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Texas Instruments LM2594N-ADJ
- Part No.:
- LM2594N-ADJ
- Manufacturer:
- Texas Instruments
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
LM2594N-ADJ.pdf
- Description:
- IC REG BUCK ADJ 500MA 8PDIP
- Quantity:
- Payment:
- Shipping:
Inventory:4,196
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Product details
Overview
LM2594N-ADJ from Texas Instruments is a monolithic nonsynchronous step-down (buck) DC-DC converter IC delivering up to 0.5 A output current with adjustable output voltage from 1.2 V to 37 V, ±4% regulation over line and load, 150-kHz fixed-frequency operation, and input voltage support up to 40 V. It serves as a primary switching regulator in industrial power supplies and embedded system rails.
For engineers reviewing the LM2594N-ADJ datasheet, LM2594N-ADJ pinout, LM2594N-ADJ application, or LM2594N-ADJ equivalent, key selection criteria include its 8-pin PDIP package, TTL-compatible ON/OFF control, 85 μA standby quiescent current, feedback reference voltage of 1.23 V, and thermal shutdown protection - all critical for robust, low-component-count buck designs.
Technical Context
The LM2594N-ADJ integrates a PWM controller, power switch, oscillator, and internal frequency compensation in a single chip. Its architecture uses external diode, inductor, and capacitors to form a classic nonsynchronous buck topology with discontinuous or continuous conduction mode operation depending on load and inductance.
It features a dedicated feedback pin sensing a resistor divider to regulate output voltage, an ON/OFF pin with 1.3 V logic threshold for shutdown control, and ground-referenced thermal shutdown that disables the switch when junction temperature exceeds safe limits. The device operates across −40°C to +125°C ambient with internally limited power dissipation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output current | 0.5 A DC maximum - supports mid-power rails 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 inputs |
| Output voltage range | 1.2 V to 37 V adjustable - set via external resistor divider; enables flexible rail generation |
| Feedback reference voltage | 1.23 V ±0.05 V - determines output accuracy and sets minimum output voltage limit |
| Switching frequency | 150 kHz ±15% - fixed internal oscillator enables predictable EMI filtering and inductor selection |
| Quiescent current | 10 mA typical - defines no-load power draw in active operation |
| Standby current | 85 μA typical - enables ultra-low-power shutdown mode for battery-backed systems |
| Thermal shutdown | Yes, junction-limited at 150°C - prevents damage during overload or poor heatsinking |
Pinout & Package
LM2594N-ADJ is supplied in an 8-pin plastic dual in-line package (PDIP), body size 9.81 mm × 6.35 mm, with through-hole mounting and standard lead pitch. Thermal resistance RθJA is 95°C/W on JEDEC 4-layer board.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3 | No connection | Internally unconnected; must be soldered to PCB for mechanical stability and thermal transfer |
| 4 | Feedback (FB) | High-impedance input sensing resistor divider; regulates output by comparing to 1.23 V reference |
| 5 | ON/OFF | TTL-compatible logic input; <1.3 V enables regulator, >1.3 V disables it with ~85 μA standby current |
| 6 | Ground | Power and signal reference return path; connects to system ground plane |
| 7 | +VIN | Main input supply pin; requires local bypass capacitor to handle high di/dt switching currents |
| 8 | Output | Internal power switch collector; switches between VIN−VSAT (~1.1 V drop) and ~−0.5 V; drives external catch diode |
Key Features
| Feature | Design Value |
|---|---|
| Fixed-frequency 150-kHz oscillator | Enables consistent EMI profile and simplifies filter design without external timing components |
| Internal frequency compensation | Eliminates need for external compensation network - reduces BOM count and layout sensitivity |
| TTL shutdown capability | Allows microcontroller or logic-level control of power sequencing with minimal external circuitry |
| Thermal shutdown & current limiting | Two-stage protection: peak current limit (~0.8 A) and junction-temperature cutoff prevent catastrophic failure |
| Only four external components required | Supports complete buck regulator with just inductor, diode, input cap, and output cap - accelerates prototyping |
Applications
| Industrial Power Supply | Embedded System Rail |
|---|---|
Use Scenario: Generating stable 5 V or 12 V from 24 V factory bus for PLC I/O modules and sensor interfaces. IC Role / Device Role / Timing Role: Primary step-down switching regulator providing regulated DC output with line/load regulation ≤±4%. Use Value: Delivers 0.5 A at high efficiency (≥82%) while operating reliably across −40°C to +85°C ambient. | Use Scenario: On-board conversion of 12 V intermediate bus to 3.3 V for MCU, FPGA, or communication peripherals. IC Role / Device Role / Timing Role: Compact, self-contained buck regulator enabling space-constrained PCB layouts with minimal external parts. Use Value: Adjustable output and 8-pin PDIP package allow reuse across multiple voltage requirements without redesign. |
| Positive-to-Negative Converter | Preregulator for Linear Regulator |
