the voltage variable material (vvm) based on surgx polymer technology has unique property that it is highly preferred in esd suppression application. the polymer matrix responds to an over-voltage condition by r apidly changing from a high impedance state to a low impedance state. cooper electronic technologies utilizes this polymeric matrix in the esd suppression device family for fast response, ultra low capacitance, and very low current leakage. the device is activated by ov er-voltage threat and clamps to a low value to protect sensitive circuit components. what is it: part pa ck ag e operating capacitance current clamp number size lines voltage (pf @ 1khz ~ leakage voltage specification (vdc) 1.8ghz) (na @ 12vdc) v 0603esda 0603 1 0 ~ 14 < 0.15 < 0.1 35 iec61000-4-2, level 4 0805ESDA 0805 1 0 ~ 12 < 0.25 < 0.1 35 iec61000-4-2, level 4 41206esda 1206 4 0 ~ 12 < 0.15 < 0.1 35 iec61000-4-2, level 4 esda series selection guide: esda series are board level circuit protection devices designed exclusively for the fast, transient over-volt- ages associated with esd. when a sufficient over- v oltage occurs it exhibits a dramatic increase in the ability to conduct electrons. the nature of the material creates a bi-directional part, which means that only one device is required to provide complete esd pro- tection regardless of the surge polarity. in a typical application, the device is placed across a signal line leading to an integrated circuit and ground. the device e xhibits minimal capacitance and is ?nvisible to the circuit during the normal operation. under normal operating voltages (typically 3 to 15v) the high imped- ance of the device insulates each signal line from gr ound. when an esd event occurs, the surgx material switches to a conductive state within nanoseconds. the voltage across signal line collaps- es to the clamping level, and current is shunted through the device to the ground. when the over-volt- age event ends, the circuit returns to its normal oper- ating state as the device switches back to its >10 12 ohm, high resistance state and ?nvisibility. how it works: features: ?the best esd protection for high frequency, low voltage applications. ?exceeds testing requirements outlined in iec 61000-4-2 ?extremely low capacitance ?very low leakage current ?fast response time ?bi-directional ?surface mount ?solder termination selection guide p olymer esd suppressors with surgx t echnology pa rt numbering note: spacing in part number is shown for clarity only. device part number contains no spaces (e.g. 0603esda-tr1) pa c kaging configuration pa c kaging options device characteristics a = standard 0603 surgx device designator esd -tr1 a -tr1 = standard, 5,000 pcs in tape-and-reel -sp1 = samples, 10 pcs on tape, in bag
selection guide p olymer esd suppressors with surgx t echnology surgx devices are marked on the tape and reel packages, not individually. since the product is bi-directional and symmetrical, no orientation marking is required. device marking full product characterization requires testing in a variety of scenarios. different test methods reveal unique informa- tion about the device response. evaluating the results for all of the tests is crucial to fully understand the surgx device response to an over-voltage event. t est methodology clamp voltage the voltage at which the surgx device stabilizes during the transition from high to low impedance. this is the voltage e xperienced by the circuit, after stabilizing, for the duration of the esd transient. t rigger voltage the voltage at which the surgx device begins to function. when the esd threat voltage reaches this level, the surgx device begins the transition from high impedance to low impedance, shunting the esd energy to ground. threat voltage the voltage that the test equipment is set to operate (i.e. the voltage across the discharge capacitor). p eak current the maximum instantaneous current level that a device will receive. iec-61000-4-2 states that the peak current should be 30a at 8kv esd and 45a at 15kv esd. definition of terms the esd pulse is the defining test for an esd protec- tive device. the esd pulse is an extremely fast rising transient event. the pulse, as characterized in iec 61000-4-2, has a rise time of less than 1ns, peak cur- rents up to 45a, and voltage levels to 15 kv. characteristics