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Texas Instruments LM2597N-3.3/NOPB
- Part No.:
- LM2597N-3.3/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
LM2597N-3.3/NOPB.pdf
- Description:
- IC REG BUCK 3.3V 500MA 8PDIP
- Quantity:
- Payment:
- Shipping:
Inventory:123
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Product details
Overview
LM2597N-3.3/NOPB from Texas Instruments is a monolithic 150-kHz nonsynchronous step-down DC-DC converter delivering 0.5-A output current with fixed 3.3-V output, ±4% output voltage tolerance over line and load, input voltage range up to 40 V (LM2597), and integrated soft-start/shutdown control. It serves as a primary buck regulator in industrial power supplies and embedded system rails.
For engineers reviewing the LM2597N-3.3/NOPB datasheet, LM2597N-3.3/NOPB pinout, LM2597N-3.3/NOPB application, or LM2597N-3.3/NOPB equivalent, key selection criteria include its 3.3-V fixed output accuracy, 85-μA standby quiescent current, 150-kHz fixed-frequency operation enabling compact filter design, and PDIP-8 package suitability for prototyping and through-hole production.
Technical Context
The LM2597N-3.3/NOPB implements a nonsynchronous buck topology with internal 150-kHz oscillator, fixed-frequency PWM control, and integrated current-limit protection. Its feedback loop uses a precision 1.23-V reference and senses output via dedicated Feedback pin, enabling stable regulation across 4.5–40 V input and –40°C to +125°C ambient.
It features dual-function Shutdown/Soft-Start pin for logic-level enable/disable and controlled output ramp-up, plus open-collector Error_Flag with built-in 5% dropout detection and programmable delay via external capacitor. Bias Supply (VBS) pin is not functional for the 3.3-V fixed version per TI documentation - internal circuitry is powered solely from VIN.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3 V ±4% over full line/load/temperature range - ensures reliable 3.3-V rail compliance without external resistor network. |
| Max Output Current | 0.5 A DC - supports moderate-power microcontrollers, FPGAs, and interface ICs without external current boosting. |
| Input Voltage Range | 4.5 V to 40 V - accommodates wide-input industrial, automotive (12-V nominal), and telecom-derived supplies. |
| Switching Frequency | 150 kHz (±15%) - enables use of low-cost, standard inductors and reduces EMI compared to higher-frequency alternatives. |
| Quiescent Current | 5–10 mA operating, 85 μA standby - minimizes no-load power loss in battery-backed or always-on systems. |
| Efficiency | 80% typical at 12-VIN/3.3-VOUT/0.5-A - delivers high conversion efficiency without requiring heatsinking on standard PCB copper. |
| Thermal Resistance | RθJA = 150°C/W (PDIP-8) - junction-to-ambient rating confirms suitability for natural-convection cooling in enclosed enclosures. |
Pinout & Package
LM2597N-3.3/NOPB is supplied in an 8-pin Plastic Dual Inline Package (PDIP) with 9.81 mm × 6.35 mm body size and 0.3-inch lead pitch - optimized for manual assembly, breadboarding, and legacy through-hole production.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - Error_Flag | Open-collector output | Asserts low when output drops >5% below 3.3 V; used for MCU reset or fault signaling; requires pull-up resistor. |
| 2 - Delay | Capacitor-connected timing node | Sets delay between output reaching 95% of 3.3 V and Error_Flag deassertion; enables sequenced power-up. |
| 3 - Bias_Supply (VBS) | Internal bias supply input | Not functional for LM2597N-3.3/NOPB - internal circuitry powered only from VIN; must be left open or tied to VIN per datasheet. |
| 4 - Feedback | Inverting input of error amplifier | Internally connected to 3.3-V reference; unused in fixed-output version - must be left unconnected. |
| 5 - Shutdown/Soft-Start | Logic-controlled enable & soft-start node | Pulled low disables switching (85-μA standby); capacitor adds controlled 3.3-V ramp-up time to limit inrush current. |
| 6 - Ground | Power and signal reference | Primary return path for switch current and control circuitry; requires low-impedance connection to PCB ground plane. |
