Varistor Products High Energy Industrial Square Disc NA Varistor Series The NA Series of transient surge suppressors are varistors (MOVs) in square disc form, intended for special industrial high-energy applications requiring unique electrical contact or packaging methods provided by the customer. The electrode finish of these devices is solderable and can also be used with pressure contacts. Discs may also be stacked. The NA Series varistor is a square 34mm device, with thicknesses ranging from 1.7mm minimum for the 250V device to 7.5mm maximum for the 750V device. For information on mounting considerations refer to Application Note AN8820. This disc is also available with encapsulation and PCB leads. See Littelfuse HB34 Sales. Features • Provided in Disc Form for Unique Packaging by Customer • Solderable Electrode Finish. • Pressure Contacts and/or Disc Stacking may be Utilized • Wide Operating Voltage Range VM(AC)RMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .250V to 750V • Peak Pulse Current Capability (ITM). . . . . . . . . . . . . . . . . . . .40,000A • High Energy Capability (WTM). . . . . . . . . . . . . . . . . . . .370J to 1050J • No Derating Up to 8oC Ambient ALSO SEE HB34 SERIES 122 w w w. l i t t e l f u s e . c o m Varistor Products High Energy Industrial Square Disc NA Varistor Series For ratings of individual members of a series, see Device Ratings and Specifications chart NA SERIES Continuous: Steady State Applied Voltage: AC Voltage Range (VM(AC)RMS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250 to 750 DC Voltage Range (VM(DC)) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 330 to 970 Transient: Peak Pulse Current (ITM) For 8/20µs Current Wave (See Figure 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40,000 Single Pulse Energy Range For 2ms Current Square Wave (WTM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 370 to1050 Operating Ambient Temperature Range (TA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -55 to 85 Storage Temperature Range (TSTG) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -55 to 125 Temperature Coefficient (αV) of Clamping Voltage (VC) at Specified Test Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . <0.01 UNITS V V A J C O C %/OC O 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. Device Ratings and Specifications MAXIMUM RATINGS (85 oC) CONTINUOUS SPECIFICATIONS (25 oC) TRANSIENT PEAK CURRENT (8/20µs) VARISTOR VOLTAGE AT 1mA DC TEST CURRENT MAXIMUM CLAMPING VOLTAGE (VC) AT 200A (8/20µs) TYPICAL CAPACITANCE VRMS VDC ENERGY (2ms) SIZE VM(AC) VM(DC) WTM ITM MIN VN(DC) MAX VC f = 1MHz (mm) (V) (V) (J) (A) (V) (V) (V) (V) (pF) V131NA34 34 130 175 270 40,0001 184 200 228 345 10,000 V141NA34 34 140 188 291 40,0003 198 220 248 375 9,000 V151NA34 34 150 200 300 40,000 2 212 240 268 405 8,000 V251NA34 34 250 330 370 40,000 354 390 429 650 5,000 V271NA34 34 275 369 400 40,000 389 430 473 730 4,500 V321NA34 34 320 420 460 40,000 462 510 561 830 3,800 V421NA34 34 420 560 600 40,000 610 680 748 1,130 3,000 V481NA34 34 480 640 650 40,000 670 750 825 1,240 2,700 V511NA34 34 510 675 700 40,000 735 820 910 1,350 2,500 V571NA34 34 575 730 770 40,000 805 910 1000 1,480 2,200 V661NA34 34 660 850 900 40,000 940 1050 1160 1,720 2,000 V751NA34 34 750 970 1050 40,000 1080 1200 1320 2,000 1,800 MODEL NUMBER NOTE: Average power dissipation of transients not to exceed 2.0W. 1. Peak current applies to applications rated up to 115VRMS . Peak current is 30kA for applications greater than 115VRMS . 2. Peak current applies to applications rated up to 132VRMS . Peak current is 30kA for applications greater than 132VRMS . 3. Peak current applies to applications rated up to 123VRMS . Peak current is 30kA for applications greater than 123VRMS . w w w. l i t t e l f u s e . c o m 123 2 VARISTOR PRODUCTS Absolute Maximum Ratings Varistor Products High Energy Industrial Square Disc NA Varistor Series Power Dissipation Ratings 100 90 PERCENT OF RATED VALUE Should transients occur in rapid succession, the average power dissipation required is simply the energy (watt-seconds) per pulse times the number of pulses per second. The power so developed must be within the specifications shown on the Device Ratings and Specifications table for the specific device. The operating values must be derated as shown in Figure 1. 