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Texas Instruments LM2597M-ADJ
- Part No.:
- LM2597M-ADJ
- Manufacturer:
- Texas Instruments
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LM2597M-ADJ.pdf
- Description:
- IC REG BUCK ADJ 500MA 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,196
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Product details
Overview
LM2597M-ADJ from Texas Instruments is a monolithic nonsynchronous step-down (buck) DC-DC switching regulator IC delivering up to 0.5 A output current, operating at a fixed 150-kHz switching frequency, with adjustable output voltage range of 1.2 V to 37 V (±4% tolerance), and input voltage support up to 40 V - used in industrial power supplies and embedded system point-of-load conversion.
For engineers reviewing the LM2597M-ADJ datasheet, LM2597M-ADJ pinout, LM2597M-ADJ application, or LM2597M-ADJ equivalent, key selection criteria include its 8-pin SOIC package, internal soft-start/shutdown control, bias supply (VBS) pin for efficiency optimization at high VIN/low VOUT, and integrated thermal/current protection - all critical for reliable buck converter design under variable load and input conditions.
Technical Context
The LM2597M-ADJ implements a fixed-frequency, current-mode controlled buck topology with an internal NPN switch, requiring external diode, inductor, and capacitors. Its feedback loop senses output voltage via the 1.23-V reference at the FB pin, enabling precise regulation across line and load variations.
It integrates supervisory functions including an open-collector error flag (active-low when VOUT drops >5%), programmable delay timing via external capacitor on the DELAY pin, and dual-function shutdown/soft-start pin that reduces inrush current and enables logic-controlled disable with ~85 μA standby current.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output current | 0.5 A maximum continuous - supports mid-power embedded loads without external current boosting. |
| Input voltage range | 4.5 V to 40 V - compatible with 12 V, 24 V, and 36 V industrial rails; HV variant extends to 60 V. |
| Output voltage range | 1.2 V to 37 V (adjustable via resistor divider) - enables flexible rail generation from single input source. |
| Switching frequency | 150 kHz (±15%) - allows use of compact, standard off-the-shelf inductors and reduces EMI filtering burden. |
| Feedback reference | 1.23 V ±2.5% - sets output accuracy; combined with resistor tolerance determines overall VOUT regulation. |
| Quiescent current | 5–10 mA typical operating, 85 μA standby - enables low-power modes while maintaining fast wake-up response. |
| Thermal protection | Internal thermal shutdown - prevents damage during overload or poor PCB heatsinking; auto-recovery on cooldown. |
Pinout & Package
LM2597M-ADJ is housed in an 8-pin SOIC (D) package measuring 4.90 mm × 3.91 mm, optimized for surface-mount assembly and thermal performance (RθJA = 95°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - Error Flag | Open-collector output | Asserts low when regulated output falls >5% below target - usable as microcontroller reset signal after programmable delay. |
| 2 - Delay | Capacitor connection node | Sets time delay between VOUT reaching 95% and Error Flag going high - enables sequenced power-up in multi-rail systems. |
| 3 - Bias Supply (VBS) | Power input for internal circuitry | Accepts regulated output (≥3.5 V) instead of VIN - improves efficiency at high input/low output conditions by reducing internal dissipation. |
| 4 - Feedback (FB) | Inverting input of error amplifier | Monitors output via resistor divider; regulates to 1.23 V reference - defines output voltage as VOUT = 1.23 × (1 + R1/R2). |
| 5 - Shutdown/Soft-Start | Dual-function digital input | Pull low to disable (85 μA IQ); add capacitor for controlled VOUT ramp - prevents inrush current and enables sequencing. |
| 6 - Ground | Analog/digital reference | Common return for internal circuitry and external components - requires low-impedance PCB plane for stability. |
| 7 - +VIN | Main power input | Accepts 4.5–40 V DC; requires local ceramic bypass capacitor - supplies energy to internal switch and gate driver. |
| 8 - Output | Internal NPN switch collector | Switches between VIN−VSAT (~1.1 V drop) and −0.5 V - drives external catch diode and inductor; minimize trace area to reduce EMI. |
Key Features
| Feature | Design Value |
|---|---|
| Adjustable output voltage | 1.2 V to 37 V set via two-resistor divider - eliminates need for multiple fixed-voltage SKUs in BOM. |
| Bias supply (VBS) pin | Enables powering internal circuitry from VOUT instead of VIN - increases efficiency by ~3–5% at high VIN/low VOUT operation. |
| Integrated soft-start | Programmable output voltage ramp using external capacitor on SD/SS pin - limits peak inrush current to ≤160 mA (vs 700 mA without). |
| Error flag with delay | Open-drain output with user-defined assertion delay - provides clean power-good signal for microcontrollers and FPGAs. |
| Thermal and current protection | Two-stage current limit + junction temperature shutdown - ensures robust operation under short-circuit or overload without external circuitry. |
Applications
| Industrial Power Supply | Embedded System Point-of-Load |
|---|---|
|
Use Scenario: Converting 24 V DC field bus to 5 V/3.3 V for PLC I/O modules and sensor interfaces. IC Role / Device Role / Timing Role: Primary step-down regulator providing stable, efficient, and protected DC output. Use Value: Delivers 0.5 A at >82% efficiency with minimal external parts - reduces board space and thermal management complexity. |
Use Scenario: Generating 3.3 V from 12 V battery input in portable test equipment with strict standby current limits. IC Role / Device Role / Timing Role: Buck converter with ultra-low 85 μA standby IQ and soft-start for cold-boot reliability. Use Value: Enables >1-year battery life in sleep mode while ensuring controlled startup without brownout on wake-up. |
| Positive-to-Negative Converter | Preregulator for Linear Regulators |
|
