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Texas Instruments LM2599S-ADJ/NOPB
- Part No.:
- LM2599S-ADJ/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- TO-263-8, D2PAK (7 Leads + Tab), TO-263CA
- Datasheet:
-
LM2599S-ADJ/NOPB.pdf
- Description:
- IC REG BUCK ADJ 3A TO263
- Quantity:
- Payment:
- Shipping:
Inventory:118
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Product details
Overview
LM2599S-ADJ/NOPB from Texas Instruments is a monolithic nonsynchronous step-down DC-DC converter IC delivering up to 3-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. It integrates internal frequency compensation, thermal shutdown, current-limit protection, and soft-start/shutdown control - used in industrial power supplies and embedded system point-of-load regulation.
For engineers reviewing the LM2599S-ADJ/NOPB datasheet, LM2599S-ADJ/NOPB pinout, LM2599S-ADJ/NOPB application, or LM2599S-ADJ/NOPB equivalent, key selection criteria include output adjustability, 3-A load capability, TO-263 package thermal performance, and integrated error flag/delay functionality for system monitoring and sequencing.
Technical Context
The LM2599S-ADJ/NOPB implements a buck topology with an internal NPN switch, fixed-frequency oscillator, and voltage-mode feedback control using a resistive divider on the Feedback pin. Its ±4% output voltage accuracy holds across –40°C to +125°C and full line/load conditions, and it features dual-stage current limiting and thermal shutdown for fault protection.
It supports soft-start via external capacitor on the Shutdown/Soft-start pin (reducing inrush current to ~650 mA), and provides an open-collector Error Flag output that asserts low when VOUT drops >5% below nominal, with programmable delay via external capacitor on the Delay pin - enabling reliable microprocessor reset signaling during power-up.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 3 A continuous - supports high-current loads 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 rails. |
| Output Voltage Range | 1.2 V to 37 V (adjustable) - set precisely via external resistor divider; VFB = 1.23 V typical. |
| Switching Frequency | 150 kHz (±15%) - allows use of standard off-the-shelf inductors and reduces EMI filtering complexity. |
| Quiescent Current | 80 μA in shutdown - minimizes standby power in battery-backed or always-on systems. |
| Efficiency | 73% at 12 VIN/3 VOUT/3 A - balances thermal performance and conversion loss in compact layouts. |
| Feedback Bias Current | 10–100 nA - enables high-impedance resistor networks for low-power voltage setting. |
Pinout & Package
LM2599S-ADJ/NOPB is supplied in a 7-pin TO-263 (KTW) surface-mount package with exposed thermal pad, measuring 10.10 mm × 8.89 mm, optimized for PCB heat dissipation using ≥2.5 in² copper area.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1: +VIN | Power Input | Accepts 4.5–40 V supply; requires local bypass capacitor to handle high di/dt switching currents. |
| 2: Output | Switch Node | Internal NPN collector node; swings between ~−0.5 V and (+VIN − VSAT); must minimize PCB copper area to reduce EMI coupling. |
| 3: Error Flag | Open-Collector Output | Asserts low when regulated output falls >5%; used for MCU reset or fault indication with external pull-up. |
| 4: Ground | Reference Node | Common return for power and signal paths; connects to thermal pad for optimal heat transfer. |
| 5: Delay | Capacitor-Controlled Timing | Sets delay between VOUT reaching 95% and Error Flag deassertion; enables sequenced system startup. |
| 6: Feedback | Voltage Sense Input | Monitors output via resistive divider; regulates based on 1.23 V reference; bias current <100 nA. |
| 7: Shutdown/Soft-start | Control Input | Logic-level shutdown (<0.6 V) or soft-start (capacitor-ramped enable); draws <10 μA in shutdown. |
Key Features
| Feature | Design Value |
|---|---|
| Adjustable Output Voltage | 1.2 V to 37 V via two-resistor feedback network - eliminates need for multiple fixed-voltage SKUs. |
| Integrated Soft-Start | Reduces peak inrush current from 2.6 A to 650 mA - prevents input rail sag and protects upstream converters. |
| Error Flag with Programmable Delay | Open-collector output with external RC timing - enables precise power-good assertion timing for microcontroller reset coordination. |
| Thermal & Current Protection | Two-stage current limit and junction-overtemperature shutdown - ensures robust operation under overload or poor heatsinking. |
| Low Standby Quiescent Current | 80 μA typical in shutdown - extends battery life in portable or energy-sensitive applications. |
Applications
| Industrial Power Supply | Embedded System PoL |
|---|---|
Use Scenario: Converting 24-V factory bus to 5-V or 3.3-V for PLC I/O modules and sensor interfaces. IC Role / Device Role / Timing Role: Primary step-down regulator providing stable, high-current DC output with built-in fault reporting. Use Value: Eliminates need for external current-sense or thermal monitoring circuitry due to integrated protection and error flag. | Use Scenario: Generating 1.8-V or 2.5-V core supply for FPGA or ARM-based controllers in edge devices. IC Role / Device Role / Timing Role: Adjustable buck converter delivering precise, low-noise voltage with soft-start for controlled power-up sequencing. Use Value: Enables single-part flexibility across multiple board revisions via resistor change - no BOM proliferation. |
| Positive-to-Negative Converter | Preregulator for Linear Regulators |
Use Scenario: Generating –5-V bias for op-amp circuits or analog front-ends from a +12-V rail. IC Role / Device Role / Timing Role: Inverting buck-derived topology using bootstrapped ground and feedback reconfiguration. Use Value: Avoids dedicated inverting ICs or charge pumps; supports up to ~1-A negative output with standard magnetics. | Use Scenario: Reducing 24-V input to 7-V intermediate rail before LDO regulation to 3.3-V for noise-sensitive ADCs. IC Role / Device Role / Timing Role: High-efficiency preregulator minimizing LDO dropout and thermal dissipation. Use Value: Improves overall system efficiency by >35% versus direct 24-V-to-3.3-V linear regulation at 500-mA load. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2596S-ADJ/NOPB | Lower 3-A rating, 150-kHz frequency, but only 37-V max input and no Error Flag/Delay pins. | Lacks integrated power-good signaling and programmable startup delay - unsuitable for sequenced multi-rail systems. | Choose when cost sensitivity outweighs need for fault reporting and precise timing control. |
| MP2307DN-LF-Z | 3-A synchronous buck, 34-V max input, 340-kHz switching, no Error Flag, smaller SO-8 package. | Higher frequency enables smaller passives but lacks open-collector flag and thermal pad for high-power dissipation. | Prefer for space-constrained designs where efficiency >85% is critical and sequencing is handled externally. |
Compared with LM2596S-ADJ/NOPB, LM2599S-ADJ/NOPB adds error flag and delay functionality for system-level reliability; compared with MP2307DN-LF-Z, it trades higher frequency for superior thermal handling in TO-263 and integrated fault signaling - making it more suitable for industrial environments requiring robustness over miniaturization.
