Metal-Oxide Varistors (MOVs) Surface Mount Varistors > SM20 Series SM20 Varistor Series RoHS Description The Littelfuse 20mm SMD Series is a surface-mount metal oxide varistor device, for use in applications requiring hi-energy / transient current capability. The AC rated parts are designed to operate continuously across AC power lines. The DC rated parts are suitable for Automotive applications. The series comprises a Nylon molded package with folded tin plated metal leads for soldering to board. The SMD Series is based on radial 20mm internal varistor element with similar characteristics to the Littelfuse LA / ZA series of varistors. Agency Approvals Agency Agency Approval Agency File Number UL1449 E320116 Additional Information Datasheet Resources Samples Features • DC Voltage Rating 26 - 420VDC • AC Voltage Rating 20Vac - 320AC • Low voltage devices specified for automotive load dump energy • No De-Rating up to 85°C ambient • Available in "waffle" tray packaging • Lead-Free, HalogenFree and RoHS Compliant Absolute Maximum Ratings • For ratings of individual members of a series, see Device Ratings and Specifications chart Continuous SM20 Series Units AC Voltage Range (VM(AC)RMS) 20 to 320 V DC Voltage Range (VM(DC)) 26 to 420 V Steady State Applied Voltage: Transients: up to 6500 A Single Pulse Energy Capability (WTM) 10/1000µs Current Wave Peak Pulse Current (ITM) 8/20µs Current Wave, Single Pulse 165 J Load Dump Energy Capability (td>=30ms) 160 J Operating Ambient Temperature Range (TA) -40 to +85 O Storage Temperature Range (TSTG) -55 to +125 O C C Temperature Coefficient (aV) of Clamping Voltage (VC) at Specified Test Current <0.01 %/OC Hi-Pot Encapsulation (COATING Isolation Voltage Capability) (Dielectric must withstand indicated DC voltage for one minute per MIL-STD 202, Method 301) 2500 V COATING Insulation Resistance 1000 MΩ CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. © 2015 Littelfuse, Inc. Specifications are subject to change without notice. Revised: 06/07/15 Metal-Oxide Varistors (MOVs) Surface Mount Varistors > SM20 Series SM20 Series Ratings & Specifications Maximum Rating (85°C) Continuous Transient VRMS VDC Part Number Branding VM(AC) VM(DC) (V) (V) V26SM20 26SM20 20 26 V175SM20 V230SM20 V250SM20 V275SM20 V300SM20 V320SM20 175SM20 230SM20 250SM20 275SM20 300SM20 320SM20 175 230 250 275 300 320 225 300 330 369 405 420 Energy Peak Current 10 x 1000µs 8 x 20µs WTM ITM 1x pulse 1x pulse (J) 20 160 (note 1) 90 122 130 140 165 150 (A) Specifications (25°C) Maximum Varistor Voltage Clamping at 1mA DC Voltage Test Current 8 x 20 µs VNOM Min VNOM Max (V) 32 (10mA) 247 324 354 389 420 462 2000 6500 6500 6500 6500 6500 6500 (V) 40 (10mA) 303 396 429 473 517 540 Typical Capacitance f = 1MHz VC IPK C (V) (A) (pF) 63 20 12000 455 595 650 710 775 810 100 100 100 100 100 100 1400 1100 1000 900 800 750 1. Energy rating for impulse duration of 30ms minimum to one half of peak current (automotive load dump). Peak Current, Energy and Power Derating Curve For applications exceeding 85ºC ambient temperature, the peak surge current and energy ratings must be reduced as shown below Repetitive Surge Capability V175SM20 - V320SM20 10,000 1 5,000 90 SURGE CURRENT (A) PERCENT OF RATED VALUE 10 2,000 100 80 70 60 50 40 30 1,000 500 MODEL SIZE 20mm V175SM20 - V320SM20 10 2 3 10 10 4 10 5 10 6 200 100 50 20 INDEFINITE 10 5 20 2 10 0 -55 2 1 50 60 70 80 90 100 110 120 130 140 150 AMBIENT TEMPERATURE ( oC) 20 100 1,000 IMPULSE DURATION (µs) 10,000 FIGURE 1. CURRENT, ENERGY AND POWER DERATING PERCENT OF PEAK VALUE Test CURVE Test Waveform for Clamping Voltage Peak Pulse Current O1 01 = Virtual Origin of Wave T = Time from 10% to 90% of Peak T1 = Rise Time = 1.25 x T T2 = Decay Time Example - For an 8/20 µs Current Waveform: 8µs = T1 = Rise Time 20µs = T2 = Decay Time 100 50 0 t TIM E t1 t2 © 2015 Littelfuse, Inc. Specifications are subject to change without notice. Revised: 06/07/15 Metal-Oxide Varistors (MOVs) Surface Mount Varistors > SM20 Series Lead (Pb) Soldering Recommendations Wave soldering is the most strenuous of the processes. To avoid the possibility of generating stresses due to thermal shock, a preheat stage in the soldering process is recommended, and the peak temperature of the solder process should be rigidly controlled. When using a