Use Scenario: Generating –5 V from +12 V input for op-amp biasing in precision analog front-ends. IC Role / Device Role / Timing Role: Inverting buck-derived topology using grounded feedback and bootstrapped ground pin. Use Value: Achieves stable negative rail without dedicated inverting IC - simplifies design and lowers component count vs charge-pump solutions. |
Use Scenario: Reducing 24 V input to 7 V before LDO stage in audio amplifier power supply to minimize LDO thermal stress. IC Role / Device Role / Timing Role: High-efficiency preregulator stepping down voltage prior to linear regulation. Use Value: Cuts LDO power dissipation by >60% versus direct 24 V → 5 V linear conversion - enables smaller heatsinks and higher reliability. |
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 | Lower max input voltage (40 V same), but lower switching frequency (150 kHz vs LM2596's 150 kHz - identical), slightly lower efficiency at light loads; same 8-pin SOIC package. | Targeted at cost-sensitive consumer power supplies; lacks bias supply (VBS) pin and error flag delay function. | Choose LM2596-ADJ only if VBS and programmable error flag timing are unnecessary and BOM cost is primary constraint. |
| LM2678-ADJ | Higher output current (5 A vs 0.5 A), higher switching frequency (260 kHz), no VBS pin, different pinout (TO-220/SOIC-20), no integrated error flag. | Designed for high-current industrial motor drives and telecom power - not drop-in compatible due to pin count, footprint, and protection feature set. | Choose LM2678-ADJ only when ≥3 A output is required; LM2597M-ADJ remains optimal for <1 A, space-constrained, feature-rich designs. |
Compared with LM2596-ADJ and LM2678-ADJ, the LM2597M-ADJ uniquely balances moderate current capability (0.5 A), integrated supervision (error flag + delay), efficiency-enhancing VBS pin, and compact 8-pin SOIC footprint - making it the preferred choice for mid-power, feature-aware buck applications where reliability and design simplicity are prioritized over raw current or lowest cost.
Availability
LM2597M-ADJ is available at Aetrix Electronics and suitable for industrial power supplies, embedded system point-of-load conversion, and positive-to-negative converter designs requiring stable component supply, long-term lifecycle support, and consistent parametric performance.
Supply support for LM2597M-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 decades of expertise in high-reliability power conversion ICs.
The LM2597M-ADJ belongs to TI's SIMPLE SWITCHER® family - designed specifically for ease-of-use in non-isolated DC-DC buck applications where minimal external components, built-in protection, and predictable performance are essential.
FAQ
What is the maximum input voltage rating for LM2597M-ADJ?
The LM2597M-ADJ has a maximum input voltage rating of 40 V, as specified in the Absolute Maximum Ratings table. Exceeding this voltage risks permanent damage. For applications requiring up to 60 V input, the LM2597HV-ADJ variant must be used instead - it shares identical functionality and pinout but is rated for higher input voltage.
How does the Bias Supply (VBS) pin improve efficiency in LM2597M-ADJ?
The VBS pin allows the LM2597M-ADJ's internal circuitry to be powered from the regulated output rather than the input rail. This reduces power dissipation inside the IC - especially beneficial at high input voltages (e.g., 36 V) and low output voltages (e.g., 3.3 V or 5 V), where efficiency gains of 3–5% are measurable per TI's Figure 19 and Figure 20.
Can LM2597M-ADJ be used in an inverting (positive-to-negative) configuration?
Yes, the LM2597M-ADJ supports inverting operation by bootstrapping its ground pin to the negative output and grounding the feedback pin - as shown in Figure 24 of the datasheet. It generates stable negative outputs (e.g., –5 V from +12 V), though maximum load current depends on |VIN| + |VOUT| ≤ 40 V, and startup current can reach 0.8 A briefly.
What is the purpose of the Delay pin on LM2597M-ADJ?
Pin 2 (Delay) on the LM2597M-ADJ sets the time interval between when the output reaches 95% of its nominal value and when the Error Flag pin transitions high. A capacitor connected to this pin determines the delay - enabling synchronized power sequencing in multi-rail systems and preventing premature processor reset assertion.
Does LM2597M-ADJ require an external catch diode, and what type is recommended?
Yes, the LM2597M-ADJ requires an external catch diode because it uses a nonsynchronous buck topology with a single internal NPN switch. A Schottky diode (e.g., 1N5822) is recommended for input voltages ≤24 V due to its low forward voltage and fast recovery; for higher inputs, a general-purpose rectifier like 1N4001 may be used if efficiency is less critical.
LM2597M-ADJ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Not For New Designs
- 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:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
LM2597M-ADJ FAQ
1.How can I place an order for LM2597M-ADJ through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2597M-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 LM2597M-ADJ reliable?
The price and inventory of LM2597M-ADJ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2597M-ADJ is usually 5 days.
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LM2597M-ADJ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2597M-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 LM2597M-ADJ?
For technical support, including LM2597M-ADJ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2597M-ADJ requirements.
6.How does Aetrix verify that LM2597M-ADJ is sourced from the original manufacturer or authorized distributors?
All LM2597M-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 LM2597M-ADJ meets industry standards.
7.What is the process for return or replacement of LM2597M-ADJ?
All LM2597M-ADJ units undergo pre-shipment inspection (PSI). If there is an issue with LM2597M-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 LM2597M-ADJ part is unused and in its original packaging.
Return procedure for LM2597M-ADJ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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