594N-3.3 FAQ
1.How can I place an order for LM2594N-3.3 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2594N-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 LM2594N-3.3 reliable?
The price and inventory of LM2594N-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 LM2594N-3.3 is usually 5 days.
3.What payment methods are accepted for LM2594N-3.3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2594N-3.3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2594N-3.3?
LM2594N-3.3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2594N-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 LM2594N-3.3?
For technical support, including LM2594N-3.3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2594N-3.3 requirements.
6.How does Aetrix verify that LM2594N-3.3 is sourced from the original manufacturer or authorized distributors?
All LM2594N-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 LM2594N-3.3 meets industry standards.
7.What is the process for return or replacement of LM2594N-3.3?
All LM2594N-3.3 units undergo pre-shipment inspection (PSI). If there is an issue with LM2594N-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 LM2594N-3.3 part is unused and in its original packaging.
Return procedure for LM2594N-3.3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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