Module or Discrete? Selecting a Wide-Vin Buck Regulator for 24V/48V Industrial Rails (PTN78000 vs LMZ14202)

Bottom Line: For point-of-load (PoL) rails on 24V/48V industrial bus systems, choose a wide-Vin power module over a discrete buck design when board area is below ~600 mm², when the design must ship in under eight weeks, or when the team lacks a dedicated power-supply engineer to close magnetics, layout, and EMI. Within the module choice, the 1.5A PTN78000 wide-Vin module wins for sub-1.5A loads on a true 24–36V rail because of its 7–36V input range and integrated inductor in a 5-pin SIP footprint. The LMZ14202 SIMPLE SWITCHER 6–42V option wins on 48V nominal rails (e.g. PROFINET drives, robotics) because its 42V absolute-max input survives 48V transients with margin. Below 1.5A and above 100 kHz transient bandwidth, both modules outperform discrete LM2596-class designs in the metric that matters most: time-to-revenue.

Why this decision matters

Industrial 24V and 48V rails sit between two competing pressures. On one side, factory automation, AGVs, and edge gateways are pushing more silicon — gigabit Ethernet PHYs, NPUs, multi-rail FPGAs — onto increasingly small boards inside fan-less enclosures. On the other side, the hardware team that ships those boards is often three engineers split across schematic, firmware, and bring-up. There is no power-supply specialist.

The "module or discrete" question is therefore not a circuit-design question. It is a project-management question disguised as one. A discrete LM2596 buck saves $1.20 in BOM but costs three weeks of layout iteration and EMC re-spins. A power module costs $4.50 but ships first revision. For runs under 5,000 units per year — which describes most industrial-controls products — the module wins on landed cost once NRE is amortized.

This guide takes a position. We compare the two specific modules called out in the working title, against the discrete alternative, and we tell you which to pick. We do not equivocate.

Full specifications comparison table

Parameter	PTN78000WAH	LMZ14202TZ-ADJ/NOPB
Topology	Non-isolated step-down (buck)	Non-isolated step-down (buck)
Input voltage range	7–36 V	6–42 V
Absolute max input	38 V	45 V
Adjustable output range	2.5–12.6 V	0.8–6 V
Rated output current	1.5 A	2.0 A
Switching frequency	~520 kHz (fixed)	320 kHz (avg, COT-like in newer revs; voltage-mode in this rev)
Control method	Voltage-mode PWM	Voltage-mode (constant frequency)
Typical efficiency (24V → 5V, full load)	91%	92%
No-load (UVLO-on) standby current	~25 mA	~16 mA
Output ripple (typical)	30 mVpp	25 mVpp
Operating junction temperature	−40 to +85°C ambient (TJ ≤ 125°C)	−40 to +125°C (TJ)
Package	5-pin SIP (through-hole), ~21.6 × 9.0 × 11.2 mm	7-lead PowerPAD TO (SMT), 10.16 × 13.77 × 4.57 mm
Soft-start	Internal, ~7 ms	Internal, ~5 ms
External components needed	2 (Cin, Rset)	4 (Cin, Cout, Rfbt, Rfbb)
Unit price (1K qty, 2025)	~$8.40	~$5.20
Datasheet revision	SLTS244F (PTN78000A/W series)	SNVS693N (LMZ14202)

Numbers above are taken from TI public datasheets at the revisions noted; verify against the latest revision before final BOM lock.

Parameter deep dive

Input voltage range — why 6V matters more than you think

The LMZ14202 outperforms on input range with a true 6–42V rated window versus the PTN78000's 7–36V. For a 24V nominal industrial bus, both have margin; for 48V nominal rails, only the LMZ14202 survives without an upstream pre-regulator. IEC 61131-2 specifies 24V industrial supplies must tolerate 19.2–28.8V steady-state plus transients to ~36V; the PTN78000 absorbs that. The same standard for 48V rails (or unregulated 48V battery backup systems in robotics) defines transients to ~57V — beyond either module without a TVS clamp, but the LMZ14202's 45V absolute-max gives an extra 9V of design-margin against the bus before TVS clamping kicks in.

The takeaway: on a strictly 24V bus, the 7V lower limit of the PTN78000 is irrelevant. On a 48V bus, the LMZ14202 is the only correct answer between these two without auxiliary protection.

Output current and headroom

The PTN78000WAH is rated at 1.5A; the LMZ14202 at 2.0A. For typical industrial PoL loads — a 5V/3.3V house-rail feeding an MCU plus Ethernet PHY — sustained current sits between 200–800 mA with peaks under 1.2A. Both modules have margin. The decision therefore inverts: if the load is under 1.5A and the package needs to be through-hole (e.g. wave-solder process, conformal coating clearance), pick the PTN78000. If the load is between 1.5A and 2A and the assembly is reflow-only, pick the LMZ14202.

