LM2596S-5.0/NOPB vs TGM-240NSLFTR: Component Comparison for Power Electronics Engineers
Quick verdict
For standard non-isolated 5 V, 3 A buck conversion from a DC rail up to 40 V, the LM2596S-5.0/NOPB is the clear choice due to its integrated control, fixed output, and straightforward design. For applications requiring galvanic isolation or where safety standards mandate isolation, the TGM-240NSLFTR transformer is essential as a magnetic component in isolated buck converter topologies, but it is not a standalone regulator IC.
Spec comparison table
| Spec | LM2596S-5.0/NOPB | TGM-240NSLFTR | Notes |
|---|---|---|---|
| Function | Step-Down (buck) regulator IC | Isolated Buck Converter Transformer | LM2596S is a full regulator IC; TGM-240NSLFTR is a transformer, not a regulator. |
| Input voltage max | 40 V | Not specified | LM2596S input voltage max of 40 V suits many DC rails; TGM transformer voltage rating not defined. |
| Input voltage min | 4.5 V | Not specified | LM2596S supports low voltage start; transformer voltage ratings depend on driver. |
| Mounting type | Surface Mount | Surface Mount | Both are SMT parts, suitable for automated assembly. |
| Number of outputs | 1 | N/A (magnetic component) | LM2596S output is regulated; TGM-240NSLFTR is a transformer, no direct output. |
| Operating temperature range | -40°C to 125°C (junction) | -40°C to 85°C | LM2596S supports wider temperature range, better for harsh environments. |
| Output configuration | Positive fixed 5 V | N/A | LM2596S fixed 5 V output; TGM transformer used in isolated buck topologies with external control. |
| Output current max | 3 A | Not specified | LM2596S rated for 3 A output current; transformer current depends on circuit and driver. |
| Output type | Fixed voltage | N/A | LM2596S fixed output; TGM transformer requires external regulation. |
| Package case | TO-263-6, D2PAK (5 leads + tab) | 8.13 mm x 7.11 mm (0.320” x 0.280”), height 5.08 mm | LM2596S is a power IC package; TGM is a discrete transformer component. |
| Switching frequency typ | 150 kHz | Not specified; switching frequency max in V-μs: 11 V-μs | LM2596S fixed switching frequency; TGM transformer rated for switching speed (V-μs) parameter. |
| Synchronous rectifier | No | N/A | LM2596S uses diode rectification; transformer does not define rectification. |
| Topology | Buck (non-isolated) | Isolated buck converter transformer | LM2596S is non-isolated; TGM is for isolated applications. |
| Chipset manufacturer | Texas Instruments | Analog Devices, Inc | Different manufacturers, which may affect support and reference designs. |
| DCR max | N/A | 0.8 Ω | Transformer winding resistance affects losses; 0.8 Ω is moderate for transformer. |
| Isolation voltage max | N/A | 4,500 Vrms | TGM transformer provides high galvanic isolation, critical for safety and noise immunity. |
| Isolation voltage typ/min | N/A | 1,500 Vrms | Minimum isolation voltage rating is 1,500 Vrms, useful for system isolation requirements. |
| Primary inductance (typ/min) | N/A | 960 μH | Inductance value critical for transformer design; LM2596S includes integrated inductor externally chosen. |
| Secondary inductance (typ/min) | N/A | 960 μH | Balanced inductance on secondary winding, important for transformer operation. |
| Height seated max | N/A | 5.08 mm | TGM transformer height is a key mechanical parameter. |
| Turns ratio primary | N/A | ±3% | Tight tolerance on turns ratio critical for predictable voltage conversion. |
Design trade-offs
The LM2596S-5.0/NOPB is a fully integrated, non-isolated buck regulator IC designed for straightforward 5 V output from input voltages up to 40 V. It integrates the control IC and requires an external inductor, diode, and capacitors. With a fixed switching frequency of 150 kHz and a maximum output current of 3 A, it fits general-purpose DC/DC conversion needs where isolation is not a requirement. The 125°C junction temperature rating provides some headroom for thermal management, but careful layout to minimize conduction and switching losses is necessary. The device uses a diode for rectification rather than synchronous rectification, which limits efficiency compared to synchronous designs, especially at higher currents.
