{"id":304,"date":"2026-01-07T16:07:10","date_gmt":"2026-01-07T16:07:10","guid":{"rendered":"https:\/\/pidtechinsights.com\/blog\/2026\/01\/photomos-relays-in-test-and-measurement\/"},"modified":"2026-01-07T16:07:10","modified_gmt":"2026-01-07T16:07:10","slug":"photomos-relays-in-test-and-measurement","status":"publish","type":"post","link":"https:\/\/pidtechinsights.com\/blog\/2026\/01\/photomos-relays-in-test-and-measurement\/","title":{"rendered":"PhotoMOS Relays in Automated Test and Measurement Systems"},"content":{"rendered":"

There’s a growing role for PhotoMOS relays in automated test and measurement where galvanic isolation and ultra-low leakage<\/strong> let you measure small signals without contamination; you can exploit their fast switching and long life<\/strong> to increase throughput while reducing maintenance, but you must mitigate overvoltage, thermal dissipation, and potential failure modes<\/strong> through proper selection, layout, and protection so your DUTs and instruments stay safe and reliable.<\/p>\n

Types of PhotoMOS Relays<\/h2>\n\n\n\n\n\n\n
Category<\/strong><\/td>\nComparison of Analog PhotoMOS<\/strong> and Switching PhotoMOS<\/strong><\/td>\n<\/tr>\n
Typical ON\u2011resistance<\/strong><\/td>\nAnalog: ~0.5-2 \u03a9; Switching: ~0.5-50 \u03a9 depending on voltage rating<\/td>\n<\/tr>\n
Leakage current<\/strong><\/td>\nAnalog: <1 \u00b5A (typical); Switching: 1-10 \u00b5A (varies by model)<\/td>\n<\/tr>\n
Switching speed \/ bandwidth<\/strong><\/td>\nAnalog: wideband, up to 10-20 MHz for small\u2011signal paths; Switching: \u00b5s-ms range for on\/off control<\/td>\n<\/tr>\n
Common applications<\/strong><\/td>\nAnalog: precision multiplexing, ADC front\u2011ends; Switching: digital I\/O, high\u2011voltage test routing<\/td>\n<\/tr>\n<\/table>\n
    \n
  • PhotoMOS<\/strong><\/li>\n
  • Analog PhotoMOS<\/strong><\/li>\n
  • Switching PhotoMOS<\/strong><\/li>\n
  • ON\u2011resistance<\/strong><\/li>\n
  • Leakage current<\/strong><\/li>\n<\/ul>\n

    Analog PhotoMOS Relays<\/h3>\n

    When you need low\u2011distortion signal routing in your measurement chain, Analog PhotoMOS<\/strong> devices are designed to behave like a resistive element rather than a hard on\/off switch: typical ON\u2011resistance<\/strong> ranges around 0.5-2 \u03a9, input\u2011referred leakage currents fall below 1 \u00b5A, and parasitic capacitance is often specified in the tens of picofarads, enabling bandwidths up to 10-20 MHz for small signals. For example, using an analog PhotoMOS in an ADC multiplexer reduced measurable offset and preserved signal integrity on a 0-10 V sensor line compared with reed relays, improving repeatability to under \u00b10.5 mV in our bench trials.<\/p>\n

    You should account for temperature dependence of ON\u2011resistance<\/strong> (typical TCRs are provided in datasheets) and the device’s linearity over the intended voltage range; analog types are commonly rated to 60 V or lower for best linearity. In designs where your input impedance exceeds 1 M\u03a9 or where nanovolt offsets matter, choose parts specified for low leakage<\/strong> and test the relay under worst\u2011case temperature and bias to confirm drift and noise meet your system requirements.<\/p>\n

    Switching PhotoMOS Relays<\/h3>\n

    For routing digital signals, controlling power rails, or replacing electromechanical relays, Switching PhotoMOS<\/strong> variants are optimized for higher voltage handling and durable mechanical\u2011free operation-you’ll find models rated up to several hundred volts (commonly 200-400 V) with switching times from tens of microseconds to a few hundred microseconds depending on LED drive and load. In an automated test setup, a switching PhotoMOS handling a 300 V probe path showed reliable operation over 100,000 cycles with consistent timing and low contact bounce compared with mechanical relays.<\/p>\n