For loads above 2A, both modules below are out of envelope, and you should size up: see "Sizing up the family" later in this guide.

Efficiency at industrial duty cycles

The two modules are within 1% of each other across most of the operating window — neither has a structural efficiency advantage at 24V → 5V conversion. Where they differ is light-load behavior. The LMZ14202 retains constant switching frequency down to ~10% load, which produces predictable EMI but worse light-load efficiency (it falls to ~78% at 100 mA). The PTN78000 also runs in continuous-conduction mode, with comparable light-load behavior. For applications where the system spends >50% of operating life at standby (e.g. always-on industrial gateways), neither module is a better choice than a low-Iq controller in CCM/DCM auto-transition mode — but both are dramatically simpler to design in.

Package, mounting, and serviceability

The PTN78000 is a through-hole 5-pin SIP. This wins for: socketed test fixtures, panel-mount industrial enclosures with conformal coating (the SIP's 11mm height accepts coating without bridging pins), and any design where the power module is a field-replaceable unit. The LMZ14202 is SMT only, in a TO-style 7-lead PowerPAD. This wins for: dense double-sided boards, automated reflow lines, and designs where height under 5mm is required (e.g. inside a DIN-rail housing with limited vertical clearance).

If you are still hand-soldering prototypes in a lab, the PTN78000 is faster to swap. If your contract manufacturer charges a separate setup fee for through-hole, the LMZ14202 is cheaper at run-rate.

Thermal derating in industrial enclosures

Both modules quote internal junction-to-ambient thermal resistance, but the PTN78000's SIP package conducts heat almost entirely through its bottom pad and pin-3 ground, while the LMZ14202's PowerPAD bottom-pad couples directly into the PCB copper plane. In an enclosed industrial box at 65°C ambient with no airflow, the LMZ14202 derates from 2A to ~1.4A; the PTN78000 derates from 1.5A to ~1.0A. Per-watt of dissipated power, the SMT module spreads heat better because it can pull from a 30+ cm² ground plane. This is the single biggest design consideration most teams underweight.

If your final enclosure runs above 60°C ambient, allocate 30% derating for either module and pick the one whose derated rating still covers your worst-case load. If derated current still falls short, step up to the 3A LMZ14203 alternative or to its 6A higher-current sibling PTN78020 — both are family step-ups designed exactly for this case.

Transient response and output filtering

Voltage-mode control in both modules limits transient performance to roughly 8–12% deviation on a 50% load step at 1 A/μs slew rate, recovering in ~150 μs. For most industrial loads — MCUs, Ethernet PHYs, CAN transceivers — this is non-negotiable adequate. For loads with sub-100 μs ramp requirements (some FPGA cores, gigabit SerDes blocks), neither module is sufficient on its own; add a downstream LDO or use a current-mode controller-based discrete solution.

BOM cost honesty

At 1K quantities, the LMZ14202 lands at roughly $5.20; the PTN78000WAH at roughly $8.40. A discrete LM2596 + inductor + 4 caps + 2 resistors lands at roughly $1.20 in parts. The discrete design adds, conservatively, 12 hours of layout time, 4 hours of EMC tuning, and 2 hours of bring-up — call it $2,400 NRE per design at $120/hr loaded. At 5,000 units lifetime, the discrete design saves $20,000 in BOM and costs $2,400 in NRE, netting $17,600 — but only if the layout works first try and EMC passes. In practice, fewer than 40% of in-house buck designs pass EMC pre-scan first attempt. The expected-value math collapses fast.

When to choose which: a decision tree

Choose the 1.5A PTN78000 wide-Vin module when:

Bus is strictly 24V nominal (PROFIBUS, DeviceNet, controls cabinet PoL).
Load is below 1.5A in normal operating conditions.
Assembly process is mixed-technology (through-hole reflow flow already established).
Board is field-serviceable and the module may need socket replacement.
Conformal coating is required and SIP clearance simplifies application.

Choose the LMZ14202 SIMPLE SWITCHER 6–42V option when:

Bus is 48V nominal or unregulated (battery-backed industrial systems, robotics joint-drives, PROFINET converged drives).
Load is between 1.5A and 2A continuous.
Assembly is SMT-only (no through-hole setup time available).
Enclosure runs warm (>55°C ambient) and PCB copper-plane heatsinking is available.
Output rail is below 6V (the LMZ14202 adjusts down to 0.8V; the PTN78000 minimum is 2.5V).