reflow process, care should be taken to ensure that the SM20 chip is not subjected to a thermal gradient steeper than 4 degrees per second; the ideal gradient being 2 degrees per second. During the soldering process, preheating to within 100 degrees of the solder's peak temperature is essential to minimize thermal shock. Once the soldering process has been completed, it is still necessary to ensure that any further thermal shocks are avoided. One possible cause of thermal shock is hot printed circuit boards being removed from the solder process and subjected to cleaning solvents at room temperature. The boards must be allowed to cool gradually to less than 50ºC before cleaning. 250 MAXIMUM TEMPERATURE 230°C 200 250 TEMPERATURE °C TEMPERATURE °C The terminals of SM20 series devices are tin plated copper, and the recommended solder is 62/36/2 (Sn/Pb/Ag), 60/40 (Sn/Pb) or 63/37 (Sn/Pb). Littelfuse also recommends an RMA solder flux. Reflow Solder Profile 40-80 MAXIMUM TEMPERATURE SECONDS 230°C ABOVE 183°C 150 200 RAMP RATE40-80 <2°C/s SECONDS ABOVE 183°C 100 150 PREHEAT DWELL RAMP RATE <2°C/s PREHEAT ZONE PREHEAT DWELL 50 100 0 50 0 0 0.5 PREHEAT ZONE 1.0 1.5 2.0 2.5 3.0 3.5 4.0 3.5 4.0 TIME (MINUTES) 0 0.5 1.0 1.5 2.0 2.5PROFILE 3.0 SOLDER FIGURE 14. REFLOW Wave Solder Profile TIME (MINUTES) FIGURE 14. REFLOW SOLDER PROFILE 300 MAXIMUM WAVE 260°C 250 300 TEMPERATURE °C TEMPERATURE °C The principal techniques used for the soldering of components in surface mount technology are IR Re-flow and Wave soldering. Typical profiles are shown on the right. MAXIMUM WAVE 260°C 200 250 150 200 SECOND PREHEAT 100 150 SECOND PREHEAT FIRST PREHEAT 50 100 0 500.0 0 0.0 Lead–free (Pb-free) Soldering Recommendations 0.5 1.0 FIRST PREHEAT 2.0 2.5 3.0 1.5 TIME (MINUTES) 3.5 4.0 4.5 0.5 1.0 15.1.5 2.5 PROFILE 3.0 3.5 FIGURE WAVE2.0SOLDER TIME (MINUTES) 4.0 4.5 FIGURE 15. WAVE SOLDER PROFILE The reflow profile must be constrained by the maximums in the Lead–free Reflow Profile. For Lead–free Wave soldering, the Wave Solder Profile still applies. Note: the Lead–free paste, flux and profile were used for evaluation purposes by Littelfuse, based upon industry standards and practices. There are multiple choices of all three available, it is advised that the customer explores the optimum combination for their process as processes vary considerably from site to site. Lead–free Re-flow Solder Profile 300 MAXIMUM TEMPERATURE 250˚C, TIME WITHIN 5˚C OF PEAK 20 SECONDS MAXIMUM 250 300 TEMPERATURE °C TEMPERATURE °C The terminals of SM20 series devices are tin plated copper, and the recommended Lead-free solder is 96.5/3.0/0.5 (SnAgCu) with an RMA flux, though there is a wide selection of pastes and fluxes available that should be compatible. MAXIMUM TEMPERATURE 250˚C, RAMP RATE TIME WITHIN 5˚C OF PEAK <3˚C/s 20 SECONDS MAXIMUM 200 250 RAMP RATE <3˚C/s 150 200 100 150 60 - 150 SEC > 217˚C 60 - 150 SEC > 217˚C PREHEAT ZONE 50 100 PREHEAT ZONE 0 50 0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 TIME (MINUTES) 0 SOLDER PROFILE 0 FIGURE 1.0 16. LEAD-FREE 2.0 3.0 RE-FLOW 4.0 5.0 6.0 7.0 TIME (MINUTES) FIGURE 16. LEAD-FREE RE-FLOW SOLDER PROFILE © 2015 Littelfuse, Inc. Specifications are subject to change without notice. Revised: 06/07/15 Metal-Oxide Varistors (MOVs) Surface Mount Varistors > SM20 Series Physical Specifications Environmental Specifications Lead Material Folded Tin Plated Metal Leads Operating Ambient Temperature Range (TA) -40°C to +85°C Soldering Characteristics J-STD-002 Storage Temperature Range(TSTG) -55°C to 125°C Coating Molded Plastic Meets UL94 V-0 Requirement Solvent Resistance MIL STD 202, Method 215 Moisture Sensitivity Level 1, J-STD-020C Product Dimensions Packaging D Symbol Min Max --- 26 H1 --- 10.5 H2 1.0 -- t 0.50 0.70 S1 32.5 35 S2 3.0 4.5 W 6.2 6.6 D W Millimeters (diameter) H1 H2 S1 t S2 Standard Packaging is in "Waffle" trays: Quantity per tray: 36 pieces Quantity per box: 108 pieces 192 mm 30 mm typical 8.4 mm typical 6 11.7 mm pocket depth 30 mm typical 8 38 192 mm Soldering Pad Layout Radius 30 mm typical Part Numbering System V 275 SM20 For “VARISTOR” Max Voltage Rating (Two or three digits -- refer to ratings and specifications table) SM20 SERIES M(AC) © 2015 Littelfuse, Inc. Specifications are subject to change without notice. Revised: 06/07/15