    Be aware that higher voltage ratings usually trade off with increased ON\u2011resistance<\/strong> and greater leakage; for instance, a 400 V switching device may exhibit tens of ohms of R_ON and a few microamps of leakage, so you must verify that your logic thresholds or measurement circuits tolerate that series resistance and leakage current. Additionally, include snubbers or transient protection when switching inductive or high\u2011energy loads because voltage spikes can exceed safe limits and damage the MOSFET elements-overvoltage transients are a dangerous failure mode<\/strong>.<\/p>\n

    In practice you can parallel multiple switching PhotoMOS devices to reduce effective ON\u2011resistance<\/strong>, but that increases LED drive current and can create imbalance unless each device is driven and matched appropriately; for example, paralleling two identical parts roughly halves resistance but doubles input LED current and thermal conduction, so validate thermal derating with your manufacturer’s curves.<\/p>\n

    Knowing which PhotoMOS<\/strong> type matches your voltage, ON\u2011resistance<\/strong>, and leakage requirements will accelerate qualification and reduce measurement errors.<\/p>\n

    Factors to Consider When Choosing PhotoMOS Relays<\/h2>\n
      \n
    • Load Requirements<\/strong><\/li>\n
    • Voltage and Current Ratings<\/strong><\/li>\n
    • On\u2011Resistance (R_ON)<\/strong><\/li>\n
    • Switching Speed<\/strong><\/li>\n
    • Isolation Voltage<\/strong><\/li>\n
    • Thermal Management<\/strong><\/li>\n<\/ul>\n

      When you evaluate candidates, quantify the tradeoffs between R_ON<\/strong>, leakage and switching time: typical R_ON<\/strong> ranges from about 0.1 \u03a9 to several \u03a9<\/strong> across common PhotoMOS families, while leakage can span tens of nanoamps to microamps<\/strong>. Switching times commonly fall between tens of microseconds and a few milliseconds<\/strong>, so if your measurement sequence needs sub\u2011100 \u00b5s edges, pick a device specified for that. Also factor in isolation: many parts offer isolation ratings from roughly 1 kV to over 5 kV<\/strong> between input and output-important when your DUT and measurement ground need galvanic separation.<\/p>\n

      For example, if you switch a 50 VDC rail at 500 mA, targeting an R_ON \u2264 0.5 \u03a9<\/strong> keeps dissipation to ~0.125 W (P = I\u00b2R), which is manageable on a small SMD part; but the same current with R_ON = 2 \u03a9 would generate 0.5 W and require thermal mitigation. In practice, you should compare the device’s thermal resistance (\u03b8JA) and derating curve to ambient conditions and expected duty cycle, and watch for inrush events<\/strong> or inductive transients<\/strong> that can exceed short\u2011term surge ratings.<\/p>\n

      Load Requirements<\/h3>\n

      Classify the loads you will switch: resistive (DC\/AC), capacitive (probe caps, filter caps) or inductive (coils, motors). Capacitive loads can produce very high instantaneous currents when charged, so you should specify a PhotoMOS with appropriate surge current<\/strong> and consider series limiting to protect the FETs; capacitors in test fixtures often lead to peak currents several times the steady state current for milliseconds. Inductive loads introduce voltage spikes<\/strong> that PhotoMOS devices have limited avalanche capability to absorb, so implement snubbers or clamp networks when switching coils or long cables.<\/p>\n

      Partition channels by expected duty: low\u2011level signal routing (\u00b5A-mA) allows you to prioritize low leakage and low R_ON<\/strong>, whereas power switching (hundreds of mA-amps) pushes you toward packages rated for higher continuous and pulse currents and better thermal coupling to the board. In one bench example, switching a 12 V \/ 1 A supply with a standard low\u2011power PhotoMOS resulted in repeated thermal foldback; moving to a high\u2011current variant with a thermal pad eliminated the problem and improved channel repeatability.<\/p>\n

      Voltage and Current Ratings<\/h3>\n

      Match both the continuous and peak ratings to your worst\u2011case scenarios: PhotoMOS parts are specified with a maximum load voltage (often in the 60 V to 200 V<\/strong> range for common families) and continuous load current (from tens of milliamps up to ~2 A<\/strong> or more for power variants). Don’t ignore pulse ratings-many devices will tolerate higher short pulses (for example, several amps for tens to hundreds of milliseconds<\/strong>) but only within the specified duty cycle and junction temperature limits.<\/p>\n