| 7 - +VIN | Main power input | Accepts 4.5–40 V DC; requires local 100-nF ceramic bypass capacitor placed adjacent to pin for stability. |
| 8 - Output | Internal N-channel switch drain | Switches between VIN−VSAT (~39 V) and −0.5 V at 150 kHz; connects to external catch diode and inductor; minimal trace area recommended. |
Key Features
| Feature | Design Value |
|---|---|
| Fixed 3.3-V output with ±4% tolerance | Eliminates external feedback resistors and calibration, reducing BOM count and layout sensitivity for 3.3-V logic rails. |
| Integrated soft-start with shutdown control | Single-pin dual functionality enables inrush current limiting and system-level power sequencing without extra ICs or discrete logic. |
| Open-collector error flag with programmable delay | Provides hardware-based power-good signaling with adjustable hold-off time, directly usable by microcontrollers for safe boot initialization. |
| Thermal shutdown and peak-current limiting | Self-protecting operation under overload, short-circuit, or high-temperature conditions - no external foldback circuitry required. |
| 150-kHz fixed-frequency operation | Enables predictable EMI filtering and compatibility with low-cost, off-the-shelf 100–220-μH shielded inductors rated for ≥0.8-A saturation current. |
Applications
| Industrial Sensor Node Power | Embedded Controller Core Rail |
|---|---|
|
Use Scenario: Powering 3.3-V microcontroller, RS-485 transceiver, and analog sensor front-end in remote environmental monitoring unit with 24-V DC input. IC Role / Device Role / Timing Role: Primary step-down regulator converting 24-V field supply to stable 3.3-V system rail; provides soft-start to avoid brownout during cold start. Use Value: Delivers 0.5-A continuous current with 80% efficiency and 85-μA standby draw - extends battery life in solar-charged deployments. |
Use Scenario: Generating 3.3-V core voltage for ARM Cortex-M4 MCU in factory automation PLC module with 12-V backplane supply. IC Role / Device Role / Timing Role: Buck converter supplying regulated core rail; Error_Flag signals MCU reset until rail stabilizes post-power-up. Use Value: ±4% output tolerance ensures reliable operation across temperature swings; PDIP-8 package simplifies rework and validation in high-reliability designs. |
| Legacy Equipment Retrofit Power | Positive-to-Negative Converter |
|
Use Scenario: Replacing aging linear regulators in legacy test equipment requiring 3.3-V rail from existing 15-V internal supply. IC Role / Device Role / Timing Role: High-efficiency preregulator reducing heat dissipation versus 78L33; operates within same footprint as original PDIP-8 component. Use Value: 150-kHz switching eliminates need for large heatsinks; thermal shutdown prevents failure during intermittent overloads. |
Use Scenario: Generating –3.3-V bias for op-amp circuits in mixed-signal instrumentation using existing +12-V supply. IC Role / Device Role / Timing Role: Inverting buck-boost configuration (per Figure 24) leveraging LM2597N-3.3/NOPB's internal switch and feedback architecture. Use Value: Enables bipolar rail generation without dedicated inverting controller; soft-start prevents output overshoot during polarity reversal. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2597MX-3.3/NOPB | SOIC-8 surface-mount package; identical electrical specs and pinout; RθJA = 95°C/W vs 150°C/W for PDIP. | Better thermal performance and smaller footprint; requires reflow assembly instead of through-hole. | Select for volume production where PCB space and thermal headroom are constrained. |
| LM2596-3.3 | Same 3.3-V fixed output but 150-kHz frequency, 3-A rating, and SOIC-8 only; no PDIP option; higher IQ (5 mA vs 85 μA standby). | Higher current capability suits more demanding loads; lacks Error_Flag and Delay pins - no hardware reset signaling. | Select when >0.5-A output or lower cost-per-amp is critical, and fault signaling is handled externally. |
Compared with LM2597N-3.3/NOPB, the LM2597MX-3.3/NOPB offers superior thermal management in space-constrained layouts, while the LM2596-3.3 trades fault diagnostics and ultra-low standby for higher current and broader distributor availability - neither is pin-compatible due to differing pin functions and package types.
