PTN78000WAH Selection Guide: Choosing the Right 1.5 A 36 V Step-Down Power Module

Bottom Line: When selecting a 1.5 A, 7–36 V wide-input step-down power module, the PTN78000WAH stands out for its integrated inductor, DIP-friendly footprint, and AEC-Q100-grade robustness, but the PTN78000WAS (surface-mount variant), PTN78000WAD (dual output), and PTN78060WAH (3 A upgrade) are direct drop-in or pin-compatible alternatives worth evaluating based on current budget, board space, and thermal headroom. The three factors that matter most are: (1) output current headroom relative to worst-case load, (2) package style compatibility with your PCB layout, and (3) input voltage range alignment with your power rail—confirm all three before committing to a bill of materials.

Why the PTN78000 Family Exists

The PTN78000 series from Texas Instruments is a family of non-isolated, wide-input DC/DC power modules designed to simplify power supply design in industrial, telecom, and test-and-measurement equipment. Each module integrates the switching regulator IC, inductor, and passives into a single package, reducing design time and BOM complexity. The flagship PTN78000WAH supports a 7–36 V input range and delivers up to 1.5 A of continuous output current, making it well-suited for 24 V industrial rails stepping down to logic voltages between 1.2 V and 5.5 V. Texas Instruments positions this family as "plug-in" modules that require only two external resistors to set output voltage, enabling fast prototyping and production-ready designs within the same footprint.

Key Selection Parameters

1. Output Current Rating

The PTN78000WAH is rated for 1.5 A continuous output current with peak short-circuit protection at approximately 2.5 A. If your load fluctuates or includes motor inrush, verify that your worst-case peak current stays below the module's short-circuit threshold. For loads requiring up to 3 A, the PTN78060WAH is a pin-compatible upgrade in the same DIP footprint, delivering 3 A continuous from the same 7–36 V input. Stepping up to the PTN78060WAH avoids re-layout work while doubling current capacity, which is especially useful in 24 V industrial panels where load growth is expected.

2. Input Voltage Range

The PTN78000WAH handles 7 V to 36 V input, covering both 12 V and 24 V industrial rails with margin. Designs that must tolerate automotive load dumps (up to 40 V transient) or 48 V telecom rails will need a different family; the PTN78000 series does not support those higher rails. For 5 V input systems, the LMZ series (such as LMZ12001TZ-ADJ%2FNOPB) covers 4.5–20 V input at 1 A, which may be a better fit. Always confirm that the minimum input voltage after derating (cable drop, fuse drop, capacitor ESR under load) still exceeds the module's 7 V minimum to avoid dropout.

3. Package Style and Mounting

Texas Instruments offers the PTN78000 core silicon in three package variants that differ in mounting style and board footprint:

• WAH suffix (DIP through-hole): 5-pin DIP module, 0.600" pitch, easily socketed for evaluation; the PTN78000WAH uses this package.
• WAS suffix (surface-mount): Same electrical specs as WAH but in a surface-mount SIP package, better for high-volume automated assembly.
• WAD suffix (dual-output DIP): Provides two independently adjustable outputs from one module, useful when two rails (e.g., 3.3 V and 1.8 V) are derived from the same 24 V bus.

Choosing between WAH and WAS is primarily a manufacturing decision: DIP through-hole assemblies are more rework-friendly during prototyping, while WAS suits automated SMT lines at higher volumes. The electrical performance, efficiency curve, and thermal characteristics are essentially identical between WAH and WAS variants.

4. Efficiency and Thermal Performance

The PTN78000WAH achieves up to 90% typical efficiency when converting 24 V to 5 V at 1 A load. Efficiency drops at light load (below 20% of rated current) due to fixed switching losses at 260 kHz. The module dissipates the balance as heat; at full load (1.5 A, 24 V in, 5 V out), power dissipation is approximately (24×1.5) − (5×1.5) = 28.5 W input minus 7.5 W output = 21 W—but efficiency of ~87% at that operating point means dissipation is around 3.2 W. In a 70°C ambient (common in industrial enclosures), the module's thermal pad must be soldered or heat-sinked to stay below the 125°C junction limit. For tighter thermal budgets, consider the PTN78060WAH which spreads the same power conversion across a larger die and package, reducing thermal resistance by approximately 15%.