80 70 60 50 40 30 20 10 0 -55 50 60 70 80 90 100 110 120 130 140 150 PERCENT OF PEAK VALUE AMBIENT TEMPERATURE ( oC) FIGURE 1. CURRENT, ENERGY AND POWER DERATING CURVE 100 O1 = Virtual Origin of Wave T = Time From 10% to 90% of Peak T1 = Virtual Front time = 1.25 • t T2 = Virtual Time to Half Value (Impulse Duration) Example: For an 8/20µs Current Waveform: 8µs = T1 = Virtual Front Time 20µs = T2 = Virtual Time to Half Value 90 50 10 O1 T TIME T1 T2 FIGURE 2. PEAK PULSE CURRENT TEST WAVEFORM Transient V-I Characteristics Curves 10000 MAXIMUM CLAMPING VOLTAGE VARISTOR SIZE 34mm 130 TO 750 VM(AC) RATING TA = -55oC TO 85oC V751NA34 V511NA34 V661NA34 V481NA34 V571NA34 VOLTAGE (V) V421NA34 1000 V321NA34 V271NA34 V131NA34 V251NA34 V151NA34 100 -5 -4 1E-3 0.01 0.1 1 10 100 CURRENT (A) FIGURE 3. CLAMPING VOLTAGE FOR V131NA34 - V751NA34 124 w w w. l i t t e l f u s e . c o m 1,000 10,000 100,000 Varistor Products High Energy Industrial Square Disc NA Varistor Series Pulse Rating Curves 50,000 DISC SIZE 34mm V131NA34 - V751NA34 1 SURGE CURRENT (A) 10,000 5,000 2,000 1,000 2 10 102 105 103 2 106 VARISTOR PRODUCTS 20,000 104 500 200 100 50 20 10 INDEFINITE 20 100 1,000 10,000 IMPULSE DURATION ( µs) FIGURE 4. SURGE CURRENT RATING CURVES FOR V131NA34 - V751NA34 NOTE:If pulse ratings are exceeded, a shift of VN(DC) (at specified current) of more than ±10% could result. This type of shift, which normally results in a decrease of VN(DC), may result in the device not meeting the original published specifications, but it does not prevent the device from continuing to function, and to provide ample protection. NA SERIES VARISTOR THICKNESS Mechanical Dimensions MILLIMETERS (MILLIMETERS) INCHES MODEL NUMBER MIN MAX MIN MAX V131NA34 1.40 2.30 0.055 0.090 V141NA34 1.45 2.55 0.057 0.100 V151NA34 1.50 2.80 0.059 0.011 V251NA34 1.70 2.30 0.066 0.090 V271NA34 1.80 2.70 0.070 0.106 V321NA34 2.10 3.00 0.082 0.118 V421NA34 3.00 4.00 0.118 0.157 V481NA34 3.20 4.40 0.125 0.173 V511NA34 3.60 4.90 0.141 0.192 V571NA34 4.00 5.60 0.118 0.220 V661NA34 4.50 6.80 0.176 0.267 V751NA34 5.20 7.50 0.204 0.294 NOTE: Parts available encapsulated with soldered tabs, to standard design or customer specific requirements. Also see HB34 Series. w w w. l i t t e l f u s e . c o m 125 Varistor Products High Energy Industrial Square Disc NA Varistor Series Passivation Layer 250 The standard NA Series is supplied with passivation layer around the outside perimeter of the disc forming an electrical insulator as detailed in the dimensional drawing. Encapsulated Recommendations After lead attachment, the disc/lead assembly may be coated or encapsulated in a package to provide electrical insulation and isolation from environmental contamination as required by the application. Coating/Filler materials for containers may include silicones, polyurethanes, and some epoxy resins. Two examples of acceptable polyurethanes are Dexter Hysol (US7013, parts A and B) and Rhenatech (resin 4714, hardener 4900), or their equivalents. Materials containing halogens, sulfides, or alkalines are not recommended. TEMPERATURE ( oC) 200 150 100 50 0 0 100 200 Electrode Metallization 300 400 500 600 700 800 900 TIME (SEC) The NA Series is supplied with a sintered silver metallization for the electrode finish. The silver metallization is typically used for solder reflow lead attach operations (I-R, Vapour-Phase). The recommended temperature profile of a belt-fed convection oven is shown in Figure 6. FIGURE 6. TYPICAL BELT OVEN TEMPERATURE PROFILE Stacking and Contact Pressure Recommendations When applications require the stacking of Littelfuse NA discs or when electrical connection is made by pressure contacts, the minimum pressure applied to the disc electrode surface should be 2.2kGs (5 pounds). The maximum recommended pressure applied to the disc electrode is 16N/CM2 (23LBs/IN2). Packaging and Shipping The NA Series is supplied in bulk for shipment. Discs are packaged in compartmentalized cartons to protect from scratching or edge-chipping during shipment. Ordering Information V 25 1 NA 34 VARISTOR DESIGNATOR DISC SIZE (mm) MAX AC RMS WORKING VOLTAGE (FIRST SIGNIFICANT DIGITS) V M(AC) SERIES DESIGNATOR VM(AC) VOLTAGE DECADE MULTIPLIER 126 w w w. l i t t e l f u s e . c o m