LM2596S-ADJ/NOPB - 3A, 40V Adjustable Buck Regulator | TI
MPN: LM2596S-ADJ-NOPB ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.36 | $2.36 |
| 10 | $2.05 | $20.50 |
| 100 | $1.68 | $168.00 |
| 500 | $1.32 | $660.00 |
| 1,000 | $1.08 | $1,080.00 |
LM2596S-ADJ-NOPB Overview
A buck (step-down) switching regulator is a DC-DC converter that uses an inductor and a switch to lower a higher DC input to a lower regulated DC output with much higher efficiency than a linear regulator. The LM2596 belongs to the SIMPLE SWITCHER family of power management ICs, sitting in the broader hierarchy of voltage regulator → DC-DC converter → power management IC → semiconductor. Its 150 kHz switching frequency allows the use of small, low-cost inductors and aluminum electrolytic output capacitors, simplifying BOM.
Key features include 3 A continuous output current, 4.5 V to 40 V input range, 1.2 V to 37 V adjustable output, 150 kHz fixed-frequency operation, internal high-current switch, thermal shutdown and current-limit protection, and an enable/ON-OFF pin for sequenced power-up. Typical standby current is 80 µA in shutdown.
Architecturally, the LM2596 uses a fixed-frequency voltage-mode control loop with a 0.2 V internal reference. The high-side NPN Darlington switch drops about 1.5 V at full load, and the device requires a flyback Schottky diode, an inductor, and input/output capacitors to complete a converter. Efficiency typically reaches 73–80% at 5 V/3 A from 12 V input. Because it is non-synchronous, designers choose a Schottky such as the 3 A 40 V SS34.
Typical applications include 24 V industrial bus to 5 V/3.3 V point-of-load conversion, battery chargers, automotive accessory supplies (with input transient protection), distributed power systems, LED drivers, hobby robotics, and any design that needs a simple, rugged, low-BOM-count buck regulator. When designing with the LM2596, ensure the input voltage never exceeds 40 V (45 V abs max), keep the catch diode loop area small, and provide a 1 oz copper pour under the tab for thermal dissipation at sustained 2–3 A loads.
Drop-in alternatives for LM2596S-ADJ-NOPB — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with LM2596S-ADJ-NOPB (same form factor and footprint) — differing in Package, RoHS Status, Switching Frequency, Output Voltage Range, Topology.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
LM2596SX-ADJ/NOPB
✅ Drop-In✓ In Stock
$1.4 / Unit
View Datasheet →LM2596S-5.0/NOPB
✅ Drop-In📋 Reference alternative (not in catalog)
LM2596HVS-ADJ
✅ Drop-In📋 Reference alternative (not in catalog)
LM2596S-ADJ
✅ Drop-In✓ In Stock
$0.8203 / Unit
View Datasheet →LM2596S-ADJ-NOPB Maximum Ratings & Electrical Characteristics
| Topology | Buck (Step-Down) |
| Input Voltage Range | 4.5 V to 40 V |
| Output Voltage Range | 1.2 V to 37 V (Adjustable) |
| Maximum Output Current | 3 A |
| Switching Frequency | 150 kHz (typ) |
| Switching Frequency Range | 110 kHz to 173 kHz |
| Switch Type | Internal NPN Darlington (non-synchronous) |
| Feedback Reference Voltage | 1.23 V (typ) |
| Maximum Switch Voltage | 45 V |
| Supply Current (operating) | 5 mA (typ) |
| Shutdown Supply Current | 80 µA (typ) |
| ON/OFF Pin Logic | Active-low enable (TTL-compatible) |
| Operating Temperature Range | -40 C to +125 C |
| Package | TO-263-5 (D2PAK, KTT) 5 leads + tab |
| Mounting Type | Surface Mount |
| Thermal Resistance (junction-to-case) | 2 C/W (typ, with tab soldered) |
| Protection Features | Current limit, thermal shutdown |
| RoHS Status | Compliant (NOPB suffix) |
| Lead-Free | Yes (NOPB suffix) |
LM2596S-ADJ-NOPB Pin Configuration
| Pin 1 | VIN — Input supply voltage (4.5 V to 40 V) |
| Pin 2 | OUTPUT — Internal switch emitter connection; routes to inductor |
| Pin 3 | GND — Ground reference |
| Pin 4 | FEEDBACK — Feedback (1.23 V nominal) from output resistor divider |
| Pin 5 | ON/OFF — Enable input (active-low; tie to GND to enable) |
Typical Applications
LM2596S-ADJ-NOPB is suitable for 6 applications: Industrial 24V to 5V/3.3V Point-of-Load Conversion, Automotive Accessory and Aftermarket Power Supplies, Battery Chargers for Lead-Acid and Li-Ion Packs, Distributed Power Systems and 48V Telecom Bricks, High-Brightness LED Drivers and Lighting Modules, Hobby Robotics, RC Chargers and DIY Bench Supplies.