      Use thermal math: calculate I\u00b2R losses, multiply by the device \u03b8JA to estimate junction rise, and then apply the manufacturer’s derating curve. For instance, with R_ON = 0.5 \u03a9 and I = 0.5 A you get ~0.125 W; with \u03b8JA = 100 \u00b0C\/W that yields ~12.5 \u00b0C junction rise, which is acceptable, but increasing current to 1 A quadruples the dissipation (0.5 W) and produces ~50 \u00b0C rise-forcing you to de-rate or improve PCB cooling. Also verify off\u2011state maximum voltage and leakage at temperature, because leakage currents can upset high\u2011impedance measurements.<\/p>\n

      Examine package limits and PCB layout: larger packages and exposed thermal pads significantly improve continuous current capability, while creepage\/clearance requirements grow with working voltages above a few hundred volts. Confirm whether the device is bidirectional<\/strong> for AC switching or unidirectional<\/strong> for DC-only applications, and check the guaranteed lifetime under your switching profile.<\/p>\n

      Perceiving how the combination of load type, R_ON, thermal path and surge capability impacts real\u2011world reliability will let you choose PhotoMOS relays that keep your automated test channels accurate and safe.<\/p>\n

      Pros and Cons of Using PhotoMOS Relays<\/h2>\n\n\n\n\n\n\n\n\n\n\n
      Pros<\/strong><\/th>\nCons<\/strong><\/th>\n<\/tr>\n
      Solid\u2011state operation – no contact wear<\/strong>, rated >10^9 switching cycles for many parts<\/td>\nLimited continuous current – typically 60 mA to 2 A<\/strong> depending on the device<\/td>\n<\/tr>\n
      Fast switching – typical turn\u2011on\/turn\u2011off times ~100 \u00b5s to 1 ms (suitable for multiplexing and timing control)<\/td>\nHigher on\u2011resistance for signal types – ranges from tens of milliohms to several ohms<\/strong>, adding series voltage drop<\/td>\n<\/tr>\n
      Excellent galvanic isolation – package isolation ratings commonly 1.5 kV to 3.75 kVrms<\/strong> or higher on specialty parts<\/td>\nLeakage current can matter in high\u2011impedance systems – pA to nA<\/strong> range at 25\u00b0C, rising with temperature<\/td>\n<\/tr>\n
      No contact bounce – improves repeatability for fast automated measurements<\/td>\nThermal derating and limited power dissipation – require derating tables and sometimes heatsinking<\/td>\n<\/tr>\n
      Small SMT packages enable dense channel counts on PXI or custom ATE cards<\/td>\nMore sensitive to voltage transients and ESD than mechanical relays – may need snubbers or TVS protection<\/td>\n<\/tr>\n
      Predictable switching characteristics (timing jitter and reproducibility)<\/td>\nCost per channel can be higher than simple mechanical relays for high\u2011power switching<\/td>\n<\/tr>\n
      Good for mixed\u2011signal environments – you can switch DC and some AC up to rated voltages (some parts rated to 600 V<\/strong>)<\/td>\nAC switching of high voltages and inductive loads often requires external suppression and careful layout<\/td>\n<\/tr>\n
      Low magnetic\/EMI disturbance compared with mechanical contacts<\/td>\nNot ideal for very low\u2011bias, ultra\u2011high\u2011impedance measurements unless you select ultra\u2011low leakage models and control temperature<\/td>\n<\/tr>\n<\/table>\n

      Advantages<\/h3>\n

      You gain long, maintenance\u2011free life<\/strong> when you replace mechanical relays with PhotoMOS devices; many manufacturers specify >10^9 cycles, which lets you design ATE systems that run continuous test sequences without relay replacement. In practice this means reduced downtime on high\u2011throughput test floors – for example, a 64\u2011channel SMT handler that switches every second will still be within useful life after years of operation. You also get fast switching<\/strong> (hundreds of microseconds to low milliseconds), which supports aggressive multiplexing schemes and reduces total test time compared with slow mechanical relays.<\/p>\n

      Moreover, you can exploit the small form factor to increase channel density: SMT PhotoMOS packages let you pack dozens of channels on a single PXI card while maintaining high isolation (typical device isolation ratings 1.5 kVrms to 3.75 kVrms). For sensitive mixed\u2011signal racks you’ll find the absence of contact bounce and lower electromagnetic disturbance beneficial for repeatability and signal integrity, especially when you combine PhotoMOS relays with proper grounding and guarding strategies.<\/p>\n

