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Texas Instruments LM2597N-ADJ/NOPB
- Part No.:
- LM2597N-ADJ/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
LM2597N-ADJ/NOPB.pdf
- Description:
- IC REG BUCK ADJ 500MA 8PDIP
- Quantity:
- Payment:
- Shipping:
Inventory:131
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Product details
Overview
LM2597N-ADJ/NOPB from Texas Instruments is a monolithic nonsynchronous step-down (buck) DC-DC switching regulator IC delivering up to 0.5 A output current with ±4% output voltage accuracy, 150-kHz fixed-frequency operation, and input voltage support up to 40 V. It implements internal frequency compensation, thermal shutdown, and current-limit protection, and is used in compact on-card power supplies requiring stable mid-power conversion.
For engineers reviewing the LM2597N-ADJ/NOPB datasheet, LM2597N-ADJ/NOPB pinout, LM2597N-ADJ/NOPB application, or LM2597N-ADJ/NOPB equivalent, key selection criteria include adjustable output range (1.2 V to 37 V), bias supply (VBS) pin for efficiency optimization at high VIN/low VOUT, shutdown/soft-start control, error flag with delay timing, and PDIP-8 package compatibility with through-hole prototyping and industrial PCB layouts.
Technical Context
The LM2597N-ADJ/NOPB integrates a PWM controller, power switch, oscillator, error amplifier, and protection circuitry into a single PDIP-8 package. Its feedback loop senses output voltage via an external resistor divider connected to the Feedback pin, referencing a precise 1.23 V internal bandgap (±1.6% over temperature). The 150-kHz oscillator enables use of standard off-the-shelf inductors while maintaining low EMI and manageable filter size.
It operates in continuous conduction mode (CCM) with a peak-current-limited internal NPN switch, supporting both buck and inverting topologies. The Bias Supply (VBS) pin allows powering internal circuitry from VOUT instead of VIN-reducing quiescent current and improving efficiency by up to 5% at light loads and high input voltages-while the Error Flag and Delay pins provide regulated power-good signaling with user-adjustable startup delay.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 0.5 A maximum continuous load-supports mid-power rails for microcontrollers, sensors, and 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 without pre-regulation. |
| Adjustable Output Range | 1.2 V to 37 V (±4% tolerance)-set via external resistor divider; supports custom rail generation across wide system requirements. |
| Switching Frequency | 150 kHz (±15%)-fixed internal oscillator enables predictable EMI profile and simplifies EMI filter design with standard 10–100 μH inductors. |
| Feedback Reference Voltage | 1.23 V (±1.6% over −40°C to +125°C)-high-precision reference ensures tight regulation across temperature and line/load variations. |
| Standby Quiescent Current | 85 μA typical-minimizes battery drain in always-on systems during shutdown mode. |
| Saturation Voltage | 1.1 V max at 0.5 A-defines minimum dropout and impacts thermal dissipation in high-current, low-VOUT applications. |
Pinout & Package
LM2597N-ADJ/NOPB is supplied in an 8-pin Plastic Dual In-line Package (PDIP) with 9.81 mm × 6.35 mm body size and 0.3 inch lead pitch-compatible with through-hole assembly, breadboarding, and legacy industrial PCBs.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Error_Flag) | Open-collector output | Asserts low when VOUT drops >5% below nominal; used as power-good reset signal with configurable delay via external capacitor on Pin 2. |
| 2 (Delay) | Capacitor connection node | Controls time delay between VOUT reaching 95% and Error_Flag going high-enables sequenced power-up in multi-rail systems. |
| 3 (Bias_Supply) | Internal bias voltage input | Accepts 3.5–30 V to power internal circuitry from VOUT instead of VIN-reduces total input current and improves efficiency at high VIN/low VOUT. |
| 4 (Feedback) | Inverting input of error amplifier | Senses divided output voltage; sets regulated VOUT = 1.23 V × (1 + R1/R2); requires ≤50 nA bias current for minimal divider error. |
| 5 (Shutdown/Soft-Start) | Dual-function logic input | Pull ≤0.6 V to shut down (IQ ≈ 85 μA); add capacitor for soft-start-controls output ramp rate and limits inrush current to ~160 mA. |
| 6 (Ground) | Power and signal reference | Common return for internal switch, error amp, and oscillator-requires low-impedance connection to minimize noise coupling. |