Industrial 24V to 5V/3.3V Point-of-Load Conversion
The LM2596S-ADJ/NOPB's 4.5-40 V input range and 3 A continuous output make it a workhorse for stepping a 24 V industrial bus down to 5 V or 3.3 V logic rails on factory PLCs, sensor boards, and motor-control daughtercards. With its 1.23 V internal reference and adjustable output from 1.2 V to 37 V, designers set the rail with a single resistor divider, and the 150 kHz fixed-frequency operation allows the use of small 33 µH inductors and standard aluminum electrolytic output capacitors, keeping BOM cost low. Compared to a 7805 linear regulator at 24 V→5 V/3 A, the LM2596 dissipates roughly 1/5 the power and removes the need for a bulky heatsink.
Recommended
Automotive Accessory and Aftermarket Power Supplies
The LM2596S-ADJ/NOPB operates from a nominal 12 V automotive rail (typical 9 V to 16 V running, 6 V cranking) and can deliver 3 A continuously to power aftermarket accessories such as dashcams, two-way radios, LED light bars, and USB charging hubs. Its 40 V input rating provides headroom above the 24 V jump-start transient, and the integrated current limit plus thermal shutdown harden the design against output shorts and stall conditions. The TO-263-5 tab solders to chassis or board copper for heatsinking, an important consideration when the device sits in an engine compartment at 3 A load.
Recommended
Battery Chargers for Lead-Acid and Li-Ion Packs
With its adjustable 1.2 V to 37 V output and 3 A current capability, the LM2596S-ADJ/NOPB is widely used as the constant-current/constant-voltage (CC/CV) stage for sealed lead-acid and small lithium-ion battery chargers in the 1-3 A range. Designers set the float voltage with the feedback divider and add an external op-amp or comparator to fold the output back for current regulation. The 80 µA shutdown current and active-low ON/OFF pin support low-quiescent standby operation, and the 150 kHz switching frequency keeps the inductor small enough for a handheld charger form factor.
Recommended
Distributed Power Systems and 48V Telecom Bricks
In distributed power architectures, the LM2596S-ADJ/NOPB can serve as a local point-of-load converter following an isolated front-end brick or 48 V telecom rail, stepping intermediate 12 V or 24 V down to 5 V, 3.3 V, or 2.5 V at up to 3 A for sub-rack logic boards. The 4.5-40 V input range comfortably handles 48 V telecom battery plants (peaking near 56 V is beyond limit; a small pre-regulator or TVS is used). The simple external-component count keeps PCB area low and reliability high in always-on telecom and networking gear.
Recommended
High-Brightness LED Drivers and Lighting Modules
The LM2596S-ADJ/NOPB drives high-brightness LED strings of 1-10 LEDs at 350-700 mA constant current when paired with a current-sense resistor and op-amp fold-back circuit, or directly drives 12 V LED strips up to 3 A when the adjustable output is set to the strip's forward voltage. Its PWM dimming capability via the ON/OFF pin and high efficiency at 24 V→12 V reduces thermal stress versus a linear driver. Designers benefit from a single 150 kHz switching frequency, eliminating the audible noise sometimes produced by cheaper variable-frequency LED drivers.