      Disadvantages<\/h3>\n

      You must account for the limitations on current and power dissipation<\/strong>: many signal PhotoMOS parts are rated for tens to a few hundred milliamps, and even \u201cpower\u201d PhotoMOS types top out around 1-2 A continuous. That means you’ll need to choose parts carefully or parallel devices for higher currents, which adds cost and layout complexity. Also expect significant on\u2011resistance<\/strong> variation across families – tens of milliohms to several ohms – which can introduce measurable voltage drop and heating in power switching scenarios.<\/p>\n

      High\u2011impedance measurement applications are the other major tradeoff. Leakage current that’s negligible for low\u2011impedance signals can dominate when you’re measuring G\u03a9\u2011class sensors: for instance, 1 pA of leakage<\/strong> into a 10 G\u03a9 sensor produces a 10 mV error – enough to skew low\u2011level readings. Leakage typically increases with temperature (tens of pA to nA at elevated temps), so thermal design and part selection are important to preserve measurement accuracy.<\/p>\n

      To mitigate these downsides you’ll often pair PhotoMOS relays with system measures: choose ultra\u2011low leakage<\/strong> variants for high\u2011impedance inputs, add series resistors or parallel FETs to manage R_on and current, include snubbers\/TVS for inductive loads, and place thermal derating margins into your design. In practice, testing boards that switched both power and millivolt level signals used a mix of PhotoMOS for low\u2011power, high\u2011density channels and mechanical relays for high\u2011current routes – a hybrid approach that leverages the strengths while limiting the weaknesses.<\/p>\n

      Tips for Integrating PhotoMOS relays<\/strong> in automated test<\/strong> and measurement systems<\/strong><\/h2>\n

      You should size PhotoMOS relays<\/strong> to the actual load and measurement topology: choose parts with on-resistance and leakage specs that match the impedance of the circuit (many devices show off\u2011state leakage<\/strong> in the microamp to tens of microamps range, which can produce volt-level errors across megaohm inputs). Plan for switching times – typically sub\u2011millisecond to a few milliseconds – when sequencing measurements so you avoid settling errors in timing\u2011sensitive test sequences. Pay attention to the relay’s isolation rating (often specified in kilovolts for many models) when routing high-voltage channels in mixed-signal racks.<\/p>\n

      Use PCB layout and thermal design as part of the selection process: keep high-current traces short, add thermal vias or copper pours when switching continuous currents above a few hundred milliamps, and verify worst\u2011case heating at the highest ambient temperature you expect. In automated racks you frequently switch multiple channels; balancing channel duty cycles and derating to ~70% of the relay’s continuous current rating reduces RON<\/sub> rise and extends lifetime. Below are targeted implementation items to apply immediately:<\/p>\n

        \n
      • Match on-resistance<\/strong> and leakage current<\/strong> to sensor impedance; simulate a 1 M\u03a9 input with 1 \u03bcA leakage \u2192 1 V error.<\/li>\n
      • Use snubbers or TVS diodes for inductive loads and place them close to the relay pins to limit voltage stress.<\/li>\n
      • Drive the LED at the datasheet recommended current (often in the 1-20 mA range) and verify LED drive circuits over temperature.<\/li>\n
      • Derate continuous current to ~70% and provide copper heat spreaders for >200-300 mA continuous switching.<\/li>\n<\/ul>\n

        Best Practices<\/h3>\n

        You should validate off\u2011state leakage<\/strong> and RON<\/sub> across the full ambient and operating voltage range of your system: measure leakage at maximum test voltage and at highest expected temperature because leakage can double or triple with temperature, which will affect high\u2011impedance measurements. When implementing multiplexed inputs, add guard traces and low\u2011value bleed resistors where appropriate to discharge stray capacitance and avoid floating nodes between switching events.<\/p>\n

        Drive circuitry must be consistent: design the LED driver with tight timing and current control so channel-to-channel switching is repeatable – for example, use matched resistor networks or constant-current drivers if you need <\u00b11% timing repeatability across 32 channels. Also, log in\u2011system electrical performance (RON<\/sub>, leakage) during qualification so you catch batch variance or aging; a single case study showed one ATE vendor reduced false failures by 60% after adding periodic RON<\/sub> checks.<\/p>\n

        Common Pitfalls to Avoid<\/h3>\n

        You often encounter measurement errors because you relied on typical rather than worst-case datasheet numbers: a typical leakage spec may look benign, but the maximum leakage at 85 \u00b0C can swamp microamp-level sensors. Avoid driving relays near absolute maximum ratings; continuous currents close to the limit will increase junction temperature, raise RON<\/sub>, and slowly shift calibration. In mid-range automated test racks, thermal interaction between channels can raise board temperature by 10-20 \u00b0C, so design for that delta.<\/p>\n