| 7 (+VIN) | Main power input | Accepts 4.5–40 V; requires local 100 nF ceramic bypass capacitor to suppress switching transients and sustain peak currents. |
| 8 (Output) | Internal NPN switch collector | Swings between (VIN − VSAT) and ~−0.5 V; connects to external catch diode and inductor-PCB copper area must be minimized to reduce EMI. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated Soft-Start | Configurable output voltage ramp via external capacitor on Shutdown/Soft-Start pin-limits inrush current and eliminates output overshoot during startup. |
| Bias Supply (VBS) Pin | Enables internal circuitry to draw power from VOUT instead of VIN-reduces total input current and improves efficiency by up to 5% at light loads and VIN ≥ 24 V. |
| Error Flag with Delay Timing | Open-drain output with user-defined delay-provides reliable power-good assertion after stable regulation, suitable for microprocessor reset sequencing. |
| Thermal Shutdown & Current Limit | Two-stage current limit (0.65–1.3 A peak) plus junction temperature cutoff at 150°C-ensures robust fault protection without external sensing components. |
| Fixed 150-kHz Oscillator | Eliminates need for external timing components-simplifies design, reduces BOM count, and ensures consistent switching behavior across units and temperatures. |
Applications
| Industrial Sensor Power Supply | Embedded Microcontroller Pre-regulator |
|---|---|
|
Use Scenario: Providing clean, adjustable 3.3 V or 5 V rail from a noisy 24 V factory bus to power analog front-ends and precision ADCs in condition-monitoring nodes. IC Role / Device Role / Timing Role: Primary step-down regulator converting unregulated 24 V to stable low-noise output; uses internal 150-kHz oscillator for deterministic ripple frequency. Use Value: ±4% output accuracy and low 85 μA standby current enable long-term reliability and battery-backed operation during brownouts. |
Use Scenario: Generating 3.3 V for an ARM Cortex-M4 MCU from a 12 V automotive or industrial supply, with soft-start to prevent reset glitches during cold cranking. IC Role / Device Role / Timing Role: Buck converter with integrated soft-start and error flag-acts as first-stage regulator before LDO post-regulation. Use Value: Shutdown/Soft-Start pin enables controlled power sequencing; Error_Flag provides hardware reset to MCU upon undervoltage detection. |
| Positive-to-Negative Converter | On-Card Switching Regulator |
|
Use Scenario: Converting +12 V to −5 V for op-amp biasing or RS-232 interface circuits in space-constrained instrumentation PCBs. IC Role / Device Role / Timing Role: Inverting buck-boost topology using internal switch and external diode-ground-referenced feedback enables stable negative output regulation. Use Value: Supports inverting configuration without external controller; VBS pin improves efficiency when generating low-magnitude negative rails from high VIN. |
Use Scenario: Local 5 V or adjustable rail generation directly on a dense digital board where linear regulators would overheat due to 12 V–5 V dropout. IC Role / Device Role / Timing Role: Compact, self-contained switching regulator-replaces discrete buck controllers and reduces layout complexity. Use Value: PDIP-8 package allows manual rework and prototyping; fixed 150-kHz frequency simplifies EMI filtering with standard inductors. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2596-ADJ | Higher 3 A output current, 150-kHz frequency, but larger SOIC-8 package and no VBS pin-requires higher IQ (5 mA vs 85 μA) and lacks error flag/delay functionality. | Preferred for higher-current applications (>0.5 A); unsuitable where power-good signaling or ultra-low standby current is required. | Select LM2596-ADJ only if load exceeds 0.5 A and VBS/error flag features are unnecessary. |
| TPS54202DRT | Synchronous 2 A buck converter in 6-pin SOT-23, 500-kHz switching, integrated high-/low-side FETs, but no VBS pin or error flag-requires external compensation. | Better suited for space-constrained, high-efficiency designs needing >0.5 A; lacks built-in power-good and soft-start timing control. | Choose TPS54202DRT for compact, high-frequency, synchronous operation-but only when external compensation and absence of error flag are acceptable. |
Compared with LM2596-ADJ and TPS54202DRT, the LM2597N-ADJ/NOPB uniquely combines PDIP-8 through-hole compatibility, integrated error flag with delay, VBS efficiency enhancement, and ultra-low 85 μA standby current-making it optimal for industrial prototyping, legacy board upgrades, and systems requiring hardware reset coordination.