Recommended
Hobby Robotics, RC Chargers and DIY Bench Supplies
Hobby and maker projects use the LM2596S-ADJ/NOPB as the core of adjustable bench supplies, RC battery chargers, and motor-power rails because it is forgiving, cheap, and easily sourced from distributors and modules. The TO-263-5 (D2PAK) variant is widely available on pre-assembled buck modules that include the inductor, Schottky, and capacitor BOM. A potentiometer replaces the fixed feedback resistor divider, giving 1.2 V to ~30 V out for prototyping. Its 3 A output covers most hobby motor and solenoid loads without active cooling.
Recommended
Recommended Products Summary
Engineering reference data for LM2596S-ADJ-NOPB — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | LM2596SX-ADJ/NOPB | LM2596S-5.0/NOPB | LM2596HVS-ADJ | LM2596S-ADJ |
|---|---|---|---|---|---|
| Package | TO-263-5 (KTT, D2PAK) | TO-263-5 (KTT) - same | TO-263-5 (KTT) - same | TO-263-5 (KTT) - same | TO-263-5 (KTT) - same (UMW 2nd source) |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | UMW |
| Input Voltage Range | 4.5 V to 40 V | 4.5 V to 40 V | 4.5 V to 40 V | 4.5 V to 60 V | 4.5 V to 40 V |
| Output Voltage | 1.2 V to 37 V (Adj) | 1.2 V to 37 V (Adj) | 5.0 V fixed | 1.2 V to 57 V (Adj) | 1.2 V to 37 V (Adj) |
| Maximum Output Current | 3 A | 3 A | 3 A | 3 A | 3 A |
| Switching Frequency | 150 kHz | 150 kHz | 150 kHz | 150 kHz | 150 kHz |
| Synchronous Rectifier | No (external Schottky) | No | No | No | No |
| RoHS / Lead-Free | Yes (NOPB) | Yes (NOPB) | Yes (NOPB) | Yes | Yes |
Key Differentiators
- Same TO-263-5 footprint, 60 V input rating (vs LM2596HVS-ADJ)
- Drop-in fixed 5.0 V option for cost-down designs (vs LM2596S-5.0/NOPB)
- Second-source availability in identical footprint (vs UMW LM2596S-ADJ)
Design Notes
The LM2596S-ADJ/NOPB TO-263-5 package relies on the tab as the primary heatsink. Estimated: at 24 V→5 V/3 A load, dissipation is approximately 4.5 W in the switch plus 0.7 W in the catch diode; with the tab soldered to ~1 square inch of 1 oz copper on a 4-layer board, junction-to-ambient is roughly 20-25 C/W. Sustained 3 A operation requires either 2 square inches of 1 oz copper or a small clip-on heatsink on the tab to keep Tj below 125 C. Datasheet figure for theta_JC is 2 C/W with the tab fully soldered.
Keep the catch-diode loop (switch node to diode to ground return) tight and minimize its area to reduce ringing and EMI. According to the TI LM2596 datasheet, place the input capacitor (at least 220 µF electrolytic plus 0.1 µF ceramic) close to VIN and GND, and keep the feedback trace short and away from the switch node to avoid noise injection. The exposed tab is electrically ground; tie it to GND with at least four thermal vias to the inner/inner layers for spreading heat.
Three common LM2596S-ADJ/NOPB pitfalls: (1) omitting the catch diode or using a slow rectifier - this causes the switch voltage to exceed 45 V abs max and destroy the IC; use a 3 A 40 V Schottky such as SS34. (2) Letting VIN rise above 40 V in load-dump conditions without a TVS clamp. (3) Forgetting that the ON/OFF pin is active-low; floating the pin enables the regulator (internal pull-up), but noise on a long trace to ON/OFF can cause intermittent shutdown - pull high to GND with a 10 kohm to disable and bypass with 1 nF.
Switch-node copper (pin 2 of the TO-263) should be kept small to reduce radiated EMI, but the GND copper should be a generous pour. According to the LM2596 datasheet's PCB layout section, place the inductor and catch diode on the same side of the board as the IC; minimize the loop between OUTPUT, inductor, output cap, and ground. The feedback divider resistors should sit at the output capacitor's remote-sense location, not at the IC pins, to avoid load-regulation error from trace resistance.
Compliance Information
NOPB suffix indicates RoHS-compliant lead-free finish. Not AEC-Q100 qualified - for automotive safety-critical designs, prefer AEC-Q100-qualified parts from TI's automotive portfolio.