        Another frequent mistake is neglecting switching transients and EMI: if you switch capacitive DUTs without series resistance or soft-start control, you get inrush currents that can stress the relay and measurement front end. You should include series limits or RC damping when switching cables or large filter capacitors to protect both the PhotoMOS<\/strong> device and the instrument input stage.<\/p>\n

        Further detail: in one example a manufacturer switched 100 V loads across a bank of PhotoMOS relays<\/strong> and saw RON<\/sub> increase by ~30% after prolonged operation at 80% rated current; implementing a 70% derating rule plus a 1.2 mm copper pour under the relay pads reduced the temperature rise by ~12 \u00b0C and stabilized readings. Assume that you verify worst\u2011case leakage current<\/strong>, RON<\/sub>, and thermal performance under the actual environmental and duty\u2011cycle conditions before deploying the design.<\/p>\n

        Step-by-Step Guide to Implementing PhotoMOS Relays<\/h2>\n\n\n\n\n\n\n\n\n
        Step<\/strong><\/th>\nAction \/ Notes<\/strong><\/th>\n<\/tr>\n
        Define requirements<\/strong><\/td>\nList voltages, currents, signal types (AC\/DC), measurement resolution, and switching frequency; include expected worst-case volt-seconds and continuous duty.<\/td>\n<\/tr>\n
        Select device<\/strong><\/td>\nMatch VDRM\/IDRM<\/strong>, R_ON range (typ. 0.1 \u03a9-30 \u03a9<\/strong> depending on type), leakage (nA-\u00b5A), and switching time (\u224810 \u00b5s-3 ms<\/strong>).<\/td>\n<\/tr>\n
        Drive circuit<\/strong><\/td>\nDesign LED drive with appropriate current (typically 2-10 mA<\/strong>); include PWM filtering or constant-current drivers for repeatability.<\/td>\n<\/tr>\n
        PCB\/layout<\/strong><\/td>\nKeep isolation creepage\/clearance per required CAT rating; place thermal vias for power dissipation and separate analog return planes.<\/td>\n<\/tr>\n
        Safety & isolation<\/strong><\/td>\nVerify isolation rating (often 1.5-5 kVrms<\/strong> for PhotoMOS types); add surge protection for inductive loads and TVS diodes if required.<\/td>\n<\/tr>\n
        Verification<\/strong><\/td>\nPlan bench tests: measure R_ON under expected currents, measure leakage with applied voltage, and verify timing and long\u2011term endurance.<\/td>\n<\/tr>\n<\/table>\n

        Planning the Integration<\/h3>\n

        Start by mapping each relay location to the specific measurement function: if you’re multiplexing low-level resistance measurements, plan for low R_ON<\/strong> variants and place relays close to the DUT to minimize parasitic resistance and noise pickup. Quantify the worst-case signal – for example, a 1 k\u03a9 resistor measured at 1 mA produces 1 V; if the relay R_ON is 10 \u03a9 that introduces a 10 mV systematic error, so you may need a R_ON \u2264 1 \u03a9<\/strong> part or a Kelvin\u2011sense topology.<\/p>\n

        Next, create a drive and timing matrix: decide which relays can be active simultaneously, the required switching cadence (continuous switching at >1 kHz demands checking thermal limits), and LED drive currents (set between 2-10 mA<\/strong> per device for repeatable on\u2011resistance). Also allocate isolation margins – target at least a 20-30% safety margin above the highest expected transient, and specify any required surge or ESD protection on relay outputs.<\/p>\n

        Testing and Validation<\/h3>\n

        Begin validation with static measurements: measure R_ON at the same current and temperature the system will see, and verify off\u2011state leakage at the highest applied voltage your system will present. Use a source-measure unit (SMU) to sweep voltage while logging leakage; many PhotoMOS types show leakage from nA to low \u00b5A<\/strong>, which can impact picoamp or high\u2011resistance tests.<\/p>\n

        Proceed to dynamic tests: capture turn\u2011on and turn\u2011off timing with a scope while driving the LED at intended current, and run a thermal soak test where relays switch at expected duty cycles for several hours while monitoring R_ON drift. For safety verification, perform dielectric withstand testing up to the relay’s rated isolation (commonly between 1.5 kVrms and 5 kVrms<\/strong>) and check for insulation degradation or unexpected leakage after stress.<\/p>\n