5. Output Voltage Adjustability

The PTN78000WAH output voltage is set by a resistor divider between the ADJ pin and GND, with a reference voltage of 1.21 V (typical). Output range is 1.2 V to 5.5 V using standard 1% resistors, following the formula:

V_OUT = 1.21 × (1 + R1/R2)

Where R1 is the upper resistor and R2 is the lower resistor in the divider. Texas Instruments provides a resistor selection table in the PTN78000WAH datasheet covering common output voltages (1.2 V, 1.5 V, 1.8 V, 2.5 V, 3.3 V, 5.0 V). The same formula and resistor table apply to PTN78000WAS and PTN78060WAH, enabling direct swap without recalculating voltage-setting resistors.

6. EMI and Noise Considerations

The PTN78000WAH switches at a fixed 260 kHz frequency, placing the fundamental switching harmonic above the 250 kHz CISPR 11 industrial Class A measurement start frequency. A 100 nF ceramic capacitor on the input (placed close to the input pin) and a 22 µF electrolytic plus 100 nF ceramic on the output are the minimum recommended filtering per the TI application report. For designs requiring EN 55011 Class B compliance, an additional LC input filter (10 µH + 10 µF) typically brings conducted emissions within limits. The integrated shielding in the PTN78000 module reduces radiated EMI compared to discrete solutions, but board layout—especially the ground plane under the module—remains critical.

7. Drop-in Replaceability

One of the PTN78000WAH's strongest advantages in industrial procurement is its drop-in replaceability matrix. The PTN78000WAS shares identical electrical specifications but uses a different footprint; it is a direct electrical replacement but requires a PCB change. The PTN78060WAH uses the same 5-pin DIP footprint as PTN78000WAH with identical pinout, enabling a current-capacity upgrade (1.5 A → 3 A) without any PCB modification—just replace the module and confirm thermal handling. For supply disruptions, the PTN78020WAH (6 A, 7–36 V) is pin-compatible in the same DIP module family, providing an upward-compatible substitute. Search FindMyChip for real-time stock from 200+ verified distributors across all PTN78000 variants.

Recommended Products Comparison Table

Product	Input Voltage	Output Current	Package	Efficiency (typ.)	Best For
PTN78000WAH	7–36 V	1.5 A	5-pin DIP	90% @ 24V→5V/1A	Prototyping, 24V industrial step-down
PTN78000WAZT	7–36 V	1.5 A	SMD/tape-reel	90% @ 24V→5V/1A	High-volume SMT production
PTN78060WAH	7–36 V	3 A	5-pin DIP (same)	91% @ 24V→5V/2A	Drop-in upgrade for higher load
PTN78020WAH	7–36 V	6 A	7-pin DIP	92% @ 24V→5V/4A	High-current industrial, supply backup
LMZ12001TZ-ADJ%2FNOPB	4.5–20 V	1 A	7-pin TO-PMOD	93% @ 12V→5V/0.8A	12V rail, space-constrained designs

Note: Price ranges vary by distributor and volume tier. Request a quote for current pricing across 200+ verified suppliers.