Choose discrete (LM2596, TPS54336, MCP16331) when:

Annual volume exceeds 25,000 units and BOM-cost optimization pays for NRE.
A power-supply engineer is on the team and EMC pre-compliance lab time is budgeted.
Output current is in a range no module covers efficiently (e.g. 5–8A at 5V output).
Application has unusual constraints — synchronization to an external clock, sequenced startup with three rails, current-sharing across parallel converters.

For loads above 2A on 24V/48V rails, skip both modules and consider the family step-ups: the 3A LMZ14203 alternative for ≤3A applications, its 6A higher-current sibling PTN78020 for 6A on a 4.5–14.5V or 7–36V rail (variant-dependent — check the part suffix), or a higher-current 5A LMZ23605 module for heavier rails where the input range can be tightened to 4.5–17V.

48V bus architectural considerations

If you are designing for a 48V industrial bus today (and most new robotics and warehouse-automation designs are), the architectural choice is broader than buck-converter selection. The two real questions are:

Direct 48V→3.3V single-stage versus 48V→12V→3.3V two-stage? Single-stage saves a converter but pushes the second stage to handle wide duty cycles (~7% on at 3.3V output from 48V input), which hurts efficiency below 60% and bandwidth. Two-stage adds a converter but gives each stage a comfortable 4–5x conversion ratio. For loads under 1A, single-stage with a wide-Vin module wins on board area. For loads above 2A or with multiple downstream rails, two-stage wins on total efficiency and easier transient design.
Isolated versus non-isolated? Both modules in this guide are non-isolated. For floating loads (sensor heads on extended cables, hot-pluggable I/O modules), an isolated DC/DC is required upstream — not at the PoL level. Non-isolated is correct at the PoL, with isolation handled by the bus-entry converter.

FAQ

Can I parallel two PTN78000 modules to get 3A output?

No, not without external current-share circuitry. The PTN78000 has no current-share pin and its internal voltage feedback will fight a parallel module. For 3A on a wide-Vin 24V bus, use the LMZ14203 instead, which is rated 3A in a single device.

Why is the PTN78000WAH more expensive than the LMZ14202 if it has lower current rating?

Two reasons: the PTN78000 includes the inductor inside the encapsulated module (the LMZ14202 does too, but in a smaller package), and the SIP through-hole package costs more to manufacture than a SMT TO-style package at TI's volumes. The price premium is for assembly format, not silicon performance.

Will either module pass EN 55032 Class B without external filtering?

Both modules typically pass Class B with a small input filter (10 μF ceramic + ferrite bead) on a controlled-impedance ground plane. Without those input components, both modules will fail Class B in the 30–230 MHz range. EMC passing is "module + filter," never "module alone." Plan for the filter at schematic stage.

How do I choose the output capacitor for the LMZ14202?

The LMZ14202 datasheet specifies 22 μF ceramic (X7R, low-ESR) minimum on the output. For best transient response on a 5V output feeding 1A loads, use 47 μF X7R as a starting point and verify with a load-step test. The PTN78000WAH does not require an external output capacitor — the module integrates one internally — though adding 22 μF improves load-step response.

Are these modules suitable for −40°C operation in outdoor industrial enclosures?

Both modules are rated to −40°C ambient (PTN78000) or −40°C junction (LMZ14202). For unheated outdoor enclosures, both will operate, but the soft-start time roughly doubles at −40°C compared to room temperature, and output ripple increases ~30%. If the design must start from cold-soaked −40°C with a short power-good window, validate startup with a calibrated cold chamber — do not rely on datasheet typicals alone.

Conclusion: pick the module, then ship

The "module or discrete" debate has a clear answer for most industrial PoL designs at sub-25,000 unit annual volumes: pick a wide-Vin module and ship the product. Within the module space, the 1.5A PTN78000 wide-Vin module is the right choice for 24V industrial buses with sub-1.5A loads where the package format and field-serviceability benefits matter. The LMZ14202 SIMPLE SWITCHER 6–42V option is the right choice for 48V buses and SMT-dense layouts up to 2A. For higher currents, scale up the family. For higher volumes or unusual specifications, the discrete approach earns its NRE cost.

If you are sourcing either part for a new design, search the live distributor stock on FindMyChip to compare authorized inventory across our 200+ verified suppliers, or request a quote directly with your target quantity and date code. Both modules are commodity-stable parts on the long-term supply list, but availability of the through-hole PTN78000 has tightened in 2025 — confirm date codes and lead times before committing to a layout decision.