In contrast, the TGM-240NSLFTR is not a regulator IC but an isolated transformer intended for isolated buck converter topologies, typically paired with Analog Devices controller ICs like MAX253 or MAX845. Its key feature is galvanic isolation up to 1,500 Vrms (typical) and up to 4,500 Vrms max, enabling use in applications where safety isolation or noise immunity is mandatory. The transformer has a primary and secondary inductance of 960 μH, with a DCR of up to 0.8 Ω, which contributes to conduction losses and impacts efficiency. The switching frequency parameter is given as a maximum of 11 V-μs, a figure related to the maximum voltage-time product the transformer can handle without saturation, rather than a fixed switching frequency.
From a layout perspective, the LM2596 requires careful placement of the external inductor and diode to minimize EMI and voltage spikes, whereas the TGM transformer requires integration into an isolated converter topology, which involves more complex PCB layout for safety and EMI compliance, including creepage and clearance distances. Also, the transformer’s 5.08 mm seated height must be considered in mechanical design.
Thermal management for the LM2596S involves ensuring the TO-263 package can dissipate up to its rated power; the integrated regulator IC will generate heat proportional to the input-output voltage differential and load current. The TGM transformer’s losses are primarily copper losses in the windings and core losses, which must be managed within the PCB copper and thermal design. Because the transformer is a passive component, no gate drive or firmware control is associated with it directly, but the associated controller ICs require proper driver design.
Cost at volume will generally favor the LM2596S as a complete IC solution, whereas the TGM transformer adds cost and complexity due to the isolation feature and the need for additional controller circuitry.
Use-case fit
Choose LM2596S-5.0/NOPB when…
- You need a simple, fixed 5 V, 3 A buck regulator for non-isolated DC/DC conversion from a max 40 V input rail.
- Thermal design constraints allow operation up to 125°C junction temperature, and a TO-263 power package is acceptable.
- Design simplicity and minimal external component count are priorities.
- Your application does not require galvanic isolation or isolation certification.
- You want a well-documented, widely supported regulator IC from a major vendor with abundant design resources.
Choose TGM-240NSLFTR when…
- Your buck converter design requires galvanic isolation of at least 1,500 Vrms, for safety or noise immunity compliance.
- You are building an isolated DC/DC converter with Analog Devices controller ICs (e.g., MAX253, MAX845) that specify this transformer.
- Your design must handle transient voltages up to 4,500 Vrms isolation.
- You can accommodate the larger PCB footprint and component height (5.08 mm seated) for the transformer.
- You are prepared to design or source isolated feedback and control loops, as this is a discrete magnetic component, not a complete regulator.
Drop-in compatibility
These parts are not pin-compatible or footprint-compatible. The LM2596S-5.0/NOPB is a power IC in a TO-263 (D2PAK-5) package with integrated control and power switching devices. The TGM-240NSLFTR is a surface-mount transformer with a completely different pin configuration and physical footprint (8.13 mm × 7.11 mm, 5.08 mm height). Substituting one for the other is not possible without a complete redesign of the power stage and control scheme.
Alternatives to consider
- Texas Instruments LM2675-5.0: Similar fixed 5 V buck regulator with higher switching frequency (~260 kHz) and smaller external component size, suitable for compact designs.
- Analog Devices ADP2302: High-efficiency synchronous buck regulator IC with integrated MOSFETs and adjustable output voltage, for designs requiring better efficiency than LM2596.
- Würth Elektronik WE-TPC Series: Isolated transformers designed for isolated DC/DC converters with various turns ratios and isolation ratings, alternative to TGM-240NSLFTR for specific isolation needs.