Availability
LM2599S-ADJ/NOPB is available at Aetrix Electronics and suitable for industrial power supplies, embedded system point-of-load regulation, positive-to-negative conversion, and preregulator applications requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LM2599S-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 solutions.
The LM2599 series belongs to TI's SIMPLE SWITCHER® portfolio, designed specifically for ease-of-use in non-isolated DC-DC buck applications where minimal external components, robust protection, and predictable thermal behavior are prioritized over ultra-high efficiency or ultra-small footprint.
FAQ
What is the minimum input voltage required for stable operation of the LM2599S-ADJ/NOPB?
The LM2599S-ADJ/NOPB requires a minimum input voltage of 4.5 V to maintain regulation across its full output range. Below this threshold, the device may enter dropout or cease switching entirely. This specification is confirmed in Section 7.3 (Recommended Operating Conditions) of the SNVS123D datasheet, where VIN(min) = 4.5 V applies across all temperature ranges and load conditions.
Can the LM2599S-ADJ/NOPB be used in a negative-output configuration?
Yes, the LM2599S-ADJ/NOPB supports inverting regulator topologies, as documented in Figure 21 and Section 8.3.2 of the datasheet. By bootstrapping the Ground pin to the negative output and referencing Feedback to ground, it generates regulated negative voltages - e.g., –5 V from +12 V input. The maximum |VIN| + |VOUT| must not exceed 40 V.
What is the purpose of the Delay pin on the LM2599S-ADJ/NOPB?
The Delay pin on the LM2599S-ADJ/NOPB sets the time interval between when the output reaches 95% of its target voltage and when the Error Flag transitions high (deasserts). An external capacitor to ground determines this delay, enabling precise power-good timing for microcontroller reset synchronization - a feature absent in most lower-cost buck regulators.
Does the LM2599S-ADJ/NOPB require an external catch diode?
Yes, the LM2599S-ADJ/NOPB requires an external Schottky or fast-recovery diode connected from the Output pin to the regulated output rail. As a nonsynchronous buck controller, it relies on this diode to provide the freewheeling path during the switch-off phase. TI recommends diodes such as SB560 or MBR20100CT depending on current and voltage requirements.
How does the soft-start function work on the LM2599S-ADJ/NOPB?
The soft-start function on the LM2599S-ADJ/NOPB is implemented by connecting a capacitor between the Shutdown/Soft-start pin and ground. During startup, internal current sources charge this capacitor, ramping the enable threshold and thereby controlling the duty cycle rise time. This limits inrush current to ~650 mA (vs. 2.6 A without soft-start), preventing input rail collapse and reducing stress on input capacitors and upstream supplies.
LM2599S-ADJ/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- TO-263-8, D2PAK (7 Leads + Tab), TO-263CA
- 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):
- 1.23V
- Voltage - Output (Max):
- 37V
- Current - Output:
- 3A
- Frequency - Switching:
- 150kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- TO-263 (DDPAK-7)
LM2599S-ADJ/NOPB FAQ
1.How can I place an order for LM2599S-ADJ/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2599S-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 LM2599S-ADJ/NOPB reliable?
The price and inventory of LM2599S-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 LM2599S-ADJ/NOPB is usually 5 days.
3.What payment methods are accepted for LM2599S-ADJ/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2599S-ADJ/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2599S-ADJ/NOPB?
LM2599S-ADJ/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2599S-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 LM2599S-ADJ/NOPB?
For technical support, including LM2599S-ADJ/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2599S-ADJ/NOPB requirements.
6.How does Aetrix verify that LM2599S-ADJ/NOPB is sourced from the original manufacturer or authorized distributors?
All LM2599S-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 LM2599S-ADJ/NOPB meets industry standards.
7.What is the process for return or replacement of LM2599S-ADJ/NOPB?
All LM2599S-ADJ/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2599S-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 LM2599S-ADJ/NOPB part is unused and in its original packaging.
Return procedure for LM2599S-ADJ/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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