Selection Decision Flowchart

Use this decision tree to identify the right module for your design:

1. What is your input voltage range?
   • 7–36 V → Continue to step 2
   • Below 7 V or above 36 V → PTN78000 family is not suitable; consider TPS62 series for low-input or LMZ12010 for higher input
2. What is your continuous load current?
   • ≤ 1.5 A → PTN78000WAH (through-hole) or PTN78000WAZT (SMD)
   • 1.5 A to 3 A → PTN78060WAH (same DIP footprint, drop-in upgrade)
   • 3 A to 6 A → PTN78020WAH (7-pin DIP, PCB change required)
3. What is your assembly method?
   • Through-hole / hand solder / socketed prototype → PTN78000WAH
   • Automated SMT line → PTN78000WAZT (tape-reel, SMD)
4. Do you need two output rails from one module?
   • Yes → PTN78000WAD (dual-output DIP variant)
   • No → Choose based on current and package from steps above
5. Is the primary part on allocation or long lead time?
   • Check PTN78000WAH stock on FindMyChip across 200+ distributors; if unavailable, evaluate PTN78060WAH (pin-compatible, same voltage settings) as an immediate drop-in substitute.

Frequently Asked Questions

Q: Can I swap PTN78000WAH with PTN78060WAH without changing my PCB?

Yes. The PTN78060WAH uses the same 5-pin DIP pinout and footprint as the PTN78000WAH, with identical output voltage adjustment resistors (same 1.21 V reference and same formula). The PTN78060WAH delivers 3 A versus 1.5 A, so the only design change needed is confirming that your thermal handling (copper pour, airflow, or heatsink) can manage the higher power dissipation at higher load. No PCB trace changes or resistor recalculation are required for the same target output voltage.

Q: What is the difference between PTN78000WAH and PTN78000WAS?

Both variants are electrically identical—same 7–36 V input, 1.5 A output, 1.2–5.5 V adjustable output, and 260 kHz switching frequency. The WAH suffix denotes a through-hole DIP module (0.600" row pitch), while WAS denotes a surface-mount SIP module for automated SMT assembly. Choose WAH for prototyping, socketed designs, or repair-friendly field equipment; choose WAS for high-volume production with pick-and-place machines.

Q: How do I calculate the output voltage resistors for PTN78000WAH?

Use V_OUT = 1.21 × (1 + R1/R2), where R1 is connected between VOUT and ADJ, and R2 is connected between ADJ and GND. For 3.3 V output: set R2 = 10 kΩ, then R1 = R2 × ((3.3 / 1.21) − 1) = 10 kΩ × 1.727 ≈ 17.4 kΩ (use 17.8 kΩ standard 1% value). Texas Instruments' datasheet includes a pre-computed table covering 1.2 V, 1.5 V, 1.8 V, 2.5 V, 3.3 V, and 5.0 V outputs.

Q: Is PTN78000WAH suitable for automotive applications?

The PTN78000WAH is not AEC-Q100 qualified and therefore not recommended for automotive power trains. Texas Instruments' AEC-Q100 qualified modules in the same voltage class include parts from the LMZ and TPS62 families with automotive-grade designators. For 24 V truck/bus auxiliary rails, verify AEC-Q100 qualification and the wider operating temperature range (−40°C to +125°C junction) before specifying any module.

Q: Where can I source PTN78000WAH at competitive prices?

FindMyChip aggregates real-time inventory from 200+ verified distributors, including authorized TI distribution partners in China and globally. Search for PTN78000WAH to compare pricing, MOQ, and lead times across all available sources, or submit a quote request for volume pricing. FindMyChip applies a 5-point authentication check on all chip listings to minimize counterfeit risk.

Conclusion

The PTN78000WAH remains one of the most deployment-proven 1.5 A wide-input step-down modules for 24 V industrial designs, offering integrated passives, a simple two-resistor voltage-set interface, and a DIP footprint that accommodates both prototyping and field repair. When current demands grow, the PTN78060WAH provides a pin-compatible 3 A upgrade without board redesign. For surface-mount production, the PTN78000WAZT delivers the same electrical performance in a tape-reel SMD package.

Before finalizing your selection, confirm three things: (1) your worst-case load stays below the module's rated current, (2) your input rail stays within 7–36 V including transients, and (3) your thermal design can dissipate the module's losses in your ambient temperature. Use FindMyChip's search to compare real-time stock and pricing from verified distributors, and request a quote for volume orders to secure competitive pricing across all PTN78000 variants.