determined by this test are those such as voltage overshoot, peak voltage, clamping voltage, peak current, and device resistance. due to the extremely fast rate of rise of the esd pulse, the test setup can have a definite impact on the above f actors. variables such as wiring inductance and probe capacitance can produce inaccurate readings on an otherwise capable oscilloscope. (per iec 61000-4-2) 0 10 20 30 40 50 60 70 80 90 100 -10 0 10 20 30 40 50 60 70 80 90 time (ns) percent current electrostatic discharge (esd) pulse the transmission line pulse tester implements a con- trolled impedance cable to deliver a square wave current pulse. the advantage of this technique is that the con- stant current of the square wave allows the behavior of the protection structure to be more accurately studied. the actual implementation of this technique produces a wa ve fo rm that has a slightly slower rise time that the esd pulse but can be correlated to the deliver approxi- mately the same surge current and energy. this con- trolled impedance pulse provides a more accurate depic- tion of the trigger voltage of the device because of the reduced voltage overshoot caused by a fast rising tran- sient and the reactive components of the test fixture. -10 10 30 50 70 90 110 -10 40 90 140 190 time (ns) input voltag e output volt age activated percent voltage t ransmission line pulse (tlp)
selection guide p olymer esd suppressors with surgx t echnology figure 1. typical device response to 8kv esd 0 -0.1 -0.2 -0.3 -0.4 -0.5 -0.6 -0.7 -0.8 -0.9 -1 0 1 2 3 4 5 6 ghz drop in attenuation (db) figure 2. surgx ? induced interference with signal quality 0.10 0.11 0.12 0.13 0.14 0.15 0.16 0.17 0.18 0.19 0.20 0500 1 000 1500 2000 frequency (mhz) capacitance (pf) 0 puls e 1 00 pulse 2 00 pulse 3 00 puls e 4 00 pulse 5 00 pulse figure 6. capacita nce vs. frequency selected characterization data esd transient pulse energy controlled by surgx figure 1 shows typical surgx device response to an 8 kv contact esd pulse. triggered polymer in surgx conducts excess energy to ground and prevents system damage by esd transient threat. as the polymer resistance drops current flows to ground. the top scope trace indicates current, and the bottom scope trace indicates voltage. surgx protects from the esd voltage tr ansient without effecting signal quality the surgx esd over voltage protection devices have an ultra low capacitance of <0.25pf and when typically installed from the signal line to ground surgx has a negligible effect on the signal. as figure 2 shows, the test conducted with a precision network analyzer on a 50 ? circuit at up to 6ghz. only a 0.2db deviation from the original signal was recorded. the setup was similar to the addition of the surgx device to a circuit with very fast digital signal or a cellular phone antenna. signal frequency does not effect the capacitance of the device the device capacitance is very low and constant over wide frequency range. the typical capacitance is less than 0.15pf over the tested range of 0.1mhz to 1.8ghz. in addition, as shown in figure 6 , the capacitance will remain same over the life cycle of the device (i.e. the n umber of the esd pulse does not change the device capacitance.)
selection guide p olymer esd suppressors with surgx t echnology 0 10 20 30 40 50 60 70 0 100 200 300 400 500 600 esd clamping voltage (v) number of 8 kv esd pulses figure 4. esd clamping voltage vs. number of 8 kv esd pulse figure 3. average off state current leakage vs. temperature 24 vdc 12 vdc 6 vd c reference temperature 0 0.2 0.4 0.6 0.8 1 55 -30 -5 20 45 70 95 120 temperature (? ) - clamp voltage remains consistent through many esd pulses as figure 4 shows, the surgx device is highly reliable and stable through over hundreds of pulses. the surgx device has been tested with fast rate esd pulses at 8kv contact discharge. clamping v oltage measured at every pulse shows minimal changes throughout the test. t ypical non-triggered (off state) current leakage of surgx is very low at normal operating voltages and temperatures as shown by figure 3 the current leakage of surgx is typically very low, well under 1na, even over 12vdc operating voltage. some increase in the current leakage may be expected at much higher operating voltage and elevated temperature.
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