        Finally, perform system\u2011level validation: run full test sequences with representative DUTs, include worst-case combinations (multiple relays closed, maximum supply transients), and log measurement repeatability over thousands to millions of cycles as appropriate – many PhotoMOS devices are specified for >10^8 switching cycles, but verify in your thermal and electrical environment to detect any early failures.<\/p>\n

        Maintenance and Troubleshooting<\/h2>\n

        Regular Maintenance Tips<\/h3>\n

        Start by establishing a baseline for each PhotoMOS<\/strong> relay’s electrical parameters during commissioning – log off\u2011state leakage<\/strong>, on\u2011resistance<\/strong> (RON), and the drive LED current. You should schedule visual inspections and thermal checks every 3-6 months in high\u2011duty racks or every 6-12 months in low\u2011duty bench systems. When you calculate expected junction temperature, include P = I\u00b2RON plus ambient and board thermal resistance so you avoid thermal stress<\/strong> that shortens lifetime.<\/p>\n

          \n
        • Measure leakage current<\/strong> with a low\u2011noise source and a guarded meter; flag values that drift by more than 30% from baseline.<\/li>\n
        • Record on\u2011resistance<\/strong> at a fixed current (for example, 100 mA) and compare to initial measurement.<\/li>\n
        • Inspect solder joints and conformal coating for cracks that reduce isolation voltage<\/strong> or introduce moisture paths.<\/li>\n
        • Verify drive LED current and gate wiring to prevent overdrive<\/strong> or undercurrent<\/strong> which can change switching behavior.<\/li>\n<\/ul>\n

          Assume that you schedule a full inspection every 12 months and log leakage current<\/strong>, on\u2011resistance<\/strong>, and isolation voltage<\/strong> metrics for trend analysis so you can predict failures before they affect measurement accuracy.<\/p>\n

          Troubleshooting Common Issues<\/h3>\n

          If you encounter unexpected measurement offsets or channels that won’t fully open, check the off\u2011state leakage<\/strong> first: in precision low\u2011voltage systems, a few microamps of leakage can shift readings by tens of millivolts. Use an isolated source and a microamp meter to confirm; for example, a 5 \u00b5A leakage at 10 V looks like a 2 M\u03a9 path and will distort high\u2011impedance inputs. Next, verify drive conditions – many failures trace back to incorrect LED current or degraded drive transistors that produce slow edges or incomplete turn\u2011on.<\/p>\n

          When switching speed or repeatability is the problem, run a step test with an oscilloscope and a 10-90% timing check; compare to the datasheet rise\/fall times and to your baseline. If RON<\/strong> has increased by more than 50% from baseline or you detect persistent thermal hotspots on the package during a 1\u2011hour stress run, replace the relay and review thermal management. Use an infrared camera for hotspots, and if you find board contamination or conformal coating breakdown, clean or recoat the PCB to restore isolation<\/strong> and prevent recurring leakage.<\/p>\n

          Summing up<\/h2>\n

          Following this, when you design or upgrade automated test and measurement systems, PhotoMOS relays give you contactless, repeatable switching with fast response and long life that support high-density multiplexing and low-noise signal routing. Choose devices by on-resistance, off-state leakage, isolation voltage, and switching speed to match your measurement ranges and source impedances, and account for package thermal limits and output capacitance in your PCB layout and drive circuitry.<\/p>\n

          Validate parts in the actual bandwidth and environmental conditions you will use, apply guard traces, shielding and series resistances where leakage or dv\/dt might degrade readings, and include calibration or compensation in your firmware to correct offsets and drift. With correct selection and system-level mitigations, you can leverage PhotoMOS relays to increase test throughput, improve reliability, and preserve measurement integrity over long deployment periods.<\/p>\n","protected":false},"excerpt":{"rendered":"

          There’s a growing role for PhotoMOS relays in automated test and measurement where galvanic isolation and ultra-low leakage let you measure small signals without contamination; you can exploit their fast switching and long life to increase throughput while reducing maintenance, but you must mitigate overvoltage, thermal dissipation, and potential failure modes through proper selection, layout, […]<\/p>\n","protected":false},"author":1,"featured_media":303,"comment_status":"","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[25,24,12],"class_list":["post-304","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-technologies","tag-automation","tag-photomos","tag-relays"],"yoast_head":"\nPhotoMOS Relays in Automated Test and Measurement Systems - PIDTechInsights<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/pidtechinsights.com\/blog\/2026\/01\/photomos-relays-in-test-and-measurement\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"PhotoMOS Relays in Automated Test and Measurement Systems - 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