Mlv Design Guide Page 15 MLV Selection Steps

EXAMPLE 2 (LOAD DUMP PROTECTION) Circuit conditions and requirements: 12VDC Current waveform for surge is Load Dump (time of emery input 40ms, interval 60 seconds) Load Dump Energy 10J for 10 pulses Other components (Most vulnerable device to be protected, such as an IC rated at 150V, typically rated with 8x20s waveform) Approach to Finding Solution Compare Requirement to V18AUMLA2220 Step 1: To find the voltage rating of the MLV, allow for 20% head room take into account voltage variations (12VDC x 1.2 + 14.4VDC; So look at 18VDC rated MLVs) (Refer to the summary in Table 15) Voltage rating of 18VDC Step 2: Determine which MLV size to use (Identify those that minimally meet the 10J (10 Pulses) surge requirement) (Refer to the summary in Table 16) Device size of 2220 (5.6 x 5.0mm) can meet 10 times Load Dump pulses (10J for each pulse) Step 3: Use V-I Curve of selected MLV to verify that he peak voltage will be below 50V ceiling (Refer to the summary in Figure 16) Peak voltage of 50V Part Number Maximum Ratings (125 C ) Specifications (25 C ) Maximum Continuous DC Voltage Jump Start Voltage (5 Min) Load Dump Energy (10 Pulses) Nominal Varistor Voltage at 10mA DC Test Current Maximum Standby Leakage (at 13V DC) Maximum Clamping Voltage (V C ) at Test Current (8/20 s) V M(DC) V JUMP W LD V N(DC) Min V N(DC) Max I L V C I P (V) (J) (V) ( A) (V) (A) V18AUMLA1206 18 24.5 1.5 23 32 50 40 1.5 V18AUMLA1210 18 24.5 3.0 23 32 50 40 1.5 V18AUMLA1812 18 24.5 6.0 23 32 100 40 5.0 V18AUMLA2220 18 24.5 25 23 32 200 40 10.0 V24AUMLA2220 24 24.5 25 32 39 200 60 10.0 V48AUMLA2220 48 24.5 25 54.5 66.5 200 105 10.0 Part Number Maximum Ratings (125 C ) Specifications (25 C ) Maximum Continuous DC Voltage Jump Start Voltage (5 Min) Load Dump Energy (10 Pulses) Nominal Varistor Voltage at 10mA DC Test Current Maximum Standby Leakage (at 13V DC) Maximum Clamping Voltage (V C ) at Test Current (8/20 s) V M(DC) V JUMP W LD V N(DC) Min V N(DC) Max I L V C I P (V) (J) (V) ( A) (V) (A) V18AUMLA1206 18 24.5 1.5 23 32 50 40 1.5 V18AUMLA1210 18 24.5 3.0 23 32 50 40 1.5 V18AUMLA1812 18 24.5 6.0 23 32 100 40 5.0 V18AUMLA2220 18 24.5 25 23 32 200 40 10.0 V24AUMLA2220 24 24.5 25 32 39 200 60 10.0 V48AUMLA2220 48 24.5 25 54.5 66.5 200 105 10.0 Step 1 - Determine the voltage rating of the MLV device Step 1 - Determine the size of the MLV device Table 15. Step 1 Illustration Table 16. Step 2 Illustration 2016 Littelfuse Multilayer Varistors (MLVs) Design Guide www.littelfuse.com Surface Mount Multilayer Varistors (MLVs) Design Guide MLV Selection - Examples (continued) 15

Previous Page
Next Page