AN2266 datasheet(10/16 Pages) STMICROELECTRONICS

10 / 16 page

Long line protection

AN2266

10/16

DocID11830 Rev 2

Figure 13. LCP1521S behavior during 600 Vrms, 600 Ω, 0.2 s metallic (on TIP) power

induction test

Figure 13 shows the voltage across the TIP pin of LCP1521S and current through it when

subjected to a 600 Vrms, 600 Ω, 0.2 s ITU-T K20 power induction test, the gate voltage (-

Vbat) is also monitored. The voltage trip at the TIP pin is between +1 V and the battery

voltage (-48 V).

The LCP1521S and the PTC still continue to operate properly after the test in accordance

with the K20 A criterion.

Figure 14. LCP1521S behavior during 230 Vrms, 10 Ω, 15 min. metallic (on TIP) power

contact test

For power contact tests, except the one with 1000

Ω resistor, the PTC heats up and then its

resistor value increases drastically, which gives a very low gate current that becomes lower

than the gate triggering current of the LCP1521S: hence, from this moment, the LCP1521S

doesn't fire anymore, but it only clamps. Figure 14 shows the voltage across the TIP pin of

LCP1521S and current through it when subjected to a 230 Vrms, 10 Ω,15 min. ITU-T K20

power contact test, the gate voltage (-Vbat) is also monitored. The voltage trip at the TIP pin

is between +1 V and the battery voltage (-48 V).

The LCP1521S and the PTC still continue to operate properly after the test in accordance

with the K20 A criterion, while this test, with 10

Ω, requires only the K20 B criterion.

I surge: 0.5A

/div

V Tip: 20V/div

-Vbat: 20V/div

I surge: 5A /div

V Tip: 20V/div

-Vbat: 20V/div

AN2266 Datasheet(PDF) 10 Page - STMicroelectronics