Availability
LM2597N-ADJ/NOPB is available at Aetrix Electronics and suitable for industrial sensor power supplies, embedded microcontroller pre-regulators, positive-to-negative converters, and on-card switching regulators requiring stable component supply across extended product lifecycles.
Supply support for LM2597N-ADJ/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 belongs to TI's SIMPLE SWITCHER® portfolio-designed specifically for ease-of-use in cost-sensitive, medium-power DC-DC applications where minimal external components, robust protection, and proven reliability are essential.
FAQ
What is the maximum input voltage supported by the LM2597N-ADJ/NOPB?
The LM2597N-ADJ/NOPB supports a maximum input voltage of 40 V under recommended operating conditions. This rating applies to the standard LM2597 variant (not the HV version). Exceeding 40 V risks permanent damage, as confirmed by absolute maximum ratings in the official TI datasheet SNVS119D. The LM2597N-ADJ/NOPB is not rated for 60 V operation-that specification applies exclusively to the LM2597HV family members.
Does the LM2597N-ADJ/NOPB require an external catch diode, and what type is recommended?
Yes, the LM2597N-ADJ/NOPB requires an external catch diode because it is a nonsynchronous buck converter with a single internal NPN switch. A Schottky diode such as the 1N5822 (rated ≥3 A, ≤0.5 V VF) is recommended for most applications to minimize conduction loss and improve efficiency. For higher-voltage inputs (>24 V), a fast-recovery diode like the MUR120 may be used-TI's application notes confirm this requirement in all typical buck configurations for the LM2597N-ADJ/NOPB.
How does the Bias Supply (VBS) pin improve efficiency in the LM2597N-ADJ/NOPB?
The VBS pin on the LM2597N-ADJ/NOPB allows internal circuitry to be powered from the regulated output voltage instead of the input supply-reducing total input current draw and lowering junction temperature. Efficiency gains of up to 5% are observed at light loads and high input voltages (e.g., VIN = 36 V, VOUT = 5 V), as documented in Figure 19 of the TI datasheet. The LM2597N-ADJ/NOPB requires ≥3.5 V on VBS at room temperature and functions up to 30 V, though benefits plateau above 15 V.
Can the LM2597N-ADJ/NOPB be used in an inverting (positive-to-negative) configuration?
Yes, the LM2597N-ADJ/NOPB supports inverting buck-boost topology-as verified in Section 8.3.3 and Figure 24 of the TI datasheet. By bootstrapping the GND pin to the negative output and grounding the Feedback pin, the device regulates inverted output voltage. A Schottky catch diode (e.g., 1N5817) and 100 μH inductor are recommended. Maximum |VIN| + |VOUT| must remain ≤40 V, and soft-start is advised due to high startup currents.
What is the purpose of the Delay pin (Pin 2) on the LM2597N-ADJ/NOPB?
The Delay pin (Pin 2) on the LM2597N-ADJ/NOPB controls the time interval between the output reaching 95% of its nominal value and the Error_Flag (Pin 1) transitioning high. An external capacitor from Pin 2 to ground sets this delay-enabling precise power-good timing for microprocessor reset sequencing or downstream enable signals. The delay function is intrinsic to the LM2597N-ADJ/NOPB's architecture and does not require additional ICs or logic.
LM2597N-ADJ/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:
- 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
LM2597N-ADJ/NOPB FAQ
1.How can I place an order for LM2597N-ADJ/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2597N-ADJ/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-ADJ/NOPB reliable?
The price and inventory of LM2597N-ADJ/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-ADJ/NOPB is usually 5 days.
3.What payment methods are accepted for LM2597N-ADJ/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2597N-ADJ/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2597N-ADJ/NOPB?
LM2597N-ADJ/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2597N-ADJ/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-ADJ/NOPB?
For technical support, including LM2597N-ADJ/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2597N-ADJ/NOPB requirements.
6.How does Aetrix verify that LM2597N-ADJ/NOPB is sourced from the original manufacturer or authorized distributors?
All LM2597N-ADJ/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-ADJ/NOPB meets industry standards.
7.What is the process for return or replacement of LM2597N-ADJ/NOPB?
All LM2597N-ADJ/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2597N-ADJ/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-ADJ/NOPB part is unused and in its original packaging.
Return procedure for LM2597N-ADJ/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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