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Home > Application > DC-DC Converter Selection & Power Architecture for DCS Analog Input Modules

DC-DC Converter Selection & Power Architecture for DCS Analog Input Modules

Time:2026-09-03 Views:

In industrial process control cabinets, Analog Input (AI) modules act as the frontline interface capturing raw signals (temperature, pressure, flow, and level) from plant sensors. Because field instruments and DCS central control racks frequently operate across distinct physical locations, large ground potential differences and inductive switching spikes inevitably couple into field cables.

Integrating high-reliability isolated DC-DC power modules is the fundamental hardware strategy to suppress common-mode noise, eliminate ground loops, and guarantee analog measurement precision.

Power Application Topologies in Multi-Channel AI Modules

A typical DCS cabinet accepts 220 VAC mains, which is stepped down to an internal 24 VDC backplane rail via a front-end DIN-rail AC-DC power supply. To deliver clean, electrically isolated excitation power to field transmitters and ADC front-ends, power designers primarily adopt two modular DC-DC topologies:


1. Centralized 10W Isolated Bus Architecture: As illustrated in Figure 1 below, a single wide-input isolated DC-DC converter steps nominal 24 VDC down to an isolated 24 VDC auxiliary rail. This rail distributes power to eight parallel transmitter loops, with each branch safeguarded by a PTC resettable fuse.

  • Power Module Role: Serves as the primary dielectric barrier (2250VDC isolation) shielding the master MCU board from field surges.
  • Design Benefits: Significantly reduces PCB footprint, minimizes BOM cost, and maximizes conversion efficiency.
DC-DC Converter Selection & Power Architecture for DCS Analog Input Modules | Aipu Power - Image 1
Figure 1: Centralized isolated power architecture for 8-channel AI transmitter excitation using a single 10W DC-DC module.

2. Distributed Channel-to-Channel Power Isolation: In high-reliability mission-critical process nodes, a secondary step-down rail (e.g., 24 V to 5 V) feeds eight independent, miniature isolated DC-DC modules (5 V input to 24 V output, 2W each), as shown in Figure 2.

  • Power Module Role: Delivers complete galvanic isolation between individual channels, ensuring that a transient fault or wire cut on one sensor loop cannot cross-couple into adjacent channels.
  • Design Benefits: Maximum signal integrity and fault tolerance for critical continuous monitoring loops.
DC-DC Converter Selection & Power Architecture for DCS Analog Input Modules | Aipu Power - Image 2
Figure 2: Channel-to-channel isolated power topology utilizing independent micro-power DC-DC converters for absolute signal decoupling.

DC-DC Converter Selection Guidelines for Industrial AI Modules

Power supplies deployed in industrial DCS cabinets must endure harsh thermal and electrical stresses. When selecting a power module for transmitter excitation and signal conditioning circuitry, power engineers should evaluate the following critical parameters:

Key Engineering ParameterRecommended Pick: FK10-36S24E2C3Alternative Option: FK10-18S24E2C3Channel-to-Channel Option: 2W SIP Series
Application Fit24V Industrial bus (Ultra-wide 18–72VDC)12V/24V Industrial bus (Wide 9–36VDC)Secondary regulated rail (Fixed 4.5–5.5VDC)
Output Power & Voltage24 VDC / 10 W (15 W Peak capability)24 VDC / 10 W (15 W Peak capability)24 VDC / 2 W
Galvanic Isolation Rating2250 VDC2250 VDC1500 VDC
Input Surge Withstand100 VDC (1 second duration)50 VDC (1 second duration)Continuous standard input
Operating Temperature-40°C to +85°C-40°C to +85°C-40°C to +105°C
Package Footprint22.0 × 9.5 × 12.0 mm (Ultra-compact DIP)22.0 × 9.5 × 12.0 mm (Ultra-compact DIP)19.5 × 7.0 × 10.1 mm (High-density SIP)
Compliance StandardsIEC/EN 62368-1, CE, RoHSIEC/EN 62368-1, CE, RoHSCE, CB, UL recognized

The FK10-36S24E2C3 module delivers up to 15W transient peak power, providing ample current headroom during simultaneous transmitter startup. For systems requiring alternative logic supply voltages (3.3V, 5V, 12V, or 15V), explore the complete model list on the FK10 series specification page, or browse Aipu Power's broader portfolio of dedicated power & electricity application modules.

Frequently Asked Questions (FAQ)

  • How does an isolated DC-DC converter eliminate ground loops in multi-channel AI modules?
  • In industrial process control, field transmitters and the DCS control station often operate on separate grounding systems with significant ground potential differences. An isolated DC-DC converter breaks the galvanic DC ground path with high dielectric withstand voltage (up to 2250VDC), stopping common-mode loop currents from distorting the 4–20mA analog sampling signals.
  • Why is 100VDC transient surge capability critical for 24VDC industrial bus converters?
  • Inductive load kicking from contactors, pumps, and relays in industrial cabinets causes severe line spikes on nominal 24V buses. Converters that withstand 100VDC input surges for 1 second, such as the FK10 series, prevent internal switching MOSFET breakdown without requiring oversized external TVS clamping circuits.
  • When is dedicated channel-to-channel power isolation required over a shared 10W isolated rail?
  • A shared 10W converter with individual PTC branch fuses provides an optimal balance between cost and footprint for localized loops. However, if any single sensor channel experiences a catastrophic high-voltage fault or short circuit, dedicated micro-power isolated modules ensure that neighboring channels remain operational with zero data corruption.

Looking for high-isolation DC-DC converters or custom pinout configurations for your automation projects? Explore our complete range of electric power application modules or contact our technical team for free engineering samples.