V250SM20

Varistor Products Surface Mount Varistors > SM20 Series SM20 Varistor Series 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 File Number Features • • • • DC Voltage Rating 26VDC AC Voltage Rating 175 - 320AC No De-Rating up to 85°C ambient Lead-Free, HalogenFree and RoHS Compliant • • Low voltage devices specified for automotive load dump energy E320116 Absolute Maximum Ratings • For ratings of individual members of a series, see Device Ratings and Specifications chart Continuous Steady State Applied Voltage: AC Voltage Range (VM(AC)RMS) DC Voltage Range (VM(DC)) SM20 Series 20 to 320 26 up to 6500 165 160 -40 to +85 -55 to +125 =30ms) Operating Ambient Temperature Range (TA) Storage Temperature Range (TSTG) Temperature Coefficient (aV) of Clamping Voltage (VC) at Specified Test Current Hi-Pot Encapsulation (COATING Isolation Voltage Capability) (Dielectric must withstand indicated DC voltage for one minute per MIL-STD 202, Method 301) COATING Insulation Resistance C C %/OC V 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. ©2010 Littelfuse, Inc. Specifications are subject to change without notice. Please refer to www.littelfuse.com/series/sm20.html for current information. Revision: May 11, 2010 SM20 Series Varistor SM20 Series Available in "waffle" tray packaging Surface Mount Varistors > SM20 Series SM20 Series Ratings & Specifications Maximum Rating (85°C) Continuous Transient VRMS Part Number V26SM20 V175SM20 V230SM20 V250SM20 V275SM20 V300SM20 V320SM20 Branding 26SM20 175SM20 230SM20 250SM20 275SM20 300SM20 320SM20 VM(AC) (V) 20 175 230 250 275 300 320 VDC VM(DC) (V) 26 225 300 330 369 405 420 Energy Peak Current 10 x 1000μs 8 x 20μs WTM ITM 1x pulse 1x pulse Varistor Products 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 (V) 40 (10mA) 303 396 429 473 517 540 VC (V) 63 455 595 650 710 775 810 IPK (A) 20 100 100 100 100 100 100 Typical Capacitance f = 1MHz C (pF) 12000 1400 1100 1000 900 800 750 (J) 20 160 (note 1) 90 122 130 140 165 150 (A) 2000 6500 6500 6500 6500 6500 6500 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 5,000 2,000 SURGE CURRENT (A) 1,000 500 200 100 50 20 10 5 2 1 INDEFINITE 1 2 MODEL SIZE 20mm V175SM20 - V320SM20 10 2 3 10 10 4 10 5 10 6 10 100 PERCENT OF RATED VALUE 90 80 70 60 50 40 30 20 10 0 -55 50 60 70 80 90 100 110 120 130 140 150 20 100 AMBIENT TEMPERATURE ( oC) 1,000 IMPULSE DURATION (μs) 10,000 Peak Pulse Current Test Waveform for Clamping Voltage PERCENT OF PEAK VALUE Test 100 50 0 t1 t O1 TIM E t 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 SM20 Series Varistor Revision: May 11, 2010 ©2010 Littelfuse, Inc. Specifications are subject to change without notice. Please refer to www.littelfuse.com/series/sm20.html for current information. Varistor Products Surface Mount Varistors > SM20 Series Lead (Pb) Soldering Recommendations 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. 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. 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. Reflow Solder Profile 250 200 TEMPERATURE °C MAXIMUM TEMPERATURE 230°C 150 100 50 0 40-80 SECONDS ABOVE 183°C RAMP RATE SM20 Series Varistor Products Product Dimensions ' : Part Numbering System Millimeters Min ----1.0 0.50 32.5 3.0 6.2 Max 26 10.5 -0.70 35 4.5 6.6 For “VARISTOR” Max Voltage Rating (Two or three digits -- refer to ratings and specifications table) Symbol D (diameter) V 275 SM20 H1 H2 t + + 6    6ROGHULQJ 3DG /D\RXW 6 SM20 SERIES S1 W S2 W Packaging 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 11.7 mm pocket depth 30 mm typical 192 mm Radius 30 mm typical SM20 Series Varistor Revision: May 11, 2010 ©2010 Littelfuse, Inc. Specifications are subject to change without notice. Please refer to www.littelfuse.com/series/sm20.html for current information.