Use Scenario: Generating −5 V from +12 V input for op-amp biasing or analog front-end circuits. IC Role / Device Role / Timing Role: Inverting buck-boost topology using grounded feedback and bootstrapped ground pin. Use Value: Enables bipolar supply generation without dedicated inverting IC; supports up to 0.5 A with proper component selection. | Use Scenario: Reducing 24 V input to 6 V before LDO stage to minimize heat dissipation in linear regulators. IC Role / Device Role / Timing Role: Efficient preregulator lowering dropout voltage seen by downstream LDO. Use Value: Achieves ≥80% efficiency at 0.5 A, reducing thermal load on final LDO and improving overall system efficiency. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2594HVN-ADJ | Higher input voltage rating: 4.5 V to 60 V vs. 4.5 V to 40 V | Suitable for 48 V telecom or automotive battery-supplied systems where transient spikes exceed 40 V | Select LM2594HVN-ADJ only if input can reach >40 V; otherwise LM2594N-ADJ offers identical performance at lower cost |
| LM2596-ADJ | Higher output current: 3 A vs. 0.5 A; same 150-kHz frequency and adjustable output | Used where higher load current is required; shares similar external component count and layout philosophy | LM2596-ADJ is not pin-compatible and requires larger inductor/capacitor; choose only when >0.5 A is needed |
Compared with LM2594HVN-ADJ, the LM2594N-ADJ trades 20 V input headroom for lower cost and identical thermal/efficiency behavior below 40 V; versus LM2596-ADJ, it provides proven reliability at lower current with smaller solution size but cannot scale to 3 A loads.
Availability
LM2594N-ADJ is available at Aetrix Electronics and suitable for industrial power supplies, embedded system rails, and positive-to-negative converters requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LM2594N-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 over 90 years of innovation history.
The LM2594xx series was designed as a family of SIMPLE SWITCHER® buck regulators targeting cost-sensitive, medium-current DC-DC conversion in industrial, instrumentation, and legacy embedded systems.
FAQ
What is the maximum input voltage rating for LM2594N-ADJ?
The LM2594N-ADJ has a maximum input voltage rating of 40 V, with recommended operating range from 4.5 V to 40 V. Exceeding 40 V risks permanent damage per absolute maximum ratings. For 60 V input capability, TI specifies the LM2594HVN-ADJ variant - the LM2594N-ADJ itself must not be used above 40 V under any condition.
How does the feedback pin (Pin 4) function in LM2594N-ADJ?
The feedback pin (Pin 4) of the LM2594N-ADJ senses the output voltage via an external resistor divider and compares it to an internal 1.23 V reference. When the divided voltage equals 1.23 V, the output is regulated precisely. This allows adjustable output from 1.2 V upward; the LM2594N-ADJ's feedback bias current is only 50 nA typical, minimizing divider resistor power loss.
Can LM2594N-ADJ be used in an inverting (positive-to-negative) configuration?
Yes, the LM2594N-ADJ supports inverting buck-boost operation by grounding the feedback pin and bootstrapping the ground pin to the negative output. TI provides validated reference designs (e.g., Figure 8-5) achieving −5 V from +12 V. However, the regulator sees the sum of |VIN| + |VOUT| across its pins - so for LM2594N-ADJ, total voltage must remain ≤40 V.
What is the purpose of the ON/OFF pin (Pin 5) on LM2594N-ADJ?
The ON/OFF pin (Pin 5) provides logic-level enable/disable control: pulling below ~1.3 V turns the LM2594N-ADJ on; pulling above ~1.3 V places it in standby mode with ~85 μA quiescent current. If unused, it may be tied to ground or left open - both default to enabled operation. This pin enables precise power sequencing in multi-rail systems using the LM2594N-ADJ.
Does LM2594N-ADJ require external compensation components?
No, the LM2594N-ADJ includes internal frequency compensation, eliminating the need for external compensation networks. This simplifies design, reduces component count to just four essentials (inductor, diode, input cap, output cap), and improves stability across operating conditions - a core feature of the SIMPLE SWITCHER® architecture used in the LM2594N-ADJ.
LM2594N-ADJ 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:
- 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:
- 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-ADJ FAQ
1.How can I place an order for LM2594N-ADJ through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2594N-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 LM2594N-ADJ reliable?
The price and inventory of LM2594N-ADJ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2594N-ADJ is usually 5 days.
3.What payment methods are accepted for LM2594N-ADJ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2594N-ADJ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2594N-ADJ?
LM2594N-ADJ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2594N-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 LM2594N-ADJ?
For technical support, including LM2594N-ADJ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2594N-ADJ requirements.
6.How does Aetrix verify that LM2594N-ADJ is sourced from the original manufacturer or authorized distributors?
All LM2594N-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 LM2594N-ADJ meets industry standards.
7.What is the process for return or replacement of LM2594N-ADJ?
All LM2594N-ADJ units undergo pre-shipment inspection (PSI). If there is an issue with LM2594N-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 LM2594N-ADJ part is unused and in its original packaging.
Return procedure for LM2594N-ADJ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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