Availability
LM2597N-3.3/NOPB is available at Aetrix Electronics and suitable for industrial sensor nodes, embedded controller rails, legacy equipment retrofits, and positive-to-negative converter designs requiring stable component supply, long-term obsolescence planning, and through-hole manufacturability.
Supply support for LM2597N-3.3/NOPB 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 LM2597 series was designed as a robust, easy-to-use SIMPLE SWITCHER® solution for cost-sensitive, medium-current DC-DC applications where reliability, minimal external components, and proven thermal behavior are prioritized over ultra-high efficiency or digital control.
FAQ
What is the maximum input voltage rating for LM2597N-3.3/NOPB?
The LM2597N-3.3/NOPB has a maximum input voltage rating of 40 V, as specified in the Absolute Maximum Ratings table. This applies to the standard LM2597 variant (not the HV version). Operation above 40 V risks permanent damage. The device is rated for continuous operation from 4.5 V to 40 V under recommended conditions, making it suitable for 24-V industrial systems and 12-V automotive-derived supplies.
Does LM2597N-3.3/NOPB require external feedback resistors?
No, LM2597N-3.3/NOPB does not require external feedback resistors. As a fixed-output variant, its 3.3-V regulation is implemented internally using a precision 1.23-V reference and trimmed feedback network. Pin 4 (Feedback) is internally connected and must remain unconnected in PCB layout - adding external resistors would disrupt regulation and is explicitly prohibited in the datasheet.
Can the Bias Supply (VBS) pin be used with LM2597N-3.3/NOPB?
No, the Bias Supply (VBS) pin is not functional for LM2597N-3.3/NOPB. Per TI's datasheet Section 8.3.1, the VBS feature requires a minimum 4-V bias source, which is incompatible with the 3.3-V output. The internal circuitry is powered exclusively from VIN. The VBS pin must be left open or tied to VIN - connecting it to any other node may cause malfunction or damage.
What is the purpose of the Delay pin on LM2597N-3.3/NOPB?
The Delay pin on LM2597N-3.3/NOPB sets the time interval between the output reaching 95% of 3.3 V and the Error_Flag output transitioning high. A capacitor connected from this pin to ground determines the delay duration, enabling controlled power sequencing in multi-rail systems. This prevents downstream logic from initializing before the 3.3-V rail is fully stabilized and verified.
Is LM2597N-3.3/NOPB RoHS compliant and lead-free?
Yes, LM2597N-3.3/NOPB is RoHS compliant and lead-free. The "/NOPB" suffix explicitly denotes "No Lead (Pb)-Free" per Texas Instruments' part numbering convention. It meets JEDEC J-STD-020 moisture sensitivity level (MSL) requirements for PDIP-8 packaging and is qualified for lead-free solder reflow processes, including wave and hand-soldering with appropriate thermal profiles.
LM2597N-3.3/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Active
- 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
LM2597N-3.3/NOPB FAQ
1.How can I place an order for LM2597N-3.3/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2597N-3.3/NOPB 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 LM2597N-3.3/NOPB reliable?
The price and inventory of LM2597N-3.3/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2597N-3.3/NOPB is usually 5 days.
3.What payment methods are accepted for LM2597N-3.3/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2597N-3.3/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2597N-3.3/NOPB?
LM2597N-3.3/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2597N-3.3/NOPB 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 LM2597N-3.3/NOPB?
For technical support, including LM2597N-3.3/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2597N-3.3/NOPB requirements.
6.How does Aetrix verify that LM2597N-3.3/NOPB is sourced from the original manufacturer or authorized distributors?
All LM2597N-3.3/NOPB 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 LM2597N-3.3/NOPB meets industry standards.
7.What is the process for return or replacement of LM2597N-3.3/NOPB?
All LM2597N-3.3/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2597N-3.3/NOPB, 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 LM2597N-3.3/NOPB part is unused and in its original packaging.
Return procedure for LM2597N-3.3/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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